Anti-clogging air preheater with purging function, intelligent control and soot blower installed in the middle

Abstract

The present invention discloses an anti-blocking air preheater with a purging function, intelligent control, and a soot blower installed in the middle. By adding a soot blower inside the heat transfer elements of the air preheater rotor, the purging effect of the air preheater soot blowing system is greatly improved. An ultrasonic generator is installed on the high-temperature steam inlet pipeline of the air preheater soot blower, enabling the soot blower to have a function of blowing and unblocking during operation, simultaneously achieving a certain degree of stripping of dirt on the surface of the heat exchange elements, and the steam soot blowing also has a cleaning function. The blockage situation of the heat transfer elements in each compartment of the air preheater is accurately monitored. The intelligent digital monitoring and control system of the air preheater accurately controls the temperature, pressure, and flow field distribution in the bin area and monitors the ash accumulation on the surface of the heat exchange elements and the analysis of the ash accumulation trend. The present invention can fully adapt to pulverized coal boilers with SCR denitration systems, can replace traditional rotary air preheaters, and solve the problem of frequent blockage of heat transfer elements after denitration of pulverized coal boilers.

Description

Technical Field

[0001] The present invention relates to the technical field of boilers and is an important device for reducing the exhaust gas temperature, increasing the air supply temperature and realizing energy saving and emission reduction. The present invention can be fully applicable to pulverized coal boilers equipped with SCR denitration systems, can replace traditional rotary air preheaters, and solve the problem of frequent blockage of heat transfer elements in pulverized coal boilers after denitration. Background Art

[0002] As the country's environmental protection requirements continue to increase, boiler NOX (nitrogen oxide) emission indicators are getting lower and lower. Regardless of whether SCR or SNCR denitration methods are used, the formation of ABS (ammonium bisulfate) products cannot be avoided. ABS products will condense at a certain temperature. When it is below 220 degrees Celsius, it will condense from gas to liquid, and when it is below 148 degrees Celsius, it will solidify from liquid to solid, which will have many negative effects on the operating performance of subsequent equipment. The equipment most seriously affected is the subsequent air preheater, especially the rotary air preheater. The reason why it is most affected is that it is a heat exchange equipment with a large difference between the inlet and outlet ends. Its flue gas temperature side end difference temperature basically works between 400 and 120 degrees Celsius. It is an important equipment for boilers to reduce exhaust gas temperature, increase air supply temperature, and achieve energy conservation and emission reduction. In this temperature range, it is also the process of denitration product ABS condensing from gas to solid mud. A large amount of solid condensate adheres to the heat exchanger plate of the air preheater, that is, the heat transfer element, with a high bonding strength. The increasing thickness of adhesion will block the flow cross section of the heat exchanger, causing the resistance of the flue and air duct to increase, affecting the air supply and exhaust of the boiler. In mild cases, the unit will be forced to operate at a reduced load, and in severe cases, it will be forced to stop operation.

[0003] In order to solve the problem of air preheater (short for air preheater) blockage, three commonly used methods are:

[0004] 1. Optimize combustion performance by adjusting boiler combustion to minimize ABS generation.

[0005] 2. By increasing the flow channel section in the heat transfer element of the rotary air preheater, the flow channel resistance is reduced and the air flow is enhanced. At the same time, it also provides certain favorable conditions for adopting the third approach.

[0006] 3. Use mechanical cleaning method to remove ABS condensed and adhered to the inner surface of the heat transfer element.

[0007] However, practice has proved that the effects of the above three methods are very limited. First, even if the boiler combustion adjustment is further optimized, it is impossible to fundamentally eliminate the generation of ABS condensates. Second, increasing the flow channel of the component will simultaneously reduce the surface area of the heat transfer component, which is not conducive to heat exchange, resulting in a decrease in air temperature and an increase in flue gas temperature, sacrificing a certain economy of the equipment. Third, the rotary air preheater component is too thick to be penetrated, and the ABS viscous substances adhering to the middle section inside the component cannot be removed online by steam or high-pressure water.

[0008] For the above reasons, the blockage problem of the heat transfer components of the air preheater has become an important problem that is difficult to completely solve in current pulverized coal boilers in power plants. And this invention is proposed for this purpose. Summary of the Invention

[0009] To meet the above requirements, the purpose of the present invention is to adopt an anti-blocking rotary air preheater with a purging function, an intelligent monitoring and control system, and a soot blower installed inside the rotor to solve the problem of frequent blockage of heat transfer components after denitrification of pulverized coal boilers.

