JP2006292549A - Exhaust gas flow rate measuring system of sintering machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flow rate measuring system capable of measuring stably the exhaust gas flow rate of sintering machine over long duration, because so much moisture and sintered dust are contained in the exhaust gas flow of sintering machine that there is a problem that long-term measurement thereof is not easy. <P>SOLUTION: The exhaust gas flow rate measuring system of sintering machine is equipped with a thermal flowmeter 51, arranged on an exhaust gas pipes of a sintering machine, outputting data of exhaust gas flow rate and temperature in time series, an arithmetic section 52 implementing a predetermined computation based on the data of exhaust gas flow rate and temperature, a memory section 54 memorizing data of flow rate and temperature, a numeric inputting section 55 inputting numeric values to the arithmetic section 52, and an input/output section 53 inputting and outputting the data between the arithmetic section 52 and an external device 56. The thermal flowmeter 51 is arranged to inside of the exhaust gas pipes so as to keep the spacing between a sheath type temperature sensor and a sheath type temperature sensor with heating coil longer than the spacing of the great bars of sintering machine. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an exhaust gas flow rate measurement system for a dwroid type sintering machine such as iron ore used in the steel industry.

FIG. 10 is a process diagram of a conventional dwytroid type sintering machine.
As shown in FIG. 10, in a dwy-toroid type sintering machine in the conventional steel industry, raw materials such as iron ore cut out from the raw material tank 1 are mixed with moisture added by a mixer 2, and then a surge hopper 3 is used. Through the pallet 5. The raw material on the pallet 5 is ignited on the surface in the ignition furnace 4, and the sintering reaction occurs when the powder coke in the raw material burns and generates heat. The sintering reaction proceeds with the movement of the pallet 5 from the upper layer to the lower layer of the raw material by suction of air. In order to suck air downward, a wind box 6 (wind box) is disposed below the pallet 5, and a main duct 8 is connected via a straight pipe portion 7 (wind leg). A dust collector 9 and a blower 10 are provided at the end of the main duct 8 to suck air and sintered exhaust gas in a unified manner.

  In the Dwytroid type sintering machine, the exhaust gas flow rate and temperature in the longitudinal direction are measured to estimate the temperature distribution in the sintered layer, and based on the results, the yield is kept constant and the cold strength of the sintered ore is stabilized. And a method for improving the stability of quality and yield are disclosed (see Patent Document 1 and Patent Document 2).

  In order to realize these methods, it is indispensable to measure the exhaust gas flow rate of the sintering machine over a long period of time. As a means for this, in the straight pipe portion 7 (wind leg), generally, a Pitot tube is used. Alternatively, a flow meter using a Venturi tube is used, and a method using an ultrasonic flow meter is also disclosed (see Patent Document 3).

FIG. 11 is a schematic diagram of a Pitot tube flow meter.
The Pitot tube type flow meter has a small hole 15 in a direction perpendicular to the front small hole 14 with respect to the flow of exhaust gas, and has a built-in thin tube for taking out pressure separately from each hole. The flow rate is obtained by measuring In FIG. 11, 12 is a flow of exhaust gas, 13 is a pipe such as an exhaust gas pipe, and 17 is a pressure gauge.

FIG. 12 is a schematic diagram of a venturi-type flow meter.
The Venturi tube type flow meter generates a pressure difference before and after the throttle part 16 (Venturi tube) of the pipe that partially restricts the exhaust gas flow, and obtains the flow velocity from this pressure difference in the same way as the Pitot tube type flow meter. It is characterized by. In FIG. 12, 12 is a flow of exhaust gas, 13 is a pipe such as an exhaust gas pipe, and 17 is a pressure gauge.

  Since each of the flow meters is a differential pressure type applying Bernoulli's formula, it is necessary to measure the pressure at two points upstream and downstream in the exhaust gas pipe to be measured. It is characterized by using a connection method.

FIG. 13 is a schematic diagram of an ultrasonic flowmeter.
The ultrasonic flowmeter 18 receives ultrasonic waves 19 from the outside of the exhaust gas pipe 13 and measures the reflection and passage of the ultrasonic flowmeters 18 to measure the flow rate. It is said. In FIG. 13, 12 indicates the flow of exhaust gas, and 13 indicates piping such as an exhaust gas pipe.

