KR100515042B1 - Waste gas recirculation type iron ore sintering apparatus and the method by using LNG - Google Patents

Abstract

The present invention relates to an exhaust gas circulating iron ore sintering apparatus and method using LNG to reduce the use of coke and the generation of pollutants by using the LNG as a clean gas in the iron ore sintering operation.

The present invention is an exhaust gas circulation type including a sintering machine bogie, a wind phase installed in the lower portion of the sintering machine bogie to suck air necessary for the sintering reaction, and a main exhaust pipe for sending the air sucked through the air phase to the electric dust collector. In the iron ore sintering apparatus, the main exhaust pipe is divided into a first main exhaust pipe, a second main exhaust pipe, a third main exhaust pipe, the exhaust gas of the second main exhaust pipe is a second electric dust collector and a second suction It is circulated by a blower and supplied to the exhaust gas collecting hood installed in the sintering machine balance light distribution unit, characterized in that the LNG collection hood is installed in the sintering machine balance light distribution unit.

In addition, the present invention is to operate by incorporating 1% or less of LNG into the air drawn into the sintered bed through the air phase in a state in which the coke is added to 2.9-3.2% of the cobalt added to complex, and the oxygen is enriched to 21-25%. It features.

Description

Waste gas recirculation type iron ore sintering apparatus and the method by using LNG}

The present invention relates to a flue gas circulating iron ore sintering apparatus using liquefied natural gas and a method thereof, in particular to the use of liquefied natural gas to reduce the use of coke and the generation of pollutants by using LNG as a clean gas in the iron ore sintering operation The present invention relates to an exhaust gas circulating iron ore sintering apparatus and a method thereof.

In general, in the sintering plant, as shown in FIG. 1, sintered raw materials including various iron ores and secondary raw materials and powdered coke are mixed and charged into the sintered raw material hopper 1 of the iron ore sintering machine 1-1. The raw material is charged to the sintering machine trolley 1-2 via the inclined plate 5 by the rotation of the drum feeder 4 over the bottom light which is first laid on the sintering machine trolley 1-2 through the bottom light hopper 3. do.

Subsequently, the surface of the sintered raw material is ignited in the ignition furnace 6, and a sintering reaction in which coke is burned in the sintered raw material layer 2 by air sucked downward from the wind phase 8 by the suction blower 7 is performed. The sintered ore is manufactured, and the air sucked through the wind phase 8 is collected in the electric dust collector 10 through the main exhaust pipe 9 and then discharged to the chimney 11.

In the case of a factory equipped with an environmental treatment equipment in the above process, as shown in Figure 2, once the exhaust gas and dust through the main exhaust pipe (9) in the heater 12, the DeNOx facility 13 and After passing through the DeSOx facility 14 is collected in the electric dust collector 10 and discharged to the chimney (11).

The exhaust gas generated in the sintering machine 1-1 is maintained at about 100 ° C. or less in the first half in the longitudinal direction of the sintering machine 1-1, and high temperature exhaust gas of up to 500 ° C. is generated in the second half on an average. The temperature of the gas discharged from the chimney 11 is about 150-200 ° C.

Meanwhile, as the coke is burned during the sintering process, sinter waste gas containing environmental pollutants such as SOx, NOx, CO ₂ gas and dust is discharged in large quantities. The technology to economically treat environmental pollutants emitted from the country is being actively researched.

In particular, a flue gas recycle sintering method that can significantly reduce the amount of sinter waste gas discharged by recycling the sintering machine flue gas has been in the spotlight. That is, in view of the fact that the exhaust gas recycle sintering method for recovering sensible heat of sintered flue gas reduces the total emission of sintered flue gas, many studies have been published or patented in the past decade for preventing environmental pollution.

The operation of sintering by circulating the exhaust gas as described above has the following problems.

