JP4770316B2 - Blast furnace tuyere and blast furnace bottom situation evaluation method - Google Patents

Description

  The present invention relates to a method for evaluating a blast furnace lower state and a tuyere used for evaluating a blast furnace lower state.

Improving productivity in the blast furnace is an important issue not only from cost reduction but also from carbon dioxide reduction. The blast furnace is a huge counter-current packed bed reaction vessel that blows high-temperature oxygen from the lower part to generate reducing gas (mainly CO), and iron oxide (mainly iron ore: mainly Fe ₂ O) from the upper part. ₃ ) and charcoal (coke: C). In accordance with the consumed carbon material and the iron oxide corresponding to the amount of pig iron produced, the charge is continuously lowered. Increasing the amount of reducing gas is indispensable for increasing productivity. However, increasing the amount of reducing gas causes non-uniformity and instability of the material drop due to its resistance (pressure loss), which increases productivity. Has a limit, and pressure loss has an upper limit. Therefore, in order to maintain high productivity, it is necessary for the operator to continuously monitor the pressure loss and manage the air flow rate so that the pressure loss that varies according to the raw material properties approaches the upper limit value. .

  The furnace body of the blast furnace is perforated at intervals of several meters in the height direction, and the pressure inside the furnace is measured. It is the quickest and most reliable to monitor charge and pressure drop (pressure loss). Assuming that load fluctuations in the charge can be ignored, the top pressure is kept constant in the blast furnace, so the bottom pressure is an important indicator. The lowermost pressure detection hole (pressure guiding tube) is often installed in a funnel-shaped place called a morning glory. However, even this cannot be said to be sufficiently close to the tuyere, and since the melt flows down on the inner surface of the morning glory, it is inevitable that the pressure detection hole is blocked due to sticking, and detection stops. Therefore, the pressure at the bottom of the furnace that is measured using the pressure detection hole is unsuitable for use as an operation management index in that the measurement cannot be performed reliably. Tube pressure) is used as an indicator. However, the annular tube pressure and the furnace pressure are clearly different for the following reasons (a) and (b).

(A) Facility pressure loss Structures such as tuyere, auxiliary fuel blow-in tubes, hot air control valves, etc. exist between the annular tube and the furnace. The air blowing pressure fluctuates due to changes in these structures. For example, the tuyere diameter may be partially reduced or closed to protect the furnace body, and may be naturally blocked by the furnace contents. Auxiliary fuel blow-in tubes that were not present when the furnace body was newly installed were added, and their thickness and insertion depth could be changed. In the hot air control valve, not only is the additional equipment, but also the valve opening adjustment itself fluctuates the pressure loss.

(B) Combustion pressure in tuyere Currently, all blast furnaces in the country are injecting pulverized coal into tuyere. Since the pulverized coal starts burning in the tuyere, the amount of gas passing through the tuyere varies depending on the combustion rate, component, amount, particle size, etc. of the pulverized coal. As a result, the blowing pressure (annular tube pressure) increases, but the amount of increase is very difficult to estimate.

  Despite such many disturbances, the airflow resistance index obtained by subtracting the influence of the airflow pressure variation and the airflow amount from the airflow pressure has long been used as an operation stability index. As a method of estimating the pressure inside the furnace near the tuyere, there is a method of inserting some detection end into the furnace including the raceway (for example, see Patent Document 1). There is also a method of extrapolating from a pressure gauge installed in the morning glory (see, for example, Patent Document 2).

  As a management index for blast furnace operation, the temperature level at the bottom of the furnace is important along with pressure loss. If there is not enough heat generated in the furnace relative to the heat required to reduce and melt the iron oxide, solidified material can be produced everywhere in the furnace, leading to an inoperable state (cooling). For this reason, the operator continuously monitors the hot metal temperature and visually monitors the luminance in the raceway through a peephole called tuyere glasses in order to detect an abnormality earlier.

In recent years, in-furnace coke temperature measured using an optical sensor in addition to visual observation has been adopted as an operation index for heat level (see, for example, Patent Document 3).
JP-A-9-143520 JP 2003-306708 A JP-A-3-291315

  However, the method for estimating the pressure and temperature in the lower part of the furnace has the following problems.

  The method of estimating the pressure inside the furnace near the tuyere by inserting the detection end described in Patent Document 1 into the furnace can only be measured for a short time from the durability of the detection end, and therefore cannot be used for operation management.

