CN106986561B - Annular lime shaft kiln - Google Patents
Annular lime shaft kiln Download PDFInfo
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- CN106986561B CN106986561B CN201710346004.9A CN201710346004A CN106986561B CN 106986561 B CN106986561 B CN 106986561B CN 201710346004 A CN201710346004 A CN 201710346004A CN 106986561 B CN106986561 B CN 106986561B
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- 235000008733 Citrus aurantifolia Nutrition 0.000 title claims abstract description 45
- 235000011941 Tilia x europaea Nutrition 0.000 title claims abstract description 45
- 239000004571 lime Substances 0.000 title claims abstract description 45
- 238000001816 cooling Methods 0.000 claims abstract description 167
- 238000002485 combustion reaction Methods 0.000 claims abstract description 139
- 239000000463 material Substances 0.000 claims abstract description 56
- 238000001354 calcination Methods 0.000 claims abstract description 35
- 230000003750 conditioning effect Effects 0.000 claims abstract description 14
- 239000000446 fuel Substances 0.000 claims description 30
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 claims description 29
- 239000003546 flue gas Substances 0.000 claims description 29
- 239000007789 gas Substances 0.000 claims description 26
- 238000003912 environmental pollution Methods 0.000 abstract description 2
- 239000003570 air Substances 0.000 description 132
- 239000000779 smoke Substances 0.000 description 15
- 238000007599 discharging Methods 0.000 description 14
- 235000019738 Limestone Nutrition 0.000 description 10
- 239000006028 limestone Substances 0.000 description 10
- 238000004519 manufacturing process Methods 0.000 description 7
- ODINCKMPIJJUCX-UHFFFAOYSA-N Calcium oxide Chemical compound [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 description 6
- 238000009826 distribution Methods 0.000 description 6
- 239000000428 dust Substances 0.000 description 6
- 239000004744 fabric Substances 0.000 description 4
- 238000010438 heat treatment Methods 0.000 description 4
- 239000001301 oxygen Substances 0.000 description 4
- 229910052760 oxygen Inorganic materials 0.000 description 4
- 238000005496 tempering Methods 0.000 description 4
- 229910000831 Steel Inorganic materials 0.000 description 3
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 3
- 235000012255 calcium oxide Nutrition 0.000 description 3
- 239000000292 calcium oxide Substances 0.000 description 3
- 238000000354 decomposition reaction Methods 0.000 description 3
- 238000005265 energy consumption Methods 0.000 description 3
- 239000002737 fuel gas Substances 0.000 description 3
- 238000000034 method Methods 0.000 description 3
- 239000010959 steel Substances 0.000 description 3
- 239000002918 waste heat Substances 0.000 description 3
- 239000003245 coal Substances 0.000 description 2
- 239000000567 combustion gas Substances 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000001914 filtration Methods 0.000 description 2
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 230000002035 prolonged effect Effects 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 230000001105 regulatory effect Effects 0.000 description 2
- 238000004062 sedimentation Methods 0.000 description 2
- 238000003860 storage Methods 0.000 description 2
- 230000009471 action Effects 0.000 description 1
- 239000012080 ambient air Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000000571 coke Substances 0.000 description 1
- 230000001276 controlling effect Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000010304 firing Methods 0.000 description 1
- 230000002401 inhibitory effect Effects 0.000 description 1
- 238000007689 inspection Methods 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000003345 natural gas Substances 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 238000010992 reflux Methods 0.000 description 1
- 230000008439 repair process Effects 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
- 239000004449 solid propellant Substances 0.000 description 1
- 239000002912 waste gas Substances 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
- 238000005303 weighing Methods 0.000 description 1
Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2/00—Lime, magnesia or dolomite
- C04B2/10—Preheating, burning calcining or cooling
- C04B2/12—Preheating, burning calcining or cooling in shaft or vertical furnaces
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P40/00—Technologies relating to the processing of minerals
- Y02P40/40—Production or processing of lime, e.g. limestone regeneration of lime in pulp and sugar mills
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Ceramic Engineering (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Materials Engineering (AREA)
- Structural Engineering (AREA)
- Organic Chemistry (AREA)
- Furnace Details (AREA)
Abstract
The invention provides an annular lime shaft kiln, which comprises a kiln body, a distributing device, a plurality of upper and lower combustion chambers, a plurality of upper and lower burners, a plurality of upper and lower arch bridges, a cooling air system and the like, wherein the kiln body is provided with an inner cylinder and an outer cylinder which are concentrically arranged and are formed with annular channels at intervals, and the distributing device is positioned at the upper end of the annular channels; the cooling air system comprises an inner cylinder cooling air system and a material layer cooling air system, the inner cylinder cooling air system is arranged in such a way that cooling air flows in from the bottom of the inner cylinder, flows out from the top of the inner cylinder and is used for cooling the inner cylinder and is introduced into the upper burner as combustion air of the upper burner, and the material layer cooling air system is arranged in such a way that the cooling air cools the material layer calcined in the annular channel and provides combustion air for the lower burner; wherein the annular channel is composed of a preheating zone, an upper countercurrent calcining zone, a middle countercurrent calcining zone, a lower non-flow conditioning zone and a cooling zone from top to bottom. The invention can stably produce high-quality active lime, has strong gas adaptability and small environmental pollution.