[0010] The technical method adopted by the present invention to achieve the above purpose is:

[0011] On the premise of ensuring that the original heat transfer efficiency of the original rotary air preheater (traditional) remains unchanged, the height positions of the heat transfer components in each compartment are rearranged to leave a layer of space inside the rotor components, and a soot blower is installed.

[0012] A soot blower is installed in the space left in each partition compartment. The number of soot blowers is the same as the number of compartments of the air preheater.

[0013] The front end of the soot blowing gun in each compartment has a vector nozzle that can change the blowing direction. This nozzle can provide the power for the soot blowing gun to swing in a fan shape, realizing the full coverage purging of the soot blowing gun in the fan-shaped flow cross-section. The layout position of this soot blower is between the stages where ABS is concentrated, and it can be used to focus on purging the blockage concentration area between the cross-sections.

[0014] An ultrasonic generator with confidentiality technology is installed on the high-temperature steam inlet pipeline of the air preheater soot blower, so that when the soot blower operates, it not only has a function of blowing and unblocking, but also uses the cavitation effect of ultrasonic waves in the medium to achieve the stripping of dirt on the surface of certain heat transfer components, making the steam soot blowing have a cleaning function. As a result, no ash will accumulate on the surface of the heat transfer components, and ABS crystals cannot adhere to the surface of the heat transfer components.

[0015] The arranged soot blower air (steam) source is introduced through the rotor central cylinder and then connected to the distribution header. Each soot blower gun is connected to the distribution header through a rotary joint and an angle valve. The opening of each angle valve is completed by the action of an actuator outside the air preheater. The actuator penetrates into the interior of the air preheater through a telescopic rod to trigger the corresponding angle valve, thereby opening the angle valve. Through the coordination of the angular velocity of the air preheater rotor and the action time of the actuator, any angle valve can be opened, thus realizing precise soot blowing action.

[0016] In order to achieve precise soot blowing of the soot blower and avoid over-blowing and under-blowing problems, the present invention installs an array of flow field sensors on the air flow channel of the air preheater to feedback the uniformity of the air flow field passing through the air preheater, thereby judging the blockage condition of the air preheater elements. According to the blockage condition, the soot blower is controlled by a program, thus realizing intelligent closed-loop precise purging.

[0017] The present invention arranges a soot blower inside the heat transfer element of the rotor, which improves the soot blowing efficiency of the air preheater soot blower and ensures the penetrability of the soot blower to the heat transfer element. Thus, it is convenient to directly wash and remove the blockage of the heat transfer element in the easily blocked section, effectively solving the problem of blockage of the air preheater heat transfer element, and providing favorable conditions for fully ensuring that the air preheater does not stop due to blockage during boiler operation. Without basically changing the overall structure of the air preheater, the anti-blocking reliability of the air preheater is realized, creating conditions for further improving the heat exchange efficiency of the air preheater and reducing the flue gas exhaust temperature. It is a new air preheater structure with small investment and large benefits. The intelligent precise purging control system adopted by the present invention is beneficial to improving the anti-blocking efficiency of the air preheater and also saves soot blowing medium at the same time. It avoids the problem of "short life" of the air preheater elements caused by over-blowing, and also improves the soot blowing efficiency at the key blocked positions.

[0018] The present invention can be fully applicable to pulverized coal boilers with SCR denitration systems, can replace traditional rotary air preheaters, and solve the problem of frequent blockage of heat transfer elements after denitration of pulverized coal boilers. The invention can essentially solve the problem of frequent blockage of the air preheater and is an ideal prevention and control measure for preventing ABS condensation blockage, which can be widely promoted and applied.

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] (1) Through a clever structure, the present invention adds a soot blower that can swing and wash inside the heat transfer element of the air preheater rotor, greatly improving the washing effect of the air preheater soot blowing system, effectively solving the problem of blockage of the air preheater heat transfer element, and fully ensuring that the air preheater does not stop due to blockage during boiler operation.

[0021] (2) Install an ultrasonic generator with confidentiality technology on the high-temperature steam inlet pipeline of the air preheater soot blower, so that when the soot blower operates, it not only has the function of blowing and unblocking, but also uses the cavitation effect of ultrasonic waves in the medium to achieve the stripping of dirt on the surface of certain heat exchange elements, so that the steam soot blowing also has a cleaning function. The final result is that the surface of the heat exchange elements will not accumulate ash, and ABS crystals cannot adhere to the surface of the heat exchange elements.

