Blast furnace blower and blast furnace blower control system

Abstract

To provide a blast furnace blower and a control system for a blast furnace blower, which are capable of starting air-blowing to the blast furnace while preventing surging.SOLUTION: A blast furnace blower comprises a blower main body 1 for sending air to a blast furnace 101, a suction valve 4, a blow-off valve 14, and a discharge sluice valve 9, and controls a stator vane angle of the blower main body 1 and opening of the suction valve 4, the blow-off valve 14, and the discharge sluice valve 9 on the basis of the measured pressure ratio of a suction pressure sensor 5 and an air-blowing pressure sensor 17. The control unit: starts the blower main body 1 with the blow-off valve 14 fully open; opens the suction valve 4 slightly; reduces the opening of the blow-off valve 14 by PID control until the measured pressure ratio becomes a target pressure ratio; after the target pressure ratio is reached, increases the opening of the suction valve 4 by step response control, until the suction pressure sensor 5 becomes equal to or higher than the target pressure; reduces the opening of the blow-off valve 14 by pressure control; maintains the measured pressure ratio constant; and when the suction valve 4 becomes fully open, opens the discharge sluice valve 9 to start air-blowing to the blast furnace 101.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a blast furnace blower and a control system for a blast furnace blower, and more particularly to a blast furnace blower and a control system for a blast furnace blower that can start blowing air to a blast furnace while preventing surging by opening and closing an intake valve and a discharge valve while detecting the pressure ratio before and after the blower. [Background technology]

[0002] Blast furnace blowers are the most important equipment for operating a blast furnace, and are energy equipment that requires sufficient reliability.

[0003] Patent Document 1 discloses a blast furnace air blast control method in which air is blown out during a hot stove switching period of the blast furnace. This control method has the problem of causing fluctuations in the air blast flow rate and pressure to the blast furnace because the hot stove is pressurized during combustion while ventilating the hot stove during air blast.

[0004] Patent Document 2 discloses a method for operating a blast furnace blower with the aim of preventing surging.

[0005] Incidentally, when a blast furnace is first lit after construction, the blowers that had been stopped up until then are started to ventilate the blast furnace. Also, blast furnaces are usually shut down (out of operation) about once a month, and the blowers are also stopped at that time, so after that, the stopped blowers are started again to ventilate the blast furnace. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-234218 [Patent Document 2] Japanese Patent Application Publication No. 55-128510 Summary of the Invention [Problem to be solved by the invention]

[0007] Immediately after starting the blower, the suction valve, which adjusts the amount of air drawn into the blower, is in a slightly open state, which is its starting position, and the operation is unstable. Therefore, after starting the blower, the suction valve must be opened and the blow-off valve closed as soon as possible (for example, within 20 minutes) to transition to minimum load operation. The blow-off valve adjusts the amount of air released from the blower into the outside air.

[0008] In order to close the blow-off valve in accordance with the opening of the suction valve so that the pressure ratio before and after the blower is constant, when the suction valve is at a low opening, the Cv value changes greatly, which increases the response of the blow-off valve and may cause hunting of the blow-off pressure or sudden closure of the blow-off valve (a sudden rise in the pressure ratio or a surging trip).

[0009] The present invention has been made in consideration of the above-mentioned conventional circumstances, and has an object to provide a blast furnace blower and a control system for the blast furnace blower that can start blowing air to the blast furnace while preventing surging by opening and closing the suction valve and the blow-off valve while detecting the pressure ratio before and after the blower.

[0010] Further objects of the present invention will become apparent from the following description. [Means for solving the problem]

[0011] The above problems are solved by the following invention.

