JP5007569B2 - Control method of dust exhaust system - Google Patents

Description

   The present invention relates to a method for controlling a dust exhaust device, and more particularly, to a method for optimally controlling an exhaust fan and an exhaust damper that exhaust dust.

   In an arc furnace, etc., a large amount of dust is discharged during operation.Therefore, exhaust hoods are installed at multiple locations around the furnace, and these exhaust hoods are connected to exhaust ducts via exhaust dampers. The inside is sucked and exhausted with an exhaust fan. Since the amount of dust discharged differs depending on the operation process such as charging, melting, and heating, conventionally, the amount of dust discharged in each process is predicted and the dust exhaust device is based on a pattern table that is predetermined for each process. The opening degree of the exhaust damper and the rotational speed of the exhaust fan constituting the above are changed.

However, the control of the exhaust damper and the exhaust fan based on a predetermined pattern table has a problem that it cannot cope with the case where the amount of discharged dust greatly fluctuates due to a disturbance such as scrap material or wind direction. Thus, for example, Patent Document 1 discloses a device in which a dust sensor is provided in the exhaust hood and the rotational speed of the exhaust fan provided in the exhaust hood is controlled according to the amount of dust actually discharged.
JP 2005-265304 A

   However, in the control method disclosed in Patent Document 1, when there are a plurality of dust generation areas and each area is provided with an exhaust damper, the balance between the opening degree of the exhaust damper and the rotational speed of the exhaust fan is determined. There is no indication of what to control.

  Accordingly, the present invention solves such a problem, and optimally controls the exhaust damper and exhaust fan provided for each of the plurality of dust generation regions, so that the dust can be exhausted quickly and the exhaust fan can be efficiently used. It is an object of the present invention to provide a method for controlling a dust exhaust device that realizes operation.

  In order to achieve the above object, in the present invention, exhaust dampers (3A, 3B) are installed in exhaust ducts (2A, 2B) provided in a plurality of dust generation regions (DR1, DR2), respectively, and each exhaust duct (2A , 2B) is a control method of a dust exhaust device in which a single exhaust fan (5) is connected, and the dust amount (h1, h2) is detected and detected for each of the dust generation regions (DR1, DR2). Depending on the amount of dust (h1, h2), the high level, medium level, and low level are judged. If the detected dust amount (h1, h2) is high in all dust generation areas (DR1, DR2), the exhaust fan If the rotational speed of (5) is increased and the detected dust amount (h1, h2) is low in all dust generation areas (DR1, DR2), the rotational speed of the exhaust fan (5) is decreased to detect the detected dust amount. (H1, h2) is a high level dust generation area When there is (DR1, DR2), if the opening (θ1, θ2) of the exhaust damper (3A, 3B) in the region is other than 100%, the opening of the damper (3A, 3B) is increased and detected Detected when there is a dust generation area (DR1, DR2) with a high level of dust (h1, h2) and the opening (θ1, θ2) of the exhaust damper (3A, 3B) in that area is 100% The opening degree of the exhaust damper (3A, 3B) in the other dust generation region (DR1, DR2) where the dust amount (h1, h2) is not at a high level is decreased.

  According to the present invention, when the detected dust amount is at a low level in all dust generation areas, the exhaust fan rotation speed is reduced, thereby avoiding unnecessary rotation of the exhaust fan and the associated waste of electric power. it can. In addition, when there is a dust generation area where the detected dust amount is high, and the opening degree of the exhaust damper in that area is 100%, the exhaust dampers of other dust generation areas where the detected dust amount is not at a high level. By reducing the opening degree of the exhaust gas, the exhaust amount in the dust generation region where the detected dust amount is high is substantially increased without increasing the rotation of the exhaust fan, and the dust concentration in the dust generation region is reduced. It can be suppressed to a range that does not exist.

  In addition, the code | symbol in the said parenthesis shows the correspondence with the specific means as described in embodiment mentioned later.

  According to the control method of the dust exhaust device of the present invention, the exhaust damper provided for each of the plurality of dust generation regions and the exhaust fan are optimally controlled to quickly exhaust the dust and efficiently operate the exhaust fan. Can be realized.

