JPH0635612B2 - Method and apparatus for measuring secondary combustion rate in smelting reduction - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method and an apparatus for measuring the secondary combustion rate of a reaction system when smelting and reducing oxide ores to produce molten metal.

[Conventional technology]

Recently, the smelting reduction smelting method has been attracting attention as a steelmaking technology that replaces the blast furnace / converter method. The smelting reduction furnace used in this method was developed for the purpose of producing molten metal of iron-based alloys with a smaller scale facility without being restricted by the raw materials used, and effectively utilizing the amount of heat generated as a by-product. It is a thing.

As one of such smelting reduction furnaces, the present inventors previously proposed a furnace of the type shown in FIG. 3 (Japanese Patent Application No. 61-22895).
issue). This furnace includes a fixed vertical furnace unit 1 and a container unit 2 which is detachably attached to the vertical furnace unit 1. The container part 2 is mounted on the trolley 3 and can be easily replaced with another container part 2.

The container portion 2 contains a melt mainly composed of a metal bath 8 and the like, and a bottom blowing tuyere 11 for blowing oxygen gas and fuel such as propane and pulverized coal into the melt is provided on the bottom wall. The gas blown into the container 2 via the bottom blowing tuyere 11 rises as bubbles 10 in the metal bath 8 and promotes a reduction reaction with respect to the charged raw material.

A tap hole 12 or a sliding gate is provided at the bottom of the container part 2.
Alternatively, the molten material such as molten metal and slag is discharged to the outside of the furnace at any time through the sliding gate.

On the other hand, the vertical furnace unit 1 has a vertical cylindrical shape or a cylindrical shape with a partially enlarged diameter. The lower part of the vertical furnace part 1 is in close contact with and detachable from the container part 2, and the upper part thereof is the exhaust gas 13
Is connected to a duct for sending to the exhaust gas utilization system.
The lower part of the vertical furnace part 1 is immersed in a part of the formed slag layer 9.

A lance 4 is inserted vertically upward and a plurality of lances 5 is inserted obliquely upward or laterally into the vertical furnace unit 1. Gas such as oxygen gas and / or powder such as ore and coal is blown into the furnace from these lances 4 and 5.
Further, the vertical furnace part 1 is provided with a lump charging device 6 for charging a lump such as an ore, a molded product thereof, and a lump carbonaceous material.

In this smelting reduction furnace, the slag layer 9 in which the carbonaceous material is suspended and the metal bath 8 are sufficiently brought into contact with each other to accelerate the smelting reaction at the interface. Further, the reaction of C + FeO → Fe + CO is performed even in the slag layer 9. The carbon monoxide CO thus generated is still a combustible component, and if it is discharged as it is, heat generation cannot be increased. Therefore, a large amount of oxygen gas is blown in as compared with normal smelting to cause the secondary combustion reaction of 2CO + O ₂ → 2CO ₂ . In addition, hydrogen, which is a combustible component other than carbon, also increases the amount of heat generated by causing the combustion reaction of 2H ₂ + O ₂ → 2H ₂ O.

[Problems to be solved by the invention]

As described above, a large amount of oxygen is required to sufficiently burn combustible components such as carbon and hydrogen. However, when the oxygen supply amount becomes excessive, reoxidation of the metal bath 8 occurs,
The reduction reaction will deteriorate. Therefore, by analyzing the exhaust gas discharged from the smelting reduction furnace, the secondary combustion rate (CO ₂ + H ₂ O) / (CO ₂ + CO + H ₂ O + H ₂ ) in the furnace was accurately grasped, and it was determined according to the furnace conditions. It is necessary to supply a quantity of oxygen. However, in the analysis of this exhaust gas, detection of the H ₂ O content becomes a problem. That is, the exhaust gas discharged from the smelting reduction furnace has a high temperature of about 1500 ° C. and contains a large amount of water. The contained water condenses. Therefore, when the exhaust gas is sent to the gas analyzer as it is, most of the water content has already been removed, and even when the exhaust gas is sent to the gas analyzer, the accurate H ₂ O content cannot be measured.

In this respect, conventionally, the H ₂ O content was estimated using past operational data and the physical properties of exhaust gas. However, this estimate is not an accurate representation of current reactor conditions. Therefore, the correct secondary combustion rate (CO ₂ + H ₂ O) / (CO ₂ + CO + H ₂ O + H ₂ )
The required oxygen supply could not be determined based on For example, under operating conditions in which a large amount of water is generated, the H ₂ O content greatly affects the secondary combustion rate. For example, when coal containing a large amount of hydrogen is charged into a smelting reduction furnace operating at a high temperature of 1500 ° C or higher, H ₂ has a higher secondary combustion rate than CO due to its equilibrium value. Has a considerable effect on the secondary combustion rate of. If an attempt is made to estimate this effect based on the assumption of the equilibrium value, etc., it is difficult to track temporal variations due to large errors.

