Vertical shaft rotary pulse valve and combustion system

Abstract

After a simple rotor similar to a vertical axis wind driven generator blown by wind power is installed on an air supply or fuel pipeline, fuel or supplied air forms pulse flow, the pulse flow is amplified by chemical reaction in the combustion process to form stronger pulse combustion, and strong physical and chemical mixing enables the heating surface in the furnace to be clean, heat transfer to be enhanced, NOx to be reduced and the load of the furnace to be increased.

Description

Technical Field

[0001] This application relates to a rotary pulse valve that enables pulsed flow in the fields of combustion system air supply, pulverized coal conveying, fuel conveying, powder conveying, fluid conveying, drying, chemical reaction, heat exchanger, etc.; in particular, it relates to a vertical axis rotary pulse valve and combustion system. Background Technology

[0002] Since the use of pulse engines during World War II, pulsed combustion, or intermittent combustion, has demonstrated numerous advantages in the field of combustion. These include self-aspiration, high heat transfer coefficients, high volumetric heat load, and low pollutant emissions. This translates to smaller, more powerful, more efficient, and lower-cost combustion systems. Pulsed jets offer significant advantages over steady-flow combustion in combustion systems, powder drying, fire suppression, and heat exchangers. Furthermore, pulsed jets can reduce air consumption, air velocity, and energy consumption, while improving efficiency in powder conveying, heat transfer, chemical reactions, and heat exchangers.

[0003] Pulse combustion, also known as pulse width modulation, is used in existing industrial heating furnaces to control furnace temperature by adjusting the duty cycle of the combustion time. The cycle of existing pulse combustion is approximately 30 to 240 seconds, while the cycle of this application is approximately 0.01 to 1 second. These two technologies are related but also different.

[0004] Short-cycle acoustic pulse combustion remains theoretically immature and has been a niche combustion technology in industrial applications. High-speed pulse valve-controlled pulse combustion, on the other hand, offers greater controllability. Since its inception, simple and reliable pulse valves have been a focus for combustion engineers. While high-speed solenoid valves and valves are undoubtedly the most successful in internal combustion engines, their application in other industrial combustion fields is limited. This is largely due to their complexity, and the fact that industrial combustion valves are larger and more difficult to open and close quickly compared to internal combustion engine valves. A closer look reveals rotary pulse valves, such as the CN202111615256 rotary valve core pulse valve used in smart toilets, as well as pulse nozzles. I myself designed a pulse nozzle that uses a spring and the conversion of hydrostatic and dynamic pressure during flow to create a pulse flow, similar in principle to a rotating sprinkler valve on a lawn. There are also pulse showerheads for bathing. I have been purchasing, improving, and prototyping all of these products for the past seven or eight years.

[0005] CN00218992, a rotary airflow pulsating pulverized coal injection device, and CN00218994, a rotary pulsating airflow generator, are pulsed pulverized coal injection devices developed by Baosteel and are undoubtedly among the patents closest to the technical field of this application. In these devices, the pulverized coal airflow is not pulsated, but the outer layer of combustion air is pulsated. I have also tried this, but it requires a motor to drive it. When the flow channel is blocked, the rotor experiences high pressure, while when it is open, the force is low. Therefore, the bearing's working conditions are very harsh, and the motor and bearings are easily damaged, easily causing sudden shutdown and fire extinguishing. This is explained in more detail in the next patent. CN202110536994, a rotary valve for high-frequency pulsating air pressure modulation, has a similar principle to the aforementioned Baosteel approach. Both belong to a plug valve structure with an open hole on the rotor, suitable for small air volumes. The rotary pulse valves in the aforementioned three patents all require motor drive and frequently experience sudden shutdowns, which limits their industrial application. CN201821439407, a low-NOx pulsating gas combustion device with a rotary throttle valve, is one of the closest patents to this application. It uses a valve core similar to a butterfly valve to continuously rotate in the air duct or fuel passage to create a pulsating flow, thereby reducing NOx during gas combustion. Its disadvantages are threefold: first, the on / off ratio of the pulsating airflow cannot be adjusted; second, it still requires a motor; and third, it fundamentally does not eliminate the problem of the rotor experiencing the greatest force and torque when fully closed, which can easily damage the motor and bearings. However, this type of valve is indeed the closest to practical application.

