CH637760A5 - Method for burning mineral, carbonate-containing raw materials in the co-current regenerative shaft furnace - Google Patents

Method for burning mineral, carbonate-containing raw materials in the co-current regenerative shaft furnace Download PDF

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Publication number
CH637760A5
CH637760A5 CH968378A CH968378A CH637760A5 CH 637760 A5 CH637760 A5 CH 637760A5 CH 968378 A CH968378 A CH 968378A CH 968378 A CH968378 A CH 968378A CH 637760 A5 CH637760 A5 CH 637760A5
Authority
CH
Switzerland
Prior art keywords
furnace
shaft
heated
cooling air
cooling
Prior art date
Application number
CH968378A
Other languages
German (de)
Inventor
Erwin Fuessl
Karl Scheibenreif
Original Assignee
Maerz Ofenbau
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 Maerz Ofenbau filed Critical Maerz Ofenbau
Priority to CH968378A priority Critical patent/CH637760A5/en
Publication of CH637760A5 publication Critical patent/CH637760A5/en

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Classifications

    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27FURNACES; KILNS; OVENS; RETORTS
    • F27BFURNACES, KILNS, OVENS, OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
    • F27B1/00Shaft or like vertical or substantially vertical furnaces
    • F27B1/005Shaft or like vertical or substantially vertical furnaces wherein no smelting of the charge occurs, e.g. calcining or sintering furnaces
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27FURNACES; KILNS; OVENS; RETORTS
    • F27BFURNACES, KILNS, OVENS, OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
    • F27B1/00Shaft or like vertical or substantially vertical furnaces
    • F27B1/10Details, accessories, or equipment peculiar to furnaces of these types
    • F27B1/24Cooling arrangements
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27FURNACES; KILNS; OVENS; RETORTS
    • F27DDETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D17/00Arrangements for using waste heat; Arrangements for using, or disposing of, waste gases
    • F27D17/004Systems for reclaiming waste heat

