JPH06105238B2 - Method for measuring oxygen partial pressure of blast furnace gas - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for directly measuring the oxygen partial pressure in a reaction gas in a blast furnace by an oxygen probe using an oxygen concentration battery, and more specifically, a method for measuring the oxygen probe in a blast furnace blade. Insert into the furnace from the mouth,
The present invention relates to a method for measuring an oxygen partial pressure of a reaction gas in a blast furnace, which can accurately and quickly perform an oxygen partial pressure in a reaction gas near a raceway under high temperature and high pressure.

[Conventional technology]

The oxygen partial pressure in the reaction gas in the vicinity of the raceway in the blast furnace is an important factor that governs in-reactor reactions such as gas-metal reaction and slag-metal reaction. Accurately measuring this oxygen partial pressure in a short time is effective for analyzing the reaction in the furnace, which has been conventionally called a black box, and is extremely useful for stabilizing the blast furnace operation. is there.

As for the measurement of oxygen partial pressure in the reaction gas in the blast furnace, only a few reports have so far been made to measure the gas phase near the coke packed layer and the cohesive zone that are located above the raceway in the test blast furnace. is there. However, the oxygen partial pressure near the raceway, which is indispensable for reaction analysis in the furnace, is a very high theoretical combustion temperature of about 2200 ° C in the combustion section,
There is no actual case measured up to now because the oxygen concentration battery and the sheathing material of the probe inserted into the raceway are melted by the time the oxygen concentration battery corresponds to the ambient temperature.

[Problems to be solved by the invention]

In order to enable measurement of oxygen partial pressure in a raceway where such a combustion temperature of about 2200 ° C is expected, the entire probe should be made of a material with high fire resistance that can withstand the thermal shock during insertion into the furnace. In addition, it is necessary to prevent crack damage due to thermal shock of the oxygen concentration battery, and on the other hand, it is also necessary to improve the response speed of the oxygen concentration battery in order to shorten the measurement time of the oxygen probe in the raceway. Becomes

Among these issues, the problem of crack damage due to thermal shock of the oxygen concentration battery is already being resolved by the improvement of the materials and structure of the oxygen concentration battery due to the efforts of researchers, and therefore the present major issue is It is being focused on improving the fire resistance and the response speed of oxygen concentration batteries. And improvement of the responsiveness of the oxygen concentration battery is particularly important from the following two viewpoints.

That is, the improvement in the responsiveness of the oxygen concentration battery enables the oxygen partial pressure to be measured for a short time, and enables the change in the oxygen partial pressure in the reaction gas in the raceway, which changes momentarily, to be detected more quickly. This is important because it makes the partial pressure measurement closer to real-time measurement.

In addition, the improved responsiveness of the oxygen concentration battery leads to a reduction in the required level for the durability of the probe in the raceway, and as a result, the thickness of the exterior material and probe diameter for the purpose of improving the durability of the probe are increased. It becomes unnecessary to increase the diameter of
It is also important in that the influence of the presence of the probe on the measurement target environment can be minimized.

In this sense, improving the responsiveness of the oxygen concentration battery is particularly important.

Furthermore, it is also necessary to prevent the metal and slag solutions that are dripping in the gas in the raceway section from adhering to the oxygen concentration battery after the furnace is inserted.

[Means for solving problems]

In order to solve the above problems, we first investigated a method of cooling the probe by circulating water inside by using an iron pipe as the exterior material of the probe, but since the handling becomes complicated and the cost of the probe increases significantly. The feasibility was thin. Therefore, we also tried a method of cooling the inside with nitrogen gas using a thicker iron pipe as an exterior material, but when inserted into the raceway part of the furnace, the iron pipe is burnt down in about 10 seconds and the oxygen concentration battery can operate. I didn't want to be heated until the condition. For these reasons, it is necessary to keep the measurement time at the raceway part within 10 seconds at the maximum to avoid burnout of the exterior material, and within this time, the temperature of the oxygen concentration battery is adjusted to It was found that the oxygen partial pressure in the raceway can be measured if there is a method that can raise it to the normal level.