Description
Technical field:
the invention relates to an industrial kiln for calcining limestone, in particular to an annular lime shaft kiln.
The background technology is as follows:
the shaft kiln for calcining lime at present mainly comprises an annular sleeve kiln, a double-chamber kiln, a double-beam kiln, a mechanized shaft kiln and the like.
The common characteristics of the double-chamber kiln, the double-beam kiln and the mechanized vertical kiln are as follows: without a separate combustion space, the combustion of the fuel takes place in the bed. This combustion mode further affects: firstly, in order to make the fuel burn fully in the material layer as much as possible, a larger air excess coefficient must be adopted, so that unnecessary combustion products are increased, and accordingly, unnecessary heat consumption of the system is increased; secondly, the combination order of the primary air, the secondary air and the fuel in the material layer is poor, and the heat value of the fuel is required to be high in order to reach the necessary temperature required by the limestone decomposition of the calcining zone; third, or when the fuel is low, the combustion temperature of the calcining zone is low due to poor combination order of the primary air, the secondary air and the fuel in the material layer, so that the residence time of the material in the calcining zone must be increased to achieve the required calcining degree, that is, the calcining space utilization coefficient of the kiln is reduced, and the design yield cannot be achieved.
The greatest features of the annular sleeve kiln in combustion are as follows: an upper layer of independent combustion space and a lower layer of independent combustion space are arranged; in the lower combustion chamber, at least two combustion-supporting gases are involved in the combustion: lime cooling air and driving air are supplemented as necessary, so that from the viewpoint of ensuring basic process, even if only lime cooling air and driving air participate in combustion, the lower combustion chamber has reached a very high air excess coefficient; in the upper combustion chamber, only burner combustion-supporting air is generally involved in combustion, and from the perspective of controlling the combustion temperature, the upper combustion chamber is generally in under-oxygen combustion, and the residual unburned fuel is combined with the redundant oxygen in the rising smoke of the lower combustion chamber and continues to burn in a material layer near the upper combustion chamber. So that: for the fuel with high heat value, the degree of the fuel in the upper combustion chamber is extremely low, and the higher the heat value is, the lower the degree of the fuel is, so that a great amount of fuel enters the material layer near the upper combustion chamber to continue to burn, and as mentioned above, the full burning of the fuel cannot be ensured by the combustion mode in the material layer. For low-calorific-value fuel, on one hand, the temperature of the combusted flue gas is difficult to reach the temperature required by material decomposition due to the high air excess coefficient of the lower combustion chamber; on the other hand, the upper combustion chamber tends to achieve a desired combustion temperature of the upper combustion chamber by increasing the air ratio, and at this time, the air ratio of the entire sleeve kiln becomes extremely high although the degree of burnout of the fuel in the upper combustion chamber increases.
In summary, with the shaft kilns currently used for calcining lime, there are problems including:
first, the fuel has higher heat value, the double-chamber kiln, the double-beam kiln and the mechanized vertical kiln generally have more than 6690kJ/Nm3, and the annular sleeve kiln generally has more than 5020kJ/Nm 3 The above.
Second, or when the heating value of the fuel is low, the kiln must be run at reduced production while the firing rate of the material will increase significantly.
Third, the air coefficient of the double-chamber kiln, the double-beam kiln and the mechanized vertical kiln is higher, and the air coefficient of the double-chamber kiln, the double-beam kiln and the mechanized vertical kiln is generally higher than 1.4, which means that the unnecessary heat consumption is higher.
Fourth, for a sleeve kiln: when the fuel with high calorific value is adopted, the air coefficient is lower, but the burn-off rate of the fuel is reduced at the same time; when low heating value fuel is used, the air ratio is high. In a word, the problems of unnecessary high heat consumption exist.
The invention comprises the following steps:
in order to overcome the problems, the invention provides the annular lime shaft kiln which can stably produce high-quality active lime, has strong gas adaptability and small environmental pollution, and is beneficial to the technical field of the annular lime shaft kiln.
