US3712600A - Heating installation for heating particulate raw materials - Google Patents

Heating installation for heating particulate raw materials Download PDF

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Publication number
US3712600A
US3712600A US00108461A US3712600DA US3712600A US 3712600 A US3712600 A US 3712600A US 00108461 A US00108461 A US 00108461A US 3712600D A US3712600D A US 3712600DA US 3712600 A US3712600 A US 3712600A
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Prior art keywords
heating
station
raw material
heated
cooling
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Expired - Lifetime
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US00108461A
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English (en)
Inventor
A Landthaler
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Veitscher Magnesitwerke AG
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Veitscher Magnesitwerke AG
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27B—FURNACES, KILNS, OVENS, OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
    • F27B7/00—Rotary-drum furnaces, i.e. horizontal or slightly inclined
    • F27B7/20—Details, accessories, or equipment peculiar to rotary-drum furnaces
    • F27B7/36—Arrangements of air or gas supply devices
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27B—FURNACES, KILNS, OVENS, OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
    • F27B7/00—Rotary-drum furnaces, i.e. horizontal or slightly inclined
    • F27B7/02—Rotary-drum furnaces, i.e. horizontal or slightly inclined of multiple-chamber or multiple-drum type
    • F27B2007/027—Rotary-drum furnaces, i.e. horizontal or slightly inclined of multiple-chamber or multiple-drum type with more than one drum

