Magnetic suspension centrifugal blower for cement kiln and working method of magnetic suspension centrifugal blower

Abstract

The invention relates to the technical field of centrifugal blowers, in particular to a magnetic suspension centrifugal blower for a cement kiln and a working method of the magnetic suspension centrifugal blower. The centrifugal blower comprises a tail coal blower, a clean air blower and a head coal blower, the tail coal blower is connected with the decomposing furnace and conveys pulverized coal to the decomposing furnace, and the clean air blower is connected with the cement kiln and supplies air to the cement kiln; the head coal fan is connected with the cement kiln and conveys pulverized coal to the cement kiln, and the tail coal fan, the clean air fan and the head coal fan are magnetic suspension air blowers respectively. On the basis of an original magnetic suspension air blower, the magnetic suspension air blower can normally operate in the whole process section from kiln lighting to normal production in the cement industry by optimizing the composition structure and the control logic of the air blower.

Description

Technical Field

[0001] The invention relates to the technical field of centrifugal blowers, and in particular to a magnetic suspension centrifugal blower for a cement kiln and a working method thereof. Background Art

[0002] Magnetic levitation centrifugal blowers have the characteristics of high efficiency, energy saving, low carbon and environmental protection, and intelligent design. The performance of the whole machine is significantly better than that of traditional blowers. Therefore, they account for a large proportion of the current suspension blower market application. Moreover, with the global attention to energy conservation and consumption reduction, the application of magnetic levitation blowers has increased year by year. At present, in cement kilns in the cement industry, most of them still use traditional blowers such as Roots blowers for air supply and combustion-supporting processes and coal powder conveying processes. The rest have been replaced with suspension centrifugal blowers. However, many units have reported that due to the small adjustment range of centrifugal fans and the easy triggering of surge, it is difficult to adapt to the entire process from kiln ignition to normal production, and the blowers need to be started and stopped frequently, and the use effect is not very good.

[0003] In cement kilns, the kiln is generally called the "head" and the decomposition furnace is called the "tail". The decomposition furnace mainly decomposes CaCO3 into CaO, and the tail coal fan transports coal powder for the equipment. The kiln mainly burns CaO into clinker, the net air fan supplies air for the equipment, and the head coal fan transports coal powder for the equipment. Figure 1 , Figure 2 , Figure 3 This is the process flow of three types of fans in a cement plant. As shown in the figure, the three fans are required to maintain different operating parameters in different process sections, and the air volume of the fans must remain stable in each operating condition.

[0004] The control logic of the existing magnetic suspension blower is: start → vent valve open → the frequency of the magnetic suspension blower increases to the valve closing frequency → vent valve closes → the frequency of the magnetic suspension blower is adjusted to the set frequency. This control logic can usually only adapt to the normal production condition, and it is difficult to adapt to the entire process from kiln start to normal production.

[0005] In addition, since centrifugal fans have the characteristics of surge, that is, when the system pressure exceeds its boosting capacity, the exhaust gas refluxes, causing the rotor and impeller to vibrate violently, causing equipment damage. The fan's anti-surge program and vent valve are designed to prevent this state from occurring. The boosting capacity of the magnetic levitation blower relies on its extremely high speed. The higher the frequency and the higher the speed, the stronger the boosting capacity. Therefore, when the system fluctuates and causes the system pressure to rise, and the real-time surge monitoring value is close to the surge protection value, the blower automatically increases the frequency to obtain a stronger boosting capacity, but at this time the blower's air volume will exceed the system's required air volume; and if the operating conditions fluctuate very quickly and the blower frequency is not increased in time, the real-time surge monitoring value is equal to or exceeds the surge protection value, and the blower will execute the surge protection program, that is, open the vent valve and shut down. Therefore, a novel magnetic suspension centrifugal blower for cement kiln is urgently needed. Summary of the invention

[0006] In order to solve the above-mentioned problems, the present invention provides a magnetic suspension centrifugal blower for a cement kiln.