First, the entire main exhaust pipe is divided into five parts for operation, with 1/5 of the exhaust gas circulation as it is, 2/5 of the exhaust gas discharge, and 3/5 of the exhaust gas after the deSOx treatment, Flue gas at the 4/5 point reduces the amount of exhaust gas and emission dust in the structure of exhaust gas circulation through the dust collector and exhaust gas at the 5/5 point, but it is necessary to extend the length of the sintering machine and reduce the layer thickness. Prerequisites are required, and in terms of energy reduction, there is a problem that only the effect of reducing Coke by about 8%.

Second, in the structure that covers the entire sintering machine with a hood, the exhaust gas flowing through the main exhaust pipe is reduced to almost 50%, and the total amount of SOx and NOx generation is also reduced, but the oxygen concentration is lowered. There is a problem that causes deterioration of the sinterability due to the increase in the concentration of water vapor.

Third, in the structure of dividing the entire main exhaust pipe into two parts, and installing a blower on the 2/2 point (light distribution part) and circulating gas at the position (later part of the sintering machine), productivity is improved, but in terms of suppressing flue gas generation There is a minor problem.

Fourth, in the structure of dividing the entire main exhaust pipe into two parts and installing and circulating a blower at the 2/2 point, the main concept of this equipment is sintering and cooling at the same time, so called 'On-Strand-Cooling'. The longer the time, there is a problem that the low-temperature reduction differentiation properties that adversely affect the sintered ore quality deteriorate.

The present invention has been made to solve the above-mentioned problems of the prior art, the exhaust gas circulation using LNG which can reduce the generation of SOx, NOx which is a pollutant, and prevent the environmental pollution by the use of LNG as a clean fuel It is an object of the present invention to provide an iron ore sintering apparatus and method thereof.

According to the present invention for achieving the above object, the sintering machine bogie to charge the raw material in the sinter raw material hopper, the air phase installed in the lower portion of the sintering machine bogie to suck the air required for the sintering reaction, and the air sucked through the air phase In the exhaust gas circulation type iron ore sintering apparatus comprising a main exhaust pipe sent to the electric dust collector, the main exhaust pipe is divided into a first main exhaust pipe, a second main exhaust pipe, a third main exhaust pipe, the second The exhaust gas of the main exhaust pipe is circulated by the second electrostatic precipitator and the second suction blower to be supplied to the exhaust gas collecting hood installed in the sintering unit balance light distribution unit, and the LNG collection hood is installed in the sintering unit balance light distribution unit. An exhaust gas circulating iron ore sintering apparatus using LNG is provided.

In the present invention as described above is characterized in that the first and second blocking holes are installed in each boundary portion of the main exhaust pipe.

In addition, according to the present invention is to ignite the blended raw material added 2.9-3.2% of the coke, and operating by injecting 1% or less of LNG into the air drawn into the sintered bed through the air phase as oxygen enriched to 21-25% A flue gas circulating iron ore sintering method using LNG is provided.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail based on an accompanying drawing.

In the exhaust gas circulation type iron ore sintering apparatus using the liquefied natural gas (LNG) according to the present invention, as shown in Figure 3 showing an embodiment of the present invention, the main exhaust pipe (9) is divided into three parts, respectively The first shut-off opening (19), which is divided into one main exhaust pipe (9-1), a second main exhaust pipe (9-2), and a third main exhaust pipe (9-3), and serves as a barrier at each boundary portion. And the second blocking holes 20 are fixedly installed.

In addition, the exhaust gas from the side of the second main exhaust pipe 9-2 is discharged from the first main exhaust pipe 9-1 and the third main by the first shutoff opening 19 and the second shutoff opening 20. In the state where the flow to the exhaust pipe 9-3 is blocked, it is circulated by the second electrostatic precipitator 15 and the second suction blower 16 to form a hood on the light distribution side of the sintering machine trolley 1-2. It is supplied to the exhaust gas collecting hood 18 installed in the furnace, and the LNG collecting hood 17 for LNG or LNG + oxygen enrichment is installed at the light-dividing part side of the sintering machine trolley 1-2.

