CN117904378A - Method for lowering burden surface of blast furnace during shutdown - Google Patents
Method for lowering burden surface of blast furnace during shutdown Download PDFInfo
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- CN117904378A CN117904378A CN202410080927.4A CN202410080927A CN117904378A CN 117904378 A CN117904378 A CN 117904378A CN 202410080927 A CN202410080927 A CN 202410080927A CN 117904378 A CN117904378 A CN 117904378A
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- 238000000034 method Methods 0.000 title claims abstract description 58
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 claims abstract description 130
- 239000007789 gas Substances 0.000 claims abstract description 87
- 229910002092 carbon dioxide Inorganic materials 0.000 claims abstract description 66
- 239000001569 carbon dioxide Substances 0.000 claims abstract description 62
- 239000000463 material Substances 0.000 claims abstract description 46
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 42
- 239000000571 coke Substances 0.000 claims abstract description 41
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 29
- 230000008569 process Effects 0.000 claims abstract description 27
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 26
- 239000001301 oxygen Substances 0.000 claims abstract description 26
- 239000007788 liquid Substances 0.000 claims abstract description 24
- 229910052739 hydrogen Inorganic materials 0.000 claims abstract description 16
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims abstract description 14
- 239000001257 hydrogen Substances 0.000 claims abstract description 14
- 238000003723 Smelting Methods 0.000 claims abstract description 5
- 238000005507 spraying Methods 0.000 claims abstract description 3
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 58
- 239000002893 slag Substances 0.000 claims description 46
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 38
- 229910052742 iron Inorganic materials 0.000 claims description 29
- 229910052757 nitrogen Inorganic materials 0.000 claims description 22
- 229910002091 carbon monoxide Inorganic materials 0.000 claims description 17
- 239000011572 manganese Substances 0.000 claims description 15
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 14
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 claims description 13
- 229910052748 manganese Inorganic materials 0.000 claims description 13
- 239000007921 spray Substances 0.000 claims description 12
- 239000003245 coal Substances 0.000 claims description 11
- 238000001816 cooling Methods 0.000 claims description 10
- 239000000203 mixture Substances 0.000 claims description 9
- WYTGDNHDOZPMIW-RCBQFDQVSA-N alstonine Natural products C1=CC2=C3C=CC=CC3=NC2=C2N1C[C@H]1[C@H](C)OC=C(C(=O)OC)[C@H]1C2 WYTGDNHDOZPMIW-RCBQFDQVSA-N 0.000 claims description 7
- WUKWITHWXAAZEY-UHFFFAOYSA-L calcium difluoride Chemical compound [F-].[F-].[Ca+2] WUKWITHWXAAZEY-UHFFFAOYSA-L 0.000 claims description 7
- 239000010436 fluorite Substances 0.000 claims description 7
- 239000000377 silicon dioxide Substances 0.000 claims description 7
- 230000003247 decreasing effect Effects 0.000 claims description 6
- 230000003014 reinforcing effect Effects 0.000 claims description 6
- 238000007664 blowing Methods 0.000 claims description 5
- 238000013016 damping Methods 0.000 claims description 5
- 239000011261 inert gas Substances 0.000 claims description 5
- 230000003068 static effect Effects 0.000 claims description 5
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims description 4
- 238000004364 calculation method Methods 0.000 claims description 4
- 229910052593 corundum Inorganic materials 0.000 claims description 4
- 238000002360 preparation method Methods 0.000 claims description 4
- 230000001105 regulatory effect Effects 0.000 claims description 4
- 229910001845 yogo sapphire Inorganic materials 0.000 claims description 4
- 229910000831 Steel Inorganic materials 0.000 claims description 3
- 238000009826 distribution Methods 0.000 claims description 3
- 238000002347 injection Methods 0.000 claims description 3
- 239000007924 injection Substances 0.000 claims description 3
- 239000008188 pellet Substances 0.000 claims description 3
- 239000010959 steel Substances 0.000 claims description 3
- 238000003466 welding Methods 0.000 claims description 3
- 230000002706 hydrostatic effect Effects 0.000 claims description 2
- 238000006243 chemical reaction Methods 0.000 abstract description 8
- 210000001015 abdomen Anatomy 0.000 abstract description 5
- 239000003034 coal gas Substances 0.000 abstract description 5
- 230000009467 reduction Effects 0.000 abstract description 4
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- KAKZBPTYRLMSJV-UHFFFAOYSA-N Butadiene Chemical compound C=CC=C KAKZBPTYRLMSJV-UHFFFAOYSA-N 0.000 description 2
- 238000010009 beating Methods 0.000 description 2
- 239000003153 chemical reaction reagent Substances 0.000 description 2
- 238000004140 cleaning Methods 0.000 description 2
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- RNFJDJUURJAICM-UHFFFAOYSA-N 2,2,4,4,6,6-hexaphenoxy-1,3,5-triaza-2$l^{5},4$l^{5},6$l^{5}-triphosphacyclohexa-1,3,5-triene Chemical compound N=1P(OC=2C=CC=CC=2)(OC=2C=CC=CC=2)=NP(OC=2C=CC=CC=2)(OC=2C=CC=CC=2)=NP=1(OC=1C=CC=CC=1)OC1=CC=CC=C1 RNFJDJUURJAICM-UHFFFAOYSA-N 0.000 description 1
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 239000003063 flame retardant Substances 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 238000002309 gasification Methods 0.000 description 1
