Method for detecting air leakage from sintering equipment

Abstract

To detect vent leak in an early stage using an electrolytic oxygen meter.SOLUTION: A method of detecting vent leak in a sintering machine facility, in which an exhaust gas processing system of the sintering machine facility is configured by consecutively arranging a wind box, a wind leg, a main duct, and an exhaust gas processing section in this order from an upstream side in an exhaust gas flow direction, includes measuring an oxygen concentration using a solid electrolytic oxygen meter at least at two different positions on a downstream side in the exhaust gas flow direction relative to the wind leg and comparing oxygen concentrations at the two measurement positions to detect presence / absence of a vent leak between the two measurement positions.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a method for detecting air leakage from a sintering machine. [Background technology]

[0002] A sintering machine is a facility in which the raw materials are loaded onto pallets in layers, ignited in an ignition furnace, and then the carbonaceous material contained in the raw materials is burned while ventilation is performed, and the resulting combustion heat is used to sinter the ore and slag-forming materials. The pallets are connected in a chain and moved on a rotating endless track to continuously produce sintered ore. In the sintering machine, ventilation is sucked in from a wind box below the pallets, driven by a blower downstream of the exhaust gas system. This draws air from the surface of the sintering raw material layer loaded on the pallets and flows downward. From the ignition furnace onwards, the combustion zone in the sintering raw material layer gradually propagates downward as the pallets move.

[0003] Since air is sucked in downwards, sealing mechanisms are installed between the pallets and at the joints between the pallets and the rails, but if gaps occur due to deformation of the pallets or rails, air leaks through the gaps and outside air enters. Air leaks prevent normal ventilation in the sintering machine and worsen the combustion state of the raw materials, which is a factor that deteriorates the productivity and properties of the sintered ore product. Therefore, it is necessary to reduce the occurrence of air leaks by repairing the equipment, but in order to carry out repairs, it is first necessary to detect the location of the air leak.

[0004] Conventionally, air leakage detection in sintering machines has mainly been performed by detecting air leakage directly under the pallet, for example, in a wind box (for example, Patent Documents 1 and 2). However, as sintering machine equipment deteriorates, there is an increasing need to detect air leakage early throughout the entire exhaust gas system. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2009-275239 A [Patent Document 2] JP 2014-092296 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, when installing continuous oxygen concentration meters (O2 meters) at multiple locations throughout the entire exhaust gas system after the wind box of the sintering machine, a method for stably using the oxygen concentration meters has not been established, and air leaks cannot be detected early. In other words, for intermittent checks such as regular equipment inspections, highly accurate information can be obtained by, for example, having an operator sample gas and analyzing the components of the sampled gas using gas chromatography. However, in order to detect the occurrence of air leaks early, it is necessary to install oxygen concentration meters and continuously collect and monitor data. There has been no sufficient consideration of how to use oxygen concentration meters to appropriately collect such data throughout the entire exhaust gas system of the sintering machine and detect air leaks.

[0007] Here, in the above Patent Documents 1 and 2, a laser type oxygen analyzer is used as the oxygen analyzer for detecting air leakage from the sintering machine. Laser type oxygen analyzers are said to be superior to zirconia type oxygen analyzers that have been used conventionally based on general knowledge of analytical technology in that they have good responsiveness, can measure even under high temperature and high dust conditions, provide highly reliable measurements, and require little maintenance. However, zirconia type oxygen analyzers do not require pre-processing when measuring oxygen concentration, and are less expensive than laser type oxygen analyzers, making them effective for installation in multiple units.

[0008] Therefore, the present invention has been made in consideration of the above problems, and an object of the present invention is to provide a method for detecting air leakage in a sintering machine, which is capable of detecting air leakage at an early stage by using an electrolyte oxygen concentration meter. [Means for solving the problem]

[0009] In order to solve the above problems, according to one aspect of the present invention, there is provided a method for detecting air leakage in a sintering machine, in which an exhaust gas treatment system of the sintering machine is configured with a wind box, a wind leg, a main duct and an exhaust gas treatment unit, which are installed in this order from the upstream side in the exhaust gas flow direction, and the method measures oxygen concentration using a solid electrolyte oxygen concentration meter at at least two different measurement positions downstream of the wind leg in the exhaust gas flow direction in the exhaust gas treatment system, compares the oxygen concentrations at the two measurement positions, and detects the presence or absence of air leakage between the two measurement positions.