[0007] In the first aspect, the present invention provides a magnetic suspension centrifugal blower for a cement kiln, which adopts the following technical solution: A magnetic suspension centrifugal blower for a cement kiln, comprising: The tail coal fan, the clean air fan and the head coal fan, wherein the tail coal fan is connected to the decomposition furnace to transport coal powder to the decomposition furnace; the clean air fan is connected to the cement kiln to supply air to the cement kiln; the head coal fan is connected to the cement kiln to transport coal powder to the cement kiln; wherein the tail coal fan, the clean air fan and the head coal fan respectively use magnetic levitation blowers.

[0008] Furthermore, the magnetic levitation blower adopts an electric vent valve, and the opening and closing of the electric vent valve is controlled by program interlocking. The prevention and control device of the magnetic levitation blower is an adjustable device.

[0009] Furthermore, the electric vent valve includes an electric butterfly valve and a pipeline assembly, wherein the electric butterfly valve is divided into two parts, namely a valve body and an electric actuator. The valve body is installed on the vent pipeline of the fan, and the circular butterfly plate of the valve body is connected to the rotating shaft of the electric actuator. During operation, the rotation of the rotating shaft of the electric actuator is controlled by the PLC control system, thereby driving the circular butterfly plate of the valve body to rotate, thereby realizing the opening and closing of the electric vent valve.

[0010] In a second aspect, a working method of a magnetic suspension centrifugal blower for a cement kiln comprises: Get the decomposition furnace temperature; Determine whether the decomposition furnace temperature reaches the set threshold; The tail coal fan is started according to the temperature of the decomposition furnace, and the coal powder is transported to the decomposition furnace after the tail coal fan is started; After the tail coal fan is started, the head coal fan and the clean air fan are used to transport coal powder and supply air to the cement kiln respectively; Among them, the tail coal fan, clean air fan and head coal fan adopt magnetic levitation blowers, and the magnetic levitation blowers adopt electric vent valves, and the opening and closing of the electric vent valves are controlled by program interlocking.

[0011] Furthermore, the use of the tail coal fan to transport pulverized coal to the decomposition furnace after starting up includes increasing the frequency of the tail coal fan before feeding, and feeding coal with the tail coal fan after feeding.

[0012] Furthermore, the head coal fan and the clean air fan are respectively used to transport coal powder and supply air to the cement kiln, including when the cement kiln is ignited and the combustible material is oil, coal is not fed at this time, and after the head coal fan is turned on, it supplies oxygen for the combustion of the oil at the same time as the clean air fan. Since it is only necessary to maintain the combustion of the oil to ensure the gradual increase of the temperature in the kiln, the head coal fan and the clean air fan are both at a low frequency. When the material is about to be added, the coal feeding amount is increased and the head coal fan is increased in frequency to feed the kiln with coal. Furthermore, the method of respectively utilizing the head coal fan and the clean air fan to transport coal powder and supply air to the cement kiln also includes utilizing the head coal fan to increase the frequency to deliver the coal powder transported by the feeder into the kiln for coal feeding, and simultaneously releasing the pressure in the kiln by increasing the frequency of the clean air fan.

[0013] All fans only have the function of blowing air, except for the head coal fan, which blows the coal powder delivered by the feeder into the kiln. When the coal feeding amount of the feeder increases, the pipeline resistance increases, and the head coal fan has to increase the frequency to obtain a stronger boosting capacity. The same is true for the tail coal fan. The air blown out by the clean air fan is used to break up, mix and wrap the coal powder blown into the kiln after passing through a special device in the owner's pipeline. When the coal feeding amount of the head coal fan increases, the coal powder entering the kiln increases, and the clean air fan naturally needs to increase the frequency to blow out more air. Since the fan itself has no pressure, the pressure depends on the pressure of the load. When the kiln is fed, the pressure in the kiln increases, so the pressure on the clean air fan also increases.

[0014] Furthermore, the program-interlocked control of the opening and closing of the electric vent valve includes dividing the entire frequency range into three parts according to the frequency of the magnetic suspension blower, and adjusting the opening of the electric vent valve respectively according to the divided frequency ranges.