Description

The invention relates to a method for burning mineral carbonate-containing raw materials in a direct-current regenerative shaft furnace with at least two shafts, of which one shaft alternately operates the burning shaft and the other shaft is the counter-current shaft with simultaneous cooling of the burned raw material in the Cooling zone of the shafts.
The known regenerative process for strongly endothermic processes, for example for burning carbonate-containing raw materials such as limestone, dolomite or magnesite, is a process that has become known since it became known (AT-PS 211 214) for the construction of direct current countercurrent shaft furnaces with two or three shafts have been used many times 5 and have also been described many times in the literature, inter alia by E. Schiele and L.W. Berens in the book «Kalk», pages 147-151, Verlag Stahl-Eisen, Düsseldorf.
The exclusively regenerative use of the heat transfer medium in this combustion process has proven itself very well, because not only the combustion material but also the combustion air is preheated in the preheating zone of the shafts; the thermal characteristic of such a furnace is the regenerative preheating of the combustion air. This combustion process can hardly be improved from a thermal point of view, but in operational terms it does not yet meet all requirements. It is therefore an object of the invention to improve the combustion method described in the introduction.
This object is achieved according to the invention in that the cooling air heated by the fired raw material in the cooling zone is at least partially removed from the furnace at the end of the cooling zone and its heat content outside the furnace shafts is recuperative for preheating the raw materials to be fed to the furnace and / or for preheating the combustion air to be supplied at the upper end of the preheating zone is used.
The method according to the invention is described, for example, on the basis of exemplary embodiments of regenerative shaft furnaces shown in the drawing. 1 shows a schematic illustration of a two-shaft furnace with a square or rectangular cross section,
2 shows a pressure model for the cooling zone of the counterflow shaft of a regenerative shaft furnace with the removal of the cooling air quantity on the outside side wall, 35 and
Fig. 4 is a schematic representation of a two-shaft furnace with a circular shaft cross-section.
In the two-shaft furnace shown in FIG. 1, the shaft 1 is the combustion shaft operated in cocurrent and the shaft 2 is the counterflow shaft. A distinction is made in the shafts 1, 2 a preheating zone V, a combustion zone B, a post-deacidification zone N and a cooling zone K. The combustion air and cooling air are supplied 45 by means of a fan 3 or 4, e.g. a rotary blower. The fuel enters the combustion shaft approximately at the beginning of the combustion zone B via burner 5, in FIG. 1 the shaft 1. The flue gases symbolically represented by an arrow 6 flow, enriched 50 by the from the raw material, e.g. Limestone escaping C02, first parallel to the bed downwards, then further into the counterflow shaft 2 and there against the pouring movement upwards to a fume cupboard 7 Cooling air 10 flows upward in the cooling zone K and after it has been heated by the burnt lime laterally via exhaust ducts 11 to the outside via a dedusting device 12, for example a cyclone, and via a line 13 into a limestone preheater 14 or via an egg-60 air recuperator 15 into the open air or into a dust removal device, not shown.
The combustion air supplied by the blower 4 via a line 16 enters the shaft 1 either directly via a line 17 or via the air recuperator 15. The limestone preheated and pre-dried in a feed bucket 18 becomes one or the other of the shafts 1, 2 as required
55
637 760
forwarded. After the firing process in shaft 1 is completed, shaft 2 is converted to burning shaft and shaft 1 to counterflow shaft.
2 and 3 show the flow conditions in the post-deacidification zone N and in the cooling zone K of the counterflow shaft 2 and the combustion shaft 1. The results found on a model by means of the electrical analogy method show that there are both in the counterflow shaft 2 and in the combustion shaft 1 it is possible to extract practically the entire amount of cooling air through the blower 3 if the exhaust ducts 11 for the counterflow shaft on the outside, ie from the shaft 1 side wall and for the burning shaft 1 on the inside, i.e. is arranged against the shaft 2 side wall.
The design of the two-shaft furnace shown in FIG. 4 is basically the same as that of the furnace in FIG. 1, which is why the same parts are given the same reference numerals and are not described again. The flue gases 6 enriched with CO 2 from the deacidification process flow from the combustion zone B of the combustion shaft 1 via overflow channels 20 into the counterflow shaft 2, while the heated cooling air 10 flows out via a central hollow cylinder 21. In furnaces with a large shaft diameter, roof-shaped cross vaults or beams 23 are expediently provided between the central hollow cylinder 21 and the cooling zone wall 22, which enable the preheated cooling air to be drawn off evenly. In the case of a smaller shaft diameter, a cover 24 is provided over the central hollow cylinder 21.
The heat balance of preheating zone V is shown below using an example:
It is assumed that
- the deacidification of the limestone begins at 810 ° C, the temperature difference between the limestone and flue gas at the beginning of combustion zone B is 30 ° C and accordingly the temperature of the flue gases entering the preheating zone V is 840 ° C,
- a free CaO of 94%,
- The heat loss of the furnace walls in the preheating zone at 10 kcal / kg lime and
- The temperature of the heated and removed from the cooling zone K cooling air is 800 ° C.
The cooling air volume is assumed to be 0.6 m3 / kg lime. It is completely removed.
The cooling air has an intake temperature of 10 ° C and 40 ° C after compression.
The heating is done with natural gas, the heat consumption is 4334 kJ / kg, the combustion of the natural gas takes place with a theoretical air requirement of 1007 m3 / kg and results in a flue gas quantity of 1135 m3 / kg. In addition, there is 0.365 m3 / kg of expelled C02, so that the total amount of flue gas entering the preheating zone is 1.50 m3 / kg of lime and its outlet temperature is 100 ° C.