JP 59-74243 JP-A-7-166251 Japanese Patent Laid-Open No. 61-282788

  However, when measuring the flow rate of exhaust gas discharged from the sintering pallet 5, the exhaust gas contains a large amount of moisture and sintering dust, so a differential pressure flow rate using a Pitot tube or a Venturi tube. In the meter, the small hole tube 14 and the small hole tube 15 connected to the pressure detection end are frequently clogged with dust, it is difficult to measure continuously, and maintenance of the small hole tubes 14 and 15 is frequently required. There are maintenance problems such as

  Also for ultrasonic flowmeters, general measurement objects are liquids with little dust and bubbles, and when measuring gas or vapor, the transducer is in a form called a liquid contact type that opens directly into the piping. Therefore, when measuring the exhaust gas flow rate of the sintering machine, the ultrasonic signal is attenuated due to contamination of the transducer due to the sintered dust, making measurement difficult.

  The ultrasonic flowmeter emits ultrasonic waves alternately from the upstream and downstream sides of the flow, and measures the difference in the propagation time of the ultrasonic waves, as well as dust (suspended substances) and bubbles in the liquid. There is a Doppler method in which ultrasonic waves are emitted toward and the flow velocity is measured from the frequency change of the reflected wave. The time difference type ultrasonic flowmeter is generally good in accuracy, but it is difficult to measure if there is moisture or dust on the ultrasonic path, and it is not suitable for measuring the exhaust gas flow rate of the sintering machine. It is. On the other hand, Doppler-type ultrasonic flowmeters are often used for liquids such as sewage and blood flow because they use suspended substances in the fluid and continuous bubbles.

  The present invention has been made in view of the above circumstances, and provides a flow rate measurement system capable of stably measuring the exhaust gas flow rate of a sintering machine for a long period of time, and the exhaust gas of the sintering machine. It aims at providing the facility diagnostic function of the flow measurement system for measuring a flow in the long term.

The exhaust gas flow rate measurement system for a sintering machine according to the present invention has the following features in order to solve the above-described problems.
The exhaust gas flow rate measurement system for a first sintering machine according to the present invention is an exhaust gas flow rate measurement system for a sintering machine in the iron and steel industry, and is disposed in an exhaust gas pipe of the sintering machine to provide a time series exhaust gas flow rate. To the thermal flow meter for outputting data and temperature data, computing means for performing a predetermined computation based on the exhaust gas flow rate and temperature data, storage means for storing the exhaust gas flow rate and temperature data, and the computing means Numerical input means for inputting numerical values, and input / output means for inputting / outputting data between the arithmetic means and an external device, the thermal flow meter is a sheath type temperature sensor inside the exhaust gas pipe And a sheath type temperature sensor with a heating coil are arranged apart from the interval of the great bar of the sintering machine.

  The exhaust gas flow rate measurement system for a second sintering machine according to the present invention is the exhaust gas flow rate measurement system for the sintering machine, wherein the thermal flow meter comprises the sheath type temperature sensor and a sheath type temperature sensor with a heating coil. In the protective case, and the interval between the sheath-type temperature sensor and the protective case and the interval between the sheath-type temperature sensor with the heating coil are wider than the interval between the great bars. To do.

  The exhaust gas flow rate measurement system for a third sintering machine according to the present invention is the exhaust gas flow rate measurement system for the first or second sintering machine, wherein the computing means is the exhaust gas flow rate data at a predetermined time. And calculating the fluctuation range of the two exhaust gas flow rate data and comparing the fluctuation range of the exhaust gas flow rate data with a predetermined numerical value. It is characterized by detecting a measurement abnormality in the meter.

  According to the exhaust gas flow rate measurement system for a sintering machine according to the present invention, the sheath type temperature sensor of the thermal type flow meter and the sheath type temperature sensor with a heating coil are arranged apart from the interval between the great bars of the sintering machine. By doing so, it is possible to prevent the sintered dust from adhering to form a lump, and it is possible to measure the exhaust gas flow rate of a sintering machine containing a large amount of moisture and sintered dust over a long period of time. Become.

