Ultrasonic atomizing nozzle for cooling radioactive waste incineration flue gas

Abstract

The invention relates to an ultrasonic atomizing nozzle for cooling radioactive waste incineration flue gas. The ultrasonic atomizing nozzle comprises an outer shell, a pre-tightening bolt, an inner shell, a piezoelectric ceramic piece, an atomizing body, a wire hole, a cooling water inlet and an air inlet. An annular piezoelectric ceramic piece is embedded in the lower portion of the inner shell, an atomizing body is arranged below the piezoelectric ceramic piece and comprises a base and an atomizing core, the atomizing core comprises an amplitude-change pole and a multi-stage atomizing structure, and the multi-stage atomizing structure comprises a water collecting tank, an atomizing disc and a water collecting atomizing disc. The base is provided with a non-penetrating type bolt hole, and the piezoelectric ceramic piece and the atomization body are fixed to the inner shell through a pre-tightening bolt. And the outer shell is provided with a plurality of cooling water inlets which are annularly and uniformly distributed along the side wall. According to the nozzle, cooling water is atomized according to the ultrasonic atomization principle, an atomization mode at the position of a nozzle spray hole is replaced with an internal atomization mode of the nozzle, arrangement of the spray hole is omitted, and the problems that the nozzle is prone to damage, and the atomization effect is prone to deterioration are fundamentally solved.

Description

Technical Field

[0001] This invention relates to the field of radioactive waste incineration flue gas cooling technology, specifically to an ultrasonic atomizing nozzle for cooling radioactive waste incineration flue gas. Background Technology

[0002] Combustible waste (such as cardboard boxes, plastic products, wood materials, protective equipment, and cotton fabrics) generated during the operation and decommissioning of nuclear facilities accounts for as much as 60%-80%. According to the principle of waste minimization, this waste needs to be reduced in volume before final disposal. At present, incineration technology is the main means of reducing the volume of radioactive waste and plays a key role in nuclear industry waste management.

[0003] After waste is incinerated, high-temperature flue gas is generated. To reduce the secondary formation of dioxins in the flue gas, it is necessary to rapidly cool the high-temperature flue gas to below 200 degrees Celsius. Furthermore, cooling the flue gas to below 200 degrees Celsius also meets the receiving requirements of downstream filtration equipment. Currently, the mainstream flue gas quenching method suitable for waste incineration is direct water cooling, mainly divided into spray quenching and scrubbing quenching. The spray quencher has a cylindrical rotating structure. The cooling principle is that atomized droplets directly contact the high-temperature gas, utilizing the latent heat of vaporization of the droplets to cool the gas. The atomization method involves compressed air and cooling water being sprayed through a dual-fluid atomizing nozzle. The cooling water is atomized into small droplets with a diameter of 45–110 micrometers under the action of compressed air. The structure and cooling principle of a spray-type quench cooler are the same as those of a mist-type cooler, but instead of using dual-flow atomizing nozzles to atomize the cooling water, it uses lower pressure to spray cooling water into the cooling chamber through spray heads. The droplet diameter is on the order of millimeters, which is larger than that of atomized droplets, resulting in lower cooling efficiency and a higher likelihood of generating secondary wastewater. Therefore, the current waste incineration field primarily uses direct water cooling methods, such as spray-type quench cooling, to cool flue gas.

[0004] Currently, in the field of radioactive combustible waste treatment, flue gas quenching employs a spray-type quenching method, with the atomizing nozzle being a compressed air-cooling water dual-flow atomizing nozzle. This type of nozzle has revealed significant drawbacks during long-term use. Specifically, the atomization effect and liquid mist spray angle of this type of nozzle mainly depend on the nozzle orifice, thus requiring a small orifice size and high precision. However, the flue gas generated from the incineration of radioactive combustible waste is at a high temperature and contains fly ash and acidic gases. Under the combined effects of salt crystallization and corrosion products, the nozzle orifice is highly susceptible to damage, such as partial blockage or deformation. Due to the high precision requirements of the nozzle, even slight changes can severely affect the spray angle and atomization effect, significantly reducing the flue gas cooling effect and potentially generating secondary wastewater due to droplet impact on the walls. Therefore, during long-term system operation, the quencher nozzles require frequent maintenance or replacement, increasing both operating costs and the radiation risk to maintenance personnel. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides an ultrasonic atomizing nozzle for cooling flue gas from radioactive waste incineration, aiming to partially solve the aforementioned technical problems.