[0010] The oxygen concentration may be measured at two different measurement positions downstream in the exhaust gas flow direction from the connection between the main duct and the exhaust gas treatment unit.

[0011] The exhaust gas treatment device may have a plurality of dust collectors, and outlets of the plurality of dust collectors may be connected to an exhaust fan. In this case, the oxygen concentration may be measured at least between a connection between the main duct and the exhaust gas treatment device and the inlets of the plurality of dust collectors, and between the outlets of the plurality of dust collectors and the inlet of the exhaust fan.

[0012] The solid electrolyte oxygen concentration meter may be a zirconia oxygen concentration meter.

[0013] Also, the oxygen concentration may be measured at a position in the exhaust gas treatment system where the CO concentration has previously been measured to be 5% or less.

[0014] In the exhaust gas treatment system, a first oxygen concentration at a first measurement position and a second oxygen concentration at a second measurement position downstream of the first measurement position in the exhaust gas flow direction are measured; If the second oxygen concentration is greater than the first oxygen concentration, it may be determined that air leakage occurs between the first measurement position and the second measurement position. Effect of the Invention

[0015] As described above, according to the present invention, air leakage can be detected at an early stage using an electrolyte oxygen concentration meter. [Brief description of the drawings]

[0016] [Figure 1] FIG. 1 is a schematic diagram showing a configuration example of a sintering machine facility according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a schematic diagram showing details of an exhaust gas system of the sintering machine according to the embodiment. [Diagram 3] 4 is a flowchart showing an air leakage detection method for a sintering machine according to the embodiment. [Figure 4] FIG. 2 is a schematic diagram showing the configuration of a test facility. [Diagram 5] 1 is a graph showing the results of an example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In this specification and the drawings, components having substantially the same functional configurations are designated by the same reference numerals, and duplicated explanations will be omitted.

[0018] [1. Sintering machine equipment] First, a schematic configuration of a sintering machine 1 according to an embodiment of the present invention will be described with reference to Fig. 1 and Fig. 2. Fig. 1 is a schematic diagram showing a configuration example of the sintering machine 1 according to this embodiment. Fig. 2 is a schematic diagram showing details of an exhaust gas system of the sintering machine 1 according to this embodiment. Fig. 1 mainly shows the exhaust gas system of the sintering machine related to the air leakage detection method according to this embodiment.

[0019] As shown in FIG. 1, a sintering machine facility 1 according to this embodiment includes a sintering machine 10, a cooler 20, an electric dust collector 30, an exhaust fan 40, and a chimney 50.

[0020] The sintering machine 10 is a facility in which the mixed raw materials are charged from a raw material hopper 11 onto multiple pallets (not shown) connected in the longitudinal direction, and are layered. After ignition in an ignition furnace 13, the carbonaceous material contained in the mixed raw materials is burned while ventilation is performed, and the ore and slag-forming material are baked by the combustion heat. The pallets rotate on rails 12. In FIG. 1, only the upper side of the rails 12 is shown in order to clearly show the exhaust gas system, but the rails 12 in FIG. 1 form an endless track symmetrically in the upper and lower directions. After passing through the ignition furnace 13, the combustion zone in the sintering raw material layer gradually propagates downward as the pallets travel, and sintered ore is produced. The produced sintered ore falls into a cooler 20 at the right end of the sintering machine 10 and is cooled.

[0021] In the sintering machine 10, ventilation is sucked from the wind box 15 below the pallet using the exhaust fan (blower) 40 downstream of the exhaust gas system as a driving force. This causes air to be drawn from the surface of the sintering raw material layer loaded on the pallet and flow downward. The exhaust gas that flows into the wind box 15 passes through the wind leg 17 (wind legs 17A and 17B in FIG. 2 are also collectively referred to as "wind legs 17") and the main duct 19 (main ducts 19A and 19B in FIG. 2 are also collectively referred to as "main duct 19"), and is discharged to the electric dust collector 30.