On the other hand, the exhaust gas circulation type iron ore sintering method using the LNG of the present invention will be described in detail.

In general, in the sintered raw material layer 2, as shown in FIG. 4, a surface where coke combustion starts after ignition (hereinafter referred to as FFP; Frame Front Plane) and a surface where combustion starts after cooling (hereinafter referred to as FBP; The sintering reaction occurs when the ore melts and condenses as the coke is burned.

At the beginning of sintering, the width of the combustion layer is narrow, and outside air at room temperature is directly introduced, so that the amount of heat necessary for the formation of sintered ore is insufficient due to cooling proceeding at the same time as sintering reaction. Increased exhaust air transfers sensible heat to the lower layer, causing excess calories in the lower layer.

Therefore, in the present invention, as shown in Figure 5, the amount of coke, which is a solid fuel required for the sintering reaction, is significantly reduced to the degree of maintaining the amount of accumulated heat accumulated in the lower part of the sintered layer or the fuel amount only for forming FFP, and the amount of heat required for other sintering. To be replaced with LNG, a clean gas.

That is, the surface of the sintered raw material containing a small amount of solid fuel is ignited in the ignition furnace 6, and then LNG is mixed and supplied to the air (oxygen enriched in a predetermined range) which is sucked into the sintered bed to supply the solid fuel. By simultaneously carrying out combustion and LNG combustion, it covers the amount of heat required for sintering, and eliminates excess calories in the lower layer, not only to balance the total amount of heat, but also to reduce the expected deterioration of sintered ore quality by reducing solid fuel, The generation amount of SOx and NOx, which are environmental pollutants due to the high content of S and N, can be drastically reduced.

In addition, by adding LNG in a state where FFP is in progress, as a result, as shown in FIG. 5, the range of the reaction zone (Zone) necessary for the reaction is increased in the first half of the sintering portion (A) as shown in FIG. The fall of a recovery rate can be prevented.

On the other hand, as shown in Figure 6 the flow rate of the exhaust gas discharged in the longitudinal direction of the sintering machine (1-1) in the sinter layer sintering layer is rapidly lowered initially to maintain a constant value while the raw material particles in the sintering layer is aligned, the sintering is almost complete From the point B, which is a starting point, there is a small increase in the layer's ventilation resistance, and this tendency increases rapidly in the case of the oxygen concentration and the gas temperature in the exhaust gas.

NOx, CO, and water vapor concentrations caused by coke combustion tend to gradually increase and maintain a constant level, and then decrease rapidly from the point B. Here, after point B, the air flow resistance is low when the flow rate is increased, and the trend of oxygen concentration indicates that the combustion of coke is almost completed, so that the amount of oxygen required is small.

From this, it can be said that the state of the recycle gas in the present invention is a state where the concentration of oxygen is low and the concentrations of water vapor, CO gas and NOx are high.

As shown in FIG. 7, the exhaust gas at the point 9-2 (the point where oxygen concentration is low and the vapor, CO gas and NOx concentrations are high) located near the point B is placed on the light distribution side of the sintering machine trolley 1-2. When injected through the installed exhaust gas collecting hood 18, the gas passes through the high temperature sintering reaction layer (combustion layer), and carbon monoxide contained in the gas is secondaryly burned in this high temperature reaction, thereby supplying reaction heat to the sintering reaction layer. In addition, the temperature of the gas itself is increased.

NOx is thermally decomposed into nitrogen and oxygen by the heat of the high temperature reaction layer and the carbon monoxide secondary combustion heat by the exhaust gas circulation. On the other hand, SOx tends to be concentrated during flue gas circulation, but rather than treating a small amount of SOx at a large flow rate due to the characteristics of the sintering process having a large flow rate, it is more preferable to concentrate the SOx in the DeSOx facility 14 as shown in FIG. 3. It can be said to be efficient.