The present invention has been made in order to achieve this object. By preheating the oxygen concentration battery before inserting it into the raceway and increasing the response speed, the measurement time in the raceway is shortened and the oxygen probe is melted and damaged. The measurement of the oxygen partial pressure is completed before the gist of the measurement is as follows. That is, as shown in FIG. 3, before inserting the probe A into the raceway C, it is preheated in the blow pipe B before the tuyere E for a certain period of time to keep the temperature of the oxygen concentration battery sufficiently operating. The temperature is raised until it becomes possible, and the electromotive force of the oxygen concentration battery is also measured to simultaneously check the function. Next, the probe A is inserted into the raceway C from the tuyere E, the probe tip A1 is stopped at the measurement position F for a certain period of time to measure the oxygen partial pressure, and then the probe A is pulled out from the raceway C. As a result of doing this,
The exterior material of the probe A is maintained without burning until the end of the measurement, and the oxygen concentration battery is preheated in the blow pipe B in advance. The oxygen partial pressure at the measurement position in C was accurately measured in a short time. The preheating in the blow pipe B is generally performed by staying in a proper place in the blow pipe B for a certain period of time, but it is not always necessary to stop the blow pipe B completely. The moving speed of A is gradually decelerated, and from a certain stage, it is accelerated in the opposite direction and inserted into the raceway C, or while the probe A is within a certain section of the blow pipe B, the movement of the probe A is It is also considered to make the stay time of the probe A in the blow pipe B longer by making it extremely slow. Then, an oxygen probe for the gas in the blast furnace was constructed as a specific device for realizing such a measuring method. In this device, the oxygen concentration battery is housed in a refractory protection tube provided with a ventilation hole, and the temperature of the oxygen concentration battery in the blow pipe can be increased between the refractory protection tube and the oxygen concentration battery. In addition, a protective breathable film having a breathability sufficient to prevent the metal and slag splashes from adhering to the oxygen concentration battery in the raceway is interposed.

[Action]

When the oxygen probe A for gas in the blast furnace configured as described above is inserted into the blow pipe B, the inside of the blow pipe B is tuyere E.
The high temperature gas flowing toward the inside flows into the inside of the tip of the fireproof protection tube from the ventilation hole provided in the fireproof protection tube, and heats the oxygen concentration battery stored inside through the fireproof breathable film. To do. The hot gas flowing in the blow pipe B is about
Since the temperature is around 900 ° C to 1200 ° C, the refractory protection tube is not burned even if it stays for a certain period of time, and the oxygen concentration battery is heated during this time until it can function sufficiently. At this time, the electromotive force of the oxygen concentration battery is measured to simultaneously check the quality of the oxygen concentration battery. After fully heating the oxygen concentration battery in the blow pipe B, from the tuyere E to the probe A
Raceway C for inserting the probe and measuring the probe tip A1
To a predetermined position inside. When the probe tip A1 is stopped at the measuring position F, the gas in the vicinity of the oxygen concentration cell passes through the ventilation hole and is quickly replaced. Since the oxygen concentration battery is preheated in the blow pipe B and is ready for measurement immediately after being inserted into the raceway C, the measurement is completed in a short time, and there is no fear that the fire resistant protection tube will be burned. Further, although the metal and flag solutions are dripping inside the raceway C, since a gas permeable coating is provided between the oxygen concentration battery and the fireproof protection tube, the movement of the metal and slag solutions can be prevented by the ventilation. The oxygen partial pressure in the reaction gas in the raceway C can be accurately measured without being blocked by the conductive film and adhering to the oxygen concentration battery.

