WO1991007631A1 - Heating device for heating a continuously, fluidized material flow with infrared radiation and preheated air - Google Patents

Heating device for heating a continuously, fluidized material flow with infrared radiation and preheated air Download PDF

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Publication number
WO1991007631A1
WO1991007631A1 PCT/DK1990/000288 DK9000288W WO9107631A1 WO 1991007631 A1 WO1991007631 A1 WO 1991007631A1 DK 9000288 W DK9000288 W DK 9000288W WO 9107631 A1 WO9107631 A1 WO 9107631A1
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WO
WIPO (PCT)
Prior art keywords
energy
heat
stream
exhaust gases
process medium
Prior art date
Application number
PCT/DK1990/000288
Other languages
French (fr)
Inventor
Mikael Kau
Lars Christensen
Original Assignee
Cimbria Unigrain Ltd. A/S
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 Cimbria Unigrain Ltd. A/S filed Critical Cimbria Unigrain Ltd. A/S
Priority to AT90916465T priority Critical patent/ATE89395T1/en
Priority to DE9090916465T priority patent/DE69001612T2/en
Publication of WO1991007631A1 publication Critical patent/WO1991007631A1/en

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Classifications

    • 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
    • F26B3/28—Drying solid materials or objects by processes involving the application of heat by radiation, e.g. from the sun
    • F26B3/30—Drying solid materials or objects by processes involving the application of heat by radiation, e.g. from the sun from infrared-emitting elements
    • F26B3/305—Drying solid materials or objects by processes involving the application of heat by radiation, e.g. from the sun from infrared-emitting elements the infrared radiation being generated by combustion or combustion gases
    • 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
    • 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

Definitions

  • the invention relates to an apparatus for continuous intensive heat-treatment of a stream of material consisting of granular or highly viscous substances.
  • Heat treatment of granular or highly viscous substances such as grain, other vegetable seed crops, nuts, spices, flavourings, meat, bone pieces as well as porridge-like and pasty substances and the like is well-known technology.
  • the purpose of a heat-treatment of e.g. the above-mentioned materials may be dehydration (drying), germ reduction, sterilizing as well as developing e.g. positive effects with regard to digestibility, or other expedient chemical, bio-chemical and/or physical changes etc., and further, combinations of the above examples.
  • the supply of energy advantageously can take place in co-current with the stream of material by means of a combination of intense radiant heat from a flame body and/or a heated surface, as well as convective heat transmission from the exhaust gases and heated air.
  • the known technology is, however, limited by the fact that the exhaust gases from the combustion process make contact with the product being treated in a state, where they are more or less diluted with air.
  • the apparatus according to the invention overcomes these drawbacks, as the effect of radiant heat liberated by the combustion process is utilized to the full for intense heat transmission, at the same time as the exhaust gases do not make contact with the products being treated.
  • Figure 1 shows the heating unit according to the invention.
  • a burner 1 solid, liquid or gaseous fuel is burned with surplus of air, so that the combustion zone 2 (the flame) has an average temperature in the interval 400°C to 1200°C, preferably 600-1000°C.
  • the combustion takes place in a burner tube 3 being insulated internally with a refractory material, so that the heat transmission from the inner wall of the burner tube to its outer wall is minimized.
  • the energy liberated by the combustion will mainly be carried to the mouth of the burner tube and out into the inner part 4 of a thin-walled chamber 5.
  • the chamber 5 may be shaped like a cylinder with a bottom shaped like a part-spherical surface, and may consist of a highly refractory material (metal or ceramics).
  • the chamber 5 will be heated in the interval 400°C to 1200°C, preferably 600-1000°C, and emit heat radiation from the external part of the chamber.
  • the exhaust gases will pass in an interspace 6 between the outside of the burner tube and the chamber 5, e.g. the cylindrical part, referred to below as the primary convective heat exchanger 7.
  • the exhaust gases may be assured a turbulent flow by means of guide plates of the like, so that the contact with the primary convective heat exchanger is maximized.
  • the exhaust gases leave the primary convective heat exchanger 7 by means of suction, and may be further cooled down in one or more external secondary convective heat exchangers 8.
  • the gaseous process -medium e.g. atmospheric air
  • the gaseous process -medium is taken in at 19 by means of the fan 18, and is heated in one or more convective heat exchangers 8, before e.g. the air passes between the refractory primary convective heat exchanger 7 and the manifold 21, and is made to flow into the process chamber 11.
  • the air can be assured a turbulent flow by means of guide plates or the like, so that the contact with the primary convective heat exchanger is maximized.
  • the material to be processed according to the invention is taken in at the inlet chute or skid 10 in the rotating chamber 11.
  • the material is held in a mechanically fluidized state, and is moved from the inlet chute or skid 10 to the ejecting box 12.
  • the material In the inlet end of the rotating chamber 11, the material is subjected to intense heat, partly in the form of radiant heat emitted by the chamber 5, partly in the form of convective energy transmission from the heated gaseous process medium.
  • the intensity of the action of heat upon the material diminishes concurrently with the movement of the material from the inlet end, at the inlet chute or skid 10, towards the outlet end at the ejecting box 12.
  • the transmission of heat from the chamber 5 to the stream of material diminishes concurrently with the units of the material, e.g. the particles, casting their shadows upon each other, and the temperature of e.g. the particles rises.
  • the transmission of heat from the heated gaseous process medium to the stream of material diminishes concurrently with the process medium being cooled and the temperature of e.g. the particles rises.
  • the material and the process medium are separated according to known principles in the ejecting box 12, and the material is taken out through the air-tight lock chamber 13.
  • the cooled process medium is made to flow through the tube 14 to the cyclone 15, in which any powdery constituents are separated out according to known principles, after which it is further cooled, possibly together with the exhaust gases, in a secondary heat exchanger 8.