- DALUDRGQOYMVLD-UHFFFAOYSA-N iron manganese Chemical compound [Mn].[Fe] DALUDRGQOYMVLD-UHFFFAOYSA-N 0.000 description 1
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Abstract
The invention relates to the technical field of blast furnace smelting, in particular to a method for reducing a material level of a blast furnace during shutdown, which comprises the following steps: in the process of lowering the material level, the liquid carbon dioxide is sprayed on the furnace top to control the temperature of the furnace top to be below 350 ℃, and meanwhile, the volume percentage of the carbon dioxide in the furnace is kept to be more than or equal to 35%, the volume percentage of the hydrogen is kept to be less than or equal to 4%, and the volume percentage of the oxygen is kept to be less than or equal to 1%. According to the invention, the liquid carbon dioxide is sprayed out of the furnace top to replace furnace top water spraying, so that the generation of hydrogen can be stopped; meanwhile, in the whole material level descending process, the volume percentage of carbon dioxide is kept above 35%, water and coke water gas reaction does not exist in the ore reduction stage, the oxygen content of the material level is very low, and the probability of gas knocking can be greatly reduced by reaching < 0.5%; and secondly, even if the material level is lowered below the furnace belly, the air and oxygen excess stage is carried out, but the density of the oxygen is very light, the oxygen can quickly float upwards, and the carbon dioxide can quickly sink, so that the carbon dioxide is covered on the surface of the furnace burden, and the combustion of the coal gas is prevented.
Description
Technical Field
The invention relates to the technical field of blast furnace smelting, in particular to a method for stopping a blast furnace and lowering a material level.
Background
At present, the design furnace age of the blast furnace is 15-20 years, and after the production reaches a certain period, the blast furnace needs to be shut down for overhaul. In the prior art, a blank line method is generally adopted for blast furnace shutdown, namely: the proportion of ore and fuel is greatly reduced in the blast furnace, the feeding is stopped, the blast furnace continues to supply air, so that coke at the lower part of the blast furnace is gradually burned off, the ore is gradually melted in the descending process, the blast furnace burden is gradually moved downwards, and the space of the blast furnace is gradually emptied from top to bottom, so that the whole space above a blast furnace tuyere is vacated. In the process of blowing out, the temperature of the furnace top is controlled by adopting the water-taking and air quantity of the furnace top, and when the material line is lowered to the vicinity of the air port, the blowing-out is carried out.
However, the empty-line method has the following disadvantages: first, during a stove top water stroke, if the water does not evaporate rapidly, water gas reactions will occur as the water droplets encounter the hot coke, i.e., 2h 2O＝2H2+O2(1),2C+O2 =2co (2). The hydrogen and oxygen generated by water decomposition are blown off the surface of the coke layer by the lower air blast, so that the water gas reaction of water beating at the top of the furnace is substantially carried out only to generate hydrogen and oxygen by the water decomposition reaction of the first step, the second step is difficult to carry out, so that the gas contains a large amount of hydrogen and oxygen, the more water falls on the surface of the coke layer, the higher the volume percentage of hydrogen and oxygen contained in the gas is, the more explosion is easily generated, and the safety is not well ensured in the furnace shutdown process. Secondly, when the material surface enters the furnace belly, the ore reduction reaction is gradually stopped, the air permeability of the furnace burden is improved, and part of O 2 in the wind enters the gas layer through the material layer to be burnt with CO and H 2 in the gas. The larger the air quantity is, the faster the gas flow velocity is, and the more O 2 enters a gas layer, the more easily the gas explosion occurs, and the safety of the furnace shutdown process is affected. This is in fact the main reason for affecting the safety of the furnace shutdown process. In the past furnace shutdown process, the main avoidance measure is that the material surface enters the furnace belly to directly cut the coal gas. The method has the defects that the gas cutting time is too early, the gas recovery is affected, the material level is too high, the cleaning workload after the furnace is cut off is large, and the surrounding environment is greatly affected. Therefore, the prior technical scheme of empty-line furnace shutdown has strict technical requirements on the volume percentage of hydrogen and the volume percentage of oxygen in the furnace shutdown process, and once the volume percentage of oxygen and hydrogen exceeds the standard in the furnace shutdown process, a fully-opened or semi-opened furnace top discharge valve is needed to directly discharge the gas in the furnace into the atmosphere, and a large amount of overflowed smoke dust, gas, dust particles and noise reach the surrounding range of about 5 km, so that the surrounding environment is polluted.