[0006] I have personally tested and used most of the aforementioned pulse valves. When the vent is blocked, the air pressure forces the rotor towards the outlet, making rotation difficult. Manually turning the valve to open the vent allows it to rotate once more. However, when the rotor speed is low and the moment of inertia is insufficient to overcome the mechanical friction caused by the pressure, the rotor is firmly pressed at the outlet. This situation is very similar to a sluice gate being blocked by water pressure. The theory is difficult to understand, but it is easier to grasp if the experimenter experiences it firsthand. I have tested and improved this approach many times but ultimately abandoned it. The pulse valves with the published patents mentioned above are close to practical use, but they have not been widely adopted. The main reason is that the rotor experiences a sudden increase in pressure when the flow channel is blocked and a decrease in pressure when the flow channel is open. This periodic change in force requires a large frequency converter to drive a large motor to control the rotation speed. The motor and frequency converter are prone to damage due to the large difference in the switching phase angles caused by the force. Worse still, if the rotor has a dead point when the flow channel is blocked, the airflow cannot enter the combustion chamber, which is equivalent to extinguishing the fire in the combustion process and poses a huge risk of explosion.

[0007] Therefore, the applicant believes that the pulse valve should first and foremost be reliable. Even if a dead point exists, this dead point should be located where the air passage is open. Although this type of accident negates the advantages of pulse combustion, at least normal combustion air supply or fuel can pass through normally, preventing more serious fire extinguishing or explosion accidents. Moreover, the applicant believes that this rotary pulse valve combustion system must first be applied to combustion systems using solid fuels, such as fixed grate or chain grate furnaces, to gain experience before it can be promoted to the more dangerous chamber combustion furnaces.

[0008] Research progress on pulse combustion in the past 10 years.

[0009] Studies have shown that unsteady jets can induce sharp oscillations. Due to their high turbulence, abrupt jet changes can also generate strong impact effects, thinning the flow boundary layer and even forcing the thermal boundary layer to rebuild. Higher-frequency unsteady jets can effectively suppress boundary layer development, thus enhancing heat transfer. Eibeck et al. conducted impact heat transfer experiments using exhaust gas jets from pulsed combustion chambers, reportedly achieving a maximum heat transfer effect more than twice that of stable jets. Zhou Jingwei et al. found that at lower frequencies, the impact heat transfer effect of unsteady jets was not as good as that of stable jets, but its advantage in enhancing heat transfer gradually became apparent when the frequency exceeded a certain threshold. The heat transfer enhancement effect is also related to the variation of the jet signal; rectangular pulsed jets with step changes significantly enhance heat transfer compared to jets with sinusoidal or triangular variations. When the pulse frequency (5–50 Hz) and amplitude reach a certain relationship, the NOx content produced by combustion decreases sharply, and the heat exchange efficiency increases significantly. Research by Shen Zhongliang, Zhong Yingjie, and others indicates that the optimal pulse frequency should be between 1 and 30 Hz, and the larger the pulse pressure amplitude, the lower the NOx value. To achieve this pulsed combustion effect, Shen Zhongliang, Zhong Yingjie, and others experimented with high-speed pulse valves and subwoofer enclosures. The difficulty with high-speed pulse valves lies in their large size and limited lifespan, while the challenge with subwoofer enclosures is their small amplitude and short lifespan. Studies show that pulsed combustion can make combustion more complete, flue gas temperature more uniform, and increase the heat transfer coefficient on the flue gas side, thereby reducing the exhaust temperature of the heating furnace and fuel consumption, thus improving the efficiency of the heating furnace. However, due to the limited lifespan of solenoid valves (only a million cycles), this type of pulse combustion operates at a low frequency. Typically, the start-up time of a single burner is measured in minutes (0.01–0.1 Hz), limiting its application to furnaces without water-cooled walls, such as those used in steelmaking. Using it in boilers with water-cooled walls would result in flameout. Furthermore, the lifespan of the solenoid valve is insufficient for the high-frequency pulse combustion of a single burner.

[0010] This application aims to break through the key technologies of high-frequency pulse combustion, overcome the shortcomings of steady-state combustion technology such as low heat transfer coefficient, long heating time, high energy consumption, high pollutant emissions, and ash accumulation on the heated surface, and completely replace the current combustion status quo that is mainly based on steady-state combustion, and get rid of the defects of pulse mechanical valves such as short life and easy jamming. Summary of the Invention

[0011] The purpose of this application is to provide a simple and reliable rotary pulse valve and combustion system or other physicochemical reaction system for use in combustion systems, pulverized coal conveying, fuel conveying, powder conveying, fluid conveying, drying, chemical reaction, heat exchanger and other fields.

[0012] Technical solution.

[0013] Rotary pulse valve.

[0014] This application utilizes a vertical axis wind turbine rotor to achieve pulsed flow opening and closing by rotating within a flow channel. Its key feature is that the rotor axis of the vertical axis wind turbine rotor-type rotary valve core is perpendicular to the inlet and outlet air passages. The flow channel is opened and closed by the pressure difference of the fluid, forming a pulsed flow. In other words, even if the rotor is driven by a motor with frequency regulation, it can still rotate due to the pressure difference of the fluid when the motor is de-energized. The torque experienced by the rotor in the closed position is greater than that in the open position. The rotor has no mechanical dead points; its essence is the rotor of a vertical axis wind turbine, capable of self-rotation using wind power. The flow pulse characteristics and bearing stress of this application have been proven reliable through decades of testing with vertical axis wind turbines.