To this end, the invention provides an annular lime shaft kiln comprising:
the kiln body is provided with an inner cylinder and an outer cylinder which are concentrically arranged, and an annular channel is formed between the inner cylinder and the outer cylinder;
the distributing device is arranged at the upper end of the annular channel;
a plurality of upper combustion chambers and a plurality of lower combustion chambers which are vertically spaced apart along the outer circumference of the outer tub;
the upper burners and the lower burners are respectively arranged on the upper combustion chambers and the lower combustion chambers in a one-to-one correspondence manner;
the upper arch bridges and the lower arch bridges are positioned between the outer cylinder and the inner cylinder and are used for connecting the upper combustion chambers and the lower combustion chambers with the inner cylinder in a one-to-one correspondence manner;
the inner cylinder cooling air system comprises an inner cylinder cooling air inlet pipe and a plurality of inner cylinder cooling air outlets which are positioned on the inner cylinder and correspond to the upper burners one by one, and the inner cylinder cooling air system is arranged so that cooling air flows in from the bottom of the inner cylinder and flows out from the top of the inner cylinder;
the material layer cooling air system comprises a material layer cooling air inlet pipe and a plurality of material layer cooling air outlets which are positioned on the outer cylinder and correspond to the lower burners one by one, and the material layer cooling air system is arranged to enable cooling air to cool the material layer calcined in the annular channel;
the annular channel is composed of a preheating zone arranged between the distributor and the top of the inner cylinder from top to bottom, an upper countercurrent calcining zone arranged between the top of the inner cylinder and the plurality of upper combustion chambers, a middle countercurrent calcining zone arranged between the plurality of upper combustion chambers and the plurality of lower combustion chambers, a lower no-flow conditioning zone arranged between the plurality of lower combustion chambers and the plurality of material layer cooling air outlets, and a cooling zone arranged below the plurality of material layer cooling air outlets.
In the invention, the countercurrent calcination and the no-flow tempering can be simultaneously completed in the space of the annular channel, so that the high-quality active lime can be stably produced;
because complex structures such as a heat exchanger and an ejector in the prior art are eliminated, and a non-flow conditioning belt is added, the combustion of fuel in a combustion chamber is easier to control, so that the adaptability to fuel gas is stronger, the investment cost is reduced, and the equipment failure rate is reduced; due to the arrangement of the inner cylinder cooling air system and the material layer cooling air system, the exhaust gas temperature is lower, so that cold air is not required to be added when the exhaust gas is discharged into the atmosphere to advance into the dust remover, on the one hand, the power consumption is reduced, on the other hand, the filtering wind speed in the dust remover can be reduced, the service life of a cloth bag is further prolonged, and the dust removal efficiency is ensured.
Further, the inner cylinder cooling air system further comprises at least one inner cylinder cooling fan, a plurality of inner cylinder cooling air branch pipes and an inner cylinder cooling air ring pipe, wherein the inner cylinder cooling fan is connected with the inner cylinder cooling air inlet pipe and used for sending cooling air into the inner cylinder, one ends of the inner cylinder cooling air branch pipes are connected to the inner cylinder cooling air outlets in a one-to-one correspondence manner, the other ends of the inner cylinder cooling air branch pipes are communicated to the inner cylinder cooling air ring pipe, and the inner cylinder cooling air ring pipe is communicated with the upper burners so as to provide combustion air for the upper burners.
Due to the structure, the cooling air which preheats the inner cylinder to about 200 ℃ is used for assisting combustion supporting of the upper burner while cooling the inner cylinder, so that the waste heat is fully utilized, and the energy consumption is reduced.
Still further, the above-mentioned a plurality of layer cooling wind export are connected to a plurality of layer cooling wind outlet branch pipes in a one-to-one correspondence, and above-mentioned layer cooling wind system still includes a plurality of layer cooling fans, and this a plurality of layer cooling fans and this a plurality of layer cooling wind outlet branch pipes one-to-one and be used for sucking the cooling wind after the heat exchange in the above-mentioned cooling band to a plurality of layer cooling wind outlet branch pipes, and this a plurality of layer cooling wind outlet branch pipes are in a one-to-one correspondence and are connected with above-mentioned a plurality of burner down in order to provide combustion-supporting air for it.
Through the structure, the temperature of the cooling air can be increased to about 400 ℃ after heat exchange with the burnt lime, and then the preheated cooling air is pumped out as the combustion air of the lower burner through the material layer cooling fan, so that the temperature of the burnt lime can be reduced to about 100 ℃ after cooling by the cooling air, the waste heat is fully utilized, and the energy consumption is reduced.
Still further, the preheating zone comprises a main smoke exhaust fan system for sucking smoke outwards from the preheating zone, the main smoke exhaust fan system comprises a smoke suction port positioned on the top of the outer barrel, a smoke sedimentation pipe communicated with the smoke suction port and a main smoke exhaust fan communicated with the smoke sedimentation pipe, wherein the main smoke exhaust fan and the plurality of material layer cooling fans are arranged so that negative pressure in the plurality of lower combustion chambers is consistent with negative pressure at the plurality of material layer cooling air outlets, and therefore no airflow flows in the lower non-flow conditioning zone.
Due to the structure, when the limestone with higher calcination degree continuously flows downwards to the lower non-flow tempering belt after passing through the middle counter-flow calcination belt, no flue gas continuously supplies heat to the limestone, but the time and space conditions are continuously created for the gradual decomposition and tempering of the material by means of the heat contained in the material, so that high-quality active lime can be stably produced.