[0022] More specifically, as shown in FIG. 2, each wind box 15 is divided into two wind legs 17A and 17B at the bottom. The wind leg 17A is connected to a main duct 19A, and the wind leg 17B is connected to a main duct 19B. The main ducts 19A and 19B are connected to a main duct outlet 61, and an exhaust gas pipe that becomes a single exhaust gas flow path is connected to an inlet of an electric dust collector 30. The electric dust collector 30 may be composed of, for example, four dust collectors (chambers A to D). After dust in the exhaust gas is removed by the electric dust collector 30, the exhaust gas passes through an exhaust fan 40 and is discharged from a chimney 50. In this embodiment, the downstream side of the outlet of the main duct 19 in the exhaust gas flow direction is also called an exhaust gas treatment section.

[0023] [2. Air leak detection in sintering machines] [2-1. Air leak detection using a zirconia oxygen analyzer] In the air leakage detection in the sintering machine according to the present embodiment, an electrolyte oxygen concentration meter is used to enable early detection of air leakage in the sintering machine. The electrolyte oxygen concentration meter is, for example, a zirconia oxygen concentration meter. In the present embodiment, a case where a zirconia oxygen concentration meter is used as the electrolyte oxygen concentration meter will be described, but the present invention is not limited to this example, and an oxygen concentration meter using another solid electrolyte may also be used.

[0024] Here, there are four main types of oxygen analyzers that continuously measure the oxygen concentration in pipes in industrial processes: zirconia oxygen analyzers, laser oxygen analyzers, magnetic oxygen analyzers, and galvanic cell oxygen analyzers. When it is assumed that each type of oxygen analyzer will be used in multiple locations throughout the exhaust gas system of a sintering machine, magnetic oxygen analyzers and galvanic cell oxygen analyzers require a pre-treatment process to remove moisture, dust, and the like from the exhaust gas before sampling it and measuring the oxygen concentration. Considering that this pre-treatment process is expensive and requires a large maintenance load, magnetic oxygen analyzers and galvanic cell oxygen analyzers are not suitable for installing multiple units and performing continuous measurement.

[0025] In contrast, zirconia-type oxygen analyzers and laser-type oxygen analyzers do not require a pre-treatment process. Laser-type oxygen analyzers are superior to zirconia-type oxygen analyzers in that they have good responsiveness, can measure even under high temperature and high dust conditions, have high reliability of measured values, and require small maintenance loads. However, laser-type oxygen analyzers are expensive precision devices, and installing multiple units requires huge costs. For this reason, from the viewpoint of cost, laser-type oxygen analyzers are not suitable for installing multiple units. Therefore, in this embodiment, an electrolyte-type oxygen analyzer such as a zirconia-type oxygen analyzer is used to detect air leakage in a sintering machine facility.

[0026] On the other hand, compared to other types of oxygen concentration meters, zirconia-type oxygen concentration meters are useful for installing multiple units and for continuous measurement, but the accuracy of evaluating the presence or absence of air leakage in sintering equipment based on the oxygen concentration measured using a zirconia-type oxygen concentration meter is not necessarily high. If the oxygen concentration is tested by sampling gas, there may be an error in the oxygen concentration. Therefore, the present inventors have studied a method for accurately detecting air leakage in sintering equipment using a zirconia-type oxygen concentration meter.

[0027] As a result, it was first discovered that CO gas, which is inevitably contained in the exhaust gas from the sintering machine 10, is an interference gas in the zirconia-type oxygen concentration meter. 2 ) and is a disturbance factor that can cause a non-negligible deterioration in measurement accuracy. Specifically, this refers to CO gas. In a zirconia oxygen analyzer, when CO gas coexists with oxygen at high temperatures, an oxidation reaction occurs and CO 2 Since gas is produced and oxygen is consumed, this disturbs the oxygen concentration measurement.

[0028] That is, a zirconia oxygen analyzer uses a heater to heat zirconia to a high temperature of about 800 to 900°C to make it conductive, and measures the oxygen concentration by measuring the electromotive force E generated by the oxygen partial pressure difference. It is known that the electromotive force E can be expressed as the Nernst equation shown in the following formula (1). In formula (1), R is the gas constant, T is the absolute temperature, and n is the oxygen concentration. 2 Valence (n=4), F is Faraday's constant, Px(O 2 ) is the oxygen partial pressure in the exhaust gas, Pa(O 2 ) is the oxygen partial pressure of the reference gas.

