Control method for online undisturbed replacement of blast furnace blower

Abstract

The invention discloses a control method for online undisturbed replacement of a blast furnace blower. The control method comprises the following steps: firstly, automatically adjusting operation parameters of a standby unit; a quick pressure reducing valve, a discharge valve and an anti-blocking valve of the standby unit are sequentially opened until a check valve of the standby unit is fully opened, then the quick pressure reducing valve is closed, and an air supply switching valve of the standby unit is fully opened; then the running unit closes the anti-surge valve according to the preset action rate, and the standby unit opens the anti-surge valve according to the action rate, so that the total flow of the pipe network is kept constant; when the anti-surge valve of the standby unit is fully opened and the anti-surge valve and the anti-blocking valve of the operating unit are fully closed, the discharge valve and the air supply switching valve of the operating unit are closed; switching the contact signal to the standby unit, and completing the unit changing operation. According to the method, it can be ensured that the pressure of the running fan is consistent with that of the standby fan, and the whole fan changing process is stable by automatically adjusting the action speed of valve switches. In addition, closing of the blocking prevention valve is used as a mixed air splitting condition, the hidden danger that the check valve is jammed is eliminated, and the operation stability and safety are improved advantageously.

Description

Technical Field

[0001] The present invention belongs to the technical field of industrial control, and particularly relates to a control method for online disturbance-free switching of blast furnace blowers. Background Art

[0002] The blast furnace blower station uses a synchronous motor to drive a fully static blade adjustable axial flow blower. Taking the example of three blower units (two operating units A1, A2 and one standby unit B) supplying two blast furnaces, each blower unit can select any blast furnace for air supply through an air supply switching valve. The system layout is shown in Figure 1 .. Large axial flow fan units have a wide range of pressure ratios and delivery flow rates, can adapt to changes in process conditions, have low power consumption and high efficiency, but are prone to reverse flow surging. In the control system of axial flow fans, anti-reverse flow surging protection is one of the most important measures for the unit. For the switching of axial flow fans, it is necessary to keep the air supply main pipe undisturbed and avoid the unit from surging.

[0003] The invention patent with the publication number CN 119878563 A discloses an online switching method for large blast furnace blower units in the technical field of large blast furnace blower units. The switching process is as follows: start the blower of the standby blower unit and make it have the air supply condition. Before the online switching of the blower unit, first switch the blower of the operating blower unit from the automatic control mode to the manual control mode, and record the air supply flow value as the condition parameter when the air mixing is disconnected; adjust the static blade angle and the anti-surge valve opening of the blower of the standby blower unit so that the exhaust pressure of the standby blower unit is 4 kPa - 8 kPa higher than the air supply pressure of the operating blower unit; fully open the outlet valve and the air supply valve of the standby blower unit in sequence to realize the air mixing of the two blower units; take the air supply flow of the blast furnace side as the reference to carry out the load transfer of the two blower units. In actual operation, since the exhaust pressure P2 of the standby blower is greater than the exhaust pressure P1 of the main blower, the air volume will fluctuate in the initial stage of the operation, affecting the subsequent operation rhythm; at the same time, since the air supply valve uses a butterfly valve, it is often not tightly sealed, and the pressure difference before and after the check valve is too small, so the standby air supply check valve cannot be normally opened before the first isolation valve is started, resulting in an extended switching time. Thus, in the actual operation of the above online switching method for large blast furnace blower units, when using the air supply flow value of the air supply pipeline as the condition for disconnecting the air mixing, the situation of reverse flow from the flow of the standby blower unit to the anti-surge valve of the main blower occurs. At this time, the disconnection will not only cause a sharp increase in the air supply volume of the main pipe, affecting the normal production of the blast furnace, but also may cause reverse flow in the main blower, and in serious cases, it will cause production accidents. Summary of the Invention

[0004] The purpose of the present invention is to provide a control method for online disturbance-free switching of blast furnace blowers, to solve the problems that currently the air supply flow fluctuates greatly, the pipeline network pressure fluctuates greatly, and the unit is prone to enter the surge condition, etc., which affect the safe operation of the blower and the stable operation of the blast furnace, and improve the equipment safety.