Still further, the plurality of upper combustion chambers and the plurality of lower combustion chambers are arranged such that the combustion gas and the combustion air are sufficiently combusted therein.
Through the arrangement, the fuel can be completely combusted in the combustion chamber, the burn-off rate of the fuel is greatly improved, and the fuel waste is avoided; in addition, the cold air is involved in the combustion of the combustion chamber through the burner after the cooling of the inner cylinder and the material layer is completed, so that the influence on the combustion chamber and the arch bridge refractory caused by the high temperature of the sufficient combustion of the combustion chamber is not required to be worried about.
Still further, when the above-mentioned gas is blast furnace gas, the excess air ratio is controlled to be 1.05-1.2.
Through the arrangement, the blast furnace gas and the air can be fully combusted in the combustion chamber, and of course, the excess air coefficient is slightly different according to the heat value of the gas, namely, the control of the excess air coefficient can be slightly changed according to the type of the gas participating in combustion so as to ensure the effect of full combustion.
Further, the plurality of upper combustion chambers and the plurality of lower combustion chambers each employ a fuel/air staged combustion scheme, and/or the plurality of upper burners and the plurality of lower burners each employ a low NOx burner.
The structure can greatly reduce the NOx emission index. For example, when a low NOx burner is used, a local flue gas recirculation zone can be formed in the combustion chamber to reduce the oxygen concentration in the combustion space and create NOx reduction conditions, thereby inhibiting the generation of thermal NOx, and therefore, the invention can strictly ensure that the NOx emission is far below 100mg/Nm 3 (in NO) 2 Meter).
Further, the kiln comprises an ash discharging platform and a plurality of ash discharging machines positioned on the ash discharging platform, wherein the material layer cooling air inlet pipe is arranged at the bottom of the ash discharging platform and sucks outside air into the kiln body by utilizing the negative pressure in the kiln body.
Further, the device also comprises a plurality of distributing plates above the ash discharging machine, wherein the upper arch bridges and the lower arch bridges and the distributing plates are arranged in a staggered manner.
Through dislocation arrangement for the material is in the annular channel in the in-process of supreme and down motion, and a certain angle side direction redistributes for many times, carries out secondary cloth promptly, makes material distribution more even, has improved the material and has heated the degree of consistency.
Further, for the same annular lime shaft kiln, the above-mentioned plural numbers are the same number of 4 or more and are all arranged uniformly in the circumferential direction.
The annular lime shaft kiln provided by the invention has the advantages that the distribution of materials, smoke and cooling wind in the circumferential direction can be uniform through the upper combustion chambers, the lower combustion chambers, the upper combustion nozzles, the lower combustion nozzles, the upper arch bridges, the lower arch bridges, the inner cylinder cooling wind outlets, the material layer cooling wind outlets, the ash discharging machines and the distributing plates.
These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter.
Description of the drawings:
the structure of the invention, as well as further objects and advantages thereof, will be better understood by reference to the following description taken in conjunction with the accompanying drawings in which like reference numerals identify like elements:
fig. 1 is a schematic structural view of an annular lime shaft kiln according to an embodiment of the present invention.
Reference numerals illustrate:
1 kiln body 10 inner cylinder
12 outer cylinder 2 annular channel
21 preheating zone 23 upper counter-current calcining zone
Lower non-flow conditioning belt of counter-flow calcining belt 27 in middle part of 25
28 cooling belt 3 distributing device
Burner nozzle on upper combustion chamber 41 of 40
Lower burner nozzle of lower combustion chamber 43 of lower part 42
50 upper arch bridge 52 lower arch bridge
60 inner cylinder cooling air inlet pipe 62 inner cylinder cooling air outlet
64 inner tube cooling air branch 66 inner tube cooling air ring tube
70 material layer cooling air inlet pipe 72 material layer cooling air outlet
74 bed cooling air outlet branch pipe 76 bed cooling fan
8 ash discharging platform 81 ash discharging machine
The specific embodiment is as follows:
specific embodiments of the present invention will be described below with reference to the accompanying drawings.
Figure 1 shows an annular lime shaft kiln according to an embodiment of the invention. In the embodiment, the annular lime shaft kiln comprises a kiln body, a distributor, a combustion chamber, a burner, an arch bridge, a cooling air system and the like, wherein the kiln body 1 is provided with an inner cylinder 10 and an outer cylinder 12 which are concentrically arranged, and an annular channel 2 is formed between the inner cylinder 10 and the outer cylinder 12; the distributor 3 is arranged at the upper end of the annular channel 2; the combustion chambers comprise 9 upper combustion chambers 40 and 9 lower combustion chambers 42, the upper combustion chambers 40 and the lower combustion chambers 42 are vertically spaced along the outer circumference of the outer cylinder 2, the 9 upper combustion chambers 40 are uniformly distributed in the circumferential direction, and the 9 lower combustion chambers 42 are also uniformly distributed in the circumferential direction; the burner comprises 9 upper burner nozzles 41 and 9 lower burner nozzles 43 which are respectively arranged on 9 upper combustion chambers 40 and 9 lower combustion chambers 42 in a one-to-one correspondence manner; the bridge includes 9 upper bridges 50 and 9 lower bridges 52 between the outer vessel 12 and the inner vessel 10 for connecting the 9 upper combustion chambers 40 and 9 lower combustion chambers 42, respectively, to the inner vessel 10 in a one-to-one correspondence.