[0012] (Claim 1) a blower body (1) having a plurality of rotating blades and a plurality of angle-adjustable stator blades, for blowing air into a blast furnace (101); a suction valve (4) provided in a suction pipe (3) arranged on the suction side of the blower body (1) for adjusting the amount of suction air; a discharge gate valve (9) provided in a blower pipe (6) connected to the blast furnace (101) and disposed on the discharge side of the blower body (1), and configured to switch between open and closed states; a blower valve (14) provided in a blower pipe (11) branched from a blower pipe (6) connected to the blast furnace (101) disposed on the discharge side of the blower body (1), the blower valve (14) adjusting the amount of blown air; a suction pressure sensor (5) for measuring the pressure between the suction valve (4) and the blower body (1) in the suction pipe (3); an air pressure sensor (17) for measuring the pressure in the air supply pipe (1) upstream of a branching portion (12) to the air discharge pipe (11); a control unit (21) that receives measured pressures from the suction pressure sensor (5) and the blow-off pressure sensor (17) and controls, based on the input measured pressures, an angle (1a) of the stator vane (1), an opening degree (4a) of the suction valve (4), an opening degree (14a, 15a) of the blow-off valves (14, 15), and opening / closing of the discharge gate valve (9); Equipped with The control unit (21) the stator blade angle (1a) of the blower body is adjusted to a preset start angle, the opening (4a) of the suction valve (4) is adjusted to a slight opening, the openings (14a, 15a) of the blow-off valves (14, 15) are adjusted to a full opening, an electric motor (1c) that rotates the rotor blades of the blower body (1) is started, the rotor blades are rotated, and a suction throttle operation is performed with the rotor blade rotation speed (1b) set to a rated rotation speed; While keeping the aperture (4a) of the suction valve (4) slightly open, the apertures (14a, 15a) of the blow-off valves (14, 15) are reduced by pressure ratio PID control until a measured pressure ratio, which is a ratio of the pressure measured by the suction pressure sensor (5) to the pressure measured by the blow-off pressure sensor (17), reaches a set target pressure ratio; After the measured pressure ratio reaches the target pressure ratio, the opening (4a) of the suction valve (4) is gradually increased by step response control until the measured pressure of the suction pressure sensor (5) becomes equal to or greater than the target pressure, and the openings (14a, 15a) of the blow-off valves (14, 15) are gradually decreased by pressure control, thereby maintaining the measured pressure ratio constant; When the opening (4a) of the suction valve (4) is fully opened, the discharge gate valve (9) is opened to start blowing air to the blast furnace (101), thereby performing a minimum load operation. A blast furnace blower characterized by: (Claim 2) A control system used in a control unit (21) in the blast furnace blower according to claim 1, the stator blade angle (1a) of the blower body is adjusted to a preset start angle, the opening (4a) of the suction valve (4) is adjusted to a slight opening, the openings (14a, 15a) of the blow-off valves (14, 15) are adjusted to a full opening, an electric motor (1c) that rotates the rotor blades of the blower body (1) is started, the rotor blades are rotated, and a suction throttle operation is performed with the rotor blade rotation speed (1b) set to a rated rotation speed; While keeping the aperture (4a) of the suction valve (4) slightly open, the apertures (14a, 15a) of the blow-off valves (14, 15) are gradually decreased by pressure ratio PID control until a measured pressure ratio, which is a ratio of the pressure measured by the suction pressure sensor (5) to the pressure measured by the blow-off pressure sensor (17), reaches a set target pressure ratio. After the measured pressure ratio reaches the target pressure ratio, the opening (4a) of the suction valve (4) is gradually increased by step response control until the measured pressure of the suction pressure sensor (5) becomes equal to or greater than the target pressure, and the openings (14a, 15a) of the blow-off valves (14, 15) are gradually decreased by pressure control, thereby maintaining the measured pressure ratio constant; When the opening (4a) of the suction valve (4) is fully opened, the discharge gate valve (9) is opened to start blowing air to the blast furnace (101), thereby performing a minimum load operation. A control system for a blast furnace blower, comprising: [Effects of the Invention]

[0013] The present invention provides a blast furnace blower and a control system for a blast furnace blower that can start blowing air to a blast furnace while preventing surging by opening and closing the suction valve and blow-off valve while detecting the pressure ratio before and after the blower. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a schematic diagram illustrating a blast furnace blower according to an embodiment of the present invention. [Figure 2]A block diagram showing the operation of a control unit of a blast furnace blower according to an embodiment. [Figure 3] Time chart showing control details in a blast furnace blower according to an embodiment [Figure 4] Graph showing the relationship between the suction air volume and the measured pressure ratio in the blast furnace blower according to the embodiment [Figure 5] Time chart showing control results in a blast furnace blower according to an embodiment DETAILED DESCRIPTION OF THE INVENTION