[0006] To achieve the above objectives, the present invention provides the following technical solution: An ultrasonic atomizing nozzle for cooling flue gas from radioactive waste incineration is proposed, comprising an outer shell, pre-tightening bolts, an inner shell, a piezoelectric ceramic plate, an atomizing body, a wire hole, a cooling water inlet, and a compressed air inlet; wherein, the inner shell and the outer shell are an integrated structure, with a bolt hole in the middle of the inner shell, and a ring-shaped piezoelectric ceramic plate embedded below the inner shell. The wire of the piezoelectric ceramic plate is led out from the wire hole at the connection between the inner shell and the outer shell. Below the piezoelectric ceramic plate is the atomizing body, which includes a base and an atomizing core. The atomizing core includes an amplitude transformer and a multi-stage atomizing structure. The multi-stage atomizing structure consists of a water collection tank, an atomizing disc, a water collection atomizing disc, a water collection guide hole, a water outlet, a water return hole, and a partition. The base is provided with non-through bolt holes. The piezoelectric ceramic plate and the atomizing body are fixed to the inner shell by pre-tightening bolts. The outer shell is provided with multiple evenly distributed cooling water inlets, the ends of which are located above the water collection tank.

[0007] As a preferred technical solution, the preload of the preload bolt is 25-40 MPa.

[0008] As a preferred technical solution, the base is cylindrical, and the atomizing core is an amplitude transformer with a multi-stage atomization structure. Each stage of the multi-stage atomization structure consists of an atomizing disc, a water-collecting atomizing disc, a water outlet, and a water return hole. The atomizing disc is a rotary thin sheet structure with a 10° downward tilt angle. The water outlet is located above its base, and the water-collecting atomizing disc is located below it. The water-collecting atomizing disc is also a rotary thin sheet structure with a 10° upward tilt angle. The water return hole is located at its base. The atomizing disc and the water-collecting atomizing disc do not contact each other. The base is connected to the atomizing core at its base, and the base and amplitude transformer are integrally formed. The multi-stage atomization structure is welded to the amplitude transformer.

[0009] As a preferred technical solution, multiple cooling water inlets are evenly distributed in a ring along the side wall of the outer casing.

[0010] As a preferred technical solution, the height of the cooling water inlet is 2mm above the edge of the water collection tank.

[0011] As a preferred technical solution, the air inlet is located above the nozzle, and the cooling water mist outlet is located below the nozzle.

[0012] As a preferred technical solution, the outer shell is designed as a gradually expanding rotating body.

[0013] As a preferred technical solution, the outer casing is provided with a mounting flange for mounting and fixing the nozzle.

[0014] As a preferred technical solution, the outer shell, inner shell, pre-tightening bolts, and atomizing body are made of corrosion-resistant stainless steel.

[0015] As a preferred technical solution, the piezoelectric ceramic sheet is made of lead zirconate titanate material.

[0016] Compared with existing technologies, the technical solution of this application has the following beneficial effects: The ultrasonic atomizing nozzle for cooling flue gas from radioactive waste incineration proposed in this invention is a key device for rapid cooling of flue gas from radioactive waste incineration. This method uses ultrasonic atomization to atomize cooling water, replacing the atomization at the nozzle orifice with an internal atomization method, thus eliminating the need for orifices and fundamentally avoiding the problems of easy nozzle damage and deterioration of atomization effect, significantly reducing the nozzle failure rate. Furthermore, the ultrasonic atomized droplet size is approximately 3-5 micrometers, less than one-tenth the size of the droplets from the original dual-flow nozzle, theoretically increasing the evaporation rate by more than 100 times, greatly improving cooling efficiency. Attached Figure Description

[0017] Figure 1 This is a front view of a cross-sectional view of an ultrasonic atomizing nozzle for cooling flue gas from radioactive waste incineration, as proposed in this invention. Figure 2 This is a left-hand cross-sectional view of an ultrasonic atomizing nozzle for cooling flue gas from radioactive waste incineration, as proposed in this invention. Figure 3 This is a front view of an ultrasonic atomizing nozzle atomizer for cooling flue gas from radioactive waste incineration, as proposed in this invention. Figure 4 This is a front view of a cross-sectional view of a single-stage atomizing unit of an ultrasonic atomizing nozzle for cooling flue gas from radioactive waste incineration, as proposed in this invention.