Although the number of the upper combustion chamber, the lower combustion chamber, and the like is 9 in the present embodiment, this is not meant to be invariable, and in practice, the number of the structures is determined according to the production of the annular lime shaft kiln, for example, when the production is relatively high, the number of the structures may be 9, the production is slightly lower, or 7, 5, or the like.
As further shown in fig. 1, in the present embodiment, the annular lime shaft kiln further includes an inner tube cooling air system, wherein the inner tube cooling air system includes an inner tube cooling air blower (not shown), an inner tube cooling air inlet pipe 60 connected to the inner tube cooling air blower, 9 inner tube cooling air outlets 62 located at an upper portion of the inner tube 10, 9 inner tube cooling air branch pipes 64 connected to the 9 inner tube cooling air outlets 62 in a one-to-one correspondence, and an inner tube cooling air loop 66 having one side communicating with the 9 inner tube cooling air branch pipes 64 and the other side communicating with the 9 upper burners 41, the inner tube cooling air inlet pipe 60 and the 9 inner tube cooling air outlets 62 are arranged such that cooling air flows in from a bottom portion and flows out from a top portion of the inner tube 10, and the inner tube cooling air loop 66 communicates with the 9 upper burners 41 to supply combustion air for the upper burners.
In the present embodiment shown in fig. 1, the annular lime shaft kiln further includes a bed cooling air system provided so that cooling air cools the calcined bed in the annular passage 2, and includes a bed cooling air inlet pipe 70, 9 bed cooling air outlet pipes 72 located on the outer tub 12, 9 bed cooling air outlet branch pipes 74 connected in one-to-one correspondence with the 9 bed cooling air outlet pipes 72, 9 bed cooling fans 76 provided in one-to-one correspondence with the 9 bed cooling air outlet branch pipes 74, wherein the 9 bed cooling fans are used for sucking cooling air having completed heat exchange in the annular passage 3 into the 9 bed cooling air outlet branch pipes 74, and the 9 bed cooling air outlet branch pipes 74 communicate in one-to-one correspondence with the 9 lower burners 43 so as to supply combustion air thereto.
As further shown in fig. 1, in the present embodiment, the annular passage 2 includes, from top to bottom, a preheating zone 21, an upper countercurrent calcining zone 23, a middle countercurrent calcining zone 25, a lower no-flow conditioning zone 27, and a cooling zone 28, wherein the preheating zone 21 is formed between the distributor 3 and the top of the inner tube 10, the upper countercurrent calcining zone 23 is located between the top of the inner tube 10 and the upper combustion chamber 40, the middle countercurrent calcining zone 25 is located between the upper combustion chamber 40 and the lower combustion chamber 42, the lower no-flow conditioning zone 27 is located between the lower combustion chamber 42 and the layer cooling air outlet 72, and the cooling zone 28 is located below the layer cooling air outlet 72.
Although not shown in fig. 1, it is to be noted that in the present embodiment, the annular lime shaft kiln further comprises a main exhaust fan system for sucking the flue gas outwardly from the preheating zone 21, the main exhaust fan system comprising a flue gas suction port located on the top of the outer tub, a flue gas settling tube communicating with the flue gas suction port, and a main exhaust fan communicating with the flue gas settling tube. It should be appreciated that in the present embodiment, the main smoke exhaust fan and the above-described 9 bed cooling fans 76 are disposed such that the negative pressure in the 9 lower combustion chambers 42 coincides with the negative pressure at the above-described 9 bed cooling air outlets 72, so that no air flow flows in the lower no-flow conditioning belt 27.
In addition, in the present embodiment, the inner tube 10 includes a steel inner shell and a refractory lining layer built around the outer wall of the inner tube 1, and the outer tube 12 also includes a steel outer shell and a refractory lining layer built around the inner wall of the outer tube 12; a fireproof lining is arranged in the combustion chamber, and the arch bridge is built by fireproof materials. The heat for calcining the annular lime shaft kiln is provided by a burner, fuel is injected into a combustion chamber through the burner, high-temperature gas generated by combustion enters a material layer through a space which is formed at the lower part of the arch bridge and is communicated with the combustion chamber, and the heat is provided for calcining in the kiln body 1.
