Surge suppression device for centrifugal fan

Abstract

The utility model discloses a surge suppression device for a centrifugal fan. The surge suppression device is connected to a variable-frequency magnetic suspension centrifugal blower and a shaft furnace. An air outlet of the variable-frequency magnetic suspension centrifugal blower is communicated with an air inlet pipeline of the shaft furnace; comprising an electric control valve, a bypass pipe, an air volume detector and a display, a bypass pipe is arranged on a pipeline for communicating the air outlet of the variable-frequency magnetic suspension centrifugal blower with the air inlet of the shaft furnace; an electric control valve is arranged on the bypass pipe; the electric control valve is arranged on the bypass pipe; the air volume detector is arranged at an air inlet of the variable-frequency magnetic suspension centrifugal blower; the air volume detector is electrically connected with the displayer. The device combines the characteristic of high-rotating-speed operation of the magnetic suspension fan, and can effectively avoid the surge phenomenon at the low-firepower preheating stage of the shaft furnace under the conditions that the pipe network resistance is not increased and the fan maintains the existing constant-pressure variable-frequency control mode.

Description

Technical Field

[0001] The present application relates to the technical field of centrifugal fans, and in particular to a centrifugal fan surge suppression device. Background Art

[0002] The vertical furnace used in the SCR continuous casting and rolling production line uses natural gas as fuel, adopts a premixed combustion system, and is provided with combustion-supporting air by a variable frequency magnetic suspension centrifugal blower. The electrolytic copper raw materials are melted through 23 burner spray guns in 6 combustion areas of the vertical furnace. In order to avoid "explosion" when the vertical furnace is ignited, a blower must be used to provide combustion-supporting air to purge and purify the furnace before the vertical furnace is ignited to ensure that the flammable gas in the furnace has been discharged before the vertical furnace is ignited.

[0003] The vertical furnace blower adopts constant pressure variable frequency control mode. After the blower is started, the control program implements variable frequency control according to the preset blower outlet pressure value (30kPa), opens the combustion air control valves of the 6 combustion area branches of the vertical furnace to the maximum limit opening (the maximum limit is set to meet the purge pressure requirements), and when the air pressure values ​​of the branches in each combustion area reach above 150H2O / cm, the control program prompts that the purge and purification conditions are met. Start the purge and purification control, and after continuous purge for 60 seconds, close the combustion air control valves of the 6 combustion area branches to the minimum limit opening (the minimum limit is set to meet the initial ignition pressure), and the pressure of each combustion area branch meets 50H2O / cm or less, which means that the blowing is completed and the conditions for starting ignition are met.

[0004] Since the variable frequency magnetic suspension centrifugal blower is a high-speed blower, when meeting the maximum purge demand, the speed of the magnetic suspension blower has almost reached 16000rpm / min. After the purge is completed, the combustion air control valves in each combustion area close quickly, and the operating characteristics of the magnetic suspension blower cause the blower to be unable to quickly drop to a low-speed operating state. At this time, the air flow at the blower inlet decreases rapidly, while the blower maintains a high speed operation, resulting in repeated pressure difference changes between the blower outlet pressure and the pressure in the pipe network, resulting in periodic low-frequency and high-amplitude pressure pulsation and airflow oscillation, and the machine vibrates violently and makes a loud noise. This phenomenon is called surge.

[0005] When the vertical furnace is started and ignited, the burner spray guns of each area need to be started and ignited one by one, and maintain a low-fire preheating state for a period of time. During this stage, each burner is in the process of using low-flow combustion air, which makes the blower continue to operate in a surge state, causing serious mechanical damage to the mechanical system, accelerating the aging of the blower and reducing the service life of the blower.

[0006] The information disclosed in the background technology section is only intended to enhance the understanding of the overall background of the invention and should not be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art. Utility Model Content

[0007] In view of the above technical problems, the present application provides a centrifugal fan surge suppression device for solving the technical problem in the prior art that when the vertical furnace burner is operating at low power, the blower inlet air volume is too low and causes surge.

[0008] The present application provides a centrifugal fan surge suppression device, which is connected to a variable frequency magnetic suspension centrifugal blower and a vertical furnace; the air outlet of the variable frequency magnetic suspension centrifugal blower is connected to the vertical furnace air inlet pipeline;

[0009] It includes: an electric regulating valve, a bypass pipe, an air volume detector, and a display; a bypass pipe is arranged on the pipeline connecting the air outlet of the variable frequency magnetic suspension centrifugal blower and the air inlet of the vertical furnace; an electric regulating valve is arranged on the bypass pipe; the electric regulating valve is arranged on the bypass pipe;

[0010] The air volume detector is arranged at the air inlet of the variable frequency magnetic suspension centrifugal blower;

[0011] The air volume detector is electrically connected to the display.