[0022] (3) It can accurately monitor the blockage of heat transfer elements in each bin of the air preheater and realize the fixed-point flushing function of the air preheater through-flow section during operation.

[0023] (4) The intelligent digital air preheater monitoring (using multi-point layout in cross-section) and control system can accurately control the temperature, pressure and flow field distribution in the bin area, and clearly monitor the ash accumulation on the surface of the heat exchange elements and the analysis of the ash accumulation trend according to the software algorithm, and accurately control the accurate position and action duration of the soot blower injection.

[0024] In summary, the present invention can fully adapt to pulverized coal boilers with SCR denitration systems, can replace traditional rotary air preheaters, and solve the problem of frequent blockage of heat transfer elements after denitration of pulverized coal boilers. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a schematic structural diagram of an anti-blocking rotary air preheater provided by an embodiment of the present invention.

[0026] Figure 2 is a schematic position diagram of the soot blower supply pipeline and control valve actuator provided by an embodiment of the present invention.

[0027] Figure 3 is a schematic diagram of the soot blower making a sector swing in the sector bin.

[0028] Figure 4 is a schematic structural diagram of the swing reversing valve provided by an embodiment of the present invention.

[0029] In the figure: 1. First, soot blower; 2. Second soot blower; 3. Third soot blower; 4. Cold air inlet; 5. Rotary joint; 6. Flue gas outlet; 7. Cross-section flow field sensor; 8. Second-stage heat transfer element; 9. ABS concentrated blockage space; 10. First-stage heat transfer element; 11. Flue gas inlet; 12. Air preheater housing; 13. Air preheater rotating shaft; 14. Hot air outlet; 15. Soot blower lift valve opening and closing actuator; 16. Soot blower lift valve; 17. Annular distribution header; 18. Soot blower gas supply pipe; 19. Upper bearing of air preheater; 20. Soot blower barrel; 21. Guide track wheel; 22. Sector swing track; 23. Iron bumper; 24. Valve core; 25. Inlet of incoming air flow. DETAILED DESCRIPTION OF THE INVENTION

[0030] In order to make the objectives, technical solutions and advantages of the present invention more clear and understandable, the present invention will be further described in detail below in conjunction with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0031] Aiming at the problems existing in the prior art, the present invention provides an anti-blocking rotary air preheater, which will be described in detail below in conjunction with the accompanying drawings.

[0032] As Figure 1 shown, there is a certain space left between the heat transfer elements at the hot and cold ends of the rotor of the traditional rotary air preheater, and a soot blower is installed (such as Figure 1 the third soot blower 3 shown in

[0033] As Figure 1 and Figure 2 shown, the air preheater housing 12 is installed with an air preheater rotating shaft 13 through the upper bearing 19 of the air preheater, and a soot blower lifting valve opening and closing actuator 15 is installed on the left side of the upper bearing 19 of the air preheater; a soot blower lifting valve 16 and an annular distribution header 17 are installed at the lower end of the upper bearing 19 of the air preheater. The annular distribution header 17 is connected to the rotary joint 5 through a pipeline, and the rotary joint 5 is respectively connected to the first soot blower 1, the second soot blower 2 and the third soot blower 3 through a soot blower gas supply pipe 18.

[0034] As Figure 3 shown, a soot blower lifting valve 16 is installed on the annular distribution header 17. The soot blower lifting valve 16 is connected to the soot blower barrel 20, and a guiding track wheel 21 is installed at the end of the soot blower barrel 20. The track of the guiding track wheel 21 is a fan-shaped swing track 22. The soot blower configured in each compartment inside the rotary air preheater rotor can perform approximate fan-shaped swing blowing in the rotor compartment grid, realizing almost full coverage blowing of the flow cross-section in the compartment grid.

[0035] As Figure 4 shown, a swing reversing valve is installed at the end of the third soot blower 3. An incoming air port 25 is arranged inside the swing reversing valve, and an armature 23 and a valve core 24 are installed inside the swing reversing valve. The armature 23 is connected to the valve core 24. The swing of each soot blower in the compartment is provided with the power of swing by the reaction force generated by the medium ejected from the adjustable nozzle at the end of the gun barrel. Relying on the limit touches on both sides to alternately open the power nozzle of the reversing valve, the reciprocating swing of the soot blower is realized.