Flue gas heat from combustion zone B 4.1855 • [1.50 X 0.397 X 840-1.5 X100 X 0.349 - 10] =
1832.70 kJ / kg
Heat requirement for preheating the limestone 4.1855 • [1.74 X 0.260 X (310 - 10)] = 1514.81 kJ / kg
Heat for preheating the combustion air 4.1855- [1.007X0.33 X (840-40)] = 1112.67kJ / kg
2627.48 kJ / kg
Heat deficit in the preheating zone without using the preheated cooling air 2627.48-1832.70 = 795.16 kJ / kg
The extracted and heated cooling air has a heat content of 4.1855 • (0.60 X 0.33 X 800) = 662.98 kJ / kg. Of this, when the stone is warmed up outside the shafts at an assumed air outlet temperature of 80 ° C, 54.1855- (0.6X0.33 X 80) = 66.30 kJ / kg,
further for wall and
Line losses approx. 41.86 kJ / kg,
and for the water evaporation of the stone "54.41 kJ / kg io total losses 162.57 kJ / kg
So it is taken up by the stone and recovered 662.98 - 162.57 = 500.42 kJ / kg. This leads to limestone heating
15
500.42
1.74X0.26-4.1855
= 264.3 ° C
20 The heat deficit in the preheating zone after adding the recuperative stone preheating is 795.16 - 500.42 = 294.37 kJ / kg, which must be compensated for by increased fuel supply. This heat deficit in the preheating zone according to the described method is about 25 the same as in the pure regenerative method, in which when burning with 20% excess air, a cooling air volume of 0.6 m3 / kg and an exhaust gas temperature of 80 ° C, about 268 kJ / kg occur.
In the regenerative process, the firing cycle is changed at certain intervals. According to the described method, it is important to control so that the limestone, which has been preheated recuperatively outside the furnace, is charged into the shaft, after which the combustion is carried out in cocurrent, so that the cold combustion air hits the preheated limestone.
The advantages of the described method consist essentially in the fact that the regenerative system of the furnace is relieved and this results in significant improvements in terms of operation, production and the usability of the furnace.
Often there are only unwashed and heavily contaminated and also very wet limestones, e.g. chalk-shaped limestones with 10-20% water content. This results in difficulties when transporting the material into the furnace, because a lot of fine material sticks to the stone, which cannot be separated by sieving and thereby adversely affects the furnace operation when firing. In winter there is also the fact that the wet limestone pieces freeze together to form larger blocks and can block the feed. Problems also arise when weighing the limestone to be applied, which are uncomfortable when the water content of the feed material is subject to strong fluctuations as a result of seasonal influences.
55 The moisture of the limestone is normally not measured before weighing, but the amount of fuel to be added should be adjusted to the water content of the stone if you want to produce good and uniform lime quality. This disadvantage is eliminated by introducing the limestone completely dried or pre-dried to a uniform moisture level.
The direct transfer of heat from the regeneration system and the cooling air heated up by the burnt lime to the limestone to be charged, or 65 into a container on the furnace, achieves heat utilization that is similar to that in the preheating zone of the regenerative system. Furthermore, the undersize and especially that
637 760 4
Now, dried fine before weighing and before opening the limestone, which is desired or at the maximum possible value, into the oven, which can be prepared for firing. An advantage of the Ver-Vernen limestone granulation according to the invention can be easily separated. driving is also given by the fact that the amount of cooling air
Another possible application of the method is the temperature desired for cooling the burnt lime.
opened by e.g. on a pelletizing plate can be limited by accessories, i.e. approx. 0.6 to 0.7 m3 / kg lime,
there would be pellets made of chalk made of water in front of which, under climatic conditions with high humidity
Loading into the oven with heated cooling air dried speed and high air inlet temperature into the cooling zone and can be hardened. due to hydration of the burnt lime
A variant of the method is that the total temperature increase of the lime to be discharged; This also increases the heat consumption or part of the heat consumed in the cooling zone of the furnace, the more the greater the amount of heated air that is passed through a recuperator and the amount of cooling air.
for preheating the combustion air to a temperature The direct current combustion process enables, because of e.g. 150 ° C or 200 ° C is used, corresponding to a fuel supply at the beginning of the deacidification zone a very ner still portable exhaust gas temperature. This means that with Si high heat, which is
security, e.g. even when starting up the furnace, one for a 15 drive can be fully utilized.
Downstream dedusting system disturbing dew point lower- Since according to the new process the cooling air is not prevented, however, the smoke gases are not exceeded. deduced by the counterflow shaft, the pressure drop between the two shaft heads is reduced, thereby the
A further variant of the method consists in the supply of heat and thus the capacity of the furnace can be increased by approximately 30 to approximately 50% of the heated cooling air, both for recuperative purposes.
heating of the firing material as well as the combustion air in which the supply of cooling air and combustion air takes place
Form that part of the preheated cooling air is additionally used with rotary lobe blowers, so that the furnace can work under pressure mixed with the cold air required for combustion. So the circulation will be dusty. Avoid gases in the blowers. Another advantage is that
A significant advantage of the method is that there are no cooling elements required in the described method or partial removal of the heated cooling air.
that the partial pressure of the carbonic acid in the exhaust gas
C.
2 sheets of drawings