〔Example〕

Next, the details of the present invention will be described using an oxygen probe for gas in a blast furnace configured to realize the present invention. FIG. 1 is a sectional view of one embodiment of an oxygen probe for gas in a blast furnace for specifically carrying out the present invention. In the figure, reference numeral 1 is a long fire-resistant protective tube, which is made of a stainless steel tube or the like in consideration of the high heat in the raceway C, and a vent hole into which gas in the blow pipe B flows into the side wall of the tip A1. An appropriate number of 2 is provided. In this embodiment, the fireproof protection tube 1 has an outer diameter
Although a stainless steel pipe having a diameter of 34 mm and an inner diameter of 21 mm is used, inexpensive carbon steel or the like can be used if the cooling means described later is more effective. Further, the vent hole 2 is set at a position in the blow pipe B where the gas can pass near the oxygen concentration battery 3 and heat the surface thereof. As shown in FIG. As described above, this object is achieved by arranging the oxygen concentration battery 3 at least on the base end side with respect to the front end. In addition, the size of the oxygen concentration battery 3 and the refractory protection tube 1 itself melts in order to raise the temperature of the oxygen concentration battery 3 in the blow pipe B and speed up the replacement of the gas to be measured in the raceway C. It is desirable to make it as large as possible without damaging it.
A discharge hole 4 for discharging the cooling nitrogen gas to the outside of the probe A is provided on the approximately middle abdominal wall in the lengthwise direction of the fire-resistant protection tube 1. At this position, the nitrogen gas discharged from the discharge hole 4 is not discharged. As long as it reaches the oxygen concentration battery 3 located at the tip of the fireproof protection tube 1 and does not give an error to the measurement of the oxygen partial pressure, another one can be appropriately adopted. Reference numeral 5 in the figure is an outer tube for filling the interior of the refractory cement 6 and holding the oxygen concentration battery 3 in a buried state at the tip thereof. The interior of the refractory cement 6 is covered with a lead wire bundle 7 derived from the oxygen concentration battery 3. It is installed in the state. A thermocouple is provided inside and outside the solid electrolyte of the oxygen concentration battery 3, and the thermocouple hot junction is also used as an electrode for detecting the oxygen concentration battery electromotive force. A fireproof breathable coating 8 is provided between the oxygen concentration battery 3 and the fireproof protective tube 1. In this embodiment, a mesh net made of stainless steel is used. This breathable coating 8 is for preventing the metal and slag solution from adhering to the oxygen concentration battery 3 when it is inserted into the raceway C. Once the fire resistance problem is resolved, the use of fire resistant fibers and other materials will not be hindered.
In addition, a plurality of vent holes 9 are provided at the tip opening of the fireproof protection tube 1.
Although the tip protection plate 10 having the above is provided, the adhesion of the metal and slag solution to the oxygen concentration battery 3 is more completely prevented.
This tip protection plate 10 may be omitted. In the figure, reference numeral 11 denotes an interior pipe that is fitted inside the exterior pipe 5 in a tightly fitted state, and the other end is supported by the joint 12 together with the fireproof protection pipe 1, and the fireproof protection pipe 1 and the interior pipe A space 13 is provided between the pipes 11, and an outflow hole 14 is formed in the side wall near the tip of the inner pipe 11 closed at the end of the outer pipe 5. As a result, the nitrogen gas supplied to the cavity 15 in the inner pipe 11 becomes the second
As shown in FIG. 2 (a), the gas is discharged from the outflow hole 14, passes through the gap 13 between the fireproof protection pipe 1 and the interior pipe 11, and is then discharged from the discharge hole 4 to the outside of the probe A to effectively cool the probe A. Is possible. 16 in the figure is a joint for probe A
It is a base pipe supported via 12 and the other end is connected to a base D arranged outside the blow pipe B at the time of use. This base D has an inlet 17 for introducing nitrogen gas and an oxygen concentration battery 3
A lead wire outlet 18 is provided for drawing out the lead wire bundle 7 drawn out from the outside. Incidentally, the base pipe 16 and the joint 12
Also, screw portions 19, 20, 21 are engraved between the fireproof protection tube 1, the interior tube 11 and the joint 12 so that they can be fitted and removed freely, and a sealing material or the like is appropriately used for the joint portion. By intervening to prevent gas leakage, the device group in front of the joint 12 is made expendable and a new probe A is used for each measurement.
Is configured to be supplied.

The oxygen probe for gas in the blast furnace of the present embodiment is constructed as described above, but the open area ratio of the vent hole 2 provided on the side wall at the tip of the refractory protection tube 1 is particularly important. This vent 2
Is necessary to preheat the oxygen concentration battery 3 by circulating the gas in the blow pipe B near the oxygen concentration battery 3 in the blow pipe B, and about 2200 ° C in the raceway C.
It is necessary to protect the oxygen-concentrated battery from the high-temperature gas so that the measuring electrode of the oxygen-concentrated battery 3 and the thermocouple lead for temperature measurement are not damaged by the extremely high-temperature gas. If the open area is too small, the oxygen concentration battery 3 is not preheated sufficiently, and if it is too large, the fire-resistant protective tube 1 itself is burnt out, so that the oxygen concentration battery 3 is sufficiently preheated and at least measured. It is important to calculate the open area ratio at which the fire resistant protection tube 1 does not burn out within the time. The one shown in FIG. 4 uses a stainless tube having an outer diameter of 34 mm and an inner diameter of 21 mm as a fireproof protection tube, and the tip protection plate 10 is provided with four ventilation holes 9 having a diameter of 5 mm to open the ventilation hole 2. The graph shows the temperature change of the measuring electrode of the oxygen concentration battery 3 in the blow pipe B when the hole area ratio is 18.4%, and the horizontal axis is the elapsed time (sec) in the blow pipe B. As shown in the figure, the oxygen concentration battery 3 could be sufficiently preheated at this opening area ratio. The opening area ratio varies depending on the material and shape of the fireproof protection tube 1, the shape of the ventilation hole 2, and the like, and it is needless to say that it is appropriately set depending on the material and shape of the fireproof protection tube 1. Absent.