In addition, according to the present invention, due to the effect of increasing the temperature of the exhaust gas itself, it is also possible to simplify the equipment by not having to install the heater 12 which is essentially used in a conventional exhaust gas treatment equipment.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail based on an Example.

EXAMPLE

Prior to applying the present invention to the field, a sintering pot (POT) test was conducted as a preliminary test. Standard formulations of the raw materials used in the pot experiments are shown in Table 1 below, and the experiment was performed while varying the necessary parts according to the characteristics.

Table 1 Standard Raw Material Formulation

 Main raw material Iron Ore A   8.81  Raw materials   SL.F   0.15   cokes    3.7 Iron Ore B  13.64   SP.F   1.81 Iron Ore C  20.85   PH.LM  12.49 Iron Ore D  22.63   BLM   1.40   Semi-gloss    9.0 Iron Ore E   5.27 Iron Ore F   0.52

First, exhaust gas recirculation and experiments without LNG were used as standard, and the test results at this time are shown in Table 2.

Table 2 Standard Experiment Results

   Recovery rate     burglar    productivity   SOx (ppm)   NOx (ppm)     Standard    65.03    68.36    32.82     130     344

Reducing the amount of coke used as fuel in the sintering process can reduce the amount of S and N components present in the coke, thereby reducing SOx and NOx, which are environmental pollutants emitted into the sinter flue gas. It is one of the ways to drastically reduce materials.

Therefore, the pot experiment at the time of reducing coke compounding quantity to 2.9% was performed, and the experiment result at that time is shown in Table 3.

Table 3 Experimental results for 2.9% coke use

   Recovery rate     burglar    productivity   SOx (ppm)   NOx (ppm)  Coke 2.9%    51.20    50.40    26.28      92     293

Although it is obvious that the amount of SOx and NOx generated can be reduced by reducing the use of fuel, it can be seen that the recovery, strength and productivity are all greatly reduced accordingly.

In order to solve this problem, the experiment was performed in the case of replacing the coke coke with LNG as a clean raw material, as used in the present invention, the results are shown in Table 4.

Table 4 Coke Alternative LNG Use Ports Experiment Results

   Recovery rate     burglar    productivity   SOx (ppm)   NOx (ppm) Standard (3.7% coke)    65.03    68.36    32.82     130     344 LNG 0% use (coke 2.9%)    51.20    50.40    26.28      92     293 LNG 1% use (coke 2.9%)    64.80    66.74    31.91      98     295 2% LNG use (coke 2.9%)    67.20    69.48    28.72     107     303 3% LNG use (coke 2.9%)    68.30    70.20    26.83     119     315 LNG 1% + oxygen hatching (coke 2.9%)    66.92    66.82    31.86     104     298

When 1% of LNG is added to 2.9% coke feedstock, the recovery, strength and productivity are improved close to that of 3.7% coke and the amount of SOx and NOx is also reduced.

However, when more than 2% of LNG is used, the recovery and strength are improved, but as the amount of heat is concentrated in the upper part of the sintering, the melt is caused to worsen the air permeability, resulting in a drastic decrease in productivity.

In addition, it can be seen that the recovery rate, strength, and productivity are improved when used by incubating 25% oxygen in air with 1% LNG. Since oxygen in the air is usually less than 21%, it can be seen that when the oxygen content is increased, the recovery, strength, and productivity are improved, but when 25% or more of oxygen is used, excessive sintering occurs in the upper layer of the sintered bed, resulting in a long sintering time. This resulted in worsening of sintering productivity.

In addition, as a result of the sintering pot test, when the coke blending ratio was 3.2% or more, when using 1% or more of LNG, the amount of heat was excessively excessive in the upper layer of the sintered bed, resulting in deterioration of air permeability, resulting in deterioration of productivity.

The point where sintering proceeds 2/3 of the mixed gas with CO 1%, O ₂ 12% and moisture 10% expected when the flue gas is circulated in the sinter plant under the condition of coke 2.9% and LNG 1% + oxygen enrichment. Table 5 shows the results of the experiment when put in the.