[0029] E = -(RT / nF) × ln{Pa(O 2 ) / Px(O 2 )} ···(1)

[0030] As a result of extensive research, the inventors of the present application have confirmed that the reason why CO gas disturbs the oxygen concentration is that when CO gas is present in the exhaust gas contacting the solid electrolyte at high temperatures, the reaction of the following formula (2) proceeds from the left side to the right side. In other words, as CO is oxidized, the oxygen concentration indicated by the zirconia oxygen analyzer becomes lower than the actual value of the exhaust gas.

[0031] CO+1 / 2O 2 =CO 2 (2)

[0032] If the difference between the actual oxygen concentration in the exhaust gas and the oxygen concentration indicated by the oxygen concentration meter is defined as the "error," then the error will become larger when the CO concentration increases in the condition where CO and oxygen coexist, which is the condition that causes the error. The wind box 15 and wind leg 17 are locations where the CO concentration varies greatly depending on the operating state of the sintering machine. For this reason, even if the oxygen concentration is measured using a zirconia oxygen concentration meter, the error also varies depending on the operating state of the sintering machine, and furthermore, even when used in conjunction with a laser oxygen concentration meter, it is difficult to evaluate the difference in oxygen concentration depending on the measuring location. This is why it is thought that zirconia oxygen concentration meters could not be used to detect air leaks in the past.

[0033] Here, in this embodiment, the oxygen concentration in the exhaust gas system of the sintering machine is measured in order to detect air leakage early. Furthermore, if information is obtained that allows air leakage in the sintering machine to be detected and the priority of repair parts to be determined, the air leakage detection method is useful. Taking these points into consideration, the air leakage detection method for the sintering machine according to this embodiment does not necessarily need to measure an accurate oxygen concentration, but only needs to detect a change in oxygen concentration that allows air leakage to be detected. Therefore, in the air leakage detection method for the sintering machine according to this embodiment, oxygen concentrations are measured at two measurement positions that are separated from each other and have clear exhaust gas flows in the exhaust gas system, and the two measured oxygen concentrations are compared to detect the presence or absence of air leakage between the two measurement positions.

[0034] That is, as shown in FIG. 3, first, the oxygen concentration is measured at two different measurement positions in the exhaust gas system by a zirconia type oxygen analyzer installed at each measurement position (S10). Then, the oxygen concentration on the upstream side in the exhaust gas flow direction is compared with the oxygen concentration on the downstream side (S20). If the oxygen concentration on the downstream side in the exhaust gas flow direction is higher than the oxygen concentration on the upstream side, it is determined that there is a high probability that there is a pipe crack or the like between the two measurement positions and that there is air leakage (S30). On the other hand, if the oxygen concentration on the downstream side in the exhaust gas flow direction is lower than the oxygen concentration on the upstream side, it is determined that there is a low possibility that air leakage occurs between the two measurement positions (S40). Since the actual air leakage location is identified by inspecting the area between the two measurement positions, it is possible to sufficiently detect air leakage by installing a zirconia type oxygen analyzer at two different measurement positions and measuring the oxygen concentration at each position.

[0035] In addition, the term "separate" measurement positions refers to a state in which they are distant and physically separated, and is also referred to as "two different measurement positions" in this embodiment. In addition, the term "the flow of exhaust gas is clear between the two different measurement positions" means that, when the sintering machine equipment is viewed as a whole between the two different measurement positions, no backflow or vortex occurs, and the upstream and downstream of the exhaust gas flow direction can be distinguished.

[0036] More specifically, of two different measurement positions in the exhaust gas system, the measurement position upstream in the exhaust gas flow direction is defined as the first measurement position, and the measurement position downstream is defined as the second measurement position. The oxygen concentration measured by the zirconia oxygen analyzer installed at the first measurement position is defined as the first oxygen concentration O1, and the oxygen concentration measured by the zirconia oxygen analyzer installed at the second measurement position is defined as the second oxygen concentration O2. When the difference between the first oxygen concentration O1 and the second oxygen concentration O2 is defined as the oxygen concentration difference ΔO (=O2-O1), a large oxygen concentration difference ΔO indicates that there is a lot of air that does not contribute to the combustion of the coke powder and there is a large amount of air leakage.

[0037] Here, when CO gas is not present, if other measurement error factors by the zirconia oxygen analyzer can be ignored, the measured oxygen concentration will be approximately the same as the actual value, and the oxygen concentration difference ΔO will be the correct value. On the other hand, when CO gas is present, if the error in the first oxygen concentration due to the presence of CO gas is e1, the error in the second oxygen concentration is e2, and the oxygen concentration difference including the error is ΔOe, the oxygen concentration difference including the error ΔOe can be expressed by the following formula (3).