[0005] To achieve the above object, the present invention adopts the following technical solution: A control method for online non-intrusive switching of blast furnace blowers, characterized by comprising the following steps: Start the standby unit and automatically adjust the power and outlet pressure of the standby unit to be the same as those of the operating unit; Adjust the opening degree V of the anti-surge valve of the operating unit A Output increases until the anti-surge deviation is greater than 20%, and at the same time adjust the static blade angle Z of the unit A Keep the power and outlet pressure of the operating unit unchanged; Open the rapid pressure reducing valve, discharge valve and anti-blocking valve of the standby unit in sequence until the check valve of the standby unit is fully open, and then close the rapid pressure reducing valve; Input the switching start command, and the air supply switching valve of the standby unit is fully open; the static blade switching of the operating unit is manually controlled; the network flow fluctuation is controlled to be less than 50 Nm 3 / min; The operating unit closes the anti-surge valve at a preset action rate, and the standby unit opens the anti-surge valve at the action rate; the action rate of the standby unit to open the anti-surge valve is calculated and executed in real time according to the action rate of the operating unit to keep the total network flow constant; when the opening degree output of the anti-surge valve of the operating unit is closed to 5%, close the anti-blocking valve of the operating unit at the same time; When the anti-surge valve of the standby unit is fully open and the anti-surge valve and anti-blocking valve of the operating unit are fully closed, close the discharge valve and air supply switching valve of the operating unit; switch the connection signal to the standby unit, and the switching operation is completed.

[0006] Preferably, in the step (5), the action rate of the operating unit to close the anti-surge valve is automatically set according to the anti-surge valve opening degree interval, and the corresponding action rate of the standby unit to close the anti-surge valve also changes accordingly.

[0007] Preferably, the action rate of the operating unit to close the anti-surge valve is set as follows: According to the historical operation data, obtain the flow change characteristic curve of the corresponding valve in different opening degree intervals, and set the action rate of the operating unit to close the anti-surge valve according to the relationship between the valve opening degree and the flow characteristics.

[0008] The beneficial effects of the present invention are: The present invention opens the check valve in advance through the rapid pressure reducing valve to ensure that the pressures of the operating blower and the standby blower are the same, and the air supply process pressure is stable. At the same time, taking the closing of the anti-blocking valve as the condition for the mixing air disconnection, the hidden danger of the check valve jamming is eliminated, and the operation stability and safety are improved. During the switching process, the action rate of the valve opening and closing is automatically adjusted through the flow characteristics of the anti-surge valve, making the switching process smoother. Brief Description of the Drawings

[0009] The present invention will be further described with reference to the accompanying drawings. However, the embodiments in the drawings do not constitute any limitation to the present invention. For those of ordinary skill in the art, other drawings can be obtained according to the following drawings without creative work.

[0010] Figure 1 It is the layout diagram of the blast system.

[0011] Figure 2 It is the method flow chart of the present invention.

[0012] In the figure: 1 - blast furnace blower; 2 - anti-surge valve; 3 - check valve; 4 - anti-blocking valve; 5 - discharge valve; 6 - rapid pressure reducing valve; 7 - air supply switching valve; 8 - No. 1 blast furnace. Specific embodiments

[0013] The present invention will be further described below according to the specific embodiments and the drawings in the specification.

[0014] As Figure 1 shown, taking the online replacement of the standby blower unit (standby unit B) and the operating blower unit (operating unit A1) for supplying air to No. 1 blast furnace 8 as an example, the detailed process of a control method for online disturbance-free replacement of blast furnace blowers of the present invention will be introduced in detail.

[0015] Start the standby unit B and obtain the power W A and the outlet pressure P A of the operating unit. At the same time, automatically adjust the power W B and the outlet pressure P B of the standby unit to make the parameters of the two units consistent, that is, W B =W A and P B =P A .

[0016] Adjust the output of the anti-surge valve opening of the operating unit to increase until the anti-surge deviation is greater than 20%. Since the power and outlet pressure of the unit will change after adjusting the anti-surge valve opening, it is necessary to adjust the static blade angle of the unit at the same time to keep the power and outlet pressure of the operating unit unchanged, that is, to maintain W B =W A and P B =P A .

[0017] Open the rapid pressure reducing valve, discharge valve and anti-blocking valve of the standby unit in sequence until the check valve of the standby unit is fully open, and then close the rapid pressure reducing valve.

[0018] Input the instruction to start the replacement. The air supply switching valve of the standby unit is fully open; the static blade switching of the operating unit is manually controlled; the network flow fluctuation is controlled to be less than 50 Nm 3 / min.

[0019] The operating unit closes the anti-surge valve at a preset action rate, and the standby unit opens the anti-surge valve at an action rate; the action rate of the standby unit to open the anti-surge valve is calculated and executed in real time according to the action rate of the operating unit, so as to maintain a constant total network flow; when the opening of the anti-surge valve of the operating unit outputs and closes to 5%, the anti-blocking valve of the operating unit is closed simultaneously.