[0015] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0016] The blast furnace blower of the present invention automatically controls the opening of the suction valve and the opening of the blower valve when starting the blower body at the time of initial lighting during construction of a blast furnace or when starting the blower body after stopping (blowing suspension), thereby enabling automatic start of blowing air to the blast furnace while preventing surging. Furthermore, the blast furnace blower according to the present invention can be constructed together with a blast furnace when the blast furnace is newly constructed, or can be applied to an existing blast furnace.

[0017] FIG. 1 is a diagram schematically showing a blast furnace blower according to an embodiment of the present invention.

[0018] Compressed air heated by a hot stove 102 is supplied to the blast furnace 101. The hot stove 102 repeats combustion, compression, and supply to the blast furnace 101.

[0019] The blast furnace blower according to the embodiment includes a blower body 1 that blows air into a hot stove 102 of a blast furnace 101. The blower body 1 is an axial flow compressor, and includes a plurality of rotor blades that are rotated by an electric motor 1c and a plurality of stator blades whose angles are adjustable.

[0020] Although not shown, the plurality of rotor blades are provided, for example, on the outer peripheral surface of a substantially cylindrical rotor that is rotated within a substantially cylindrical casing. The plurality of stator vanes are provided, for example, on the inner peripheral surface of the casing. The angle of each stator vane can be adjusted by a control unit 21 shown in Fig. 2. The control unit 21 executes the control system for a blast furnace blower of the present invention.

[0021] Fan body 1 has an air filter 2 through which purified outside air is drawn into suction pipe 3, which is located on the suction side of fan body 1. Suction pipe 3 is provided with suction valve 4, which adjusts the amount of suction air passing through suction pipe 3. In addition, suction pipe 3 is provided with suction pressure sensor 5. Suction pressure sensor 5 measures the pressure between suction valve 4 in suction pipe 3 and fan body 1, and outputs the measured value.

[0022] A blower pipe 6 connected to a hot stove 102 of a blast furnace 101 is arranged on the discharge side of the blower body 1. A check valve 7, an anti-choke valve 8, and a discharge gate valve 9 are provided in this order, for example, in series, in the blower pipe 6.

[0023] The blower duct 6 is provided with an air discharge duct 11 as a branch duct. The air discharge duct 11 is a pipe that extends from a branch point 12 from the blower duct 6 to an air discharge silencer 13. The air discharge silencer 13 reduces noise when the air blown from the blower main body 1 is released through the air discharge duct 11.

[0024] A main blow-off valve 14 is provided in the blow-off duct 11. A sub blow-off valve 15 is provided in parallel to the main blow-off valve 14. In other words, the sub blow-off valve 15 is provided in a bypass pipe 16 that runs from an upstream position of the main blow-off valve 14 to a downstream position of the main blow-off valve 14. The main blow-off valve 14 and the sub blow-off valve 15 adjust the amount of blow-off air that passes through the blow-off duct 11. The main blow-off valve 14 largely adjusts the amount of blow-off air that passes through the blow-off duct 11, and the sub blow-off valve 15 finely adjusts the amount of blow-off air that passes through the blow-off duct 11.

[0025] The blower duct 6 is provided with an air pressure sensor 17. The air pressure sensor 17 measures the pressure upstream of the branching point 12 to the discharge duct 11 in the blower duct 6, and outputs the measured value.

[0026] FIG. 2 is a block diagram showing the operation of the control unit of the blast furnace blower according to the embodiment.