(First embodiment)
FIG. 1 shows a schematic system diagram of a dust exhaust apparatus for an arc furnace that implements the control method of the present invention. Above the arc furnace 1, exhaust hoods 2 </ b> A and 2 </ b> B constituting a part of the exhaust duct for sucking dust discharged during operation are provided at two locations of the dust generation regions DR <b> 1 and DR <b> 2. The exhaust hoods 2A and 2B are collectively connected to an exhaust duct 4 via exhaust dampers 3A and 3B. The exhaust duct 4 is exhausted by a single exhaust fan 5. The dust passes through the exhaust fan 5 and reaches the subsequent bag filter 6 where it is collected. The exhaust hoods 2A and 2B are provided with known dust sensors 7A and 7B, and the dust concentration (dust amount) is detected. As the dust sensors 7A and 7B, for example, a photoelectric sensor that collects and detects scattered light, which is diffused and reflected when the light emitted from the light emitter 71 hits the floating dust, can be used. A control device 8 is provided, and the control device 8 has a built-in computer that realizes the control described below with software. Detection signals of the dust sensors 7A and 7B are input to the control device 8, and the opening / closing of the exhaust dampers 3A and 3B and the rotational driving of the exhaust fan 5 are controlled by the output signals from the control device 8 as follows. .

  Within the control device 8, two threshold values H1H, H1L, H2H, and H2L are used for the dust concentration signals h1 and h2 (FIG. 2) from the dust sensors 7A and 7B provided in the dust generation regions DR1 and DR2, respectively. Determine the level, medium level, and low level. That is, the high level is when the dust concentrations h1 and h2 are equal to or higher than the threshold values H1H and H2H, the intermediate level is higher than the threshold values H1L and H2L, and the lower level is lower than the threshold values H1H and H2H. Is below the thresholds H1L and H2L. The control device 8 performs control as shown in Table 1 in accordance with the dust concentration levels of the dust generation regions DR1 and DR2 detected by the dust sensors 7A and 7B.

  That is, when the dust concentrations h1 and h2 in the dust generation regions DR1 and DR2 are both medium, the opening degrees θ1 and θ2 of the exhaust dampers 3A and 3B and the rotational speed N of the exhaust fan 6 are both present. Leave it unchanged. When the dust concentrations h1 and h2 in the dust generation regions DR1 and DR2 are both high, the rotational speed N of the exhaust fan 6 is increased by Δn to increase the exhaust capability of the entire apparatus. Further, when the dust concentrations h1 and h2 in the dust generation regions DR1 and DR2 are both low level or medium level, the rotational speed N of the exhaust fan 6 is decreased by Δn to suppress power consumption.

  When the dust concentration h1 in the dust generation region DR1 is high and the dust concentration h2 in the dust generation region DR2 is medium or low, C1 control is performed as shown in Table 1 above. On the other hand, when the dust concentration h2 in the dust generation region DR2 is high and the dust concentration h1 in the dust generation region DR1 is medium or low, C2 control is performed as shown in Table 1 above. The contents of the C1 control and C2 control are as follows depending on whether or not the exhaust dampers 3A and 3B are fully opened (opening degree 100%). In the table, Δθ is a fixed amount determined by design. By performing such control, the dust concentration in each of the dust generation regions DR1 and DR2 can be suppressed to a problem-free range while avoiding unnecessary rotation of the exhaust fan and wasteful power consumption.

C1 control If θ1 <100%, θ1 is opened by Δθ. If θ1 = 100%, θ2 is closed by Δθ. C2 control If θ2 <100%, θ2 is opened by Δθ. If θ2 = 100%, θ1 is Δθ. Just closed

(Second Embodiment)
In this embodiment, as shown in FIG. 3, the dust exhaust device includes exhaust hoods 2 </ b> A, 2 </ b> B, 2 </ b> C that constitute part of the exhaust duct in three dust generation regions DR <b> 1, DR <b> 2, DR <b> 3 in the arc furnace 1. And exhaust dampers 3A, 3B, 3C and dust sensors 7A, 7B, 7C. The exhaust hoods 2 </ b> A to 2 </ b> C are collectively connected to the exhaust duct 4 through exhaust dampers 3 </ b> A to 3 </ b> C, respectively, and the exhaust duct 4 is exhausted by a single exhaust fan 5. A control device 8 is provided, and the control device 8 has a built-in computer that realizes the control described below with software. Detection signals of the dust sensors 7A to 7C are input to the control device 8, and the opening / closing of the exhaust dampers 3A to 3C and the rotational drive of the exhaust fan 5 are controlled by the output signals from the control device 8 as follows. Other configurations are the same as those of the first embodiment.