[0018] Explanation of reference numerals in the attached drawings: 1. Outer shell; 2. Pre-tightening bolt; 3. Inner shell; 4. Piezoelectric ceramic plate; 5-1. Atomizer base; 5-2. Atomizing rod; 5-4. Atomizing disc; 5-5. Water collecting atomizing disc; 5-6. Water collecting guide hole; 5-7. Water outlet; 5-8. Water return hole; 5-9. Partition plate; 6. Wire hole; 7. Cooling water inlet; 8. Compressed air inlet. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] Please see Figure 1-4The main function of this nozzle device is as follows: a novel ultrasonic atomizing nozzle for rapid cooling of flue gas from radioactive waste incineration. Its working principle is that the piezoelectric ceramic sheet 4 is connected to a high-frequency alternating current wire. Under the action of the alternating current, the piezoelectric ceramic sheet 4 generates high-frequency vibration (not less than 2 × 10⁻⁶ Hz). 4 (Hz), the piezoelectric ceramic plate 4 drives the atomizing body 5 connected to it to vibrate at the same frequency. The cooling water entering the nozzle through the cooling water inlet 7 falls into the water collection tank 5-3 of the atomizing body under the combined action of pressure and gravity. After the water level in the water collection tank 5-3 reaches the height of the water collection guide hole 5-6, the cooling water flows from the water collection guide hole 5-6 into the inner cavity of the amplitude transformer 5-2 and flows out from the water outlet 5-7. When it flows over the upper surface of the atomizing disk 5-4, it is atomized by the high-frequency vibration of the atomizing disk 5-4. The atomized cooling water flows downwards along the surface of the atomizing disk 5-4, falls onto the inner surface of the water collecting atomizing disk 5-5, and continues to atomize under the high-frequency vibration of the water collecting atomizing disk 5-5. The portion that has not yet formed an atomization flows into the cavity of the amplitude transformer 5-2 from the return water hole 5-8 at the root of the water collecting atomizing disk 5-5, and flows out from the water outlet below the cavity, continuing the same atomization process in the next atomization unit. After multiple stages of atomization, the cooling water is completely atomized, forming micron-sized droplets. At the same time, air is introduced from the air inlet 8 above the nozzle. When the air flows through the atomization wall area, it impacts the atomized droplets. The atomized droplets are carried by the compressed air, forming a liquid mist flow inside the nozzle. Under the action of the gradually expanding structure of the outer shell, the liquid mist flow gradually diffuses and is ejected at high speed with the nozzle outlet at the lower nozzle outlet. The innovation of this atomizing nozzle lies in its use of ultrasonic atomization and multi-stage atomization structure. Cooling water is fully atomized within the nozzle itself, and the atomization effect is completely independent of the nozzle outlet. Therefore, the nozzle outlet is changed from an orifice to an open outlet, essentially eliminating precision requirements. This innovation avoids the problem of atomization deterioration caused by nozzle orifice damage. Furthermore, the atomized droplets generated by ultrasonic vibration have a particle size of less than 10 micrometers, while traditional dual-flow atomization produces droplets on the order of tens of micrometers. Therefore, the liquid mist generated by the ultrasonic atomization principle has a higher cooling efficiency.