[0012] Preferably, one end of the bypass pipe is connected to a pipeline connecting the air outlet of the magnetic suspension centrifugal blower and the air inlet of the vertical furnace, and the other end extends outward and is emptied.

[0013] Preferably, it comprises: a butterfly valve; a butterfly valve is arranged on the pipeline connecting the air outlet of the variable frequency magnetic suspension centrifugal blower and the air inlet of the vertical furnace.

[0014] Preferably, it comprises: a pressure detector; the pressure detector is arranged at the air outlet of the variable frequency magnetic suspension centrifugal blower and is electrically connected to the display.

[0015] Preferably, it comprises: a PLC control module; the PLC control module is electrically connected to the electric regulating valve and the pressure detector respectively.

[0016] The beneficial effects of this application include:

[0017] 1) The centrifugal fan surge suppression device provided in the present application, which combines the characteristics of the high-speed operation of the magnetic suspension fan, can effectively avoid the surge phenomenon in the low-fire preheating stage of the vertical furnace without increasing the pipe network resistance and maintaining the existing constant pressure frequency conversion control mode of the fan.

[0018] 2) The centrifugal fan surge suppression device provided in the present application increases the blower inlet air volume by adding a bypass exhaust regulating valve to the blower outlet main duct. When the vertical furnace burner is in a low-fire state and the amount of combustion air used is small, the exhaust regulating valve on the bypass duct controls the exhaust, thereby effectively suppressing the blower surge. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A schematic diagram of the structure of a centrifugal fan surge suppression device provided in this application;

[0020] Figure 2 A schematic diagram of the connection of the centrifugal fan surge suppression device module provided in this application;

[0021] Figure 3 A schematic diagram of the blower operation monitoring result state in the embodiment provided in this application;

[0022] Legend:

[0023] Variable frequency magnetic suspension centrifugal blower 1, air inlet 2, air outlet 3, butterfly valve 4, electric regulating valve 5, bypass pipe 6, air volume detector 7, PLC control module 8, display 9, pressure detector 11. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0025] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] The controller used in this embodiment is an existing structure, and the control circuit can be implemented through simple programming by technicians in this field. It belongs to the common knowledge in this field. It is only used without modification, so the control method and circuit connection are not described in detail.

[0027] The technical means that are not described in detail in this application and are not used to solve the technical problems of this application are all set according to the common knowledge in the field, and can be implemented in a variety of common knowledge settings.

[0028] See also Figures 1 to 3The centrifugal fan surge suppression device provided by the present application, the air outlet 3 of the variable frequency magnetic suspension centrifugal blower 1 is connected to the pipeline of the vertical furnace air inlet; it includes: an electric regulating valve 5, a bypass pipe 6, an air volume detector 7, and a display 9; one end of the bypass pipe 6 is connected to the pipeline connecting the air outlet 3 and the vertical furnace air inlet, and the other end is vented; the electric regulating valve 5 is arranged on the bypass pipe 6; the air volume detector 7 is arranged in the air inlet pipe of the variable frequency magnetic suspension centrifugal blower 1; the air volume detector 7 is electrically connected to the display 9 arranged on the outer wall of the air inlet pipe. It is convenient to display the air volume at the air inlet in real time, and it is convenient for the operator to open or close the electric regulating valve 5 according to the change of air volume, and use the bypass pipe 6 to exhaust or stop exhausting, thereby eliminating the surge caused by small air flow and excessive attack angle in the preheating state of the vertical furnace with low firepower, and effectively suppressing the occurrence of surge.

[0029] The exhaust and venting method of the air outlet pipe is adopted. A bypass pipe is added to the air outlet pipe. Once the air volume at the air inlet is reduced to the minimum surge air volume (80m 3 / min), open the electric regulating valve on the bypass pipe to release air through the bypass pipe. At this time, even if the air volume at the air inlet increases, the working point will move from the original surge area to the stable working area. As the preheating firepower of the vertical furnace increases, the combustion air volume of the fan gradually increases to 120m 3 / min, the electric regulating valve 5 on the bypass pipe is slowly closed, thereby eliminating the surge caused by small air flow and excessive attack angle in the preheating state of the vertical furnace with low firepower, thereby effectively suppressing the occurrence of surge.

[0030] In a specific embodiment, it includes: a PLC control module 8; the PLC control module 8 is electrically connected to the air volume detector 7 and the electric regulating valve 5 respectively.

[0031] Through the bypass pipe 6 and the electric regulating valve 5 arranged thereon, a threshold value can be preset in the PLC control module 8, and the electric regulating valve 5 can be controlled to open or close according to the air volume result detected by the detector 7 according to the threshold value.