[0027] As shown in Fig. 2, this blast furnace blower is equipped with a control unit 21. The control unit 21 receives the measured pressures from the suction pressure sensor 5 and the blowing pressure sensor 17, and controls the stator blade angle 1a of the blower main body 1, the opening 4a of the suction valve 4, the opening 14a of the main blowing valve 14, the opening 15a of the auxiliary blowing valve 15, the opening and closing of the check valve 7, the opening and closing of the anti-choke valve 8, and the opening and closing of the discharge gate valve 9 based on the measured pressures that have been input.

[0028] When the blast furnace blower according to the present invention is applied to an existing blast furnace, it can be installed in place of an existing blast furnace blower attached to the existing blast furnace. Alternatively, the control unit 21 and sensors and on-off valves required for control can be added to an existing blast furnace blower attached to an existing blast furnace.

[0029] FIG. 3 is a time chart showing the control details in the blast furnace blower according to the embodiment. In this blast furnace blower, the control unit 21 executes the following control as shown in FIG.

[0030] [1] Start-up preparation and start-up of the blower body 1 The stator blade angle 1a of the blower body 1 is adjusted to a preset starting angle (for example, -15°), the opening 4a of the suction valve 4 is adjusted to a slight opening (for example, 15% opening), and the opening 14a of the main blow-off valve 14 and the opening 15a of the auxiliary blow-off valve 15 are adjusted to full opening (100% opening). The check valve 7, choke prevention valve 8, and discharge gate valve 9 of the blower duct 6 are all closed (0% opening). This completes the air flow path that passes through the air filter 2 and reaches the air discharge silencer 13.

[0031] The electric motor 1c that rotates the rotor blades of the blower body 1 is started, and the rotor blades are rotated to perform suction throttle operation with the rotor blade rotation speed 1b set to the rated rotation speed (e.g., 3,000 rpm). In this embodiment, the power source for the blower body 1 is three-phase AC, and power is turned on in synchronization with the cycle of the AC power supply.

[0032] [2] Transition to minimum load operation (1) While keeping the opening 4a of the suction valve 4 slightly open, the opening 14a of the main blow-off valve 14 is reduced by pressure ratio PID control until the measured pressure ratio, which is the ratio of the measured pressure of the suction pressure sensor 5 to the measured pressure of the blow-off pressure sensor 17, gradually rises in a ramp function and reaches a preset target pressure ratio.

[0033] [3] Transition to minimum load operation (2) After the measured pressure ratio reaches the target pressure ratio, the opening 4a of the suction valve 4 is gradually increased by step response control until the measured pressure of the suction pressure sensor 5 becomes equal to or greater than the preset target pressure, and the opening 14a of the main blow-off valve 14 is gradually decreased by pressure control, thereby maintaining the measured pressure ratio constant.

[0034] FIG. 4 is a graph showing the relationship between the suction air volume and the measured pressure ratio in the blast furnace blower according to the embodiment.

[0035] Here, maintaining the measured pressure ratio constant means that the suction air volume (Nm 3 / min.dry) while preventing the measured pressure ratio (Pr) from entering the surge region for that suction airflow.

[0036] That is, as shown in Figure 4, the suction air volume is 0 to 3000 Nm 3 When the pressure is d / min.dry, the measured pressure ratio (Pr) should be in the range of 2.5 to 4.5 between the choke prevention line and the surge emergency opening line, or 2.7 to 4.5, and the suction volume should be 3000 to 5000 Nm 3When the pressure is d / min.dry, the measured pressure ratio (Pr) should be in the range of 2.7-4.5 between the choke prevention line and the surge emergency opening line, or 3.0-6.0, and the suction volume should be 5000-7000 Nm 3 / min.dry, the measured pressure ratio (Pr) is in the range of 3.0 to 6.0, which is between the choke prevention line and the surge emergency opening line, and is in the range of 3.5 to 6.2. In this way, by keeping the measured pressure ratio constant so as to maintain it between the choke prevention line and the surge emergency opening line as the suction air volume increases, it is possible to automatically transition to the blowing start stage without manual intervention and with reduced load on the blower.