Claims (10)

  1. 637 760
    2nd
    PATENT CLAIMS
    1.Procedure for burning mineral carbonate-containing raw materials in a direct current regenerative shaft furnace with at least two shafts (1, 2), one of which alternately is the direct current combustion shaft and the other is the counterflow shaft with simultaneous cooling of the burned one Raw material in the cooling zone (K) of the shafts, characterized in that the cooling air heated by the fired raw material in the cooling zone (K) is at least partially removed from the furnace at the end of the cooling zone and its heat content outside the shafts (1,2) is recuperative Preheating of the raw materials to be supplied to the furnace and / or for preheating the combustion air to be supplied at the upper end of the preheating zone (V) is used.
  2. 2. The method according to claim 1, characterized in that the heated cooling air is removed on the side walls of the cooling zone (K).
  3. 3. The method according to claim 2, characterized in that the heated cooling air of the DC shaft in the inner side wall and the heated cooling air of the countercurrent shaft is discharged on the outer side wall of the cooling zone (K) in a square DC regenerative shaft furnace.
  4. 4. The method according to claim 2, characterized in that the heated cooling air in a direct current regenerative shaft furnace with a circular shaft cross section is discharged inwards and downwards through a central hollow cylinder (21) arranged in the cooling zone.
  5. 5. The method according to claim 4, characterized in that the heated cooling air through a free space below roof-shaped cross-extending vaults or beams (23) between side masonry of the cooling zone and a central hollow cylinder (21) and further through the interior this hollow cylinder is discharged downwards.
  6. 6. The method according to claim 1, characterized in that the heated and discharged cooling air from the furnace at the lower end of a directly above the furnace shafts (1, 2) located raw material container (18) is supplied.
  7. 7. The method according to any one of claims 1 to 6, characterized in that the heated and discharged cooling air from the furnace is used to preheat the raw material outside the furnace and / or to preheat the combustion air in a recuperator (15).
  8. 8. The method according to claim 1, characterized in that the heated and discharged cooling air from the furnace is at least partially mixed with cold combustion air.
  9. 9. The method according to claim 1, characterized in that the raw material recuperatively preheated recuperatively is completely or predried to a uniform moisture content in the direct current regenerative furnace.
  10. 10. The method according to claim 1, characterized in that the CO 2 content of the exhaust gases withdrawing from the DC regenerative furnace is regulated by the amount of the removed and heated cooling air.
    25th
CH968378A 1978-09-15 1978-09-15 Method for burning mineral, carbonate-containing raw materials in the co-current regenerative shaft furnace CH637760A5 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CH968378A CH637760A5 (en) 1978-09-15 1978-09-15 Method for burning mineral, carbonate-containing raw materials in the co-current regenerative shaft furnace

Applications Claiming Priority (7)

Application Number Priority Date Filing Date Title
CH968378A CH637760A5 (en) 1978-09-15 1978-09-15 Method for burning mineral, carbonate-containing raw materials in the co-current regenerative shaft furnace
DE19792927834 DE2927834A1 (en) 1978-09-15 1979-07-10 METHOD FOR BURNING MINERAL RAW MATERIALS IN A DC-REGENERATIVE SHAFT
AT482379A AT372519B (en) 1978-09-15 1979-07-11 Method for burning mineral raw materials in a direct-current regenerative shaft, and shaft for carrying out the method
SE7906176A SE7906176L (en) 1978-09-15 1979-07-18 PROCEDURE FOR THE USE OF MINERAL MATERIALS IN A DIRECTORY-REGENERATIVE CHAMBER
FR7920765A FR2436346B1 (en) 1978-09-15 1979-08-16
JP54117469A JPS5816932B2 (en) 1978-09-15 1979-09-14
CA335,698A CA1124513A (en) 1978-09-15 1979-09-14 Process for calcining mineral raw materials in a uniflow regenerative shaft furnace

Publications (1)

Publication Number Publication Date
CH637760A5 true CH637760A5 (en) 1983-08-15

Family

ID=4354532

Family Applications (1)

Application Number Title Priority Date Filing Date
CH968378A CH637760A5 (en) 1978-09-15 1978-09-15 Method for burning mineral, carbonate-containing raw materials in the co-current regenerative shaft furnace

Country Status (7)