[0021] Example For details, see Figure 1-4As shown, this embodiment proposes an ultrasonic atomizing nozzle for cooling flue gas from radioactive waste incineration, comprising an outer shell 1, a pre-tightening bolt 2, an inner shell 3, a piezoelectric ceramic plate 4, an atomizing body 5, a wire hole 6, a cooling water inlet 7, and an air inlet 8. The inner shell 3 and the outer shell 1 are an integral structure. A bolt hole is located in the center of the inner shell 3. A ring-shaped piezoelectric ceramic plate 4 is embedded below the inner shell 3. The wire of the piezoelectric ceramic plate 4 is led out through the wire hole 6 at the connection between the inner shell 3 and the outer shell 1. Below the piezoelectric ceramic plate 4 is the atomizing body 5, which includes a base 5-1 and an atomizing core. It includes an amplitude transformer 5-2 and a multi-stage atomizing structure. The amplitude transformer 5-2 is a multi-section cavity structure, with baffles 5-9 separating the cavities. The wall surface is provided with multiple water collection guide holes 5-6, water outlet holes 5-7, and water return holes 5-8 evenly distributed in a ring along the side wall. The multi-stage atomizing structure includes a water collection tank 5-3, an atomizing disc 5-4, and a water collection atomizing disc 5-5. The base 5-1 is provided with non-through bolt holes. The piezoelectric ceramic sheet 4 and the atomizing body 5 are fixed to the inner shell 3 by pre-tightening bolts. The outer shell 1 is provided with multiple cooling water inlets 7 evenly distributed in a ring along the side wall. The end of the cooling water inlet 7 is located above the water collection tank 5-3.

[0022] Preferably, the preload of the preload bolt 2 is 25-40 MPa. Under the action of alternating current, the piezoelectric ceramic sheet 4 vibrates up and down. Since the atomizing body 5 is preloaded and connected to the piezoelectric ceramic sheet 4, the atomizing body 5 is also driven by the piezoelectric ceramic sheet 4 to vibrate at the same frequency, with a vibration amplitude of about 2-5 micrometers.

[0023] Preferably, the base 5-1 is cylindrical, and the atomizing core is an amplitude transformer 5-2 with a multi-stage atomizing structure. In the multi-stage atomizing structure, each atomizing unit consists of an atomizing disc 5-4, a water outlet 5-7, a water return hole 5-8, and a water collecting atomizing disc 5-5. The atomizing disc 5-4 is a rotary thin sheet structure with a downward tilt angle of 10°. The water outlet 5-7 is located above its base, and the water collecting atomizing disc 5-5 is located below it. The water collecting atomizing disc 5-5 is also a rotary thin sheet structure with a upward tilt angle of 10°. The water return hole 5-8 is located at its base. The atomizing disc 5-4 and the water collecting atomizing disc 5-5 do not contact each other. The base 5-1 is connected to the atomizing core at its base. The base 5-1 and the amplitude transformer 5-2 are integrally formed, and the multi-stage atomizing structure is welded to the amplitude transformer 5-2.

[0024] Preferably, multiple water collection and diversion holes 5-6, water outlet holes 5-7, and water return holes 5-8 are evenly distributed in a ring along the side wall of the amplitude transformer 5-2.

[0025] Preferably, the height of the cooling water inlet 7 is 2mm above the edge of the water collection tank 5-3.

[0026] Preferably, the height of the cooling water inlet 7 is 2mm above the edge of the water collection tank 5-3. The cooling water entering through the cooling water inlet 7, under inertia, falls into the atomizer water collection tank 5-3. When the water level reaches the height of the water collection guide hole 5-6, the cooling water flows from the water collection guide hole 5-6 into the inner cavity of the amplitude transformer 5-2, and flows out from the lower water outlet 5-7, flowing onto the upper surface of the atomizing plate 5-4. Because the atomizing body 5 vibrates at the same frequency (vibration frequency not less than 2×10⁻⁶) driven by the piezoelectric ceramic sheet... 4 (Hz, different vibration frequencies can be set according to different atomization effect requirements). Under the Faraday wave effect, the water on the upper surface of the atomizing disk 5-4 will form an atomized state. Some of the un-atomized water flows into the water collecting atomizing disk 5-5 along the surface of the atomizing disk 5-4 and is further atomized by the water collecting atomizing disk 5-5. The still un-atomized water flows into the inner cavity of the amplitude transformer 5-2 from the return water hole 5-8 at the root of the water collecting atomizing disk 5-5, and flows out from the water outlet hole 5-7 below the inner cavity. The above atomization process is repeated in the next stage atomization unit. The atomized droplet particle size generated by ultrasonic atomization is much better than that of dual-flow atomization. This particle size is related to the vibration frequency and vibration amplitude of the atomizing body 5, the viscosity of the water, and the surface tension. Under reasonable parameter settings, the particle size can reach the range of 3 to 5 micrometers.