The following will briefly explain the flow of the material in the kiln body 1, in particular in the preheating zone 21, the upper counter-current calcining zone 23, the middle counter-current calcining zone 25, the lower non-flow conditioning zone 27 and the cooling zone 28:
qualified limestone is weighed by a weighing hopper and then is loaded into a skip, a winch lifts the skip to the kiln top of an annular lime shaft kiln, the limestone in the skip is added into a distributing device 3 on the kiln top, and the limestone enters the kiln body 1 through the distributing device 3. Then, the material, limestone in this embodiment, passes through a preheating zone 21, an upper countercurrent calcining zone 23, a middle countercurrent calcining zone 25, a lower non-flow conditioning zone 27 and a cooling zone 28 in the kiln body 1, then enters a kiln bottom bin, finally is discharged out of the kiln, and is conveyed to a finished product bin for storage by a conveyor.
The combustion flue gas of the lower combustion chamber 42 flows upward into the middle counter-current calcination zone 25 due to the suction of the main exhaust fan and is mixed with the combustion flue gas of the upper combustion chamber 40 near the upper arch bridge 50 and then enters the upper counter-current calcination zone 23 together. Since in both calciner zones the combustion gas flow is in the opposite direction to the running direction of the material, it is called counter-current calciner zone.
The calcination degree is already high (about 70% -90%) when the material flows down to the bottom of the middle counter-current calcination zone 25. While continuing down to the lower, non-flowing conditioning belt 27, no flue gas continues to provide heat thereto, but continues to create time and space conditions for the materials to decompose and condition gently, depending on the heat contained in the materials themselves, thereby enabling the production of highly reactive lime.
After the high-temperature flue gas combusted in the upper combustion chamber 40 and the lower combustion chamber 42 flows through the material layer and provides heat for decomposing the limestone, the flue gas flows upwards under the action of the main smoke exhaust fan, fully enters the preheating zone 21 and exchanges heat with the limestone in the preheating zone 21, and the temperature of the flue gas reaching the top of the kiln body 1 is 90-120 ℃. The flue gas at the top of the preheating zone 21 is uniformly sucked into the flue gas settling tube through the flue gas suction port and enters the main flue gas exhaust fan in a stepping manner.
Below the layer cooling air outlet 72 in the annular channel 2 is the cooling belt 28. The annular lime shaft kiln of the embodiment further comprises an ash discharging platform 8 and an ash discharging machine 81 positioned on the ash discharging platform, wherein 1 self-suction type material layer cooling air inlet pipe 70 is arranged at the bottom of the ash discharging platform 8, external air (called cooling air) is sucked into a kiln bottom bin (not shown) by utilizing the negative pressure of the kiln body 1, and flows through the ash discharging machine 8 to enter the cooling belt 28. After heat exchange between cooling air and burnt lime, the temperature is raised to about 400 ℃.
In the lower non-flow conditioning zone 27, each bed cooling air outlet 72 is drawn by 1 variable frequency controlled bed cooling fan 76, drawing preheated cooling air out as combustion air for the lower burner 43. The temperature of the lime after the calcination is reduced to about 100 ℃ after passing through the cooling belt 28, and the lime enters a kiln bottom bin for storage through an ash discharger 81.
The following describes the combustion of gas and combustion air in the kiln body 1:
gas from a gas platform (not shown) enters 18 burners up and down. The amounts of fuel supplied from the upper burner 41 and the lower burner 43 are different, and the distribution ratio is about: up/down=1/1.8. The combustion air of the upper burner 41 comes from the cooling air of the inner cylinder 10, specifically, the ambient air blown out by the inner cylinder cooling fan enters the inner cylinder 10, the steel shell of the inner cylinder is cooled, the self temperature of the air is preheated to about 200 ℃, then the air is discharged from 9 inner cylinder cooling air outlets 62 at the top of the inner cylinder, and is collected by an inner cylinder cooling air branch pipe 64 and an inner cylinder cooling air ring pipe 66, and most of the air enters combustion air branch pipes (not shown) of the 9 upper burners 41 to be used as the combustion air of the upper combustion chamber 40. A small portion of the excess cooling air is vented to the atmosphere through a bleed duct (not shown) in the inner barrel cooling air collar 66.
In the upper combustion chamber 40, the gas and the air are sufficiently combusted, and the excess air ratio is slightly different according to the heat value of the gas, and when the blast furnace gas is used, the excess air ratio of the present embodiment is controlled to be 1.2.
The combustion air of the lower burner 42 comes from the cooling air after cooling the lime. As previously described, 9 independently controlled and regulated bed cooling fans 76 draw the preheated cooling air from the cooling zone 28 as combustion air for the lower burner tip 42. In the lower combustion chamber 42, the gas and the air are also fully combusted, and the excess air ratio is slightly different according to the heat value of the gas, and when the blast furnace gas is used, the excess air system of the present embodiment is also controlled to be 1.2.