[0038] ΔOe=(O2-e2)-(O1-e1) ···(3)

[0039] Equation (3) can be transformed into the following equation (4).

[0040] ΔOe=(O2-O1)+(e1-e2) =ΔO+(e1-e2) (4)

[0041] Here, if air leakage occurs between the two measurement positions and air is added to the downstream side, the amount of CO gas itself at the two measurement positions does not change, and the denominator increases due to the increase in air due to air leakage, so the CO gas composition is large on the upstream side (first measurement position) and small on the downstream side (second measurement position). As a result, the error e1 influenced by the CO gas composition increases and the error e2 decreases. That is, (e1-e2) in the second term on the right side of equation (4) becomes positive. Therefore, the oxygen concentration difference ΔOe including the error is larger than the oxygen concentration difference ΔO without the error (ΔOe>ΔO). From the viewpoint of air leakage detection, the presence of CO gas is not necessarily an obstruction factor. In other words, when evaluating the oxygen concentration in absolute value, it is necessary to consider the error, but in the first place, in air leakage detection, the change in oxygen concentration can be used as a guideline, and it is not evaluated in absolute value, so even if there is an error in the measured oxygen concentration, there is no big problem.

[0042] [2-2. Measurement location of oxygen concentration] The exhaust gas treatment system of the sintering machine 1 is composed of, from the upstream side in the exhaust gas flow direction, a wind box 15, a wind leg 17, a main duct 19, and an exhaust gas treatment section (i.e., an electric dust collector 30 and an exhaust fan 40). In the method for detecting air leakage from a sintering machine according to this embodiment, zirconia-type oxygen concentration meters are installed at least at two different measurement positions downstream of the wind leg 17 in the exhaust gas flow direction to measure oxygen concentration.

[0043] The wind boxes 15 and wind legs 17, which are located upstream of the exhaust gas treatment system in the exhaust gas flow direction, are generally installed at several tens of locations in the longitudinal direction of the sintering machine, and it is not realistic to install zirconia oxygen analyzers in all of them. In addition, the wind boxes 15 and wind legs 17 have a relatively short equipment length, and there is a possibility that air (leakage) entering through cracks or the like generated in these locations does not mix sufficiently with the exhaust gas, and it is also considered that the distance between the wind boxes 15 and wind legs 17 is insufficient as measurement positions for comparing oxygen concentrations. Therefore, in this embodiment, zirconia oxygen analyzers are installed at least at two different measurement positions downstream of the wind legs 17 in the exhaust gas flow direction to measure the oxygen concentration.

[0044] For example, zirconia-type oxygen concentration meters may be installed at two different measurement positions downstream in the exhaust gas flow direction from the main duct outlet 61, which is the connection between the main duct 19 and the exhaust gas treatment unit, to measure the oxygen concentration. At the main duct outlet 61, which is the connection after the main ducts 19A and 19B join, the time fluctuation of CO gas is small, so the influence of interference gas can be reduced. Alternatively, zirconia-type oxygen concentration meters may be installed at measurement positions between the main duct outlet 61, which is the connection between the main duct 19 and the exhaust gas treatment unit, and the inlet of the electrostatic precipitator 30, and between the outlet of the electrostatic precipitator 30 and the exhaust fan inlet 63 of the exhaust fan 40, to measure the oxygen concentration. In this way, by measuring the oxygen concentration between any two measurement positions, the presence or absence of air leakage between the two measurement positions can be detected.

[0045] The measurement position of the oxygen concentration may be a position where the CO concentration previously measured in the exhaust gas treatment system is 5% or less. This is because the zirconia oxygen analyzer can be used more stably and continuously at a position where the influence of CO gas, which is an interfering gas in the oxygen concentration measurement by the zirconia oxygen analyzer, is minor.

