WO1987007937A1 - Procede et dispositif de sechage pulsatoire de materiaux granulaires presentant des pores capillaires, notamment du grain a l'aide d'un milieu seche au prealable - Google Patents

Procede et dispositif de sechage pulsatoire de materiaux granulaires presentant des pores capillaires, notamment du grain a l'aide d'un milieu seche au prealable Download PDF

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Publication number
WO1987007937A1
WO1987007937A1 PCT/HU1987/000025 HU8700025W WO8707937A1 WO 1987007937 A1 WO1987007937 A1 WO 1987007937A1 HU 8700025 W HU8700025 W HU 8700025W WO 8707937 A1 WO8707937 A1 WO 8707937A1
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WO
WIPO (PCT)
Prior art keywords
drying
grain
air
moisture
drier
Prior art date
Application number
PCT/HU1987/000025
Other languages
English (en)
Inventor
József ASZLA^´NYI
György BARTA
István BELLER
A^´rpád GALAMBOS
A^´rpád TO^´TH
Original Assignee
Mezo^"Gazdasa^´Gi Kombina^´T Aga^´Rd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Mezo^"Gazdasa^´Gi Kombina^´T Aga^´Rd filed Critical Mezo^"Gazdasa^´Gi Kombina^´T Aga^´Rd
Publication of WO1987007937A1 publication Critical patent/WO1987007937A1/fr

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26—DRYING
    • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B21/00—Arrangements or duct systems, e.g. in combination with pallet boxes, for supplying and controlling air or gases for drying solid materials or objects
    • F26B21/06—Controlling, e.g. regulating, parameters of gas supply
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26—DRYING
    • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B23/00—Heating arrangements
    • F26B23/02—Heating arrangements using combustion heating
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26—DRYING
    • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B3/00—Drying solid materials or objects by processes involving the application of heat
    • F26B3/02—Drying solid materials or objects by processes involving the application of heat by convection, i.e. heat being conveyed from a heat source to the materials or objects to be dried by a gas or vapour, e.g. air
    • F26B3/06—Drying solid materials or objects by processes involving the application of heat by convection, i.e. heat being conveyed from a heat source to the materials or objects to be dried by a gas or vapour, e.g. air the gas or vapour flowing through the materials or objects to be dried
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26—DRYING
    • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B9/00—Machines or apparatus for drying solid materials or objects at rest or with only local agitation; Domestic airing cupboards
    • F26B9/06—Machines or apparatus for drying solid materials or objects at rest or with only local agitation; Domestic airing cupboards in stationary drums or chambers
    • F26B9/063—Machines or apparatus for drying solid materials or objects at rest or with only local agitation; Domestic airing cupboards in stationary drums or chambers for drying granular material in bulk, e.g. grain bins or silos with false floor