Disclosure of Invention
Therefore, the invention aims to overcome the defects that the existing empty-stockline method is high in hydrogen and oxygen content in gas, easy to knock and the cut gas pollutes the surrounding environment prematurely, thereby providing a method for solving the problems in the blast furnace shutdown material level.
In order to achieve the above purpose, the present invention provides the following technical solutions:
A method for blowing out and lowering a charge level of a blast furnace, comprising the following steps: in the process of lowering the material level, the liquid carbon dioxide is sprayed on the furnace top to control the temperature of the furnace top to be below 350 ℃, and meanwhile, the volume percentage of the carbon dioxide in the furnace is kept to be more than or equal to 35%, the volume percentage of the hydrogen is kept to be less than or equal to 4%, and the volume percentage of the oxygen is kept to be less than or equal to 1%.
Preferably, the flow of carbon dioxide entering from the material level lowering process is obtained by the following calculation formula: the flow rate of carbon dioxide t/h = molar volume constant x [ Q gas x (CO% + CO 2％×2+O2% ×2) ×1000/molar volume constant-2 x (Q gas x N 2％-Q External nitrogen )/79% ×0.21×1000/molar volume constant ]/2/1000 x 2/1000, wherein Q gas is the blast furnace top gas volume, CO% is the measured volume percent of CO in the top gas composition, CO 2% is the measured volume percent of CO 2 in the top gas composition, O 2% is the measured volume percent of O 2 in the top gas composition, N 2% is the measured volume percent of N 2 in the top gas composition, Q External nitrogen is the flow rate of nitrogen in the furnace shaft hydrostatic system.
Preferably, after the material level is lowered to below the central line of the tuyere, the last furnace iron is discharged until the blast furnace is down;
and/or, the material level is lowered before the preliminary preparation work is carried out.
Preferably, the preliminary preparation work includes the steps of:
(1) Before the material is dropped in the furnace, the edge load is gradually reduced, and meanwhile, the water flow of the cooling wall is reduced so as to wash the furnace wall;
(2) The coke load, the molten iron temperature and the slag components are regulated, so that the slag alkalinity is slowly reduced, the molten iron temperature is slowly increased, and the blast furnace gas flow distribution is gradually regulated to be close to the state during the shutdown period;
(3) Charging and stopping furnace materials;
(4) Pre-damping down.
Preferably, in the step (1), the edge load and the cooling wall water flow are gradually reduced in six steps three days before the furnace is shut down and the material level is lowered;
And/or, the edge load is reduced to 1.3-1.5;
And/or the stave water flow rate is reduced to 3700-3900m 3/h.
Preferably, in the step (2), coke load, coke breeze and coal ratio are gradually reduced in six steps, and manganese ore, fluorite, silica and serpentine are simultaneously added to adjust iron slag components; wherein the coke load is gradually reduced from 5.1 to 5.5 to 2.8 to 3.2, the coke consumption is gradually increased from 350 to 370kg/t to 460 to 540kg/t, the coal ratio is gradually decreased from 170 to 190kg/t to below 60kg/t, and the amount of the coke breeze is gradually reduced from 1.1 to 1.3t to 0t; the mass percentage of si in the molten iron is controlled to be gradually increased from 0.35-0.45% to 0.85-0.95%, the mass percentage of manganese is gradually increased from less than 0.1% to 0.35-0.45%, the temperature of the molten iron is more than or equal to 1500 ℃, the alkalinity of slag is gradually decreased from 1.10-1.20 to 0.93-0.97%, the content of Al 2O3 in the slag is gradually decreased from 15.2-15.8% to 13.9-14.1%, and the content of MgO/Al 2O3 is gradually increased from 0.45-0.55 to 0.55-0.65.
Preferably, in the step (3), the furnace stopping structure requires that the sum of the proportion of lump ore and pellets is not more than 20%, wherein the proportion of lump ore is not more than 10%, coal injection is stopped, full coke smelting is performed, and the coke load is less than 3.0 and Jiao Hao >600kg/t; adding manganese ore, fluorite, silica and serpentine to adjust the iron slag component; wherein, the mass percentage of si in the molten iron is controlled to be 0.95-1.05%, the mass percentage of manganese is more than or equal to 0.4%, the temperature of the molten iron is more than or equal to 1500 ℃, the alkalinity of slag is less than 0.95, and the Al 2O3≤15.0％,MgO/Al2O3 in the slag is more than or equal to 0.55; and after the last batch of stopping materials are distributed, covering the coke surface by water slag.
Preferably, the weight of the water slag is calculated according to the formula m=pi d 2 δρ/4 when the material level is reduced to the waist, wherein m is the weight of the water slag, pi is 3.1415, d is the diameter of the waist, δ is the thickness of the water slag on the waist, and ρ is the density of the water slag;
and/or the thickness of the water slag at the waist is not less than 300mm.