In such a case, if the oxygen supply amount is determined based on the secondary combustion rate that incorporates the estimated value of the H ₂ O content, insufficient supply or excess supply may occur, resulting in not only wasting oxygen but also the metal bath. It is also supposed to reduce the productivity such as reoxidation of the.

Therefore, in the present invention, the secondary combustion rate is accurately obtained by directly measuring the H ₂ O content contained in the exhaust gas discharged from the smelting reduction furnace, and the heat generation amount is high with a sufficient amount of blowing acid. The purpose is to perform smelting reduction.

[Means for solving problems]

In order to achieve the object, the measurement method of the present invention collects a part of the exhaust gas discharged from the smelting reduction furnace, and sends a part of the collected exhaust gas to a moisture detector equipped with a heat retention mechanism. The proportion of water contained in the exhaust gas is measured, and the rest of the collected exhaust gas is sent to a gas analyzer for CO and CO
The content ratio of ₂ is measured, and the measured value obtained in this way is sent to the computing unit. Secondary combustion rate (CO ₂ + H ₂ O) / (CO ₂ + CO + H ₂ O +
It is characterized by finding H ₂ ).

Further, one device used for that purpose, in the middle of the pipe for sending a part of the exhaust gas discharged from the smelting reduction furnace to the gas analyzer, connecting the pipe for sorting the exhaust gas and sending it to the moisture detector, It is characterized in that the pipe extending from the collecting section to the moisture detector is surrounded by a heat insulating unit.

Further, another device used here is to arrange a moisture detector in the middle of a pipe for sending a part of the exhaust gas discharged from the smelting reduction furnace to the gas analyzer, and to connect the moisture detector to the moisture detector. The pipe is surrounded by a heat insulation unit, and a cooler is provided in the middle of the pipe from the moisture detector to the gas analyzer.

[Action]

In the present invention, the pipe system is kept warm so that the moisture contained in the collected exhaust gas is not condensed during being sent to the moisture detector. Therefore, the measurement value obtained by the water content detector is an accurate representation of the water content of the exhaust gas discharged from the smelting reduction furnace. Also, since the pipe for sending the exhaust gas to the moisture detector is connected in the middle of the pipe for sending a part of the exhaust gas discharged from the smelting reduction furnace to the gas analyzer, the exhaust gas collected from the same place in the furnace On the other hand, H ₂ O, CO ₂ , CO and H ₂ are analyzed. Therefore, the measured values obtained in this way are an accurate representation of the furnace conditions, and when determining the oxygen supply based on the secondary combustion rate incorporating these measured values,
The required and sufficient oxygen will be delivered.

〔Example〕

The features of the present invention will be specifically described below with reference to the embodiments shown in the drawings.

FIG. 1 shows an outline of the measuring device used in this example.
Note that, in FIG. 1, components corresponding to the members shown in FIG. 3 are designated by the same reference numerals.

A sampling pipe 15 is exposed to a flue 14 connected to the upper portion of the vertical furnace unit 1. Exhaust gas 13 flowing through the flue 14
Is collected by this pipe 15 and sent to a gas analyzer 16 such as a gas chromatograph. When the exhaust gas 13 is provided with a filter 17 for removing dust contained in the exhaust gas 13 before reaching the gas analyzer 16, the gas analyzer 16
The analysis is performed with high accuracy. Then, by the gas analyzer 16, CO, CO ₂ , O ₂ , N ₂ , contained in the exhaust gas 13,
Find the contents of Ar, H _2, etc. Of these, N ₂ and Ar are not directly involved in the secondary combustion rate, but other gas amounts are corrected to actual ratios with the air entrainment amount calculated from the N ₂ amount or the known bottom blown Ar amount as a reference. However, when air is involved, the O ₂ content is represented by the following formula.

On the other hand, a branch pipe 18 is connected in the middle of the pipe 15: O ₂ = (air entrainment) + (upstream unburned)-(exhaust gas combustion)
The closer the branch pipe 18 is connected, the more effective it is to the extraction portion of the exhaust gas 13. Exhaust gas collected in the branch pipe 18
13 flows through the branch pipe 18 surrounded by the heat insulation unit 19, passes through the filter 20, and reaches the moisture detector 21. In this way, since the exhaust gas 13 flows through the branch pipe 18 surrounded by the heat retention unit 19, the temperature drop of the exhaust gas 13 to the moisture detector 21 is small. Therefore, the moisture contained in the exhaust gas 13 is not condensed during the transportation, and the same amount of moisture as in the furnace is sent to the moisture detector 21. As a result, the water content detected by the water content detector 21 accurately represents the situation inside the furnace. In this way, the measured values detected by the gas analyzer 16 and the moisture detector 21 are calculated by a calculator.
Send to No.22, secondary combustion rate (CO ₂ + H ₂ O) / (CO ₂ + CO + H ₂ O + H ₂ )
Is calculated. Next, this secondary combustion rate is compared with a set value by the calculator 22, and the result is sent to the lance 4, and the operating conditions such as the amount of top-blown acid plant are controlled so that the set secondary combustion rate is obtained. Since the gas analyzer 16 also measures the O ₂ content, it is possible to calculate the utilization efficiency of the oxygen gas used for blowing acid.