Definitions

  • This invention relates to a process of drying granular materials with capillary pores, especially of grain crops, in the cours of which, in order to draw off the water, two individual, with each other in series operating drying steps are applied, wherefrom in the first step water contained in the surface and in the capillaries are drawn off, while in the second ones, drawing away of so called bounded moisture takes place.
  • the invention relates to the apparatus carrying this process into effect, consisting of a grain pre-dr'ier with continuousor in ⁇ termittent operation, and of a series of grain compartments to be aerated, receiving the pre-dried grain where it is dried to an end- -moisture content enabling long-lasti-ng storage.
  • Materials to be dried consist in practice mainly of agricultural grain crops, for the drying of which there are many kinds of processes and apparatus in wide use performing them. These are generally charac- terized by continuous or batch-type operation depending on the fact whether the grain stream is continous or batches are dryed in each cycle.
  • ambiant air is the drying medium, which after being warmed up is passed over the layer of grain in the apparatus at least once, sometimes twice but in rare cases several times.
  • interim heating is frequently required.
  • the aim is that moisture to be drawn off the grain should be drawn away with the least amount of drying medium and by spending possibly moderate quan ⁇ tities of fuel.
  • gryer-structures of above category are described in French Patents Nos 2300 981, 2284 845, 1477 608, 2402 170, 2444 907, 2463 373, in USA Patents Nos 1127974, 3129 073, 3406 463, 4004351, 4048 727, in British Patents Nos 376 871, ⁇ 1224 794, 1437 578, in German Patent No 481 282, and in the Hungarian Patent No 183 005.
  • Dryers are known, which are combined with ventilated storage connected in series on the grain-line, such as e.g. the dry-aeration process, but here 'moisture of the grain drawn off is almost at the rate enabling prolo keeping, aerated space is essentially a cooling zone set out of the dryer for long-lasting keeping of the grain, however, the already mentioned aer ⁇ storage spaces are also needed.
  • Object of this invention is to provide a drying process, whereby above ⁇ mentioned troubles and disadvantages are eliminated, i.e. exploitation of the dryers is substantially improved, further the storage bins can be fit with the equipment, enabling total after-drying which by itself renders long-lasting keeping of the grain possible without any demage, reducing at the same time total power consumption of drying below all known rates.
  • the process according to the invention can advantageously be applied with substantially all already existing dryers and the connected grain storage equipment, needed according to the invention, can be sited in each case.
  • This invention can, of course, be implemented also in case of newly con ⁇ structed grain storages as well, in particular advantageously combined with dryers in which capillary poral structure of the grain is subject, to no or only slight shrinkage.
  • Increase in drying capacity is further instrumental in using also the drying space formerly serving for cooling, for removing the surface mois ⁇ ture from the grain. Both effects jointly result in about doubling of the drying capacity, considering grain of average moisture. In case of any functioning or new dryer, doubling in exploitation by volume com- • pared to the previous can be attained,. Besides, heat consump.tion of any kind of dryer can be improved, whatever extent it had earlier, be ⁇ cause drawing off surface moisture is always feasible with lower heat ' consumption than former simultaneous removal of surface- and bounded moisture had required.
  • the invention is based further also on the recognition that in case of any drying process and anysort of grain, especially in case of those where surface and the capillary poral structure near to the surface of the grain does not shrink, feeding of heat energy into drying medium required to draw off bounded moisture, can, also by maintaining conti ⁇ nuity of drying, be intermittent.
  • a further recognition is related to aforementioned, i.e. that there is an unambiguous correlation to be drawn up also mathematically, between mass-stream, absolute moisture content and temperature of the aerating air, temperature of the grain developing during drying as well as the moisture content in the grain dried with said parameters.
  • Mass-stream as compared with grain quantity measures 0.1-0.3-fold at a drying medium temperature of 48°C and absolute moisture of the drying medium of 4 g/kg, i.e. 10% relative humidity, at a grain- emper ⁇ ature of about 28°C, equilibrium grain-moisture belonging to these parameters is only 4%.
  • duration of drying a bulk of grain and end-moisture to be reached during drying may properly be determined by described choice of drying medium parameters and mass-stream.
  • Total time of drying can namely not exceed fouling-free storing period of the grain suited to actual mois ⁇ ture content and at temperature and reaching the point of complete dry- ness, can not bring about overdrying not even on surfaces where the grains will be exposed to longest contact with the drying medium. This latter would impair energy-efficiency of the process.
  • the ration of 0.1 to'0.3 kg/kg mass-stream relating to weights of air and grain results in a maximum of 110 hours drying time at 40°C drying maximn temperature, when stored in maize has a moisture content of 20% and a layer of 3 m' height.” This period is securely below starting time of fouling.
  • Values of absolute moisture content by fi-constant of drying medium are indicated from 2 g/kg up to 10 g/kg.
  • the set of curves present points of fi-constants. It is shown that e.g. equilibrium grain temperature of 5% (d.b.) can be attained at a drying medium moisture rate of 2 g/kg at already 20°C grain temperature, while the same can be secured in the case of absolute moisture content of 10 g/kg, at grain temperature of abo 42°C only. At the same time, should it be needed to attain grain moisture of 15%, it has to be realized by a drying medium streaming in only one third of the time, and thus energy-feeding is also required in only one third of the time.
  • a drying medium having timely varying para ⁇ meters is applied in a pulsating way, i.e. in a manner that temperature and own moisture content are varying periodically, sometimes streaming of the drying medium is interrupted, finally that pulsating parameters and intensity of streaming, experimentally determined values of equilib ⁇ rium moisture and that of equilibrium temperature, during evaporation, are mathematically modelled on the basis of known principles and used to determining time and/or sequence of the individual pulsation periods.