Preferably, the specific process of pre-damping down in the step (4) is as follows:
① Installing a furnace top liquid spraying carbon dioxide system, wherein the number of spray guns is at least 8, and the maximum flow rate of the spray guns is more than or equal to 67t/h;
② Overhauling a static pressure hole of the furnace body, and introducing inert gas;
③ Checking a furnace top large diffusing device, and welding, repairing and reinforcing a furnace shell;
④ Handling damaged cooling equipment and replacing a water leakage tuyere small sleeve;
⑤ Modifying a stock rod encoder, lengthening the stock rod, and reinforcing the stock rod steel wire rope connector;
⑥ And checking a radar trial rod.
Preferably, the maximum flow rate of the spray gun is 1/n of the maximum flow rate of the required liquid carbon dioxide, n is the number of spray guns, and the maximum flow rate of the required liquid carbon dioxide is calculated according to the maximum volume percent of the carbon dioxide in the coal gas as 50 percent.
In the invention, the flow calculation method of the carbon dioxide externally fed in the process of stopping the furnace and lowering the material level is as follows: assuming the gas quantity at the top of the blast furnace is Q gas, the air quantity of the blast furnace is Q air quantity, and according to nitrogen balance: if the inert gas is introduced into the furnace body static pressure system, the formula of nitrogen balance can be converted into Q air volume multiplied by 79% + Q External nitrogen =Q gas multiplied by N 2%, wherein the Q gas volume can be obtained through a furnace top gas flow meter, N 2% is the volume percent of N 2 in the measured furnace top gas component, and Q External nitrogen is the flow of nitrogen in the furnace body static pressure system and can be detected through the flow meter;
1) First, the number of moles of oxygen atoms taken into the furnace from the wind=2×q air volume×0.21×1000/mole volume constant=2× (Q gas×n 2％-Q External nitrogen )/79% ×0.21×1000/mole volume constant is calculated;
2) According to the oxygen balance, the mole number of oxygen atoms brought into the furnace by wind+the mole number of oxygen brought by liquid carbon dioxide outside the furnace=the mole number of O atoms brought by CO+CO 2+O2 in the gas=Q gas× (CO% +CO 2％×2+O2%. Times.2). Times.1000/mole volume constant, wherein CO% is the measured volume percent of CO in the top gas component, CO 2% is the measured volume percent of CO 2 in the top gas component, and O 2% is the measured volume percent of O 2 in the top gas component;
3) The flow rate of carbon dioxide introduced from outside t/h=molar volume constant× [ (the number of moles of O atoms carried by co+co 2+O2 in gas) -the number of moles of oxygen atoms carried into the furnace by wind ]/2/1000×2/1000. In summary, the flow rate of carbon dioxide t/h=molar volume constant× [ Q gas× (CO% +co 2％×2+O2% ×2) ×1000/molar volume constant-2× (Q gas×n 2％-Q External nitrogen )/79% ×0.21×1000/molar volume constant ]/2/1000×2/1000. Wherein 0.5m 3 gas is produced from 1kg liquid carbon dioxide.
The technical scheme of the invention has the following advantages:
1. A method for blowing out and lowering a charge level of a blast furnace, comprising the following steps: in the process of lowering the material level, the liquid carbon dioxide is sprayed on the furnace top to control the temperature of the furnace top to be below 350 ℃, and meanwhile, the volume percentage of the carbon dioxide in the furnace is kept to be more than or equal to 35%, the volume percentage of the hydrogen is kept to be less than or equal to 4%, and the volume percentage of the oxygen is kept to be less than or equal to 1%. According to the invention, by simulating the principle of a carbon dioxide fire extinguisher, liquid carbon dioxide is sprayed out of the furnace top and the lower coal stopping is combined to replace the furnace top water taking, so that the generation of hydrogen can be stopped; meanwhile, in the whole material level descending process, the volume percentage of the carbon dioxide is kept above 35%, on one hand, because the carbon dioxide has higher density and is about 1.5 times of air, liquid carbon dioxide sprayed out of the furnace top can be immediately vaporized to replace gas in the furnace and cover the surface of the furnace burden, the oxygen concentration on the surface of the furnace burden is reduced, and the choking effect is generated so as to prevent knocking; on the other hand, when the liquid carbon dioxide is sprayed out of the storage container, the liquid is quickly vaporized into gas, and part of heat is sucked from the periphery to play a role of cooling, so that the temperature of the top gas and the surface temperature of the furnace burden are reduced. Compared with the traditional furnace top water-beating material-lowering surface, the method has the advantages that water and coke water gas reaction does not exist in the ore reduction stage, and the volume percentage of the material surface oxygen is very low and can reach <0.5%, so that the gas knocking probability is greatly reduced; and secondly, even if the material level is lowered below the furnace belly, the air and oxygen excess stage is carried out, but the density of the oxygen is very light, the oxygen can quickly float upwards, and the carbon dioxide can quickly sink, so that the carbon dioxide is covered on the surface of the furnace burden, and the combustion of the coal gas is prevented. Therefore, the method not only avoids the occurrence of gas knocking in the process of stopping the blast furnace by a blast furnace material dropping line, but also avoids the pollution of dust, waste gas and noise to the surrounding environment.