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  • Engineering & Computer Science (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Microbiology (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Sustainable Development (AREA)
  • Drying Of Solid Materials (AREA)
  • Incineration Of Waste (AREA)
  • Fertilizers (AREA)
  • Heating, Cooling, Or Curing Plastics Or The Like In General (AREA)
  • Crucibles And Fluidized-Bed Furnaces (AREA)

Abstract

In an apparatus for continuous heat treatment, a mechanically fluidized stream of material consisting preferably of a granular or highly viscous material is heated in a rotating chamber in co-current with heat energy originating from a burner (1), in which solid, liquid or gaseous fuel is burned. A portion of the energy liberated by the combustion heats the internal part of a thin-walled chamber (5), the external part of which at the material inlet (10) transfers energy to said stream of material in the form of radiant heat. The remaining portion of the energy liberated by the combustion, bound in the exhaust gases from the combustion process, are subjected to heat exchange in a primary convective heat exchanger (7) and one or more secondary heat exchangers (8) in counter-current with a gaseous process medium, preferably atmospheric air, said process medium transferring further energy to said stream of material in the form of convective energy.

Description

HEATING DEVICE FOR HEATING A CONTINUOUSLY, FLUIDIZED MATERIAL FLOW WITH INFRARED RADIATION AND PREHEATED AIR,
TECHNICAL FIELD
The invention relates to an apparatus for continuous intensive heat-treatment of a stream of material consisting of granular or highly viscous substances.
BACKGROUND ART
Heat treatment of granular or highly viscous substances, such as grain, other vegetable seed crops, nuts, spices, flavourings, meat, bone pieces as well as porridge-like and pasty substances and the like is well-known technology.
The purpose of a heat-treatment of e.g. the above-mentioned materials may be dehydration (drying), germ reduction, sterilizing as well as developing e.g. positive effects with regard to digestibility, or other expedient chemical, bio-chemical and/or physical changes etc., and further, combinations of the above examples.
It is known technology (cf. e.g. patent applications Nos. 5276/83 and 6408/88) that the above heat treatment takes place in a rotating chamber, into which the material has been brought in a mechanically fluidized state.
Further it is known technology that the supply of energy advantageously can take place in co-current with the stream of material by means of a combination of intense radiant heat from a flame body and/or a heated surface, as well as convective heat transmission from the exhaust gases and heated air.
The advantages of the above-mentioned technology are inter alia to be found in a very flexible process adaptation covering the interval from gentle drying to intense heat-treatment of the material by heating to a high temperature (130-170°C) in a short period of time (on the average 30-360 seconds), a small surplus of air and hence good energy economy, as well as the possibility of heat-treating materials of widely differing consistency, extending from free-running, grainy particles (also of fine grain) to paste-like or porridge-like substances.
The known technology is, however, limited by the fact that the exhaust gases from the combustion process make contact with the product being treated in a state, where they are more or less diluted with air.
Frequently, it is not desirable to establish contact between the products being treated and the exhaust gases in a more of less diluted state.
In all combustion processes, a series of chemical compounds (N0X, CO, PAH etc.) are formed, said compounds in certain cases, often in connection with biological products, e.g. foodstuffs, forming toxic compounds.
DISCLOSURE OF THE INVENTION
The apparatus according to the invention overcomes these drawbacks, as the effect of radiant heat liberated by the combustion process is utilized to the full for intense heat transmission, at the same time as the exhaust gases do not make contact with the products being treated.