[0015] Furthermore, the entire frequency band is divided into three parts according to the frequency of the magnetic levitation blower, including dividing the entire frequency band of the magnetic levitation blower into three parts by setting the valve closing frequency and the second-order frequency, and obtaining three valve openings according to the three frequency bands, namely, full open, first-order valve opening and second-order valve opening, wherein the second-order frequency>valve closing frequency, the maximum valve opening is recorded as 100%, i.e., fully open, wherein fully open>first-order valve opening>second-order valve opening.

[0016] Furthermore, the opening of the electric vent valve is adjusted according to the divided frequency segments. When the frequency of the magnetic levitation blower is less than the valve closing frequency, the vent valve of the fan is in a fully open state; when the frequency of the magnetic levitation blower is greater than or equal to the valve closing frequency and less than the second-order frequency, the vent valve of the fan is closed to the first-order valve opening; when the frequency of the magnetic levitation blower is greater than or equal to the second-order frequency, the vent valve of the fan is closed to the second-order valve opening.

[0017] In summary, the present invention has the following beneficial technical effects: 1. Based on the existing magnetic levitation blower, the present invention optimizes the blower structure and control logic, so that the magnetic levitation blower can operate normally in the entire process from kiln starting to normal production in the cement industry.

[0018] 2. The present invention effectively solves the problem that centrifugal blowers represented by magnetic levitation blowers cannot adapt well to the entire process of cement kilns from kiln ignition to normal production, and the blowers need to be frequently started and stopped. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the process flow of the tail coal blower according to an embodiment of the present invention.

[0020] Figure 2 It is a schematic diagram of the process flow of the first coal blower according to an embodiment of the present invention.

[0021] Figure 3 It is a schematic diagram of the process flow of the air purification fan according to an embodiment of the present invention. DETAILED DESCRIPTION

[0022] The present invention is further described in detail below in conjunction with the accompanying drawings.

[0023] Example 1 Reference Figure 1 In the magnetic suspension centrifugal blower for cement kiln of the present embodiment, the original pneumatic vent valve is replaced with an electric vent valve, and the vent device of the blower is changed from a switch type to a regulating type through program interlocking control.

[0024] At the same time, the present invention divides the entire frequency segment into three parts by adding the "valve closing frequency" point and the "second-order frequency" point, and thus obtains three valve openings: full open, first-order valve opening, and second-order valve opening (the highest speed is recorded as 100%, where the second-order frequency>valve closing frequency; the maximum valve opening is recorded as 100%, where full open>first-order valve opening>second-order valve opening). When the frequency of the magnetic levitation blower is less than the valve closing frequency, the blower's vent valve is in a fully open state; when the frequency of the magnetic levitation blower is greater than or equal to the valve closing frequency and less than the second-order frequency, the blower's vent valve is closed to the first-order valve opening; when the frequency of the magnetic levitation blower is greater than or equal to the second-order frequency, the blower's vent valve is closed to the second-order valve opening.

[0025] Since the air volume required by the cement kiln is stable, the frequency increase near the surge protection value in the surge protection program is changed to valve opening near the surge protection value.

[0026] The specific structure includes: The tail coal fan, clean air fan and head coal fan, wherein the tail coal fan is connected to the decomposition furnace to transport coal powder to the decomposition furnace; the clean air fan is connected to the cement kiln and supplies air to the cement kiln; the head coal fan is connected to the cement kiln and transports coal powder to the cement kiln; wherein the tail coal fan, clean air fan and head coal fan respectively use magnetic levitation blowers. The magnetic levitation blower uses an electric vent valve, and the opening and closing of the electric vent valve is controlled by program interlocking. The control device of the magnetic levitation blower is an adjustable device.

[0027] The electric vent valve includes an electric butterfly valve and a pipeline assembly, wherein the electric butterfly valve is divided into two parts: a valve body and an electric actuator. The valve body is installed on the vent pipeline of the fan, and the circular butterfly plate of the valve body is connected to the rotating shaft of the electric actuator. During operation, the rotation of the rotating shaft of the electric actuator is controlled by the PLC control system, thereby driving the circular butterfly plate of the valve body to rotate, thereby realizing the opening and closing of the electric vent valve.