Compared with the prior art, the invention has the following technical effects:
1) The annular lime shaft kiln can finish countercurrent calcination and non-flow tempering in the same annular space, so that high-quality active lime can be stably produced;
2) The gas has high adaptability and can adopt the lowest heating value of 3000 kJ/Nm 3 The blast furnace gas of (2) can also adopt high-heat-value high-rotation mixed gas, converter gas, coke oven gas, natural gas and other gas fuels and coal and other solid fuels, and can also adopt gas-coal dual-fuel mixed combustion if necessary;
3) The energy consumption is lower: the fuel gas and air in the upper combustion chamber and the lower combustion chamber are independently regulated according to respective temperature control requirements and are completely combusted, and the fuel gas burn-out rate is extremely high; in addition, the waste heat of the inner cylinder cooling wind, the material layer cooling wind and the like is fully utilized;
4) After the kiln tail gas is dedusted by a cloth bag, the discharge of waste gas particles can reach less than or equal to 10mg/Nm 3 The environment-friendly performance is good; particularly, the annular lime shaft kiln has the advantages that cold air is not required to be added before the flue gas enters the dust remover due to low flue gas discharge temperature, so that on one hand, the power consumption is reduced, on the other hand, the filtering wind speed in the dust remover can be reduced, the service life of a cloth bag is further prolonged, and the dust removal efficiency is ensured;
6) Extremely low NOx emission index: firstly, the upper combustion chamber and the lower combustion chamber adopt a fuel/air staged combustion mode; secondly, a low NOx burner is adopted to form a local smoke reflux zone in the combustion chamber, so that the oxygen concentration of the combustion space is reduced, and the reduction condition of NOx is created; furthermore, due to the existence of the smoke backflow area, the temperature distribution in the combustion chamber is relatively uniform, the peak flame temperature is reduced, and the generation of thermal NOx is inhibited. Thus, the kiln strictly ensures that NOx emissions are well below 100mg/Nm 3 (in NO) 2 Counting);
7) The kiln body equipment is simple, and the equipment failure rate is low;
8) The production process of the annular lime shaft kiln under the negative pressure operation well reduces pollution to the surrounding environment caused by kiln operation, improves the working environment of operators, is convenient for the operators to grasp the working condition of the equipment of the whole kiln system, is convenient for equipment inspection, maintenance and repair work, can timely find potential faults for normal production, and ensures the quality of active lime;
9) The upper arch bridge and the lower arch bridge of the annular lime shaft kiln and the lower arch bridge and the distributing plate above the ash discharging machine are arranged in a staggered manner, so that materials entering the kiln are laterally redistributed at a certain angle for multiple times in the downward movement process, namely secondary distribution, the distribution of the materials is more uniform, and the heating uniformity of the materials is improved.
While the technical content and features of the present invention have been disclosed above, it will be understood that various changes and modifications to the above-described structure, including combinations of technical features individually disclosed or claimed herein, and other combinations of these features as apparent to those skilled in the art may be made under the inventive concept of the present invention. Such variations and/or combinations fall within the technical field to which the invention relates and fall within the scope of the claims of the invention.
Claims (8)
1. An annular lime shaft kiln, comprising:
the kiln body is provided with an inner cylinder and an outer cylinder which are concentrically arranged, and an annular channel is formed between the inner cylinder and the outer cylinder;
the distributing device is arranged at the upper end of the annular channel;
a plurality of upper combustion chambers and a plurality of lower combustion chambers which are vertically spaced apart along the outer circumference of the outer tub;
the upper burners and the lower burners are respectively arranged on the upper combustion chambers and the lower combustion chambers in a one-to-one correspondence manner;
the upper arch bridges and the lower arch bridges are positioned between the outer cylinder and the inner cylinder and are used for connecting the upper combustion chambers and the lower combustion chambers with the inner cylinder in a one-to-one correspondence manner;
the inner cylinder cooling air system comprises an inner cylinder cooling air inlet pipe and a plurality of inner cylinder cooling air outlets which are positioned on the inner cylinder and correspond to the upper burners one by one, and the inner cylinder cooling air system is arranged so that cooling air flows in from the bottom of the inner cylinder and flows out from the top of the inner cylinder;
the material layer cooling air system comprises a material layer cooling air inlet pipe and a plurality of material layer cooling air outlets which are positioned on the outer cylinder and correspond to the lower burners one by one, and the material layer cooling air system is arranged to enable cooling air to cool the material layer calcined in the annular channel;
the annular channel is composed of a preheating zone arranged between the distributor and the top of the inner cylinder, an upper countercurrent calcining zone arranged between the top of the inner cylinder and the plurality of upper combustion chambers, a middle countercurrent calcining zone arranged between the plurality of upper combustion chambers and the plurality of lower combustion chambers, a lower no-flow conditioning zone arranged between the plurality of lower combustion chambers and the plurality of material layer cooling air outlets and a cooling zone arranged below the plurality of material layer cooling air outlets from top to bottom.