[0046] The components of the exhaust gas from the wind box 15 and the wind leg 17 fluctuate greatly due to changes in the operation of the sintering machine 10. Therefore, even if the wind leakage from the wind box 15 and the wind leg 17 is evaluated based on the change in the oxygen concentration measured by a zirconia oxygen analyzer, it is not possible to obtain information with sufficient accuracy due to the influence of interference gases. For this reason, the measurement of the oxygen concentration in the wind box 15 and the wind leg 17 is mainly performed by a laser oxygen analyzer. In view of this situation, the inventor of the present application has found that the trend management of the oxygen concentration using a zirconia oxygen analyzer works sufficiently in a place where the influence of interference gases is minor. CO gas is normally generated in the sintering process, and its influence is considered to be minor within the range of the normally generated CO concentration, for example, at a position where the CO concentration is 5% or less.

[0047] Even if the fluctuation of interference gas is large, by installing multiple zirconia oxygen concentration meters and simultaneously measuring the oxygen concentration at different measurement positions, it is possible to make a relative comparison under conditions where the interference gas concentration is substantially the same. That is, in the sintering machine equipment air leakage detection method according to this embodiment, if the oxygen concentration measured at two different measurement positions is higher on the downstream side in the exhaust gas flow direction than on the upstream side, it is determined that there is air leakage between the two measurement positions, but CO gas has the effect of expanding the range of increase in oxygen concentration. For this reason, the sintering machine equipment air leakage detection method according to this embodiment is advantageous in terms of detecting the presence or absence of air leakage.

[0048] The above describes a method for detecting air leakage in a sintering machine according to one embodiment of the present invention. According to this embodiment, oxygen concentration is measured by a solid electrolyte oxygen analyzer such as a zirconia oxygen analyzer at at least two different measurement positions downstream of a wind leg in the exhaust gas flow direction of the exhaust gas treatment system, and the oxygen concentrations at the two measurement positions are compared to detect the presence or absence of air leakage between the two measurement positions. By comparing the measurement results of the multiple solid electrolyte oxygen analyzers, the difference in oxygen concentration can be detected with high sensitivity, and air leakage can be detected early. EXAMPLES

[0049] The results of applying the present invention to a Dwight Lloyd type sintering machine (width 5.4 m × length 100 m) shown in Figures 1 and 2 are shown. As shown in Figure 2, the exhaust gas treatment system has two main ducts 19A and 19B along the length of the sintering machine, and the part where the two main ducts 19A and 19B join together is the main duct outlet 61. The electric dust collector 30 has four dust collectors and is connected to an exhaust fan (blower) 40. In this embodiment, two zirconia type oxygen concentration meters (TF-10D101 manufactured by Energy Support Co., Ltd.) were installed at the main duct outlet 61 and the exhaust fan inlet 63.

[0050] The test outline is shown in Figure 4. The zirconia oxygen concentration meter 73 is connected to a control device 75 that controls oxygen concentration measurement. The control device 75 has a power supply unit 76 for heating the zirconia sensor 73a of the zirconia oxygen concentration meter 73, and a pump 77 for supplying purge air for calibrating the zirconia sensor 73a and removing dust adhering to the zirconia sensor 73a. The power supply unit 76 is connected to the zirconia oxygen concentration meter 73 via a power cable 76a. The pump 77 is connected to the zirconia oxygen concentration meter 73 via a tube 77a.

[0051] The zirconia oxygen concentration meter 73 was inserted into the duct 71 so as to be approximately perpendicular to the exhaust gas flow in the duct of the exhaust gas treatment system in the duct 71. A 3 mm thick SUS protective cover 73b was provided on the upstream side of the zirconia sensor 73a in the exhaust gas flow direction. The protective cover 73b prevented the measurement and measurement results of the zirconia sensor 73a from becoming unstable due to dust attack or dust clogging in the presence of high dust. In addition, purging air, which also served as equipment calibration, was supplied to the zirconia sensor 73a from the pump 77 via the tube 77a to stabilize the measurement and measurement results of the zirconia sensor 73a. In other words, in this test, the presence of dust in the duct 71 was considered not to cause the measurement results to become unstable.

[0052] The control device 75 has a function of controlling the air supply by the pump 77, converting the electromotive force of the zirconia oxygen concentration meter 73 into oxygen concentration, and transmitting oxygen concentration data to the outside. In addition, by providing the control device 75 with a wireless transmitter 78, it is not necessary to install a data processing device that processes oxygen concentration data at the measurement position.