[0028] Example 2 The difference between this embodiment and embodiment 1 is that this embodiment provides a working method of a magnetic suspension centrifugal blower for a cement kiln, comprising: Get the decomposition furnace temperature; Determine whether the decomposition furnace temperature reaches the set threshold; The tail coal fan is started according to the temperature of the decomposition furnace, and the coal powder is transported to the decomposition furnace after the tail coal fan is started; After the tail coal fan is started, the head coal fan and the clean air fan are used to transport coal powder and supply air to the cement kiln respectively; Among them, the tail coal fan, clean air fan and head coal fan adopt magnetic levitation blowers, and the magnetic levitation blowers adopt electric vent valves, and the opening and closing of the electric vent valves are controlled by program interlocking.

[0029] The method of using the tail coal fan to transport pulverized coal to the decomposition furnace after starting up the tail coal fan includes increasing the frequency of the tail coal fan before feeding, and feeding coal by using the tail coal fan after feeding.

[0030] The head coal fan and the clean air fan are respectively used to transport coal powder and supply air to the cement kiln. When the cement kiln is ignited, the combustible material is oil and no coal is fed at this time. After the head coal fan is turned on, it supplies oxygen for the combustion of the oil together with the clean air fan. Since it is only necessary to maintain the combustion of the oil to ensure the gradual increase of the temperature in the kiln, the head coal fan and the clean air fan are both at a low frequency. When the material is about to be added, the coal feeding amount is increased and the head coal fan is frequency-increased to feed the kiln with coal. The method of using the head coal fan and the clean air fan to transport coal powder and supply air to the cement kiln respectively also includes using the head coal fan to increase the frequency to deliver the coal powder transported by the feeder into the kiln to feed the coal, and at the same time releasing the pressure in the kiln by increasing the frequency of the clean air fan.

[0031] Among them, the head coal fan blows the coal powder delivered by the feeder into the kiln by blowing air. When the coal feeding amount of the feeder increases, the pipeline resistance increases, and the head coal fan has to obtain a stronger boosting capacity by increasing the frequency. The same is true for the tail coal fan. The wind blown out by the clean air fan is used to break up, mix and wrap the coal powder blown into the kiln after passing through a special device in the owner's pipeline. When the coal feeding amount of the head coal fan increases, the coal powder entering the kiln increases, and the clean air fan naturally needs to increase the frequency to blow out more air. Since the fan itself has no pressure, the pressure depends on the pressure of the load. When the kiln is fed, the pressure in the kiln increases, so the pressure on the clean air fan also increases.

[0032] The program-interlocked control of the opening and closing of the electric vent valve includes dividing the entire frequency range into three parts according to the frequency of the magnetic suspension blower, and adjusting the opening of the electric vent valve respectively according to the divided frequency ranges.

[0033] The method divides the entire frequency band into three parts according to the frequency of the magnetic levitation blower, including dividing the entire frequency band of the magnetic levitation blower into three parts by setting the valve closing frequency and the second-order frequency, and obtains three valve openings according to the three frequency bands, namely, full open, first-order valve opening and second-order valve opening, wherein the second-order frequency>valve closing frequency, the maximum valve opening is recorded as 100%, namely, full open, wherein the full open>first-order valve opening>second-order valve opening.

[0034] The opening of the electric vent valve is adjusted according to the divided frequency segments. When the frequency of the magnetic levitation blower is less than the valve closing frequency, the vent valve of the fan is in a fully open state; when the frequency of the magnetic levitation blower is greater than or equal to the valve closing frequency and less than the second-order frequency, the vent valve of the fan is closed to the first-order valve opening; when the frequency of the magnetic levitation blower is greater than or equal to the second-order frequency, the vent valve of the fan is closed to the second-order valve opening.