  • Variable drying medium parameters the predetermined value of own mois ⁇ ture content during pulsation is processed by an air drier suitably opera ing on the sorption principle, and regeneration heat, continuously pro ⁇ claimed by air drier is used to heat the drying medium itself. It is advantageous when drying zone of the grain dryer used in the first step of drying, is enlarged by engaging the cooling zone, here ⁇ by increasing drying volumen of grain drier, as well as mass-stream belonging to the same drying temperature.
  • the first step serving only for drawing off surface moisture, can be implemented through minor structural changes in any grain drier operating on known principles, while its former mass-stream significant ⁇ ly increases.
  • any grain dryer can be advantageously used as the first step, where drying medium gets into contact with the entering moist grain in a manner that it has before at least once passed over the layer of grain.
  • drying can be effected within the bin serv- ing for prolonged storing and parameters of the drying medium, such as temperature and moisture content .are varying in time " , moreover streaming of the drying medium can be temporarily interrupted. During a considerabl time there is no need of energy feed, i.e. to heat the drying medium.
  • Fig.l is a diagram showing the relationship between equilibrium tempe ⁇ rature and equilibrium moisture belonging to different relative moisture of the drying medium
  • Fig.2 is a cross-sectional view of an equipment performing the process according to the invention, shown diagrammatically
  • Fig. 3 is a plan view of a drying medium producing equipment which is intended for use with the invention, shown diagrammatically.
  • the exhaust outlet 9 is enlarged by part 10 .
  • Bucket lifting set 11 lifts the dry uncooled grain which is discharged at place 2 , to a conveyor 12 spreading the grain in a uniform, by way of " example, layer 3 m high within storage 13 .
  • the grain is placed on an air-permeable wire-mesh construction platform 14 , spreading the blown drying medium through airchannel 15 uniformly over the whole surface .
  • the drying medium is pressed by fan 16 into channel 15 .
  • Suction channel 17 is provided with two slots. Through slot 18 ambiant air is drawn into the sytem, dependent upon the fact whether flap valve 19 is kept open or cbsed.
  • Flap valve 19 is kept closed in the drawing, therefore, streaming takes place from air space 21 of oil-fired air heater 20 .
  • ambiant air drawn in through aperture 30 loses its moisture content at a predetermined rate in air drier 27 and then passes to air heater 20. From this place, under the heating effect of the furnace chamber 22 warmed up by oil-burner 23 , the air is sucked at a 'prescribed temperature into suction channel 17 . Flue 24 ex- hausts combustion products.
  • Regenerator 28 serves for continuous or intermittent dewatering of the active ingredient in air drier 27. Reutilization of the heat released during regeneration is not depicted.
  • flap valve 29 In case flap valve 29 is kept closed, open flap valve 26 admits ambiant air through aperture 25 into the system, into air heating space 21. After having been warmed up in air heater 20 , ambiant air is drawn into suction tube 12.
  • drying medium in different states may have access to air channel 15 , such as
  • any flow can of course temporarily be stopped.
  • Parameter (temperature and absolute humidity) of the drying agent, its medium stream applied in individual drying phases as well as the combination to be chosen from abovementioned five options for the given grain, and its course in time are set according to experiments or rather to an adapted computer program elaborated on the results of experiments.
  • parameters of the second phase of pulsation drying are basically determined by the fact of how much time is available to avoid organic fouling of the grain pre-dried in the first phase.
  • Two tables below show results of the experiments done.
  • First table deals with bread grain, second one with combine harvested maize (shelled during harvesting) .
  • FIG. 3 shows a drying medium producing equipment, layout of which en ⁇ ables linking with all storage sections of 533 m 2 , by means of air- channel 15 .
  • conveyor 12 is connected to elevator 1 in such a way that ail storage sections can be filled up (or discharged)
  • partition walls 31 and movable lock paltes 32 individua storage sections can in succession constitute the second step of the drying process.
  • Power consumption of the grain drier follows from the total -consumption of the two steps.
  • 6000 tons of maize are dried from 30% moisture content to
  • total heat demand of first step amounts to 2,5x10 kJ.
  • second step supposing there is an airing in the first quarter of the time by ambiant air of about e.g. 15°C, in the second quarter of time an intermediate heating is effected by ambiant air heated to 45°C, in the third quarter of time medium feed is completely discontinued, and thereafter in the fourth quarter of time, drying with air heated to 45°C, desiccated to an absolute humidity of 2 g/kg, energy demand of the second step is as follows: Air demand as per 1 m 2 storage is 160 kg/h, therefore, considering
  • Specific heat consumption of drying in the second- step amounts to 3684 kJ/kg water, or with a more favourable use of heat in air drying, 2552 kJ/kg water.
  • dryer of the first step can be any type of continuously operated drier, which is shaped according to principles of procedure of the present invention. But it may, likewise, be any non-continuously operated, intermittently running drier, drying in batches, where cooling of the grain is not effected or not operated.
  • Second step can instead of a horizontal structure, be vertical, be of metal or concrete, having an inner exe ⁇ cution enabling intermittent drying medium feed.
  • measurement of the ambient parameters of air varying in time, of the sort of grain varying in time and of moisture of the grain can be done with individually mounted indicators, being continuously employed by the operator, operation, however, can also be automatic, when measuring instruments give electric or other sig ⁇ nals, to be used by means of algorhythm included in computer software for automatic control of the apparatus.
  • Steam or heat carrying oil can serve as a source of energy of the airdrier to be applied, or execution can be apt for so called direct firing as well.
  • Any sort of heat energy to be used can be produced e.g. by means of liquid or -gaseous hydro ⁇ carbons or solid combustibles, which can probably be agricultural wastes.