  In addition, the fluctuation range of the exhaust gas flow data output from the thermal flow meter at a predetermined time is calculated, and the adhesion of the sintered dust or the like to the thermal flow meter is determined from the fluctuation range of the flow rate data. By detecting a measurement abnormality of the flow meter, it is possible to provide a facility diagnosis function for measuring the exhaust gas flow rate of the sintering machine for a long period of time.

  Hereinafter, an embodiment of an exhaust gas flow rate measurement system for a sintering machine according to the present invention will be described with reference to the drawings.

  With reference to FIG.1 and FIG.2, the exhaust gas flow measuring system of the sintering machine which concerns on Example 1 of this invention is demonstrated. FIG. 1 is a schematic diagram showing a configuration of an exhaust gas flow rate measuring system of a first sintering machine according to the present invention, and FIG. 2 is a schematic diagram of a pallet of the sintering machine.

  As shown in FIG. 1, the exhaust gas flow rate measurement system for a sintering machine according to Example 1 of the present invention is a sheath type using a thermocouple or a resistance temperature detector inside the exhaust gas pipe 13 of the sintering machine. It is configured by installing a thermal flow meter 22 provided with a temperature sensor 20 and a sheath-type temperature sensor 21 using a thermocouple or a resistance temperature detector that includes a heating coil. In FIG. 1, 12 indicates the flow of exhaust gas.

The thermal flow meter 22 is a kind of flow meter that has been put into practical use, and the mass flow rate of the fluid to be measured can be obtained as follows.
That is, when a heated object is placed in the fluid flow, the heated object is deprived of thermal energy by the fluid, so that it is cooled and its temperature changes. Conversely, the fluid takes heat energy from the heated object and raises its temperature. At this time, the mass flow rate can be measured by utilizing the fact that the amount of heat that moves per unit time corresponds to [constant specific pressure heat of fluid] × [fluid temperature rise difference] × [fluid mass flow rate].

  In the exhaust gas flow rate measurement system for a sintering machine according to the first embodiment of the present invention, the sheath type temperature sensor 20 for measuring the fluid temperature and the sheath type temperature sensor 21 with a heating coil are connected to the fluid from the side of the exhaust gas pipe 13. Install in the pipe so that it is perpendicular to the flow. As described above, the thermal flow meter requires a constant pressure specific heat of the fluid, which is set in advance according to the exhaust gas component measured in advance.

  Also in the thermal flow meter, when measuring the exhaust gas flow rate of the sintering machine, sintered dust is clogged between the sheath type temperature sensor 20 and the sheath type temperature sensor 21 with the heating coil as time passes. The amount of heat transferred to the exhaust gas may not be measured correctly. Sintered dust is mostly powdered particles having a diameter of less than 1 mm, but there is also pebbled sintered dust having a diameter of about 5 mm. As shown in FIG. 2, these sintered dusts pass between a plurality of great bars 26 laid as a bottom plate of the pallet 5 and are sucked into the main duct 8 from the straight pipe portion 7 (wind leg). The gap between the great bars 26 is a passage for air and exhaust gas for firing the sintering raw material 25 placed on the pallet 5 and is usually a gap of about 5 mm.

  The inventors conducted an experiment on a process in which the thermal flow meter 22 is inserted into the straight pipe portion 7 (wind leg) of the sintering machine and the thermal flow meter 22 is clogged with sintered dust. As a result, when the space between the sheath-type temperature sensor 20 and the sheath-type temperature sensor 21 with the heating coil is narrower than the gap 27 of the great bar 26, first, a pebbled sintered dust having a diameter of about 5 mm is firstly provided. However, it is sandwiched between the sheath-type temperature sensor 20 and the sheath-type temperature sensor 21 with the heating coil, and dust particles having a diameter of less than 1 mm including moisture adhere to the core and the dust eventually becomes hardened. It was found that normal measurement was difficult to form.

Therefore, in the exhaust gas flow rate measuring system for the sintering machine according to the first embodiment of the present invention, the sheath type temperature sensor 20 inserted into the exhaust gas pipe 13 of the sintering machine such as the straight pipe portion 7 (wind leg). Since the interval 23 between the sheath type temperature sensor 21 with the heating coil and the interval 27 between the great bars 26 which are the bottom plates of the pallet 5 of the sintering machine is disposed, the sintered dust forms a lump. This makes it possible to measure the exhaust gas flow rate of the sintering machine over a long period of time.
The exhaust gas flow rate measurement system for a sintering machine according to the present invention can be arranged not only as shown in FIG. 1 but also as shown in FIG.