[0035] As a further embodiment, Take the tail coal fan process of a cement plant as an example. Figure 1 As shown, the maximum speed of the fan is 36000rpm, recorded as 100%. Set the valve closing speed and the second-order frequency to 30% and 70% of the maximum speed respectively, and set the first-order valve opening and the second-order valve opening to 25% and 5% of the maximum valve opening. When the temperature of the decomposition furnace exceeds 300℃, turn on the tail coal fan. At this time, the fan frequency is set to 60% (greater than the valve closing frequency and less than the second-order frequency). After the start-up program is completed, the vent valve is closed from the fully open state to the first-order valve opening of 25%. At this time, the pressure is small and the flow rate is about 20m³ / min; before feeding, the tail coal fan frequency is increased to 90% (greater than the second-order frequency). At this time, the vent valve is closed to the second-order valve opening of 5%, the flow rate increases to about 45m³ / min, and the pressure rises to about 35kpa after feeding.

[0036] As a further embodiment, Take the process flow of the first coal fan of a cement plant as an example. Figure 2 As shown, the maximum speed of the fan is 36000rpm, recorded as 100%. Set the valve closing speed and the second-order frequency to 30% and 70% of the maximum speed respectively, and set the first-order valve opening and the second-order valve opening to 25% and 5% of the maximum valve opening. When the kiln is started, turn on the first coal fan. At this time, the fan frequency is set to 50% (greater than the valve closing frequency and less than the second-order frequency). After the start-up program is completed, the vent valve is closed from the fully open state to the first-order valve opening of 25%. At this time, the first coal fan does not feed coal, and the air blown in is only for the combustion of oil in the kiln. The pressure and flow are both small; before feeding, the frequency of the first coal fan is increased to 88% (greater than the second-order frequency). At this time, the vent valve is closed to the second-order valve opening of 5%, the flow rate increases to about 34m³ / min, and the pressure increases to about 25kpa.

[0037] As a further embodiment, Take the process flow of the clean air blower in a cement plant as an example. Figure 3 As shown, the maximum speed of the fan is 27000rpm, recorded as 100%. Set the valve closing speed and the second-order frequency to 30% and 60% of the maximum speed respectively, and set the first-order valve opening and the second-order valve opening to 30% and 10% of the maximum valve opening. When the head coal fan is turned on, the tail coal fan is turned on. At this time, the fan frequency is set to 50% (greater than the valve closing frequency and less than the second-order frequency). After the startup program is completed, the vent valve is closed from the fully open state to the first-order valve opening of 30%. At this time, the pressure is small and the flow rate is about 25m³ / min; when the material is about to be fed, the coal feeding amount of the head coal fan is increased. At this time, the frequency of the net air fan is increased to 92% (greater than the second-order frequency). At this time, the vent valve is closed to the second-order valve opening of 10%, the flow rate increases to about 65m³ / min, and the pressure rises to about 60kpa after feeding. In addition, when the system has a violent pressure fluctuation and the fan is close to surge, the fan will automatically open the valve to release the pressure to ensure the normal operation of the entire system.

[0038] To sum up, the magnetic levitation blower does not need to be shut down during the entire process, has a stable flow rate, and performs well, and has been widely recognized and praised by users in related industries.

[0039] The above are all preferred embodiments of the present invention, and are not intended to limit the protection scope of the present invention. Therefore, any equivalent changes made based on the structure, shape, and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A magnetic suspension centrifugal blower for cement kiln, characterized in that: include: The tail coal fan, the clean air fan and the head coal fan, wherein the tail coal fan is connected to the decomposition furnace to transport coal powder to the decomposition furnace; the clean air fan is connected to the cement kiln to supply air to the cement kiln; the head coal fan is connected to the cement kiln to transport coal powder to the cement kiln; wherein the tail coal fan, the clean air fan and the head coal fan respectively use magnetic levitation blowers.

2. A magnetic suspension centrifugal blower for cement kiln according to claim 1, characterized in that: The magnetic levitation blower adopts an electric vent valve, and the opening and closing of the electric vent valve is controlled by program interlocking. The prevention and control device of the magnetic levitation blower is an adjustable device.