  The method of extrapolating from the pressure gauge installed in the morning glory part described in Patent Document 2 is an extrapolation estimation value, and as described above, the pressure detection stop caused by the transfer of the melt on the inner surface of the morning glory occurs. Therefore, it cannot be used as an operation index.

  The optical information obtained by the method described in Patent Document 3 and visual observation using tuyere glasses is only the state of the coke combustion zone (raceway) at the tip of the tuyere, and the heat level of the lower part of the furnace existing in the back Is not a direct indication.

  As described above, it is difficult to accurately estimate the pressure and temperature in the lower part of the blast furnace and use it as an operation management index.

  Accordingly, it is an object of the present invention to provide a blast furnace lower part state evaluation method that can solve the problems of the prior art, measure the pressure and temperature of the blast furnace lower part, and can be used as an operation management index. Moreover, the objective of this invention is providing the tuyere which can measure the pressure and temperature of a blast furnace lower part.

The features of the present invention for solving such problems are as follows.
(1), between the furnace interior and Rosotogawa through the bottom tuyere body, using blast furnace blast tuyere that having a hole in which the end portion of the furnace interior is open to the tuyere outer periphery of該羽port A method for evaluating the state of a blast furnace lower part, wherein one or more of pressure, brightness, temperature, and image information in the furnace are measured via a hole .
(2) The blast furnace lower part situation evaluation method according to (1), characterized in that the tuyere has a hole whose inner end is opened at the lower part of the outer part of the tuyere.
(3), by measuring the blowing, the pressure of該吹included gas into the furnace an inert gas from the hole of the tuyere, and measuring the pressure of the blast furnace bottom (1) or (2 ) Blast furnace lower part situation evaluation method.
( 4 ) The blast furnace lower part situation evaluation method according to ( 1) or (2 ), wherein a temperature measurement terminal is inserted into the hole of the tuyere and the temperature of the lower part of the blast furnace is measured.

  According to the present invention, it is possible to accurately and continuously detect the pressure loss (furnace ventilation) and the furnace lower temperature level in the furnace. By using these as operation indexes, it is possible to operate at a high output ratio and low reducing material ratio close to the limits.

  The present inventors examined a method for measuring pressure and temperature in the lower part of the blast furnace. And it is possible to directly measure the pressure and temperature by forming a hole that penetrates between the inside and outside of the furnace in the tuyere body and measuring the pressure and temperature in the furnace through the hole. As a result, the present invention has been completed.

  First, the tuyere used in the blast furnace lower part state evaluation method of the present invention will be described.

  FIG. 1 shows a longitudinal sectional view of a tuyere, which is an embodiment of the present invention. Installed at the bottom of the blast furnace, with the right side facing the inside of the furnace. The material of the tuyere 1 is made of copper in the same manner as a normal tuyere, and is high-speed circulating water cooling. A hole 2 penetrating between the furnace inner side and the furnace outer side is formed in the lower part of the tuyere body. Although the diameter of the hole 2 can be set arbitrarily, it can be set to, for example, about 5 to 20 mm. An end 2a which is an outlet on the side exposed to the furnace when the tuyere is installed in the hole 2 is open to the outer part of the tuyere. The end 2a is preferably open at the lower part of the outer peripheral portion of the tuyere in order to avoid the influence of the melt dripping from above or the drop of the solid. The end 2b, which is the end of the hole 2 on the opposite side, opens to the outside of the furnace when the tuyere is installed. For temperature measurement in the furnace, a temperature measuring terminal 3 such as an optical fiber, a thermocouple, an endoscope or the like is inserted into the hole 2.

  The lower part of the tuyere, which is a preferred opening position of the end 2a, is the lower half of the outer part of the tuyere, and particularly preferably, the lower part of the outer part of the tuyere is the vertical lower part of the hot air blowing portion. .

  The tuyere is preferably provided with gas supply means for injecting an inert gas into the hole from the outside of the furnace. By blowing the inert gas, it is possible to measure the pressure in the furnace while preventing the outflow of the gas in the furnace and preventing the clogging of the hole 2.

  Next, the blast furnace lower part situation evaluation method using the tuyere described above will be described. In the present invention, one or more of pressure, brightness, temperature, and image information in the furnace are measured via the hole of the tuyere. Using these pieces of information, the situation in the lower part of the blast furnace can be accurately grasped.