  With reference to FIG. 4, the exhaust gas flow measurement system of the sintering machine which concerns on Example 2 of this invention is demonstrated. FIG. 4 is a schematic diagram showing a main configuration of an exhaust gas flow rate measurement system for a sintering machine according to Example 2 of the present invention.

  A protective case 24 is provided around the sheath type temperature sensor 20 of the thermal flow meter inserted into the exhaust gas pipe of the sintering machine such as the straight pipe part 7 (wind leg) and the sheath type temperature sensor 21 with the heating coil. In some cases, sintered dust is clogged between the sheath type temperature sensor 20 and the sheath type temperature sensor 21 with the heating coil and the protective case 24, and the amount of heat transferred to the exhaust gas may not be measured normally.

According to an experiment conducted by the inventors by inserting a thermal flow meter with a protective case 24 into the straight pipe portion 7 (wind leg), the process of clogging the sintered dust was the same as in the first invention. It was.
Therefore, in the exhaust gas flow rate measurement system for a sintering machine according to the second embodiment of the present invention, the sheath type temperature sensor 20 inserted into the exhaust gas pipe of the sintering machine such as the straight pipe portion 7 (wind leg) and the heating are used. By arranging the gap 23 between the sheath type temperature sensor 21 with the coil and the protective case 24 away from the gap 27 of the great bar which is the bottom plate of the pallet 5 of the sintering machine, the sintered dust forms a lump. This makes it possible to prevent the generation of nuclei and to measure the exhaust gas flow rate of the sintering machine over a long period of time.

  The protective case 24 may be attached to prevent the sintered dust mass from directly hitting the thermal flow meter and damaging the sheath type temperature sensor 20 or the sheath type temperature sensor 21 with the heating coil. That is, the wind box 6 (wind box) and the straight pipe portion 7 (wind leg) of the sintering machine are configured by combining iron structures, and the inner surface is not necessarily flat. Since the sintered dust forms a lump in a bad street and the lump may peel off and pass through the straight pipe portion 7 (wind leg), the protective case 24 is attached.

  With reference to FIG.1 and FIG.5, the exhaust gas flow volume measuring system of the sintering machine which concerns on Example 3 of this invention is demonstrated. FIG. 5 is a schematic diagram showing a configuration of an exhaust gas flow rate measurement system for a sintering machine according to Example 3 of the present invention.

The inventors of the present invention have found that the flow of gas in the exhaust gas pipe of the sintering machine is turbulent, and when the thermal flow meter can measure normally, the flow data constantly fluctuates, and conversely, When there was no fluctuation, it was found that the measurement was not performed normally due to clogging of sintered dust.
As shown in FIG. 5, the exhaust gas flow rate measurement system for a sintering machine according to Example 3 of the present invention includes a thermal flow meter 51 including a sheath type temperature sensor 20, a sheath type temperature sensor 21 with a heating coil, and the like. A calculation unit 52, an input / output unit 53, a storage unit 54, and a numerical value input unit 55 are provided. An external device 56 is connected to the calculation unit 52 and the input / output unit 53.

  In the exhaust gas flow rate measurement system for a sintering machine according to Embodiment 3 of the present invention, a thermal flow meter comprising a sheath type temperature sensor 20 and a sheath type temperature sensor 21 with a heating coil inside the exhaust gas pipe 13 of the sintering machine. By inserting 51, flow rate data and temperature data in the exhaust gas pipe are output. The output data is recorded in the storage unit 54 via the calculation unit 52 and the input / output 53 unit. The calculation unit 52 reads flow rate data for a predetermined time from the storage unit 54 and calculates the fluctuation range of the flow rate data.

  With reference to FIG.6 and FIG.7, the procedure which performs abnormality detection in the exhaust gas flow measurement system of the sintering machine which concerns on Example 3 of this invention is demonstrated. FIG. 6 is a flowchart of a first procedure for performing abnormality detection, and FIG. 7 is a flowchart of a second procedure for performing abnormality detection.