2. In the method for reducing the burden surface of the blast furnace in the shutdown of the blast furnace, in order to prevent the gasification reaction of carbon dioxide and coke, after the final batch of furnace stopping materials are distributed, the water slag is used for covering the surface of the coke, so that the volume percentage of carbon monoxide in the gas is reduced, the volume percentage of the carbon dioxide is improved, and the flame retardant effect of the carbon dioxide is fully exerted.
3. According to the method for reducing the burden surface of the blast furnace in the shutdown state, manganese ore is added, so that the mass percentage of Mn element in molten iron is increased to 0.35-0.45% (the mass percentage of normal molten iron manganese is about 0.2%), the lower slag alkalinity is controlled to be 0.93-0.97, the viscosity of slag iron is reduced, and smooth discharge of molten iron and slag is accelerated.
4. According to the method for reducing the material level of the blast furnace in the blowing-out process, the edge load is reduced in advance, the soft water flow of the cooling wall is reduced, the furnace wall is flushed, the regularity of the furnace in the blowing-out process is ensured, the fluctuation of the edge air flow and the fluctuation of the furnace temperature are reduced, the smooth running of the blowing-out process is ensured, and the cleaning work of slag skin of the furnace wall after the blowing-out is lightened.
5. In the method for blowing out the material level of the blast furnace, the whole process only needs to pre-blow down the blast furnace once, so that the blowing-out process of a material-dropping line of the blast furnace is optimized, and the blowing-out efficiency of the blast furnace is improved.
Detailed Description
The following examples are provided for a better understanding of the present invention and are not limited to the preferred embodiments described herein, but are not intended to limit the scope of the invention, any product which is the same or similar to the present invention, whether in light of the present teachings or in combination with other prior art features, falls within the scope of the present invention.
The specific experimental procedures or conditions are not noted in the examples and may be followed by the operations or conditions of conventional experimental procedures described in the literature in this field. The reagents or apparatus used were conventional reagent products commercially available without the manufacturer's knowledge.
In the embodiment 1-2 of the invention, the gas components during normal production are as follows: 24.34% CO, 22.35% CO 2、49.31％N2、3.51％H2、0.49％O2.
Example 1
The embodiment provides a method for reducing a material level of a blast furnace during the shutdown of the blast furnace, which comprises the following steps:
(1) The edge load is gradually reduced in six steps, and meanwhile, the water flow of the cooling wall is reduced to flush the furnace wall. The specific procedure is shown in Table 1:
TABLE 1
Wherein, edge load= (edge ore turns/edge coke turns) × (total coke turns/total ore turns) ×coke load; the blast furnace throat is divided into 11 equal-part rings by an equal-area method, namely 11 gears (11 at the outermost side and 1 at the innermost ring), wherein 11-9 gears belong to an edge area, 8-7 gears all belong to an annular area, and 6-1 gears belong to a central area.
(2) And (3) about three days before the furnace is shut down and the material level is lowered, coke load, molten iron temperature and slag components are adjusted, so that the slag alkalinity is slowly lowered, the molten iron temperature is slowly increased, and the blast furnace gas flow distribution is gradually adjusted to be close to the state during the furnace shutdown. Wherein, the coke load, the coke butadiene and the coal ratio are gradually reduced in six steps, and manganese ore, fluorite, silica and serpentine are added simultaneously to adjust the iron slag component, and the temperature of molten iron is 1510-1520 ℃; the specific procedures and data are shown in table 2:
TABLE 2
| First step | Second step | Third step | Fourth step | Fifth step | Sixth step | During the period of furnace shutdown | |
| Batch t/p | 70 | 67 | 63 | 60 | 57 | 54 | 51 |
| coke oven batch t/p | 13.4 | 13.6 | 13.9 | 14.3 | 14.9 | 17.1 | 20.3 |
| Jotin t/p | 1.1 | 1.1 | 0.5 | 0.5 | 0.25 | 0 | 0 |
| Coal amount t/h | 45 | 40 | 35 | 30 | 20 | 10 | 0 |
| Coke loading | 5.25 | 4.88 | 4.56 | 4.22 | 3.84 | 3.17 | 2.52 |
| Coal ratio kg/t | 176.3 | 156.3 | 149.2 | 127.3 | 84.7 | 42.3 | 0 |
| Coke consumption kg/t | 367 | 372 | 397 | 406 | 415 | 467 | 659 |
| Manganese ore t/p | 0.3 | 0.6 | 0.85 | 1 | 1.2 | 1.35 | 1.5 |
| Fluorite t/p | 0.1 | 0.2 | 0.3 | 0.4 | 0.6 | 0.8 | 0.8 |
| Silica t/p | 0.2 | 0.4 | 0.6 | 0.8 | 0.8 | 0.8 | 0.8 |
| Serpentine t/p | 0.1 | 0.2 | 0.3 | 0.4 | 0.5 | 0.6 | 0.7 |