[0037] [4] Start blowing air When the opening 4a of the suction valve 4 is fully opened and it is possible to send air at the designated air volume and pressure to the hot stove 102 of the blast furnace 101, the check valve 7, choke prevention valve 8, and discharge sluice valve 9 of the blower duct 6 are opened to start sending air to the hot stove 102 of the blast furnace 101, and minimum load operation is performed, as shown in Figure 3. In the example shown, the discharge sluice valve 9 is first opened and fully opened, and then the check valve 7 is gradually opened, and immediately after the check valve 7 starts to open, the choke prevention valve 8 is opened, and after the choke prevention valve 8 is fully opened, the check valve 7 is fully opened, but the arrangement is not limited to this. The main blow-off valve 14 starts closing at approximately the same time as the anti-choke valve 8 starts opening. In addition, the auxiliary blow-off valve 15 starts closing just before the anti-choke valve 8 is fully opened. At this time, the main blow-off valve 14 and the auxiliary blow-off valve 15 automatically close while adjusting the closure degree of each valve by pressure ratio PID control. In addition, the stator vane angle 1a of the blower body 1 is increased (for example, +15°).

[0038] FIG. 5 is a time chart showing the control results in the blast furnace blower according to the embodiment.

[0039] In FIG. 5, the area surrounded by the two-dot chain line is the scene of the transition to minimum load operation in the present invention, and corresponds to points A, B, C, and D in FIG.

[0040] These positions will be explained with reference to FIG. In the illustrated example, point A is the time point at which pressure ratio PID control starts, and is the point at which the pressure ratio calculated from the pressures measured by suction pressure sensor 5 and blowing pressure sensor 17 starts to increase.

[0041] Between points A and B, the suction valve opening 4a is fixed at approximately 15 degrees, and the main blow-off valve opening 14a is operated to gradually close so that the measured pressure ratio reaches the set target pressure ratio.

[0042] Point B is the point at which the measured pressure ratio reaches the target pressure ratio, which in the illustrated example is a pressure ratio of 3.5, and at this point B, the main blow-off valve opening 14a operates so as to be closed from 100% opening to approximately 50% opening. At this point B, the measured pressure ratio is then kept constant while the suction pressure is operated so as to reach the target pressure.

[0043] Specifically, it can be seen that between point B and point C, the suction valve opening 4a is gradually opened by a slight opening signal, and the main blow-off valve opening 14a is slowly closed. In other words, between point B and point C, while maintaining the target pressure ratio constant at 3.5, the suction valve opening 4a and the main blow-off valve opening 14a are controlled, and the measured suction pressure rises from approximately 50 kPaG to 80 kPaG, and the main blow-off valve is gradually closed while the suction valve is gradually opened until the target pressure of 100 kPaG or more is reached.

[0044] At point C, the opening of the main blow-off valve 14a is fully closed, and the suction valve is gradually opened with a slight opening signal. At 4:11, after point C is passed, it is found that the suction pressure has reached the target pressure of 100 kPaG or more.

[0045] When the suction pressure reaches the target pressure, an open signal is sent to the suction valve, which opens wider until point D is reached, at which point the suction valve opens fully, and at 4:12 the transition to minimum load operation is complete.

[0046] That is, this invention has established a startup control technology for blowers, which has succeeded in automatically transitioning to minimum load operation after powering on the blower main body 1 while stabilizing the measured pressure ratio, as shown in Figure 5. In the example shown, after powering on the blower main body 1 at 4:00, the suction pressure reaches the target pressure just before 4:11, and at point D just before 4:12, the suction valve is fully opened, transitioning to minimum load operation. [Explanation of symbols]

[0047] 1 Blower body 1a Stator blade angle 1b Rotor blade rotation speed 1c electric motor 2. Air filter 3 Suction pipe 4. Suction valve 4a Suction valve opening 5 Suction pressure sensor 6 Air pipe 7. Check valve 8. Choke prevention valve 9. Discharge gate valve 11 Air discharge pipe 12 Branch 13. Vent silencer 14 Main blow-off valve 14a Main blow-off valve opening 15 Sub-vent valve 15a Sub-vent valve opening 16 Bypass pipe 17. Air pressure sensor 21 Control section 101 Blast Furnace 102 Hot stove