[0036] The working principle of the present invention is as follows: Without changing the original heat transfer efficiency of the rotary air preheater (traditional), the height positions of the heat transfer elements in each compartment are rearranged to leave a layer of space inside the rotor elements, and soot blowers are installed. A soot blower is installed in the space left in each separation compartment. The number of the soot blowers is the same as the number of compartments of the air preheater. The front end of the soot blowing gun in each compartment is equipped with a vector nozzle that can change the spraying direction. This nozzle can provide the power for the soot blowing gun to swing in a fan shape, realizing the full coverage cleaning of the soot blowing gun in the fan-shaped flow cross-section. The arrangement position of the soot blower is in the stage where ABS is concentrated, and it can be used to focus on blowing and washing the clogging area between the cross-sections.

[0037] An ultrasonic generator with confidentiality technology is installed in the high-temperature steam inlet pipeline of the air preheater soot blower, so that when the soot blower operates, it not only has the function of blowing and unclogging, but also uses the cavitation effect of ultrasonic waves in the medium to achieve the peeling of dirt on the surface of certain heat transfer elements, making the steam soot blowing have a cleaning function. The final result is that no ash will accumulate on the surface of the heat transfer elements, and ABS crystals cannot adhere to the surface of the heat transfer elements.

[0038] The gas (steam) source of the soot blower arranged as above is introduced through the central cylinder of the rotor and then connected to the distribution header. Each soot blowing gun is connected to the distribution header through a rotary joint and an angle valve. The opening of each angle valve is completed by the action of an actuator outside the air preheater. The actuator penetrates into the air preheater through a telescopic rod to trigger the corresponding angle valve, thereby opening the angle valve. By coordinating the angular velocity of the air preheater rotor and the action time of the actuator, any angle valve can be opened, thus realizing precise soot blowing action. In order to achieve precise soot blowing of the soot blower and avoid over-blowing and under-blowing problems, an array of flow field sensors is installed on the air flow channel of the air preheater to feedback the uniformity of the air flow field passing through the air preheater, so as to judge the clogging situation of the air preheater elements. According to the clogging situation, the soot blower is controlled by a program, thereby realizing intelligent closed-loop precise cleaning.

[0039] In the description of the present invention, unless otherwise specified, "a plurality of" means two or more; the orientation or positional relationship indicated by the terms "upper", "lower", "left", "right", "inner", "outer", "front end", "rear end", "head", "tail", etc. is the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the present invention.

[0040] The above is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be covered within the protection scope of the present invention.

Claims

1. An anti-clogging air preheater with a purging function, intelligent control, and a soot blower installed in the middle, characterized in that: Install soot blowers between the hot and cold end heat transfer elements of the rotary air preheater rotor; The number of soot blowers installed inside the rotor is the same as the number of compartments of the rotary air preheater, and each compartment is equipped with a soot blowing gun; the medium pipeline of the soot blower passes through the rotary joint inside the rotor central cylinder to connect the soot blowing medium to the annular distribution box, and each soot blowing gun is connected to the distribution box through a rotary joint and an angle valve; Install an array type flow field sensor group at the flue gas outlet end of the air preheater rotor medium; install an ultrasonic generator at the inlet of the soot blower pipeline; The soot blowing gun configured in each compartment inside the rotary air preheater rotor makes an approximate sector surface swing purge within the rotor compartment grid; The swing of each soot blowing gun in the compartment is provided with the driving force for swinging by the reaction force generated by the medium ejected from the adjustable nozzle at the end of the gun rod; rely on the limit on both sides to touch the reversing valve to alternately open the adjustable nozzle to realize the reciprocating swing of the soot blowing gun; The opening of the soot blowing gun depends on the action of the actuator outside the air preheater. After the actuator acts, the telescopic rod extends into the air preheater to touch the angle valve of the corresponding soot blowing gun, causing the angle valve to open. According to the angular velocity of the air preheater rotor, the positions corresponding to each angle valve are programmed into the control system program to achieve precise alignment control of each soot blowing gun and freely select the soot blowing gun to be opened.

2. The anti-blocking air preheater with purging function, intelligent control and soot blower installed in the middle according to claim 1, characterized in that: Install an ultrasonic generator on the high-temperature steam inlet pipeline of the air preheater soot blower, so that the steam soot blowing has a cleaning function.

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