| Basicity of slag | 1.132 | 1.085 | 1.040 | 1.025 | 0.982 | 0.966 | 0.861 |
| Al2O3％ | 15.28 | 14.94 | 14.65 | 14.64 | 14.10 | 14.10 | 14.03 |
| MgO％ | 7.69 | 7.82 | 7.97 | 7.96 | 8.34 | 8.51 | 8.52 |
| MgO/Al2O3 | 0.50 | 0.52 | 0.54 | 0.54 | 0.59 | 0.60 | 0.59 |
| Si％ | 0.4 | 0.5 | 0.6 | 0.7 | 0.8 | 0.9 | 1.0 |
| Mn％ | 0.08 | 0.15 | 0.23 | 0.27 | 0.32 | 0.36 | 0.47 |
(3) And adding a stopping furnace burden. The furnace stopping structure requires that the sum of the proportion of lump ore and pellets is 18%, wherein the proportion of lump ore is below 8%, coal injection is stopped, full coke smelting is performed, the coke load is below 3.0, and the coke consumption is above 600 kg/t; according to the current production situation, manganese ore, fluorite, silica and serpentine are added to adjust the iron slag component; wherein, the mass percentage of [ si ] in the molten iron is controlled to be 0.95-1.05%, the mass percentage of manganese is controlled to be 0.45-0.50%, the temperature of the molten iron is 1510-1520 ℃, the slag alkalinity is 0.85-0.90, the Al 2O3 is 14.0-14.5%, and the MgO/Al 2O3 is 0.55-0.60; and after the last batch of stopping materials are distributed, covering the coke surface by water slag. The weight of the grain slag is calculated by the formula m=pi d 2 δρ/4, wherein m is the weight of the grain slag (52.4 t), pi is 3.1415, d is the diameter of the furnace waist (13.5 m), δ is the thickness of the grain slag at the furnace waist (300 mm), ρ is the density of the grain slag (1220 kg/m 3), based on the thickness of the grain slag at the furnace waist being 300 mm.
(4) Pre-damping down. The specific process is as follows: ① The spray gun is provided with a spray-state carbon dioxide system at the top of the furnace, the number of spray guns is 8, and the maximum flow rate of the spray guns is 67t/h; ② Overhauling a static pressure hole of the furnace body, and introducing inert gas; ③ Checking a furnace top large diffusing device, and welding, repairing and reinforcing a furnace shell; ④ Handling damaged cooling equipment and replacing a water leakage tuyere small sleeve; ⑤ Modifying a stock rod encoder, lengthening the stock rod, and reinforcing the stock rod steel wire rope connector; ⑥ And checking a radar trial rod. Wherein the maximum flow rate of the spray gun is one eighth of the maximum flow rate of the required liquid carbon dioxide, and the maximum flow rate of the required liquid carbon dioxide is calculated according to the maximum volume percent of the carbon dioxide in the coal gas being 50 percent.
(5) And (5) stopping the furnace and lowering the material level. The liquid carbon dioxide is sprayed on the furnace top to control the temperature of the furnace top below 350 ℃, meanwhile, the volume percentage content of the carbon dioxide in the furnace is kept to be 50%, the furnace is stopped, the material level is lowered to below the center line of the tuyere, and the last iron discharge is completed until the blast furnace is down. The flow rate of the carbon dioxide which is externally introduced is calculated through nitrogen balance and oxygen balance.
The flow calculation method of the carbon dioxide externally fed in the process of stopping the furnace and lowering the material level is as follows:
Assuming the gas quantity at the top of the blast furnace is Q gas, the air quantity of the blast furnace is Q air quantity, and according to nitrogen balance: q air volume×79++q External nitrogen =q gas×n 2), wherein the amount of Q gas can be obtained by a top gas flow meter (the top gas generation amount is 560000m 3/h),N2% being the volume percentage content (35%) of N 2 in the measured top gas composition, the inert gas flow rate is 0m 3/h, and Q air volume= (Q gas×n 2％-Q External nitrogen )/79％＝248101.27m3/h≈248101m3/h is obtained by substitution;
1) Firstly, calculating the mole number of oxygen atoms brought into the furnace from wind=2×q wind quantity×0.21×1000/mole volume constant; substituting the Q air quantity of 248101.27m 3/h and the molar volume constant of 22.4L/mol into the furnace to obtain the molar number of oxygen atoms brought into the furnace by wind of 4651899mol/h;
2) According to the oxygen balance: the number of moles of oxygen atoms brought into the furnace by wind+the number of moles of oxygen brought into the liquid carbon dioxide=the number of moles of O atoms brought into the gas by co+co 2+O2 =q gas× (CO% +co 2％×2+O2% ×2) ×1000/mole volume constant; wherein, the mol number of O atoms carried by CO+CO 2+O2 in the gas is=560000× [14.4% +50% ×2+0.3% ×2] ×1000/22.4= 28750000mol/h, thereby obtaining the mol number of oxygen carried by liquid carbon dioxide= 28750000-4651899 = 24098101mol/h;
3) The flow rate of carbon dioxide introduced from outside t/h=molar volume constant× [ the number of moles of O atoms in co+co 2+O2 in gas-the number of moles of oxygen atoms introduced into the furnace by wind ]/2/1000×2/1000= 539.8t/h≡540t/h.