Country Link
JP (1) JPS5816932B2 (en)
AT (1) AT372519B (en)
CA (1) CA1124513A (en)
CH (1) CH637760A5 (en)
DE (1) DE2927834A1 (en)
FR (1) FR2436346B1 (en)
SE (1) SE7906176L (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102010036587A1 (en) 2009-07-23 2011-01-27 Caldery France S.A.S. Hanging wall for deflecting hot gases in calcium carbonate burning furnace, has recesses provided for fastening of wall elements and area of refractory material, where fixed weight of material does not exceed strength of material of holders

Families Citing this family (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3006980A1 (en) * 1980-02-25 1981-09-10 Krupp Polysius Ag Cement mfg. plant using fluidised bed - where part of air preheated in clinker cooler is used to heat air of combustion carrying precalcined cement flour into bed
CH647313A5 (en) * 1980-04-30 1985-01-15 Maerz Ofenbau Regenerative shaft oven for the burning of carbonate-containing raw materials.
DE3409727C2 (en) * 1984-03-16 1990-03-29 Peter Dipl.-Ing. 4630 Bochum De Zeisel
DE3601572C2 (en) * 1986-01-21 1989-06-01 Waermestelle Steine Und Erden Gmbh, 4000 Duesseldorf, De
JPH02597U (en) * 1988-06-14 1990-01-05
DE59900088D1 (en) * 1999-02-27 2001-06-13 Zeisel Peter Process for burning lumpy fired material, in particular limestone, dolomite and magnesite, and regenerative shaft furnace for carrying out the process
DE10324953A1 (en) * 2003-06-03 2004-12-23 Maerz Ofenbau Ag Method for firing lumpy kiln
DE102006039204B4 (en) * 2006-08-22 2011-12-08 Rheinkalk Gmbh Annular shaft kiln
DE102009058304B4 (en) * 2009-12-15 2013-01-17 Maerz Ofenbau Ag DC countercurrent regenerative lime kiln and method of operating the same
DE102010016059A1 (en) * 2010-03-22 2011-11-24 Polysius Ag Process for the preparation of chalk lime
DE102013108410B3 (en) * 2013-08-05 2014-11-06 Maerz Ofenbau Ag Process for burning and cooling carbonate rocks in a DC regenerative lime shaft furnace and a DC regenerative lime shaft furnace
CN104501578A (en) * 2014-12-18 2015-04-08 南京净环热冶金工程有限公司 Multistage heat-storage double shaft kiln type calcinator
DE102016104076A1 (en) * 2016-03-07 2017-09-07 Maerz Ofenbau Ag Plant with a furnace and method of operating such a plant

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1087071B (en) * 1952-11-12 1960-08-11 Hildegard Seeger Geb Brockhaus Method and shaft furnace for burning lumpy limestone or the like.
DE1008641B (en) * 1954-10-21 1957-05-16 Rheinische Kalksteinwerke Method and device for burning limestone, dolomite or magnesite in a gas-fired shaft furnace with exhaust gas circulation
AT211214B (en) * 1958-08-09 1960-09-26 Alois Schmid Process for carrying out any endothermic processes in the shaft furnace, e.g. B. for burning lime, and furnace for carrying out the process
DE1157133B (en) * 1958-08-09 1963-11-07 Alois Schmid Process for burning and cooling grainy material, for example limestone in a shaft furnace, and a furnace for carrying out the process
FR1440786A (en) * 1965-04-21 1966-06-03 Sofim Saar Saarofenbau Fuer In Method for firing limestone and device for carrying out this process
AT301430B (en) * 1970-08-27 1972-09-11 Beckenbach Karl Inclined furnace
GB1510877A (en) * 1975-09-24 1978-05-17 Zytan Anlagenbau Gmbh Shaft kiln

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102010036587A1 (en) 2009-07-23 2011-01-27 Caldery France S.A.S. Hanging wall for deflecting hot gases in calcium carbonate burning furnace, has recesses provided for fastening of wall elements and area of refractory material, where fixed weight of material does not exceed strength of material of holders

Also Published As

Publication number Publication date
FR2436346B1 (en) 1984-08-31
JPS5816932B2 (en) 1983-04-04
AT372519B (en) 1983-10-25
FR2436346A1 (en) 1980-04-11
JPS5539300A (en) 1980-03-19
ATA482379A (en) 1983-02-15
CA1124513A (en) 1982-06-01
SE7906176L (en) 1980-03-16
DE2927834A1 (en) 1980-03-27
CA1124513A1 (en)

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