Oxygen probe A for blast furnace gas constructed in this way
Is used as follows. The probe A, which is a consumable part, is screw-connected to the joint 12 and is inserted into the blow pipe B and stopped as shown in FIG. 3, or the slow moving state is maintained and the blow pipe B is kept for a certain time. Let them stay. In the blow pipe B, high temperature gas flows in one direction toward the tuyere E, and this high temperature gas flows in from the ventilation hole 2 of the fireproof protection tube 1 and passes through the ventilation hole 9 of the tip protection plate 10 to probe again. A flows out. The high-temperature gas passing through the inside of the probe A reaches the surface layer of the oxygen concentration battery 3 via the fireproof gas permeable coating 8 and heats the oxygen concentration battery 3. Since the breathable film 8 is formed of a mesh net so that the high temperature gas can sufficiently flow, the high temperature gas heats the oxygen concentration battery 3 to a temperature at which normal operation is possible, and at this stage, the oxygen concentration battery 3 The response speed of is sufficiently improved. At this time, the electromotive force of the oxygen concentration battery 3 is measured at the same time to check whether the oxygen concentration battery 3 is good or bad.
It is possible to prevent the failure of the measurement of oxygen partial pressure due to the failure of. On the other hand, on the base pipe 16 side (the right side in the figure) from the refractory cement starting end portion 22 in which the gas flow is blocked by the refractory cement 6, the nitrogen gas passing through the cavity 15 as shown in FIG. The refractory protection tube 1 is cooled from the inside by passing through the gap 13 between the interior pipe 11 and the fireproof protection tube 1 through the outflow hole 14 and being discharged from the discharge hole 4 to the outside of the probe A. .

In this way, the probe A is stopped in the blow pipe B, or is maintained in a slow moving state so that it stays in the section of the blow pipe B for a certain time, and the oxygen concentration battery 3
However, in this example, an experiment was performed by a method of temporarily stopping the probe, and the stop time was 20 seconds to 30 seconds.
Good results were obtained when seconds were reached. However, the stop time is not limited to this, and the stop time can be further shortened by devising the wall thickness, diameter or shape of the tip of the fireproof protection tube, or the area ratio of the opening. After preheating the oxygen concentration battery 3 and sufficiently increasing its response speed, the probe A is inserted through the tuyere E, and its tip A1 is measured at a measurement position F in the raceway C about 1.5 m away from the tuyere E. Move to and stop. Blow pipe B for oxygen concentration battery 3 in advance
Since the response speed is increased inside, the oxygen partial pressure at the measurement position F can be measured quickly and can be measured in a short time. Although the solution of metal and slag is dripping inside Raceway C, the solution of metal and slag is covered with the breathable film 8 formed of the mesh net made of stainless steel, so the solution of metal and slag is concentrated in oxygen. It does not adhere to the battery 3 and does not give an error to the measurement of the oxygen partial pressure. In this example, the measurement of the oxygen partial pressure was completed in about 6 seconds, during which the measuring electrode of the oxygen concentration battery 3 sufficiently fulfilled its function without being melted. It was also confirmed that the refractory protection tube 1 can also be sufficiently maintained by cooling with nitrogen gas without melting damage during the measurement time. FIG. 5 shows an example of this measurement result. The solid line is the oxygen partial pressure, the broken line is the temperature measured by the thermocouple disposed on the standard electrode side of the oxygen concentration battery, and the dashed line is the oxygen concentration battery. 3 shows changes in temperature measured by a thermocouple arranged on the measuring electrode with time. The horizontal axis represents time, and the vertical axis represents the natural logarithm of oxygen partial pressure and the temperature in degrees Celsius. The portion indicated as a represents the change in the blow pipe B, but in the blow pipe B, 3
Air was pumped at atmospheric pressure, and the oxygen partial pressure value calculated from this condition and the oxygen partial pressure value measured using probe A were in good agreement. Since the oxygen partial pressure in the blow pipe B can be easily calculated, if this value is compared with the oxygen partial pressure value measured by the probe A, it is determined whether the oxygen concentration battery is good or bad by inserting the probe A into the raceway C. It turns out that you can check before you do. The portion indicated by b shows the change within the raceway, and the measurement results were obtained in the range of 10 ^-11 atm to 10 ^-14 atm at the back of the raceway. The measured value may increase up to 10 ^-11 atm because the iron oxide (FeO) concentration in the slag collected inside the raceway is 2 to 50% in addition to the fluctuation of the combustion state. It is thought to be influenced by iron oxide (FeO) flowing into the. Also, assuming that the temperature inside the raceway, which is the measurement position, is 1800 ° C, the measured oxygen partial pressure tends to oxidize carbon (C) in the atmosphere while reducing silicon dioxide (SiO). I understood.