Definitions

  • a succession of interconnected rotary kilns are independently heatable, with the burner of at least one [30] Foreign Apphcatmn Pnomy Data kiln receiving an oxygen supply.
  • the exhaust gases Jan. 22,1970 Austria ..607 from the kilns are delivered to a pre heating tation p w for the raw material at the input end of the installa- 52 U.S. c
  • the present invention relates to improvements in heating installations for calcining or sintering preferably mineral raw materials, such as carbonates, oxides or hydroxides, including, for instance, magnesite in the production of calcined magnesia.
  • High-quality refractories are produced in such installations at high calcining temperatures which are obtained by enriching the combustion air with oxygen or by using pure oxygen as the combustion atmosphere.
  • the oxygen or oxygen-enriched air is usually supplied to the heating station by means of an injection nozzle or jet.
  • the most economical use of the generated heat is of utmost commercial importance.
  • a heating installation for calcining magnesite for instance, which comprises two or more interconnected heating stations arranged in parallel and each provided with an independently operable burner, the raw material passing sequentially from an input end to an output end through the successive heating stations.
  • One such known installation comprises a rotary kiln heated by a gas burner and a subsequent shaft or cupola furnace to which the magnesite is transferred from the rotary kiln with the admixture of a solid fuel, temperatures as high as 1,900 C being attained in the furnace.
  • the exhaust gases from the furnace are passed through the rotary kiln. Since such gases are rich on nitrogen, they constitute ballast in the combustion process in the rotary kiln as far as heat economy is concerned.
  • a calcining installation for cement clinker has also been proposed wherein two interconnected rotary kilns are provided.
  • the exhaust gases of each kiln are collected and delivered to heat exchangers which serve as pre-heaters for the combustion gases of the kilns. While this arrangement avoids passing the exhaust gases from one kiln through the other kiln, the clinker is not pre-heated. Very high calcining temperatures cannot be reached in such an installation, such as have become desirable in more recently developed calcining processes.
  • a first heating station including means for heating the station, a second heating station arranged in parallel with the first heating station and also including means for heating the station, which is independent of the heating means for the first station, and a connecting station for connecting the heating stations for transferring the raw material from the first to the second station.
  • a pre-heating station for pre-heating the raw material is at the input end at the first station, and a cooling station is at the output end of the second station for cooling the heated raw material coming from the second heating station.
  • the cooling station has an inlet for combustion air which is pre-heated in the cooling station by the heat released from the heated raw material.
  • the exhaust gases of each heating station are collected and delivered to the pre-heating station, and means is provided for supplying oxygen to the heating means of at least one heating station.
  • the heating means are selectively operable for heating selected heating station and the collected exhaust gases of the second station are selectively passed through or by the first station.
  • each heating station consists of a rotary kiln, and a conduit delivers the pre-heated combustion air from the cooling station to the first heating station and by-passes the second heating station.
  • connection station comprises a stationary connecting head and the heating means for the first heating station is mounted in the connecting head.
  • the conduit means for delivering the collected exhaust gases comprises a conduit selectively operable to receive the collected exhaust gases from the second heating station and to deliver the same to the pre-heating station. In some calcining operations, it will be useful to provide discharge means for the raw material at the connecting head.
  • the installation may include more than two heating stations, i.e., three stations, wherein the third station is included in the connecting station between the first and second heating station.
  • FIG. I is a schematic side view of a two-station heating installation according to one embodiment of this invention.
  • FIG. la shows a temperature operating chart of the installation of FIG. 1;
  • FIG. 2 is a view similar to that of FIG. 1 of a modified two-station heating installation
  • FIG. 2a shows a temperature operating chart of the installation of FIG. 2'; and a FIG. 3 is a view similar to that of FIG. 1 of a three station heating installation in accordance with another embodiment of the invention.
  • FIG. 1 there is shown a heating installation comprising a preheater 1 for the raw material to be heated or calcined in the installation.
  • the path of the raw material, which enters the installation at input end 3, is indicated by the chain-dotted line 2.
  • the raw material After the raw material has been pre-heated, it passes into a rotary kiln constituting the first heating station 4, whence it is transferred through the connecting station 14, which is a fixed connecting head interposed between the first station 4 and the rotary kiln constituting the second heating station 5.
  • the heated or calcined material passes from the station 5 into the cooling station 6 at the output end of the installation, where the hot material is cooled and the heat released from the material is used to preheat the combustion air being delivered into the cooling station through inlet 7.
  • the pre-heated combustion air follows the path of broken line 11 through the combustion air conduit 9, into the first heating station 4 and by-passing the second heating station '5.
  • Heating station 4 is independently heated by burner 8 whose exhaust gases follow the path of broken line 15 into the pre-heating station 1 where they are exhausted at 10.
  • the second heating station 5 is independently heated by burner 12 which receives oxygen or oxygen-enriched air through injection nozzle 13.
  • the exhaust gases of the second heating station follow the path of broken line 15a into the connecting head 14 whence they are lead through exhaust gas conduit 16 into the pre-heating station 1.
  • the installation operates as follows:
  • the material to be heated or calcined is charged into the pre-heating station 1 where it is pre-heated by the exhaust gases coming from the first and second heating stations 4 and 5, i.e., the exhausted heat energy of both stations is utilized.
  • the first heating station 4 is preferably heated with a fuel having a theoretically high flame temperature, for instance fuel oil. High temperatures are assured in the first heating station since it receives pre-heated combustion air from cooling station 6 through combustion air conduit 9, this conduit bypassing the second heating station 5 and thus preventing an admixture of exhaust gases thereto.
  • a suitable conveyor or transfer arrangement moves the material heated in the first heating station 4 to the second heating station 5 where the highest calcining temperature is reached because of the use of an oxygen-enriched combustion air therein.
  • the fuel used at burner 12 is again one having a high flame temperature, and oxygen or oxygen-enriched air is supplied through jet or nozzle 13.
  • the exhaust gas from the second heating station 5 by-pass the first heating station and are delivered through conduit 16 directly to the pre-heating station 1. In this manner, the operation of the two rotary kilns is largely independent of each other, and the temperature in the first kiln 4 is not depressed by leading into it the exhaust gases from the second kiln 5, which are rich in nitrogen.
  • the calcined or sintered material is discharged from the second kiln 5 into the cooling station 6 wherein it transfers its heat to the combustion air entering the cooling station at 7, thus pre-heating the combustion air which is supplied to the first kiln 4.
  • the cooling station will be so dimensioned that the material discharged therefrom may be transferred immediately to a further processing station while the pre-heated combustion air may be transferred in its entirety and at its highest temperature to first kiln 4. It is, of course, desirable to avoid heat losses.
  • FIG. 2 The modified installation of FIG. 2 is similar to the installation of FIG. 1 and, to avoid redundancy in the description, like reference numerals in this figure indicate like parts operating in a like manner.
  • the conduits 9 and 16 are omitted in this modification. This may be accomplished, of course, simply by closing the valves in these conduits so that no combustion air may enter into conduit 9 and no exhaust gases may enter into conduit 16. In this way, the installation operates as though it had a single heating station consisting of kilns 4 and 5.
  • the burner 8 remains in operation but the pre-heated combustion air from cooling station 6 passes (along the broken line path) consecutively through kiln 5 and then kiln 4.
  • the installation works with a shortened heating path of high intensity, i.e., only kiln 4 because the burner 12 and oxygen-supply nozzle 13 are disconnected so that the second kiln 5 is heated solely by the pre-heated combustion air coming from cooling station 6.
  • this operation may be reversed, i.e., the burner 8 may be turned off and the burner 12 may be operated to heat the second kiln instead of the first one.
  • the material charged into the installation will be gradually heated in the first heating station, the temperature will reach a peak in the second heating station, and the hot material will be rapidly cooled in the cooling station.
  • FIG. 3 A three-station installation embodying the principles of the present invention is illustrated in FIG. 3. This installation operates along the lines of the previously described embodiments, the connecting station herein including a third heating station.
  • the material is charged into a pre-heating station 20 and follows the path indicated by chain-dotted line 2 through the installation.
  • the first heating station is designated 22, followed by the third heating station 24 which connects the first heating station to the second heating station 26, each of the heating stations being constituted by a rotary kiln.
  • Cooling station 28 is arranged at the discharge end of the installation to enable the heated material to be cooled, the heat of the cooled material being transferred to the combustion air charged into the cooling station at 30.
  • Each heating station has a selectively operable burner 38, and selectively operable oxygen-supply nozzles 32, 34 and 36 may supply oxygen or oxygen-enriched air to the respective kilns.
  • exhaust gas conduits 40 and 42 are arranged to collect the exhaust gases from kilns 26 and 24, respectively, and to deliver these gases to respective zones in the pre-heating station 20 where they transfer their heat to the material being charged into the installation.
  • the exhaust gases of the first kiln 22 are also collected at M and delivered into a third zone of the pre-heating station, as shown.
  • the exhaust gases are removed from the pre-heating station through exhaust conduits by a blower 46, control vanes or valves 48 in the exhaust conduits regulating the draft so that no exhaust gases enter into the kilns with the pre-heated material.
  • the combustion air pre-heated in the cooling station 28 is removed therefrom by blower 50 and selectively delivered to nozzles 34 and 36 by operation of the control vanes or valves 52 in the supply conduits.
  • the combustion air may be enriched by an admixture of oxygen.
  • shut-off valves in conduits 40 and 42 so that the exhaust gases of the heating stations 26 and 24 do not by-pass the respectively preceding heating stations to be delivered directly to the p re-heating station but, instead, pass through these heating stations to combine with the exhaust gas in conduit 44.
  • the kilns are connected by connecting heads 54 and 56 through which the material is transferred from one station to the next and through which, if desired, the exhaust gases are removed. It may be useful to provide material discharge means at least at one of the connecting heads, preferably connecting head 56, so that partially calcined material may be removed at an intermediate point of the installation while the fully calcined or sintered material is transferred into the cooling station at the discharge end of the installation.
  • a heating installation for heating a raw material comprising 1. a first heating station including means for heating the station, said station having a raw material input end;
  • a second heating station arranged in series with the first heating station and including means for heating the station, said station having a heated raw material output end,
  • the heating means for the second station being independent of the heating means for the first station
  • the connecting station including a third heating station including selectively operable means for heating the station;
  • the heating means being selectively operable for heating selected ones of the heating stations
  • a conduit means for selectively delivering the pre-heated combustion air from the cooling station to the third or first heating station and by-passing the second heating station.
  • a first rotary kiln including means for heating the kiln, the kiln having a raw material input end;
  • a second rotary kiln arranged in series with the first kiln and including means for heating the kiln, the kiln having a heated raw material output end, a. the heating means for the second kiln being independent of the heating means for the first kiln;
  • a cooling station downstream of the output end for cooling the heated raw material coming from the second rotary kiln
  • connecting station respectively connecting the pre-heating station to the first rotary kiln, the first and second rotary kilns, and the second rotary kiln to the cooling station for transferring the raw material therebetween;