[0015] The role of rotary pulse valves in combustion systems.

[0016] Pulse valves are primarily recommended for use in furnaces burning solid fuels, such as fixed grate furnaces, chain grate furnaces, and the air supply ducts of waste incinerators; they can also be installed in flues. Pulse valves should be installed on the ducts closest to the furnace inlet to ensure a strong pulse within the furnace. It is recommended to install them in pairs on the furnace inlet duct. If two identical pulse valves are used, with similar duct lengths and shapes, and similar resistance, the paired valves will automatically operate in staggered phases, with one valve opening while the other closes.

[0017] In powder conveying systems, such as those for pulverized coal, pulse valves should be installed before the air-coal mixer, before the coal is carried in. Pulse conveying results in low flow velocity, low resistance, low energy consumption, and reduced clogging. For example, in a pulverized coal boiler, taking a storage-type system, the pulse valve is installed before the air-coal mixer, and after being carried in, the coal is fed into the furnace through pipes and burners. Pulse valves on the secondary air duct of a pulverized coal boiler should preferably be installed on the secondary air duct before it enters the furnace. The pulse valve serves two purposes: firstly, it prevents clogging in the dense phase; secondly, it provides pulsed combustion, ensuring complete combustion and reducing ash accumulation in the furnace. The characteristics of pulse combustion include intense mixing, stronger mass and heat transfer compared to steady flow, fewer high-temperature points, lower thermal NOx levels, and higher combustion efficiency. Ignition conditions on chain grates are superior to existing steady flow systems, potentially allowing the chain grate's combustion efficiency to reach 98%, similar to that of pulverized coal boilers and circulating fluidized bed boilers. After applying pulse combustion, boiler soot blowers are no longer needed. Generally, the flue gas temperature can be reduced by 20-30℃ before and after soot blowing. Typically, for every 17℃ increase in flue gas temperature, boiler efficiency decreases by 1%. Using pulse valves for fuel and air supply cleans the boiler's heating surfaces, enhances heat exchange due to turbulence, and results in a flue gas temperature even lower than after soot blowing. Therefore, pulse combustion is more suitable for industrial heating applications such as billet heating furnaces and ceramic sintering furnaces, not only improving combustion efficiency but also shortening heating time.

[0018] Furthermore, regardless of the furnace type, the pulse valve can be installed on the flue, and the pulse of the flue gas drives the pulse inside the furnace.

[0019] Theoretically, the frequency required for combustion, heat exchange, and mixing of pulse valves should fall within a certain range of 1-50Hz. However, the optimal fuel-efficient speed of an internal combustion engine varies depending on the engine and fuel used. Therefore, the true optimal combustion frequency differs for different fuels and furnace types. Current data in the literature cannot be universally applied as the optimal frequency for pulse valves. Future frequency designs should be quantitatively revised based on further engineering experience. For pulse valves with inverters and motors, fine-tuning within a certain range is permissible. Attached Figure Description

[0020] Appendix Figure 1 This is a schematic diagram of the structure of a vertical axis rotary pulse valve according to the present invention, in which the rotary valve core is located in the fully open position.

[0021] Appendix Figure 2 This is a schematic diagram of the structure of a vertical axis rotary pulse valve according to the present invention, in which the rotary valve core is located in the fully closed position.

[0022] Appendix Figure 3 This is a schematic diagram of the rotary valve core of a vertical axis rotary pulse valve according to the present invention. Detailed Implementation

[0023] The technical solution of the present invention will be further described below with reference to the accompanying drawings.

[0024] like Figure 1 and Figure 2 This is a case where a vertical axis rotary pulse valve is used in a damper. Figure 1 This is the rotor position when the valve is fully open. Figure 2 This shows the rotor position when the valve is fully closed. In the diagram, 1 is the valve body, 2 is the air outlet, 3 is the air inlet, and 4 is the rotary valve core. Air enters the valve body 1 through the air inlet 3, and under the action of pressure difference and dynamic pressure, it drives the rotary valve core 4 to rotate (it can also be driven by a motor). Air flows out intermittently from the air outlet 2, forming a pulse flow. The diagram above shows the clockwise rotation. Its characteristic is that the rotation axis is perpendicular to the air inlet and outlet, which is called a vertical axis wind turbine in wind turbines. The center of the air inlet 3 is offset towards the air outlet side. The rotary valve core 4 is fully open when it is in the position shown in the left diagram. If the rotary valve core 4 is fixed in this position, the flow is continuous. Therefore, this pulse valve can be made fully open by a fixing mechanism, which can easily deactivate the pulse function from the system, which is very important in the initial stage of ignition.