When the furnace is stopped by using carbon dioxide, the gas comprises the following components: 14.4% CO, 50% CO 2、35％N2、0.3％H2、0.3％O2. The specific furnace-down level control parameters are shown in table 3.
TABLE 3 Table 3
| CO2 | 50％ |
| Top gas production (m 3/h) | 560000 |
| Volume of nitrogen in gas (m 3/h) | 196000 |
| Air volume (m 3/h) | 248101 |
| Air volume (m 3/min) | 4135 |
| Molar volume constant (L/mol) | 22.4 |
| Mole number of oxygen atoms in wind (mol/h) | 4651899 |
| Mole number (mol/h) of O atoms in CO+CO2+O2 bands in gas | 28750000 |
| The number of moles of oxygen atoms (mol/h) | 24098101 |
| Carbon dioxide mole number (mol/h) of the external application | 12049051 |
| Carbon dioxide volume (m 3/h) of the external application | 269899 |
| Liquid carbon dioxide header flow (t/h) | 540 |
| Flow of single spray gun (t/h) | 67 |
The embodiment is safe and stable in furnace shutdown, water-gas reaction of water and coke does not exist in the ore reduction stage, gas knocking during the blast furnace material-dropping and furnace-shutting down process is avoided, and pollution of dust, waste gas and noise to the surrounding environment is avoided.
Example 2
This example differs from example 1 in that the volume percent of carbon dioxide in the furnace was maintained at 35% and the other conditions were as described in example 1.
In the embodiment, when the furnace is shut down by using carbon dioxide, the gas comprises the following components: 15.1% CO, 35% CO 2、49.3％N2、0.3％H2、0.3％O2. The specific furnace-down level control parameters are shown in table 4.
TABLE 4 Table 4
| CO2 | 35％ |
| Top gas production (m 3/h) | 450000 |
| Volume of nitrogen in gas (m 3/h) | 221850 |
| Air volume (m 3/h) | 280823 |
| Air volume (m 3/min) | 4680 |
| Molar volume constant (L/mol) | 22.4 |
| Mole number of oxygen atoms in wind (mol/h) | 5265427 |
| Mole number (mol/h) of O atoms in CO+CO2+O2 bands in gas | 17216518 |
| The number of moles of oxygen atoms (mol/h) | 11951091 |
| Carbon dioxide mole number (mol/h) of the external application | 5975545 |
| Carbon dioxide volume (m 3/h) of the external application | 133852 |
| Liquid carbon dioxide header flow (t/h) | 268 |
| Flow of single spray gun (t/h) | 33 |
The embodiment is safe and stable in furnace shutdown, water-gas reaction of water and coke does not exist in the ore reduction stage, gas knocking during the blast furnace material-dropping and furnace-shutting down process is avoided, and pollution of dust, waste gas and noise to the surrounding environment is avoided.
Comparative example 1
This comparative example differs from example 1 in that the volume percent of carbon dioxide in the furnace was maintained at 30% and the other conditions were as described in example 1.
In the comparative example, when the furnace is shut down by using carbon dioxide, the gas comprises the following components: 22% CO and 30% CO 2、33％N2、12％H2、3.0％O2. In the comparative example, CO 2 in blast furnace gas is not high in volume percentage, but the volume percentage of CO is more than 20%, the volume percentage of O 2 is more than or equal to 3.0%, the volume percentage of H 2 is more than 10%, a large amount of CO and H 2 are generated once the material level is lowered to the belly in a blast furnace closed container, and meanwhile, the explosion reaction of gas or hydrogen is extremely easy to occur due to the fact that the temperature above the material level is higher than 1000 ℃, so that the safety of the blast furnace is influenced.
It is apparent that the above examples are given by way of illustration only and are not limiting of the embodiments. Other variations or modifications of the above teachings will be apparent to those of ordinary skill in the art. It is not necessary here nor is it exhaustive of all embodiments. While still being apparent from variations or modifications that may be made by those skilled in the art are within the scope of the invention.
Claims (10)
1. A method for blowing out and lowering a charge level of a blast furnace, which is characterized by comprising the following steps: in the process of lowering the material level, the liquid carbon dioxide is sprayed on the furnace top to control the temperature of the furnace top to be below 350 ℃, and meanwhile, the volume percentage of the carbon dioxide in the furnace is kept to be more than or equal to 35%, the volume percentage of the hydrogen is kept to be less than or equal to 4%, and the volume percentage of the oxygen is kept to be less than or equal to 1%.