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Muffle Furnaces And Rotary Kilns (AREA)
  • Furnace Details (AREA)
  • Feeding, Discharge, Calcimining, Fusing, And Gas-Generation Devices (AREA)
US00108461A 1970-01-22 1971-01-21 Heating installation for heating particulate raw materials Expired - Lifetime US3712600A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
AT60770A AT310650B (de) 1970-01-22 1970-01-22 Ofenanlage zum Brennen vorzugsweise mineralischer Stoffe

Publications (1)

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US3712600A true US3712600A (en) 1973-01-23

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US00108461A Expired - Lifetime US3712600A (en) 1970-01-22 1971-01-21 Heating installation for heating particulate raw materials

Country Status (8)

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US (1) US3712600A (de)
JP (1) JPS4933730B1 (de)
AT (1) AT310650B (de)
BE (1) BE761862A (de)
CS (1) CS191865B2 (de)
DE (1) DE2102398A1 (de)
FR (1) FR2075741A5 (de)
GB (1) GB1341278A (de)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4105396A (en) * 1976-01-27 1978-08-08 Polysius Ag Apparatus for heat treatment of fine grained materials
US6488765B1 (en) * 1997-07-30 2002-12-03 Cemex, Inc. Oxygen enrichment of cement kiln system combustion

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19749183C2 (de) * 1997-11-07 2000-02-24 Feuerfestwerke Wetro Gmbh Verfahren für den keramischen Brand von Tonen

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1468168A (en) * 1922-07-05 1923-09-18 Robert D Pike Apparatus for calcining and clinkering
US1828270A (en) * 1927-02-14 1931-10-20 Int Precipitation Co Method and apparatus for burning portland cement

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1468168A (en) * 1922-07-05 1923-09-18 Robert D Pike Apparatus for calcining and clinkering
US1828270A (en) * 1927-02-14 1931-10-20 Int Precipitation Co Method and apparatus for burning portland cement

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4105396A (en) * 1976-01-27 1978-08-08 Polysius Ag Apparatus for heat treatment of fine grained materials
US6488765B1 (en) * 1997-07-30 2002-12-03 Cemex, Inc. Oxygen enrichment of cement kiln system combustion
US6688883B2 (en) * 1997-07-30 2004-02-10 Cemex, Inc. Apparatus for oxygen enrichment of cement kiln system

Also Published As

Publication number Publication date
DE2102398A1 (de) 1971-07-29
FR2075741A5 (de) 1971-10-08
CS191865B2 (en) 1979-07-31
JPS4933730B1 (de) 1974-09-09
BE761862A (fr) 1971-07-01
AT310650B (de) 1973-10-10
GB1341278A (en) 1973-12-19

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