Claims

1. a blower body (1) having a plurality of rotating blades and a plurality of angle-adjustable stator blades, for blowing air into a blast furnace (101); a suction valve (4) provided in a suction pipe (3) arranged on the suction side of the blower body (1) for adjusting the amount of suction air; a discharge sluice valve (9) provided in a blower pipe (6) connected to the blast furnace (101) disposed on the discharge side of the blower body (1), and adapted to switch between opening and closing; a blower valve (14) provided in a blower pipe (11) branched from a blower pipe (6) connected to the blast furnace (101) disposed on the discharge side of the blower body (1), for adjusting the amount of blown air; a suction pressure sensor (5) for measuring the pressure between the suction valve (4) in the suction pipe (3) and the blower body (1); an air pressure sensor (17) for measuring the pressure upstream of a branching portion (12) into the air discharge pipe (11) in the air blowing pipe (1); a control unit (21) that receives the measured pressures from the suction pressure sensor (5) and the blow-off pressure sensor (17) and controls the angle (1a) of the stator vane (1), the opening degree (4a) of the suction valve (4), the opening degree (14a, 15a) of the blow-off valve (14, 15), and the opening / closing of the discharge gate valve (9) based on the measured pressures that have been input; Equipped with The control unit (21) the stator blade angle (1a) of the blower body is adjusted to a preset start angle, the opening degree (4a) of the suction valve (4) is adjusted to a slight opening, the opening degrees (14a, 15a) of the blow-off valves (14, 15) are adjusted to a full opening, an electric motor (1c) that rotates the rotor blades of the blower body (1) is started, the rotor blades are rotated, and a suction throttle operation is performed with the rotor blade rotation speed (1b) set to a rated rotation speed; While keeping the opening (4a) of the suction valve (4) slightly open, the openings (14a, 15a) of the blow-off valves (14, 15) are reduced by pressure ratio PID control until a measured pressure ratio, which is a ratio of the measured pressure of the suction pressure sensor (5) to the measured pressure of the blow-off pressure sensor (17), reaches a set target pressure ratio; After the measured pressure ratio reaches the target pressure ratio, the opening (4a) of the suction valve (4) is gradually increased by step response control until the measured pressure of the suction pressure sensor (5) becomes equal to or greater than the target pressure, and the openings (14a, 15a) of the blow-off valves (14, 15) are gradually decreased by pressure control, thereby maintaining the measured pressure ratio constant; When the opening (4a) of the suction valve (4) is fully opened, the discharge gate valve (9) is opened to start blowing air to the blast furnace (101), thereby performing a minimum load operation. A blast furnace blower characterized by:

2. A control system used in a control unit (21) in the blast furnace blower according to claim 1, the stator blade angle (1a) of the blower body is adjusted to a preset start angle, the opening degree (4a) of the suction valve (4) is adjusted to a slight opening, the opening degrees (14a, 15a) of the blow-off valves (14, 15) are adjusted to a full opening, an electric motor (1c) that rotates the rotor blades of the blower body (1) is started, the rotor blades are rotated, and a suction throttle operation is performed with the rotor blade rotation speed (1b) set to a rated rotation speed; While keeping the opening (4a) of the suction valve (4) slightly open, the openings (14a, 15a) of the blow-off valves (14, 15) are gradually reduced by pressure ratio PID control until a measured pressure ratio, which is a ratio of the measured pressure of the suction pressure sensor (5) to the measured pressure of the blow-off pressure sensor (17), reaches a set target pressure ratio; After the measured pressure ratio reaches the target pressure ratio, the opening (4a) of the suction valve (4) is gradually increased by step response control until the measured pressure of the suction pressure sensor (5) becomes equal to or greater than the target pressure, and the openings (14a, 15a) of the blow-off valves (14, 15) are gradually decreased by pressure control, thereby maintaining the measured pressure ratio constant; When the opening (4a) of the suction valve (4) is fully opened, the discharge gate valve (9) is opened to start blowing air to the blast furnace (101), thereby performing a minimum load operation. A control system for a blast furnace blower, comprising:

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