  In order to detect abnormality using the exhaust gas flow rate measurement system of the sintering machine of Example 3, first, as shown in FIG. 6, the gas flow rate is measured with the thermal flow meter 51 (S1), and the measured exhaust gas is measured. The gas flow rate is stored in the storage unit 54 (S2), the flow rate data for a fixed time is read from the storage unit 54 to the calculation unit 52 (S3), and the calculation unit 52 calculates the fluctuation range of the flow rate data from the flow rate data for the fixed time. (S4).

  Subsequently, α1 is obtained by comparing the fluctuation ranges of two flow rate data having different measurement start times calculated by the calculation unit 52 (S5), and the comparison value β1 of the fluctuation range ratio of the exhaust gas flow rate data is obtained by the numerical value input unit 55. Is set (S6).

  Here, α1 and β1 are compared (S7), and when α1 is smaller than β1, it can be determined that the measurement error of the thermal flow meter 51 is abnormal for the reason described above. Therefore, an abnormal signal is output to the external device 56 via the input / output unit 53 (S8). On the other hand, when α1 is larger than β1, it is determined that the thermal flow meter 51 is measuring normally (S9).

  In this way, it is possible to provide a facility diagnosis function of the flow system for measuring the exhaust gas flow rate of the sintering machine for a long period of time and to prevent dust from adhering to the exhaust gas flow system of the sintering machine at an early stage. It becomes.

Moreover, you may detect abnormality by the procedure shown in FIG.
In the procedure shown in FIG. 7, first, the gas flow rate is measured by the thermal flow meter 51 (S11), the measured exhaust gas flow rate is stored in the storage unit 54 (S12), and the storage unit 54 transfers to the calculation unit 52 for a certain period of time. The flow rate data is read out (S13), and the fluctuation range of the flow rate data is calculated from the flow rate data for a predetermined time by the calculation unit 52 (S14).

Subsequently, the fluctuation range α2 of the flow rate data at a certain time T3 calculated by the calculation unit 52 is obtained (S15), and the comparison value β2 of the fluctuation range of the exhaust gas flow rate data is set by the numerical value input unit 55 (S16).
Here, α2 and β2 are compared (S17), and when α2 is smaller than β2, it can be determined that the measurement error of the thermal flow meter 51 is abnormal for the reason described above. Therefore, an abnormal signal is output to the external device 56 via the input / output unit 53 (S18). On the other hand, when α2 is larger than β2, it is determined that the thermal flow meter 51 is normally measuring (S19).

  In this way, it is possible to provide a facility diagnosis function of the flow system for measuring the exhaust gas flow rate of the sintering machine for a long period of time and to prevent dust from adhering to the exhaust gas flow system of the sintering machine at an early stage. It becomes.

A specific result of measuring the exhaust gas flow rate using the exhaust gas flow rate measurement system of the sintering machine according to the present invention will be described.
FIG. 8 is an explanatory view of the exhaust gas flow rate measurement data of the sintering machine in operation.

  The exhaust gas flow rate measurement data shown in FIG. 8 shows the interval 23 between the sheath type temperature sensor 20 inserted into the straight pipe portion 7 (wind leg) of the sintering machine and the sheath type temperature sensor 21 with the heating coil. The exhaust gas flow rate of the sintering machine is measured by disposing 5 mm away from the interval 27 between the great bars 26 which are the bottom plates of No. 5.

  As is clear from FIG. 8, it was possible to measure the gas flow rate over a long period of 7 days, and the effectiveness of the present invention could be confirmed. In FIG. 8, the flow rate ratio on the vertical axis is a value representing the maximum value of the measurement range of the flow meter as 1.

FIG. 9 is an explanatory diagram of exhaust gas flow rate measurement data of the sintering machine before and after dust adhesion.
The exhaust gas flow rate measurement data of the sintering machine before and after the dust adhesion is based on the fact that the sintered dust adheres to the sheath type temperature sensor 20 inserted into the straight pipe portion 7 (wind leg) of the sintering machine and the sheath type temperature sensor 21 with the heating coil. The exhaust gas flow rate was measured in a state in which no sintering was performed and in a state in which sintered dust was intentionally adhered.