3. A magnetic suspension centrifugal blower for cement kiln according to claim 2, characterized in that: The electric vent valve includes an electric butterfly valve and a pipeline assembly, wherein the electric butterfly valve is divided into two parts: a valve body and an electric actuator. The valve body is installed on the vent pipeline of the fan, and the circular butterfly plate of the valve body is connected to the rotating shaft of the electric actuator. During operation, the rotation of the rotating shaft of the electric actuator is controlled by the PLC control system, thereby driving the circular butterfly plate of the valve body to rotate, thereby realizing the opening and closing of the electric vent valve.

4. A method for operating a magnetic suspension centrifugal blower for a cement kiln, characterized in that: include: Get the decomposition furnace temperature; Determine whether the decomposition furnace temperature reaches the set threshold; The tail coal fan is started according to the temperature of the decomposition furnace, and the coal powder is transported to the decomposition furnace after the tail coal fan is started; After the tail coal fan is started, the head coal fan and the clean air fan are used to transport coal powder and supply air to the cement kiln respectively; Among them, the tail coal fan, clean air fan and head coal fan adopt magnetic levitation blowers, and the magnetic levitation blowers adopt electric vent valves, and the opening and closing of the electric vent valves are controlled by program interlocking.

5. The method for operating a magnetic suspension centrifugal blower for a cement kiln according to claim 4, characterized in that: The method of using the tail coal fan to transport pulverized coal to the decomposition furnace after starting up the tail coal fan includes increasing the frequency of the tail coal fan before feeding, and feeding coal by using the tail coal fan after feeding.

6. The method for operating a magnetic suspension centrifugal blower for a cement kiln according to claim 5, characterized in that: The head coal fan and the clean air fan are respectively used to transport coal powder and supply air to the cement kiln. When the cement kiln is ignited, the combustible material is oil and no coal is fed at this time. After the head coal fan is turned on, it supplies oxygen for the combustion of the oil together with the clean air fan. Since it is only necessary to maintain the combustion of the oil to ensure the gradual increase of the temperature in the kiln, the head coal fan and the clean air fan are both at a low frequency. When the material is about to be added, the coal feeding amount is increased and the head coal fan is frequency-increased to feed the kiln with coal.

7. The method for operating a magnetic suspension centrifugal blower for a cement kiln according to claim 6, characterized in that: The method of using the head coal fan and the clean air fan to transport coal powder and supply air to the cement kiln respectively also includes using the head coal fan to increase the frequency to deliver the coal powder transported by the feeder into the kiln to feed the coal, and at the same time releasing the pressure in the kiln by increasing the frequency of the clean air fan.

8. The method for operating a magnetic suspension centrifugal blower for a cement kiln according to claim 7, characterized in that: The program-interlocked control of the opening and closing of the electric vent valve includes dividing the entire frequency range into three parts according to the frequency of the magnetic suspension blower, and adjusting the opening of the electric vent valve respectively according to the divided frequency ranges.

9. The method for operating a magnetic suspension centrifugal blower for a cement kiln according to claim 8, characterized in that: The method divides the entire frequency band into three parts according to the frequency of the magnetic levitation blower, including dividing the entire frequency band of the magnetic levitation blower into three parts by setting the valve closing frequency and the second-order frequency, and obtains three valve openings according to the three frequency bands, namely, full open, first-order valve opening and second-order valve opening, wherein the second-order frequency>valve closing frequency, the maximum valve opening is recorded as 100%, namely, full open, wherein the full open>first-order valve opening>second-order valve opening.

10. The method for operating a magnetic suspension centrifugal blower for a cement kiln according to claim 9, characterized in that: The opening of the electric vent valve is adjusted according to the divided frequency segments. When the frequency of the magnetic levitation blower is less than the valve closing frequency, the vent valve of the fan is in a fully open state; when the frequency of the magnetic levitation blower is greater than or equal to the valve closing frequency and less than the second-order frequency, the vent valve of the fan is closed to the first-order valve opening; when the frequency of the magnetic levitation blower is greater than or equal to the second-order frequency, the vent valve of the fan is closed to the second-order valve opening.

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