Table 5 Port Test Results Considering Flue Gas Circulation

 Recovery rate   burglar   productivity    SOx    NOx Exhaust gas temperature   Dust Standard (3.7% coke)   65.03   88.38   32.82    130    344    240    50 LNG 0% (coke 2.9%)   51.20   50.40   26.28     92    293    182    54 LNG 1% + oxygen hatching   66.92   66.82   31.88    104    298    251    49 LNG 1% + Oxygen Enrichment + Flue Gas Circulation   66.79   66.64   31.42    125    274    320    30

As shown in the above experimental results, despite the exhaust gas circulation, SOx was concentrated, without affecting productivity, recovery, strength, and sinterability.

In addition, it can be seen that the NOx is decomposed to reduce the emissions and the exhaust gas temperature is increased. As a result, as the exhaust gas temperature increases, it is possible to process the exhaust gas generated in the DeNOx and DeSOx facilities 13 and 14 without using the heater 12, and also, the amount of dust generated is sharply reduced.

As described above, according to the present invention, while reducing the amount of coke without significantly affecting the sinterability, such as sintered ore productivity, recovery and quality, the generation of SOx and NOx, which are pollutants, is greatly reduced, and the circulation rate of the flue gas is greatly increased. There is an effect that can be reduced.

In addition, the secondary combustion of CO gas in the circulating raw material layer increases the temperature of the exhaust gas, thereby eliminating the need for a heater used in a conventional flue gas treatment facility, and providing the discharged dust to the sintered raw material layer itself, thereby additionally recycling waste resources. It works.

1 is a block diagram of a typical sintering apparatus

2 is a configuration diagram showing that the DeNOx facility and DeSOx facility is installed in the sintering apparatus of FIG.

3 is a block diagram of an exhaust gas circulating iron ore sintering apparatus using LNG according to the present invention

Figure 4 is a schematic diagram showing the reaction layer in the sintering machine in the conventional flue gas circulation iron ore sintering method

5 is a schematic view showing the reaction in the sintering machine when using LNG + air or LNG + oxygen enrichment in the sintering method according to the present invention

Figure 6 is a schematic diagram showing the change in exhaust gas components, temperature and flow rate according to the sintering trend in a conventional sintering process

Figure 7 is a schematic diagram showing the reaction in the sintering machine when the exhaust gas circulation in the sintering method according to the present invention

<Explanation of symbols for main parts of drawing>

1: sintered raw material hopper 1-1: iron ore sintering machine

1-2: sintering machine balance 2: sintering raw material layer

5: inclined plate 6: ignition furnace

7: suction blower 8: wind

9: main exhaust pipe 10: electrostatic precipitator

15: second electric dust collector 16: second suction blower

17: LNG collection hood 18: flue gas collection hood

19: 1st block 20: 2nd block

Claims (3)

A sintering bogie having a light feeding portion into which the raw material in the sintering raw material hopper is loaded and a light distribution portion for discharging the sintered sintered mineral; In the exhaust gas circulation type iron ore sintering apparatus comprising a main exhaust pipe for sending the air to the electric dust collector, The main air pipe is divided into a first main air pipe, a second main air pipe, and a third main air pipe; An exhaust gas collecting hood installed at the light distribution unit to supply exhaust gas discharged from the second main exhaust pipe; An exhaust gas circulation type iron ore sintering apparatus using LNG further comprising an LNG collecting hood installed to supply LNG to the light feeding part. The method of claim 1, The exhaust gas circulation type iron ore sintering apparatus using LNG, characterized in that the first and second blocking holes are installed at each boundary of the main exhaust pipe. In the flue gas circulating iron ore sintering method, LNG which is characterized by operating by injecting 1% or less of LNG into the air drawn into the sintered bed through the air phase while igniting the compounding material to which coke is added 2.9-3.2% and enriched with oxygen at 21-25%. Exhaust gas circulating iron ore sintering method using.