2. The method according to claim 1, wherein the flow of carbon dioxide introduced during the material level lowering is obtained by the following calculation formula: the flow rate of carbon dioxide t/h = molar volume constant x [ Q gas x (CO% + CO 2％×2+O2% ×2) ×1000/molar volume constant-2 x (Q gas x N 2％-Q External nitrogen )/79% ×0.21×1000/molar volume constant ]/2/1000 x 2/1000, wherein Q gas is the blast furnace top gas volume, CO% is the measured volume percent of CO in the top gas composition, CO 2% is the measured volume percent of CO 2 in the top gas composition, O 2% is the measured volume percent of O 2 in the top gas composition, N 2% is the measured volume percent of N 2 in the top gas composition, Q External nitrogen is the flow rate of nitrogen in the furnace shaft hydrostatic system.
3. The method according to claim 1 or 2, wherein after the material level is lowered below the tuyere center line, the last furnace iron is discharged until the blast furnace is down;
and/or, the material level is lowered before the preliminary preparation work is carried out.
4. A method according to claim 3, wherein the pre-preparation comprises the steps of:
(1) Before the material is dropped in the furnace, the edge load is gradually reduced, and meanwhile, the water flow of the cooling wall is reduced so as to wash the furnace wall;
(2) The coke load, the molten iron temperature and the slag components are regulated, so that the slag alkalinity is slowly reduced, the molten iron temperature is slowly increased, and the blast furnace gas flow distribution is gradually regulated to be close to the state during the shutdown period;
(3) Charging and stopping furnace materials;
(4) Pre-damping down.
5. The method according to claim 4, wherein in the step (1), the edge load and the cooling wall water flow rate are gradually reduced in six steps three days before the furnace is shut down and the material level is lowered;
And/or, the edge load is reduced to 1.3-1.5;
And/or the stave water flow rate is reduced to 3700-3900m 3/h.
6. The method according to claim 4 or 5, wherein in the step (2), coke load, coke breeze and coal ratio are gradually reduced in six steps while manganese ore, fluorite, silica and serpentine are added to adjust slag iron components; wherein the coke load is gradually reduced from 5.1 to 5.5 to 2.8 to 3.2, the coke consumption is gradually increased from 350 to 370kg/t to 460 to 540kg/t, the coal ratio is gradually decreased from 170 to 190kg/t to below 60kg/t, and the amount of the coke breeze is gradually reduced from 1.1 to 1.3t to 0t; the mass percentage of si in the molten iron is controlled to be gradually increased from 0.35-0.45% to 0.85-0.95%, the mass percentage of manganese is gradually increased from less than 0.1% to 0.35-0.45%, the temperature of the molten iron is more than or equal to 1500 ℃, the alkalinity of slag is gradually decreased from 1.10-1.20 to 0.93-0.97%, the content of Al 2O3 in the slag is gradually decreased from 15.2-15.8% to 13.9-14.1%, and the content of MgO/Al 2O3 is gradually increased from 0.45-0.55 to 0.55-0.65.
7. The method according to claim 5 or 6, wherein in the step (3), the furnace stopping structure requires that the sum of the proportion of lump ore and pellets is not more than 20%, wherein the proportion of lump ore is not more than 10%, coal injection is stopped, full coke smelting is performed, and coke load is <3.0, jiao Hao >600kg/t; adding manganese ore, fluorite, silica and serpentine to adjust the iron slag component; wherein, the mass percentage of si in the molten iron is controlled to be 0.95-1.05%, the mass percentage of manganese is more than or equal to 0.4%, the temperature of the molten iron is more than or equal to 1500 ℃, the alkalinity of slag is less than 0.95, and the Al 2O3≤15.0％,MgO/Al2O3 in the slag is more than or equal to 0.55; and after the last batch of stopping materials are distributed, covering the coke surface by water slag.
8. The method of claim 7, wherein the weight of the water slag is calculated by the formula m = pi d 2 δρ/4, where m is the weight of the water slag, pi is 3.1415, d is the diameter of the waist, δ is the thickness of the water slag at the waist, ρ is the density of the water slag, based on the thickness of the water slag when the charge level is lowered to the waist;
and/or the thickness of the water slag at the waist is not less than 300mm.
9. The method according to any one of claims 5 to 8, wherein the pre-damping down in step (4) is performed by:
① Installing a furnace top liquid spraying carbon dioxide system, wherein the number of spray guns is at least 8, and the maximum flow rate of the spray guns is more than or equal to 67t/h;
② Overhauling a static pressure hole of the furnace body, and introducing inert gas;
③ Checking a furnace top large diffusing device, and welding, repairing and reinforcing a furnace shell;
④ Handling damaged cooling equipment and replacing a water leakage tuyere small sleeve;
⑤ Modifying a stock rod encoder, lengthening the stock rod, and reinforcing the stock rod steel wire rope connector;
⑥ And checking a radar trial rod.
10. The method of claim 9, wherein the maximum flow rate of the lance is 1/n of the maximum flow rate of the desired liquid carbon dioxide, n being the number of lances, and the maximum flow rate of the desired liquid carbon dioxide being calculated as 50% of the highest volume percent of carbon dioxide in the gas.
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