Abstract

Le dispositif permettant l'application du procédé comprend un pré-séchoir fonctionnant en continu ou en discontinu, une série de parties aérables recevant le grain préséché, dans lesquelles le grain peut être séché jusqu'à atteindre une teneur en humidité garantissant une longue durée de stockage. L'espace de stockage dans le pré-séchoir (3) peut être augmenté à l'aide d'une zone de refroidissement (5), et en même temps des canaux d'alimentation et de soufflage d'air (8, 7) peuvent être élargis par des parties correspondantes (6, 10), un élévateur (11) permettant la diffusion uniforme du grain non refroidi à l'aide d'une bande transporteuse (12) à l'intérieur d'une structure de stockage (13) présentant une plate-forme perméable à l'air (14) dans chacune des parties A à E. Sont également prévus un séchoir d'air (27) par sorbtion équipé d'un régénérateur (28) qui extrait l'humidité contenue dans l'air ambiant, une vanne à volet (29) régulant l'air entrant, un dispositif de chauffage d'air (20) équipé d'un brûleur (23), une vanne à volet (26) pour l'admission de l'air ambiant, montée dans la section de canal située entre le dispositif de chauffage d'air (20) et le séchoir d'air (27), une soufflante (16) qui souffle le milieu de séchage sous la plate-forme (14), une vanne à volet (19) faisant passer l'air ambiant à travers l'ouverture (18) reliée à une section du canal d'aspiration. La structure de stockage de grains (13) présente des parties (A à E), ces dernières étant séparées par des cloisons de séparation (31) et pouvant par la suite être mises en contact, chacune séparément, avec le courant d'air de séchage dans le canal d'air (15) à l'aide de plaques de retenue (32).
PCT/HU1987/000025 1986-06-23 1987-06-23 Procede et dispositif de sechage pulsatoire de materiaux granulaires presentant des pores capillaires, notamment du grain a l'aide d'un milieu seche au prealable WO1987007937A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
HU2617/86 1986-06-23
HU261786A HU199615B (en) 1986-06-23 1986-06-23 Method and apparatus for pulsation drying granular capillary-porous matters particularly cereals by predried medium