Trials with the apparatus according to claims 1-4 have surprisingly shown that the chimney loss (volume x heat content x ΔT) corresponds to approximately 15% of the energy supplied in the fuel, whilst in the conventional system with contact between flue gas and product and without heat exchange there is a chimney loss of approximately 20% of the fuel energy.
BRIEF DESCRIPTION OF THE DRAWING
Now, the apparatus according to the invention will be described in more detail below:
Figure 1 shows the heating unit according to the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
In a burner 1, solid, liquid or gaseous fuel is burned with surplus of air, so that the combustion zone 2 (the flame) has an average temperature in the interval 400°C to 1200°C, preferably 600-1000°C.
The combustion takes place in a burner tube 3 being insulated internally with a refractory material, so that the heat transmission from the inner wall of the burner tube to its outer wall is minimized.
Thus, the energy liberated by the combustion will mainly be carried to the mouth of the burner tube and out into the inner part 4 of a thin-walled chamber 5.
As shown, the chamber 5 may be shaped like a cylinder with a bottom shaped like a part-spherical surface, and may consist of a highly refractory material (metal or ceramics).
The chamber 5 will be heated in the interval 400°C to 1200°C, preferably 600-1000°C, and emit heat radiation from the external part of the chamber.
After a stay in the inner part 4 of the chamber 5 the exhaust gases will pass in an interspace 6 between the outside of the burner tube and the chamber 5, e.g. the cylindrical part, referred to below as the primary convective heat exchanger 7.
By means of the above-mentioned passage, the exhaust gases may be assured a turbulent flow by means of guide plates of the like, so that the contact with the primary convective heat exchanger is maximized.
The exhaust gases leave the primary convective heat exchanger 7 by means of suction, and may be further cooled down in one or more external secondary convective heat exchangers 8.
After cooling and after having been exhausted by means of the fan 16, the exhaust gases leave the system at 17.
The gaseous process -medium, e.g. atmospheric air, is taken in at 19 by means of the fan 18, and is heated in one or more convective heat exchangers 8, before e.g. the air passes between the refractory primary convective heat exchanger 7 and the manifold 21, and is made to flow into the process chamber 11.
By the above-mentioned passage, e.g. the air can be assured a turbulent flow by means of guide plates or the like, so that the contact with the primary convective heat exchanger is maximized.
The material to be processed according to the invention is taken in at the inlet chute or skid 10 in the rotating chamber 11.
By means of vanes, scoops or the like and using known principles, the material is held in a mechanically fluidized state, and is moved from the inlet chute or skid 10 to the ejecting box 12.
In the inlet end of the rotating chamber 11, the material is subjected to intense heat, partly in the form of radiant heat emitted by the chamber 5, partly in the form of convective energy transmission from the heated gaseous process medium.
The intensity of the action of heat upon the material diminishes concurrently with the movement of the material from the inlet end, at the inlet chute or skid 10, towards the outlet end at the ejecting box 12.
The transmission of heat from the chamber 5 to the stream of material diminishes concurrently with the units of the material, e.g. the particles, casting their shadows upon each other, and the temperature of e.g. the particles rises. The transmission of heat from the heated gaseous process medium to the stream of material diminishes concurrently with the process medium being cooled and the temperature of e.g. the particles rises.
After a predetermined interval of influence by heat, the material and the process medium are separated according to known principles in the ejecting box 12, and the material is taken out through the air-tight lock chamber 13.
The cooled process medium is made to flow through the tube 14 to the cyclone 15, in which any powdery constituents are separated out according to known principles, after which it is further cooled, possibly together with the exhaust gases, in a secondary heat exchanger 8.
Any condensate formed by the further cooling of the process medium and possibly the exhaust gases is drained at 20.