[0025] This application discloses a vertical axis wind turbine impeller-type pulse valve that overcomes the shortcomings of existing technologies. During valve closure, the rotating valve core experiences a greater torque than during valve opening, eliminating the possibility of mechanical dead spots blocking the air outlet and preventing air from entering the combustion chamber. Considering that low-pressure gases also have slight compressibility, the pressure before the valve increases when the valve is closed, pushing the rotating valve core to open and creating a larger amplitude pulse. When the valve is fully open, the dynamic pressure of the fluid creates torque on the rotating valve core, and the inertia of the rotating valve core rotor continues to rotate forward. The next blade of the rotating valve core then blocks the flow channel, entering the next cycle.

[0026] like Figure 3 The rotary valve core 4 shown consists of a shaft 41, reinforcing ribs 42, and blades 43. The disc-shaped reinforcing ribs 42 are connected to the blades 43 at both ends. This design reduces the possibility of air leakage between the blades and the valve housing and increases the pulse intensity. The blades 43 are typical drag-type wind turbine blades, generally with one convex side and one concave side. The convex side experiences higher drag when facing the wind, while the concave side experiences lower drag. The number of blades is generally 2-8, preferably 3. Of course, straight blades can also be used for easier manufacturing. Figure 1 Curved blades are acceptable, but straight blades should also be included within the scope of this application. Since vertical axis wind turbine blades come in lift and drag types and are diverse, it is impossible to list them all in this application. All pulse valves that utilize existing vertical axis wind turbine blades and impellers in a similar configuration should be considered as a type of this invention.

[0027] The preferred cross-sectional shape of the air inlet and outlet is rectangular, with the long side of the rectangle parallel to the axis of the rotary valve core.

[0028] Preferably, the axis of the air inlet is biased toward the side of the rotary valve core closer to the air outlet.

[0029] During the design process, such as Figure 1 As shown, for larger dampers, by fixing the outlet center to coincide with the rotation axis and moving the inlet position vertically left and right, the on / off ratio can be easily adjusted. By measuring the ratio of the arc when the rotary valve core is fully open and fully closed as shown in the diagram, the theoretical on / off ratio can be easily measured. This is equivalent to pulse width modulation as described in existing pulse combustion heaters.

[0030] Furthermore, a simple pulse valve with a rotary valve core 4 installed in a straight ventilation duct should also be considered as a type of this application.

[0031] Furthermore, a simple pulse valve with a rotary valve core 4 installed in an eccentrically shaped duct should also be considered as a type of this application.

[0032] Furthermore, a dual-channel pulse valve consisting of two rotors connected in parallel on a single shaft and having two outlets forming an open-closed configuration should also be considered a type of this application; even further, a multi-channel pulse valve consisting of two or more outlets should also be considered a type of this application.

[0033] Since vertical axis wind turbines are well-developed and have diverse impeller types, rotary pulse valves utilizing other types of existing vertical axis wind turbine impellers should also be considered as a type of this application.

Claims

1. A vertical axis rotary pulse valve and combustion system, characterized in that: The rotary valve core of the pulse valve adopts an impeller similar to that of a vertical axis wind turbine. The rotating shaft is perpendicular to the inlet and outlet air passages. The rotating impeller achieves self-rotation by relying on the pressure difference of the fluid before and after the valve.

2. The vertical axis rotary pulse valve and combustion system according to claim 1, characterized in that: The combustion system has at least one pulse valve in its air supply, fuel supply, and flue pipes.

3. The vertical axis rotary pulse valve and combustion system according to claim 1, characterized in that: The rotary valve core is driven by an electric motor, but when the motor loses power, the impeller can still rotate by relying on the pressure difference of the fluid.

4. The vertical axis rotary pulse valve and combustion system according to claim 1, characterized in that: The blades of the rotary valve core are convex on one side and concave on the other. The convex side has greater resistance when facing the wind, while the concave side has less resistance when facing the wind.

5. A vertical axis rotary pulse valve and combustion system according to claim 1, characterized in that: The rotary valve core has 3 blades.

6. The vertical axis rotary pulse valve and combustion system according to claim 1, characterized in that: The inlet and outlet of the pulse nozzle or pulse valve are rectangular, with the long side of the rectangle parallel to the rotary valve spindle.

7. The vertical axis rotary pulse valve and combustion system according to claim 1, characterized in that: The rotary valve core has disc-shaped reinforcing ribs at both ends.

8. The vertical axis rotary pulse valve and combustion system according to claim 1, characterized in that: The frequency of the pulse valve in the combustion system is 1~50Hz.

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