[0053] The verification results of the sintering machine air leakage detection are shown in Fig. 5. The main exhaust air volume from the exhaust fan during the verification was 1300 Nm3, as shown in Fig. 5 (graph c). 3 / hr. The period from the 11th to the 12th day after the start of the verification where there is no data is the period during which the sintering machine was stopped. The readings of the zirconia oxygen concentration meter are shown in Fig. 5 (graph a). The oxygen concentration was about 12-13 volume %, and fluctuations were observed in response to changes in the operating state even during the day. The readings of the zirconia oxygen concentration meter at the two locations of the main duct outlet 61 and the exhaust fan inlet 63 both showed the above fluctuations, but it can be seen that the reading at the exhaust fan inlet 63 was higher than that of the main duct outlet 61. The result of calculating the difference (ΔO2) between the reading at the exhaust fan inlet 63 and the reading at the main duct outlet 61 is shown in Fig. 5 (graph b). As mentioned above, the readings showed a fluctuation of about 1%, but it was found that ΔO2 was approximately 0.4 volume %.

[0054] Based on these measured values, the leakage air volume was calculated using the following formula (5), and the results are shown in (graph d) of Figure 5. Note that Oa is the oxygen concentration indication value at the main duct outlet, and Vg is the main exhaust air volume.

[0055] Air leakage amount VL=ΔO2 / (21-Oa)×Vg (5)

[0056] As shown in FIG. 5 (graph d), a flow rate of 50 Nm between the main duct outlet 61 and the exhaust fan inlet 63 is 3 It was estimated that there was air leakage of about 1000 sq. m / hr. Although the absolute value is considered to include an error due to the influence of interfering gases, it was shown that the air leakage detection method of the present invention can detect the occurrence of air leakage between the main duct outlet 61 and the exhaust fan inlet 63.

[0057] Although the preferred embodiment of the present invention has been described in detail above with reference to the accompanying drawings, the present invention is not limited to such an example. It is clear that a person having ordinary knowledge in the technical field to which the present invention pertains can conceive of various modified or altered examples within the scope of the technical ideas described in the claims, and it is understood that these also naturally belong to the technical scope of the present invention. [Explanation of symbols]

[0058] 1 Sintering machine equipment 10 Sintering machine 11 Raw material hopper 12 Rail 13 Ignition furnace 15 Windbox 17, 17A, 17B Wind Leg 19, 19A, 19B Main duct 20 Cooler 30 Electrostatic Precipitator 40 Blower 50 Chimney 61 Main duct outlet 63 Exhaust fan inlet 71 Duct 73 Zirconia Oxygen Concentration Meter 73a Zirconia sensor 73b Protective cover 75 Control Device 76 Power supply section 76a Power Cable 77 Pump 77a tube 78 Radio transmitter

Claims

1. A method for detecting air leakage in a sintering machine, comprising: The exhaust gas treatment system of the sintering machine is configured by installing a wind box, a wind leg, a main duct, and an exhaust gas treatment unit, which are installed in this order from the upstream side in the exhaust gas flow direction, measuring oxygen concentrations using zirconia oxygen concentration meters at at least two different measurement positions downstream in an exhaust gas flow direction from a connection portion between the main duct and the exhaust gas treatment portion in the exhaust gas treatment system; A method for detecting air leakage in a sintering machine, comprising: comparing oxygen concentrations at two measurement positions; and detecting the presence or absence of air leakage between the two measurement positions.

2. The exhaust gas treatment device has a plurality of dust collectors, The outlets of the plurality of dust collectors are connected to an exhaust fan, The oxygen concentration is at least Between a connection portion between the main duct and the exhaust gas treatment device and an inlet of each of the plurality of dust collectors; The method for detecting air leakage in a sintering machine according to claim 1 , wherein the air leakage is measured between outlets of the plurality of dust collectors and an inlet of the exhaust fan.

3. 3. The method for detecting air leakage in a sintering machine according to claim 1, further comprising the step of measuring an oxygen concentration at a position in the exhaust gas treatment system where a CO concentration previously measured is 5% or less.

4. In the exhaust gas treatment system, a first oxygen concentration at a first measurement position and a second oxygen concentration at a second measurement position downstream of the first measurement position in an exhaust gas flow direction are measured; When the second oxygen concentration is greater than the first oxygen concentration, it is determined that air leakage occurs between the first measurement position and the second measurement position. The sintering machine equipment air leakage detection method according to any one of claims 1 to 3.

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