  In the control device 8, two threshold values H1H, H1L, H2H, H2L, H3H and H3L are used for the dust concentrations h1, h2 and h3 detected by the dust sensors 7A to 7C in the dust generation regions DR1 to DR3, respectively. Determine the level, medium level, and low level. That is, as shown in FIG. 4, when the dust concentration h1 to h3 is greater than or equal to the threshold value H1H to H3H, the high level is such that the dust concentration h1 to h3 exceeds the threshold value H1L to H3L and less than the threshold value H1H to H3H. In this case, the low level is when the dust concentrations h1 to h3 are below the threshold values H1L to H3L. The control device 8 performs control as shown in Tables 2 to 4 in accordance with the dust concentration levels of the dust generation regions DR1 to DR3 detected by the dust sensors 7A to 7C.

  That is, when the dust concentrations h1 to h3 in the dust generation regions DR1 to DR3 are all at a medium level (Table 3), or the dust concentration h3 in the dust generation region DR3 is low, the dust concentrations h1 in the dust generation regions DR1 and DR2 When h2 is at a medium level (Table 4), the opening degrees θ1, θ2, θ3 of the exhaust dampers 3A to 3C and the rotational speed N of the exhaust fan 5 are all left unchanged and are not changed. When the dust concentrations h1 to h3 in the dust generation regions DR1 to DR3 are all high (Table 2), the rotational speed N of the exhaust fan 5 is increased by Δn to increase the exhaust capacity of the entire apparatus. When the dust concentrations h1 to h3 in the dust generation regions DR1 to DR3 are all low level or medium level (Tables 3 and 4), the rotational speed N of the exhaust fan 5 is decreased by Δn to suppress power consumption.

  Further, when the dust concentration h3 in the dust generation region DR3 is high and any one of the dust concentrations h1 and h2 in the dust generation regions DR1 and DR2 is medium level or low level, as shown in Table 2 above, C1 control to Each control of C6 control (refer Table 5-Table 10) is performed. The contents of each control described below including these controls are to appropriately change these opening degrees θ1 to θ3 depending on whether or not the exhaust dampers 3A to 3C are fully opened (opening degree 100%). In the table, Δθ is a fixed amount determined by design. When the dust concentration h3 in the dust generation region DR3 is at a medium level, as shown in Table 3 above according to the levels of the dust concentrations h1 and h2 in the dust generation regions DR1 and DR2, C7 control to C9 control (Tables 11 to 11). Each control of Table 13) is performed. Further, when the dust concentration h3 in the dust generation region DR3 is low, as shown in Table 4 above according to the levels of the dust concentrations h1 and h2 in the dust generation regions DR1 and DR2, C10 control to C12 control (Table 14 to Table 16). By performing such control, the dust concentrations h1 to h3 in the dust generation regions DR1 to DR3 are suppressed to a range in which there is no problem while avoiding unnecessary rotation of the exhaust fan 5 and waste of electric power associated therewith. Can do.

It is a schematic system diagram of the dust exhaust apparatus controlled by the control method in the first embodiment of the present invention. It is a figure explaining the determination level of dust concentration. It is a schematic system diagram of the dust exhaust apparatus controlled by the control method in 2nd Embodiment of this invention. It is a figure explaining the determination level of dust concentration.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Arc furnace, 2A, 2B, 2B ... Exhaust hood (exhaust duct), 3A, 3B, 3C ... Exhaust damper, 4 ... Exhaust duct, 5 ... Exhaust fan, 7A, 7B ... Dust sensor, 8 ... Control device, DR1 , DR2, DR3 ... Dust generation area.

Claims (1)

A control method of a dust exhaust device in which an exhaust damper is installed in each exhaust duct provided in each of a plurality of dust generation regions, and each exhaust duct is connected to a single exhaust fan, and the amount of dust is determined for each of the dust generation regions. Detect, determine the high level, medium level, low level according to the detected dust amount, if the detected dust amount is high level in all the dust generation area, increase the rotation speed of the exhaust fan, When the detected dust amount is low in all the dust generation areas, the rotational speed of the exhaust fan is decreased, and when there is the dust generation area where the detected dust amount is high, the opening degree of the exhaust damper in the area If the opening of the exhaust damper in that area is 100% when there is the dust generation area where the detected dust amount is a high level, the opening of the damper is increased. powder The method quantities dust discharge apparatus that reduce the degree of opening of the exhaust damper of the other of the dust-generating region that is not in a high level.

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