[0020] When the anti-surge valve of the standby unit is fully open and the anti-surge valve and anti-blocking valve of the operating unit are fully closed, close the discharge valve and air supply switching valve of the operating unit; switch the connection signal to the standby unit, and the unit change operation is completed.

[0021] Preferably, in the step (5), the action rate of the operating unit to close the anti-surge valve changes dynamically according to the anti-surge valve opening interval, and the corresponding action rate of the standby unit to close the anti-surge valve also changes accordingly.

[0022] Specifically, according to the flow characteristics of the anti-surge valve, the relationship between the required flow change and the opening change rate is obtained;

[0023] Among them: ΔQ is the flow change rate; Q is the current flow; Δα is the valve opening action rate. In this way, according to the historical operation data, the flow change characteristic curve of the corresponding valve in different opening intervals can be obtained. According to the relationship between the valve opening X A and the flow characteristics, the action rate Δα A of the operating unit to close the anti-surge valve is preset as follows in the table.

[0024] <![CDATA[X A (0~100)]]> <![CDATA[Δα A (0~1)]]> <![CDATA[X A1 -X A2 > <![CDATA[Δα1]]> <![CDATA[X A2 -X A3 > <![CDATA[Δα2]]> <![CDATA[X A3 -X A4 > <![CDATA[Δα3]]> <![CDATA[X A4 -X A5 > <![CDATA[Δα4]]> <![CDATA[X A5 -X A6 > <![CDATA[Δα5]]> <![CDATA[X A6 -X A7 > <![CDATA[Δα6]]> During the unit change process, according to the valve opening of the actual working condition, the corresponding action rate is automatically selected to operate the anti-surge valve of the operating unit A to close.

[0025] When adjusting the opening of the anti-surge valve of the operating unit A (closing, reducing the bypass flow), the standby unit B also needs to adjust the opening of the anti-surge valve (opening, increasing the bypass flow), and gradually transfer the flow from the operating unit A to the standby unit B. The total network flow needs to be maintained constant throughout the process, that is: ΔQ A -ΔQ B = 0. Through calculation: the action rate Δα B of the standby unit B to open the anti-surge valve A = f(Δα B ). In this way, according to the action rate Δα

[0026] calculated in real time, the anti-surge valve of the standby unit B is controlled to open, so as to achieve a constant total network flow.Although the preferred embodiments of the present invention are listed above, it should be noted that although those skilled in the art can make various changes and modifications, unless such changes and modifications deviate from the scope of the present invention, they should all be included within the protection scope of the present invention.

Claims

1. A control method for online disturbance-free switching of blast furnace blowers, characterized in that, It includes the following steps: Start the standby unit and automatically adjust the power and outlet pressure of the standby unit to be the same as those of the operating unit; Adjust the output of the anti-surge valve opening of the operating unit to increase until the anti-surge deviation is greater than 20%. At the same time, adjust the stator blade angle of the unit to keep the power and outlet pressure of the operating unit unchanged; Open the emergency pressure reducing valve, discharge valve and anti-blocking valve of the standby unit in sequence until the check valve of the standby unit is fully open, and then close the emergency pressure reducing valve; Input the start command for the switching unit, and fully open the air supply switching valve of the standby unit; manually control the stator blade switching of the operating unit; control the stator blade angle of the operating unit to control the network flow fluctuation to be less than 50 Nm 3 / min; The operating unit closes the anti-surge valve at a preset action rate, and the standby unit opens the anti-surge valve at an action rate; the action rate of the standby unit to open the anti-surge valve is calculated and executed in real time according to the action rate of the operating unit to keep the total network flow constant; when the output of the anti-surge valve opening of the operating unit is closed to 5%, close the anti-blocking valve of the operating unit at the same time; When the anti-surge valve of the standby unit is fully open and the anti-surge valve and anti-blocking valve of the operating unit are fully closed, close the discharge valve and air supply switching valve of the operating unit; switch the connection signal to the standby unit, and the unit change operation is completed.

2. The control method of online seamless switching of blast furnace blowers according to claim 1, characterized in that, In step (5), the action rate of the operating unit to close the anti-surge valve is automatically set according to the anti-surge valve opening interval, and the corresponding action rate of the standby unit to close the anti-surge valve also changes accordingly.

3. The control method for online seamless switching of blast furnace blowers according to claim 1 or 2, characterized in that The action rate of the operating unit to close the anti-surge valve is set as follows: according to the historical operation data, obtain the flow change characteristic curve of the corresponding valve in different opening intervals, and set the action rate of the operating unit to close the anti-surge valve according to the relationship between the valve opening and the flow characteristics.

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