The difference between the secondary combustion rate obtained in this way and the secondary combustion rate obtained by incorporating an estimated value for the water content
Shown in the figure. Here, the estimated value regarding the water content is
I asked for it as follows.

There are the following three reaction equations for secondary combustion.

CO + 1 / 2O ₂ → CO ₂・ ・ ・ ・ (1) H ₂ ＋ 1 / 2O ₂ → H ₂ O ・ ・ ・ ・ (2) CO ₂ ＋ H ₂ CO ＋ H ₂ O ・ ・ ・ ・ (3) = 1700K, the equilibrium value of Eq. (3) Is 3.4, and the amount of H ₂ O can be estimated from the analytical values of CO, CO ₂ , and H ₂ O.

As is clear from FIG. 2, the actual secondary combustion rate changes with the transition of the smelting time. The difference between the actual secondary combustion rate and the secondary combustion rate obtained by the estimation becomes large when the secondary combustion rates of CO and H ₂ show different fluctuations.

In the example of FIG. 1, the gas analyzer 16 and the moisture detector 21 are arranged in the respective branched pipes 15 and 18. However, instead of this parallel arrangement, it is also possible to arrange the gas analyzer 16 in series behind the moisture detector 21. In this case, a cooler may be arranged between the moisture detector 21 and the gas analyzer 16, the moisture may be condensed and discharged, and the remaining exhaust gas may be sent to the gas analyzer 16.

Further, in the above example, the description has been given by taking the vertical separation type smelting reduction furnace as an example. However, it goes without saying that the present invention is not restricted to this, and can be applied to various other types of smelting reduction furnaces. Furthermore, in the example shown in FIG. 1, the exhaust gas 13 is sampled from one location of the flue 14, but when these sampling points are provided at various locations in the furnace, it is possible to grasp the furnace condition more accurately. Become.

〔The invention's effect〕

As described above, in the present invention, when analyzing the exhaust gas discharged from the smelting reduction furnace, since the exhaust gas is sent to the moisture detector through the branch pipe surrounded by the heat retention unit, Water does not condense during transportation. Therefore, the water content can be accurately measured. In addition, the exhaust gas whose moisture content is to be measured is an exhaust gas sampled to analyze other components, so the measured values for water content and other components indicate the conditions inside the furnace. It will be an accurate representation. Based on the secondary combustion rate obtained by incorporating the measured values obtained in this way, when controlling the amount of blowing acid, it is possible to perform a smelting reduction with a high heat generation amount with a sufficient amount of blowing acid. It will be possible.

[Brief description of drawings]

FIG. 1 shows an example in which the present invention is applied to an upper and lower separation type smelting reduction furnace, and FIG. 2 shows a case where a secondary combustion rate is obtained by directly measuring the water content and an estimated value of the water content. 6 is a graph showing the difference when the secondary combustion rate is obtained by incorporating the above equation. Further, FIG. 3 shows a smelting reduction furnace previously developed by the present inventors.

Claims (3)

[Claims] 1. A part of the exhaust gas discharged from the smelting reduction furnace is sampled, and a part of the sampled exhaust gas is sent to a moisture detector equipped with a heat retention mechanism to measure the proportion of water contained in the exhaust gas. Is measured, and the rest of the collected exhaust gas is sent to a gas analyzer to measure the content ratio of components other than water, and the measured value thus obtained is sent to a computing device for secondary combustion rate (CO ₂ + H ₂
O) / (CO ₂ + CO + H ₂ O + H ₂ ), which is a method for measuring the secondary combustion rate in smelting reduction. 2. A pipe for sending a part of the exhaust gas discharged from the smelting reduction furnace to a gas analyzer and connecting the pipe for sending the exhaust gas to a moisture detector to detect the water content from the collecting part. A device for measuring a secondary combustion rate in smelting reduction, characterized in that the pipe reaching the vessel is surrounded by a heat insulating unit. 3. A moisture detector is arranged in the middle of a pipe for sending a part of the exhaust gas discharged from the smelting reduction furnace to a gas analyzer, and the pipe extending from the fractionation unit to the moisture detector is surrounded by a heat insulation unit. A device for measuring a secondary combustion rate in smelting reduction, wherein a cooler is provided in the middle of a pipe for sending from the moisture detector to the gas analyzer.