〔The invention's effect〕

The present invention preheats the oxygen probe in advance before inserting it into the raceway, sufficiently enhances the response speed of the oxygen concentration battery, and then positions the oxygen concentration battery at the measurement position in the raceway. Is capable of quickly measuring the oxygen partial pressure at the measurement position in a short time and accurately in response to the surrounding environment. And since the measurement is completed in a short time, the oxygen concentration battery is maintained without being burnt out, and the probe itself is not melted during the measurement time, which enables stable measurement with a high success rate. . As described above, according to the present invention, the oxygen partial pressure in the reaction gas under high temperature and high pressure in the vicinity of the raceway, which has hitherto been impossible, can be measured accurately in a short time. It is possible to analyze addition and removal reactions, and to provide important data for analysis of blast furnace reaction for low silicon operation.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an embodiment of an oxygen probe for gas in a blast furnace that specifically implements the present invention, and FIG. 2 (a) is an explanatory view showing a flow path of nitrogen gas in the same embodiment. ) Is an explanatory view showing the flow of high-temperature gas in the vicinity of the oxygen concentration battery of the same embodiment, and FIG. 3 is a simplified explanatory view showing the concept of the present invention,
Figure 4 shows a stainless steel tube with an outer diameter of 34 mm and an inner diameter of 21 mm as the fireproof protection tube of the probe, and
It is a figure which shows the temperature change of the oxygen concentration battery in a blow pipe at 18.4%, and FIG. 5 is a figure which shows the result of having measured the oxygen partial pressure in a raceway by the method concerning this invention. A: Oxygen probe for blast furnace gas, A1: Probe tip, B: Blow pipe, C: Raceway, D: Base, E: Tuyere, F: Measurement position, 1: Fireproof protection tube, 2: Vent hole , 3: Oxygen concentration battery, 4: Discharge hole, 5: Exterior tube, 6: Fire resistant cement, 7: Lead wire bundle, 8: Breathable coating, 9: Vent hole, 10: Tip protection plate, 11: Interior tube, 12: Joint, 13: Void, 14: Outflow hole, 15: Cavity, 16: Base pipe, 17: Inlet, 18: Lead wire outlet, 19,20, 21: Threaded part, 22: Fire resistant cement starting end .

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hitoshi Yoshida 1 Fuji-machi, Hirohata-ku, Hyogo Prefecture 1 Nippon Steel Corporation Hirohata Works (72) Inventor Masahiko Hamada 2-6 Otemachi, Chiyoda-ku, Tokyo No. 3 In Nippon Steel Co., Ltd. (72) Inventor Masao Matsuoka, 1264-1 Minamibeppu-cho, Settsu-shi, Osaka Prefecture Yamasato Electron Knight Co., Ltd. (72) Hiroaki Kosaka 12264-1, Minamibeppu-cho, Settsu-shi, Osaka Prefecture Yamasato (56) References JP-A-60-213845 (JP, A) JP-A-48-88994 (JP, A) JP-A-50-15598 (JP, A) Actual development Sho-53-133685 ( JP, U) JP-B-55-27300 (JP, B1)

Claims (2)

[Claims] 1. A method for measuring an oxygen partial pressure in a reaction gas in a blast furnace using an oxygen concentration battery comprising a solid electrolyte, wherein the oxygen probe containing the oxygen concentration battery is inserted into a blow pipe before being inserted into a raceway. The hot gas flowing in the blow pipe is controlled by controlling the passage speed of the oxygen probe in the blow pipe or by controlling the time that the oxygen concentration cell of the oxygen probe exists in the blow pipe. By preheating the oxygen concentration battery to make the response speed sufficient, then insert the oxygen probe into the raceway and position the oxygen concentration battery at the tip to the measurement point to measure the oxygen partial pressure Method for measuring oxygen partial pressure of blast furnace gas. 2. The blast furnace according to claim 1, wherein the oxygen concentration battery is preheated in the blow pipe and the electromotive force of the oxygen concentration battery is also measured to inspect whether the oxygen concentration battery is good or bad. Method for measuring oxygen partial pressure of gas.