Claims

1. An apparatus for continuous heat treatment of a stream of material being mechanically fluidized in a rotating chamber and preferably consisting of a granular or highly viscous material, in co-current with heat energy originating from a burner (1), in which solid, liquid or gaseous fuel is burned, c h a - r a c t e r i z e d in that a portion of the energy liberated by the combustion heats the internal part of a thin-walled chamber (5), whereby the external part of said thin-walled chamber at the material inlet (10) transmits energy to said stream of material in the form of radiant heat, and that the remaining portion of the energy liberated by the combustion, bound in the exhaust gases from the combustion process, is heat-exchanged in a primary convective heat exchanger. (7) and one or more secondary convective heat exchangers (8) in counter-current with a gaseous process medium, preferably atmospheric air, said process medium transferring further energy to said stream of material in the form of convective energy.
2. Apparatus according to claim 1, c h a r a c¬ t e r i z e d in that the thin-walled chamber (5) and the primary convective heat exchanger (7) are constructed as bottom and cylinder in a co-terminus unit.
3. Apparatus according to claim 1 and 2, c h a ¬ r a c t e r i z e d in that the cylinder-shaped, primary convective heat exchanger (7) on its outside and inside is provided with guide plates so as to ensure a turbulent flow of process medium and exhaust gases.
4. Apparatus according to claim 1, c h a r a c ¬ t e r i z e d in that the gaseous medium after exiting the ejecting box (12) is made to flow through the conduit (14) together with the exhaust gases to one and more secondary convective heat exchangers and are heat-exchanged in counter-current with the gaseous process medium, before the latter is made to flow to the primary convective heat exchanger.
5. Apparatus according to claim 1, c h a r a c¬ t e r i z e d in that the static gas pressure in the gaseous process medium is always higher than the gas pressure in the exhaust gases.
PCT/DK1990/000288 1989-11-13 1990-11-08 Heating device for heating a continuously, fluidized material flow with infrared radiation and preheated air WO1991007631A1 (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
AT90916465T ATE89395T1 (en) 1989-11-13 1990-11-08 DEVICE FOR HEATING A CONTINUOUS FLOW OF MATERIAL IN A FLUIDIZED BED BY MEANS OF INFRARED RADIATION AND PREHEATED AIR.
DE9090916465T DE69001612T2 (en) 1989-11-13 1990-11-08 DEVICE FOR HEATING A CONTINUOUS MATERIAL FLOW IN A FLUID BED BY MEANS OF INFRARED RADIATION AND PRE-WARMED AIR.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DK5658/89 1989-11-13
DK565889A DK168319B1 (en) 1989-11-13 1989-11-13 Appliance for heating food material

Publications (1)

Publication Number Publication Date
WO1991007631A1 true WO1991007631A1 (en) 1991-05-30

Family

ID=8144273

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/DK1990/000288 WO1991007631A1 (en) 1989-11-13 1990-11-08 Heating device for heating a continuously, fluidized material flow with infrared radiation and preheated air

Country Status (5)

Country Link
EP (1) EP0500636B1 (en)
AT (1) ATE89395T1 (en)
DE (1) DE69001612T2 (en)
DK (2) DK168319B1 (en)
WO (1) WO1991007631A1 (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0854337A1 (en) * 1997-01-16 1998-07-22 René Besnard Apparatus for drying crop material
WO1999042776A1 (en) * 1998-02-23 1999-08-26 Biokasvu Oy Continuous method and apparatus for heat treatment of mass
US9302231B2 (en) 2012-04-03 2016-04-05 Dubois Agricultural Engineering Incorporated Seed treating device

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1985002248A1 (en) * 1983-11-17 1985-05-23 Dantoaster Aps A method of heat treating particulate materials and heater for use in performing the method

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1985002248A1 (en) * 1983-11-17 1985-05-23 Dantoaster Aps A method of heat treating particulate materials and heater for use in performing the method

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0854337A1 (en) * 1997-01-16 1998-07-22 René Besnard Apparatus for drying crop material
WO1999042776A1 (en) * 1998-02-23 1999-08-26 Biokasvu Oy Continuous method and apparatus for heat treatment of mass
US9302231B2 (en) 2012-04-03 2016-04-05 Dubois Agricultural Engineering Incorporated Seed treating device

Also Published As

Publication number Publication date
ATE89395T1 (en) 1993-05-15
DK565889D0 (en) 1989-11-13
EP0500636A1 (en) 1992-09-02
DE69001612D1 (en) 1993-06-17
DK168319B1 (en) 1994-03-14
DK565889A (en) 1991-07-08
DK0500636T3 (en) 1993-06-07
DE69001612T2 (en) 1993-08-19
EP0500636B1 (en) 1993-05-12

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