2. The annular lime shaft kiln of claim 1, wherein the inner barrel cooling air system further comprises at least one inner barrel cooling fan, a plurality of inner barrel cooling air branch pipes and an inner barrel cooling air ring pipe, wherein the inner barrel cooling fan is connected with the inner barrel cooling air inlet pipe for feeding cooling air into the inner barrel, one ends of the plurality of inner barrel cooling air branch pipes are connected to the plurality of inner barrel cooling air outlets in a one-to-one correspondence manner, the other ends of the plurality of inner barrel cooling air branch pipes are communicated with the inner barrel cooling air ring pipe, and the inner barrel cooling air ring pipe is communicated with the plurality of upper burners to provide combustion air for the plurality of upper burners.
3. The annular lime shaft kiln according to claim 1 or 2, wherein the plurality of layer cooling air outlets are connected to a plurality of layer cooling air outlet branch pipes in one-to-one correspondence, the layer cooling air system further comprising a plurality of layer cooling fans in one-to-one correspondence with the plurality of layer cooling air outlet branch pipes and for sucking the cooling air after heat exchange in the cooling zone into a plurality of layer cooling air outlet branch pipes in one-to-one correspondence with the plurality of lower burners to supply combustion air thereto.
4. The annular lime shaft kiln of claim 3, further comprising a primary flue gas fan system for drawing flue gas outwardly from the preheating zone, the primary flue gas fan system comprising a flue gas suction port located on top of the outer barrel, a flue gas settling tube in communication with the flue gas suction port, and a primary flue gas fan in communication with the flue gas settling tube, wherein the primary flue gas fan and the plurality of bed cooling fans are arranged such that negative pressure within the plurality of lower combustion chambers is consistent with negative pressure at the plurality of bed cooling air outlets such that no air flow occurs within the lower non-flow conditioning zone.
5. The annular lime shaft kiln of claim 4, wherein the plurality of upper combustion chambers and the plurality of lower combustion chambers are configured to substantially combust gas with the combustion air therein.
6. The annular lime shaft kiln of claim 1, wherein the plurality of upper combustion chambers and the plurality of lower combustion chambers each employ a fuel/air staged combustion approach and/or wherein the plurality of upper burners and the plurality of lower burners each employ a low NOx burner.
7. The annular lime shaft kiln of claim 1, further comprising an ash discharge platform and an ash discharge machine positioned on the ash discharge platform, wherein the material layer cooling air inlet pipe is arranged at the bottom of the ash discharge platform and sucks external air into the kiln body by utilizing negative pressure in the kiln body.
8. The annular lime shaft kiln of claim 7, further comprising a plurality of divider plates positioned above the ash ejector, wherein the upper arch bridges and the lower arch bridges, and the lower arch bridges and the divider plates are offset.
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| CN109160749B (en) * | 2018-11-09 | 2021-06-15 | 余松涛 | A kind of internal circulation fine particle lime shaft kiln and its calcining method |
| CN109437605A (en) * | 2018-12-11 | 2019-03-08 | 南京钢铁股份有限公司 | A kind of building method of LIME DOUBLE D kiln interface channel |
| CN109574522B (en) * | 2018-12-25 | 2024-06-21 | 石家庄新华能源环保科技股份有限公司 | Sleeve kiln combustion system |
| CN110981229A (en) * | 2019-12-26 | 2020-04-10 | 余松涛 | A kind of ring-shaped shaft kiln and mixed-burning lime calcining method |
| EP4111118B1 (en) * | 2020-02-25 | 2024-01-03 | Maerz Ofenbau AG | Device and method for firing and/or calcining lumpy goods |
| TWI817086B (en) * | 2020-02-26 | 2023-10-01 | 瑞士商邁爾茲歐芬堡公司 | Method for burning carbon-containing material in a pfcfr shaft kiln |
| CN112146447B (en) * | 2020-09-15 | 2022-08-19 | 广西柳州钢铁集团有限公司 | Method for preventing ash spraying of air release valve of double-hearth kiln |
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| CA2098861A1 (en) * | 1992-06-23 | 1993-12-24 | Yasuo Ohtani | Calcination furnace |
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| EP1669709A1 (en) * | 2004-12-13 | 2006-06-14 | Terruzzi Fercalx S.p.A. | Beams for kilns processing lumpy materials |
| CN101592436B (en) * | 2009-07-02 | 2010-09-29 | 江苏中圣园科技股份有限公司 | Three-cylinder concentric shaft kiln |
| CN201449130U (en) * | 2009-07-16 | 2010-05-05 | 南京中圣园机电设备有限公司 | Exhaust recirculating calcining kiln |
| CN203284334U (en) * | 2013-03-07 | 2013-11-13 | 上海宝冶建设工业炉工程技术有限公司 | Energy-saving twin-tube vertical lime kiln |
| CN204612446U (en) * | 2015-04-10 | 2015-09-02 | 武汉艾蒙窑炉技术有限公司 | The roasting shaft kiln of integral type bulk material |
| CN206751666U (en) * | 2017-05-17 | 2017-12-15 | 江苏中圣园科技股份有限公司 | Annular lime shaft kiln |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CA2098861A1 (en) * | 1992-06-23 | 1993-12-24 | Yasuo Ohtani | Calcination furnace |
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