  As is clear from FIG. 9, there is a large difference in the fluctuation range of the exhaust gas flow rate depending on whether or not the sintered dust adheres, and the effectiveness of the present invention for detecting an abnormality can be confirmed using this difference. It was. In addition, the flow rate ratio on the vertical axis in FIG. 9 is a value that represents 1 as the maximum value of the measurement range of the flow meter.

1 is a schematic diagram illustrating a configuration of an exhaust gas flow rate measurement system according to Embodiment 1 of the present invention. It is a schematic diagram of the pallet of the sintering machine in Example 1 of this invention. It is a schematic diagram which shows the other structure of the exhaust gas flow measuring system of the sintering machine which concerns on Example 1 of this invention. It is a schematic diagram which shows the principal part structure of the exhaust gas flow measuring system of the sintering machine which concerns on Example 2 of this invention. It is a schematic diagram which shows the structure of the exhaust gas flow measuring system of the sintering machine which concerns on Example 3 of this invention. It is a flowchart of the 1st procedure which performs abnormality detection. It is a flowchart of the 2nd procedure which performs abnormality detection. It is explanatory drawing of the exhaust gas flow rate measurement data of the sintering machine in operation. It is explanatory drawing of the exhaust gas flow rate measurement data of the sintering machine before and behind dust adhesion. FIG. 6 is a process diagram of a conventional dwelloid type sintering machine. It is a schematic diagram of a Pitot tube type flow meter. It is a schematic diagram of a venturi type flow meter. It is a schematic diagram of an ultrasonic flowmeter.

Explanation of symbols

1 Raw Material Tank 2 Mixer 3 Surge Hopper 4 Ignition Furnace 5 Pallet 6 Wind Box (Wind Box)
7 Straight pipe (wind leg)
DESCRIPTION OF SYMBOLS 8 Main duct 9 Dust collector 10 Blower 11 Chimney 12 Gas flow 13 Exhaust gas pipe 14 Front small hole pipe 15 Right angle small hole pipe 16 Piping throttle part (Venturi pipe)
17 Pressure gauge 18 Ultrasonic flow meter 19 Ultrasonic 20 Sheath type temperature sensor 21 Sheath type temperature sensor with heating coil 22 Thermal flow meter 23 Spacing between sheath type temperature sensor and sheath type temperature sensor with heating coil 24 Sheath type temperature sensor Case for protection of sheath type temperature sensor with heating coil 25 Sintering raw material 26 Great bar 27 Great bar interval 51 Thermal flow meter 52 Calculation unit 53 Input / output unit 54 Storage unit 55 Numerical input unit 56 External device

Claims (3)

In the exhaust gas flow measurement system for sintering machines in the steel industry,
A thermal flow meter arranged in the exhaust gas pipe of the sintering machine and outputting time-series exhaust gas flow rate data and temperature data;
A calculation means for performing a predetermined calculation based on the exhaust gas flow rate and temperature data;
Storage means for storing the exhaust gas flow rate and temperature data;
Numerical value input means for inputting numerical values to the arithmetic means;
I / O means for inputting and outputting data between the arithmetic means and an external device,
In the thermal flow meter, the sheath-type temperature sensor and the sheath-type temperature sensor with a heating coil are disposed inside the exhaust gas pipe so as to be separated from the interval of the great bar of the sintering machine. The exhaust gas flow measurement system of the machine. The thermal flow meter comprises the sheath type temperature sensor and a sheath type temperature sensor with a heating coil housed in a protective case,
2. The exhaust of a sintering machine according to claim 1, wherein an interval between the sheath type temperature sensor and the protective case and an interval between the sheath type temperature sensor with a heating coil are wider than an interval between the great bars. Gas flow measurement system.   The calculation means calculates a fluctuation range of the exhaust gas flow rate data at a predetermined time and compares the fluctuation ranges of two flow rate data having different measurement start times, or the fluctuation range of the exhaust gas flow rate data 3. The exhaust gas flow rate measurement system for a sintering machine according to claim 1, wherein a measurement abnormality of the thermal type flow meter is detected by comparing with a predetermined numerical value.

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