Publications (1)

Publication Number Publication Date
WO1987007937A1 true WO1987007937A1 (fr) 1987-12-30

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PCT/HU1987/000025 WO1987007937A1 (fr) 1986-06-23 1987-06-23 Procede et dispositif de sechage pulsatoire de materiaux granulaires presentant des pores capillaires, notamment du grain a l'aide d'un milieu seche au prealable

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Country Link
EP (1) EP0270649A1 (fr)
HU (1) HU199615B (fr)
WO (1) WO1987007937A1 (fr)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0396175A1 (fr) * 1989-05-03 1990-11-07 INTEROX CHIMICA S.p.A. Procédé pour la conservation du perborate monohydraté
EP1006329A1 (fr) * 1998-12-01 2000-06-07 digicolor GmbH Procédé de séchage de matières plastiques brutes, et procédé de régénération du fluide de séchage
WO2008012590A1 (fr) * 2006-07-25 2008-01-31 Peter Koltay Dispositif destiné au séchage de céréales durant le stockage et permettant de préserver leur qualité par aérage
US20180283787A1 (en) * 2017-03-31 2018-10-04 Conleymax Inc. Grain and Crop Drying Method, System, and Apparatus
CN109173560A (zh) * 2018-10-19 2019-01-11 吉林工商学院 一种冷凝循环增热连续式变温谷物干燥节能装置及其控制方法

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN107083465B (zh) * 2017-04-26 2019-01-25 中冶南方工程技术有限公司 热风炉烟气余热用于鼓风脱湿的工艺系统

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4045882A (en) * 1976-06-30 1977-09-06 Buffington James F Grain drying apparatus and process
WO1984001502A1 (fr) * 1982-10-07 1984-04-26 Andras Kovacs Tablettes vaginales contraceptives et leur procede de fabrication

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4045882A (en) * 1976-06-30 1977-09-06 Buffington James F Grain drying apparatus and process
WO1984001502A1 (fr) * 1982-10-07 1984-04-26 Andras Kovacs Tablettes vaginales contraceptives et leur procede de fabrication

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0396175A1 (fr) * 1989-05-03 1990-11-07 INTEROX CHIMICA S.p.A. Procédé pour la conservation du perborate monohydraté
EP1006329A1 (fr) * 1998-12-01 2000-06-07 digicolor GmbH Procédé de séchage de matières plastiques brutes, et procédé de régénération du fluide de séchage
WO2008012590A1 (fr) * 2006-07-25 2008-01-31 Peter Koltay Dispositif destiné au séchage de céréales durant le stockage et permettant de préserver leur qualité par aérage
US20180283787A1 (en) * 2017-03-31 2018-10-04 Conleymax Inc. Grain and Crop Drying Method, System, and Apparatus
US10746465B2 (en) * 2017-03-31 2020-08-18 Conleymax Inc. Grain and crop drying method, system, and apparatus
CN109173560A (zh) * 2018-10-19 2019-01-11 吉林工商学院 一种冷凝循环增热连续式变温谷物干燥节能装置及其控制方法
CN109173560B (zh) * 2018-10-19 2023-10-24 吉林工商学院 一种冷凝循环增热连续式变温谷物干燥节能装置及其控制方法

Also Published As

Publication number Publication date
HUT47727A (en) 1989-03-28
EP0270649A1 (fr) 1988-06-15
HU199615B (en) 1990-02-28

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