[0032] In a specific embodiment, an air inlet pipe is provided on the air inlet 2 of the variable frequency magnetic suspension centrifugal blower 1 ; and an air outlet pipe is provided on the air outlet 3 .

[0033] In a specific embodiment, it includes: a pressure detector 11, which is arranged on the pipe of the air outlet 3 to detect the outlet pressure there. The flow rate of the air inlet can also be determined according to the measured air outlet pressure value in combination with the relationship diagram obtained in daily production, such as Figure 3 As shown, according to the pressure change at the outlet, the corresponding inlet flow condition is determined, thereby determining the opening and closing of the electric regulating valve 5.

[0034] In a specific embodiment, the pressure detector 11 is electrically connected to the PLC control module 8 and the display 9 respectively, so that the operator can obtain the pressure value at the air outlet in time, and it is also convenient to preset the threshold through the PLC control module 8 and control the opening and closing of the electric regulating valve 5 according to the change of the air outlet pressure.

[0035] In a specific embodiment, it includes: a butterfly valve 4; the butterfly valve 4 is arranged on the air outlet pipe of the variable frequency magnetic suspension centrifugal blower 1. The butterfly valve 4 is used to adjust the air volume entering the vertical furnace to control the firepower of the vertical furnace.

[0036] In a specific embodiment, if Figure 1 As shown, after the vertical furnace is purged and purified, the combustion air control valves of the branch pipes in each combustion area are closed to the initial ignition position, the burner spray guns in each combustion area are at low firepower, the overall air volume of the vertical furnace is relatively small, and in the constant pressure control mode, the air volume of the variable frequency magnetic suspension centrifugal blower 1 air inlet 2 drops significantly; Figure 1 As shown in the figure, when the outlet pressure of variable frequency magnetic suspension centrifugal blower 1 is maintained at a constant 30kPa, the fan inlet air volume 2 is less than 80m 3 / min, the fan enters the surge operation period; therefore, add a bypass exhaust electric regulating valve 5 on the outlet 3 main pipe, and the air inlet 2 is lower than 80m 3 / min, the PLC control module 8 controls the exhaust electric regulating valve 5 to open, the air volume of the main air outlet 3 increases, and the air volume of the air inlet 2 also increases to 80m 3 / min or more, the fan surge is eliminated. At any time, the firepower of the vertical furnace burner spray gun is gradually increased, and the air volume of the vertical furnace is continuously increased. When the air volume at the air inlet 2 is higher than 120m 3 / min, the PLC control module 8 controls the exhaust air electric regulating valve 5 to close and end the control.

[0037] In this embodiment, the air volume detector 7 disposed on the inner wall of the duct of the air inlet 2 detects the relationship between the gas flow rate at the air inlet 2 and the outlet pressure. Figure 3 shown.

[0038] Therefore, the device solves the problem of fan surging caused by low firepower and low air volume of the vertical furnace burner by controlling the exhaust of the bypass pipe 6. The device has a simple and reliable structure and strong applicability.

[0039] The air volume detector 7, PLC control module 8, display 9, and pressure detector 11 used in the present application are all commonly used devices in the field. For example, the PLC control module 8 is a Siemens PLC ET200S module 6ES71314BFOOOAAO.

[0040] Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A centrifugal fan surge suppression device, connected to a variable frequency magnetic suspension centrifugal blower and a vertical furnace; the air outlet of the variable frequency magnetic suspension centrifugal blower is connected to the vertical furnace air inlet pipeline; It is characterized in that include: Electric regulating valve, bypass pipe, air volume detector, display; a bypass pipe is arranged on the pipeline connecting the air outlet of the variable frequency magnetic suspension centrifugal blower and the air inlet of the vertical furnace; an electric regulating valve is arranged on the bypass pipe; the electric regulating valve is arranged on the bypass pipe; The air volume detector is arranged at the air inlet of the variable frequency magnetic suspension centrifugal blower; The air volume detector is electrically connected to the display.

2. The centrifugal fan surge suppression device according to claim 1, characterized in that: One end of the bypass pipe is connected to a pipeline connecting the air outlet of the frequency magnetic suspension centrifugal blower and the air inlet of the vertical furnace, and the other end extends outward and is emptied.

3. The centrifugal fan surge suppression device according to claim 1, characterized in that: include: Butterfly valve: A butterfly valve is arranged on the pipeline connecting the air outlet of the variable frequency magnetic suspension centrifugal blower and the air inlet of the vertical furnace.

4. The centrifugal fan surge suppression device according to claim 1, characterized in that: include: Pressure detector; the pressure detector is arranged at the air outlet of the variable frequency magnetic suspension centrifugal blower and is electrically connected to the display.

5. The centrifugal fan surge suppression device according to claim 1 or 4, characterized in that: include: PLC control module; The PLC control module is electrically connected to the electric regulating valve and the pressure detector respectively.

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