  In measuring the pressure, the pressure in the lower part of the blast furnace can be accurately measured by blowing an inert gas into the furnace through the hole of the tuyere and measuring the pressure of the blown gas. The tuyere is installed in a blast furnace, and a constant amount of inert gas such as nitrogen is constantly flowed into the furnace from the hole 2. The pressure in the furnace is measured by measuring the pressure of the gas while preventing the clogging of the hole 2 by the inert gas. As the inert gas, helium gas, argon gas or the like can be used in addition to nitrogen gas. In order to avoid the influence of pressure loss at the hole, it is desirable that the flow rate be as small as possible. However, the pressure at a flow rate of 0 may be estimated from the pressure measurement result by changing the flow rate.

  In addition, a temperature measurement terminal can be inserted into the hole of the tuyere to directly measure the temperature at the bottom of the blast furnace. By inserting a temperature measuring optical fiber or a thermocouple into the hole 2, the temperature of coke or in-furnace gas can be directly measured. If the thermocouple is damaged, it is necessary to wait for the tuyere to be replaced after a break, but when the optical fiber is worn out, it can be continuously measured by sending it in. It is very rare that the hole 2a, which is opened under the tuyere and the gas always flows out, is blocked, but even if a blockage occurs, it can be released by feeding an optical fiber if it is slightly blocked. . Even if a completely fixed blockage occurs, it will be restored if the tuyere is replaced, so it is more reliable than the impulse tube provided in the furnace body itself. The tuyere can be replaced by working for several hours when the blast furnace is closed, and the tuyere of the present invention can be easily installed in the blast furnace by replacing the tuyere. By installing the tuyere of the present invention in a plurality of tuyere, it is possible to improve the reliability of measurement by backup and to detect the circumferential deviation of the in-furnace situation.

  By using the above blast furnace lower part state evaluation method, the pressure and temperature in the lower part of the blast furnace can be accurately evaluated. Therefore, by using these evaluation results as a management index for blast furnace operation, it is possible to maintain the furnace pressure (pressure loss) and temperature at a predetermined value and stably continue the desired operation mode. .

The present invention was carried out in a blast furnace having an internal volume of 4000 m ³ . In the high blast furnace ratio operation in the blast furnace, the operation is performed with the goal of increasing the brew amount by controlling the blast volume and reducing material ratio based on the blast pressure and brew temperature, which is a conventional method. As a result, it was not possible to sufficiently suppress raw material lowering and hot metal temperature fluctuation, and the operation was not stable. Therefore, using the tuyere of the present invention shown in FIG. 1, the pressure in the furnace is obtained by measuring the pressure of the nitrogen gas while flowing 1000 cm ³ / min from the hole into the furnace. The furnace temperature was measured. The diameter of the hole part of the tuyere was 10 mm, and the end part inside the furnace of the hole part was installed so as to be the lowest part of the outer part of the tuyere. Control for adjusting the blast volume based on the furnace pressure determined as described above, and control for adjusting the temperature of the blast gas and the reducing material ratio based on the furnace temperature determined as described above were performed. . As a result, both the raw material drop and the hot metal temperature became stable, and as a result, it became possible to increase the average amount of molten iron and reduce the ratio of the reducing material. Changes in production volume and reducing material ratio are shown in FIG. By carrying out the operation method of the present invention from August, the ratio of reducing material, which was 500 kg / t or more, was stabilized to 500 kg / t or less, and the production amount was stabilized to about 8960 t / day.

The longitudinal cross-sectional view of a tuyere which is one Embodiment of this invention. The graph which shows the change of the reducing material ratio and production amount by implementation of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Tuyere 2 Hole 2a Hole end 2b Hole end 3 Temperature measurement terminal

Claims (4)

Between the furnace interior and Rosotogawa through the tuyere main body bottom, using a blast furnace blast tuyere that having a hole in which the end portion of the furnace interior is open to the tuyere outer peripheral portion, via the hole portion of該羽port Then, one or more types of pressure, brightness, temperature, and image information in the furnace are measured . The blast furnace lower part situation evaluation method according to claim 1, wherein the tuyere has a hole whose inner end is opened at a lower part of the outer part of the tuyere. From the hole of the tuyere to the inert gas into the furnace blowing, by measuring the pressure of該吹inclusive gas, according to claim 1 or claim 2, characterized in that for measuring the pressure of the blast furnace bottom Blast furnace bottom situation evaluation method. The blast furnace lower part situation evaluation method according to claim 1 or 2 , wherein a temperature measurement terminal is inserted into the hole of the tuyere and the temperature of the lower part of the blast furnace is measured.

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