[0027] Preferably, the air inlet 8 is located above the nozzle, and the cooling water mist outlet is located below the nozzle.

[0028] Preferably, the outer shell 1 is configured as a gradually expanding rotating body.

[0029] Preferably, the outer casing 1 is provided with a mounting flange for mounting and securing the nozzle. It can be bolted to the top of the quencher or other locations.

[0030] Preferably, the outer shell 1, inner shell 3, pre-tightening bolt 2, and atomizing body 5 are made of corrosion-resistant stainless steel.

[0031] Preferably, the piezoelectric ceramic sheet 4 is made of lead zirconate titanate material.

[0032] During operation, a high-frequency alternating current is introduced into the nozzle through the wire hole 6. Under the inverse piezoelectric effect, the piezoelectric ceramic plate 4 vibrates at the same frequency as the alternating current, which in turn drives the atomizing body 5 below to vibrate at the same frequency. The cooling water entering the atomizing core forms micron-sized atomized droplets under the vibration of the atomizing disk 5-4 and the water collecting atomizing disk 5-5. The air introduced above the nozzle enters the nozzle from the air inlet 8, which impacts and carries the atomized droplets, causing them to flow downstream and blow them out of the nozzle, providing cooling water mist into the quencher cavity to achieve the effect of cooling the flue gas.

[0033] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. An ultrasonic atomizing nozzle for cooling flue gas from radioactive waste incineration, characterized in that, The system includes an outer shell (1), pre-tightening bolts (2), an inner shell (3), a piezoelectric ceramic plate (4), an atomizer (5), a wire hole (6), a cooling water inlet (7), and an air inlet (8). The inner shell (3) and the outer shell (1) are an integral structure. A bolt hole is located in the middle of the inner shell (3). A ring-shaped piezoelectric ceramic plate (4) is embedded below the inner shell (3). The wire of the piezoelectric ceramic plate (4) is led out through the wire hole (6) at the connection between the inner shell (3) and the outer shell (1). Below the piezoelectric ceramic plate (4) is the atomizer (5). The atomizer (5) includes a base (5-1) and an atomizer core. The atomizer core package... The system includes an amplitude transformer (5-2) and a multi-stage atomizing structure. The amplitude transformer (5-2) is a multi-section cavity structure, with baffles (5-9) separating the cavities. The wall surface is provided with multiple water collection guide holes (5-6), water outlet holes (5-7), and water return holes (5-8) evenly distributed in a ring along the side wall. The multi-stage atomizing structure includes a water collection tank (5-3), an atomizing disc (5-4), and a water collection atomizing disc (5-5). The base (5-1) is provided with non-through bolt holes. The piezoelectric ceramic sheet (4) and the atomizing body (5) are fixed to the inner shell (3) by pre-tightening bolts. The outer shell (1) is provided with multiple cooling water inlets (7) evenly distributed in a ring along the side wall. The end of the cooling water inlet (7) is located above the water collection tank (5-3).

2. The ultrasonic atomizing nozzle for cooling flue gas from radioactive waste incineration according to claim 1, characterized in that, The preload of the preload bolt (2) is 25-40 MPa.

3. The ultrasonic atomizing nozzle for cooling flue gas from radioactive waste incineration according to claim 1, characterized in that, The base (5-1) is cylindrical. The atomizing core is an amplitude transformer (5-2) with a multi-stage atomizing structure. The amplitude transformer (5-2) is a multi-section cavity structure, with each section welded together. The cavities are separated by baffles (5-9). The wall surface is provided with multiple water collection guide holes (5-6), water outlet holes (5-7), and water return holes (5-8) evenly distributed in a ring along the side wall. In the multi-stage atomizing structure, a single atomizing unit is divided into an atomizing disc (5-4), a water collection atomizing disc (5-5), a water outlet hole (5-7), and a water return hole (5-8). The water collection tank (5-3) is a rotary thin sheet structure with an inclination angle of 45° upward from the horizontal. The atomizing disc (5-4) has multiple water collection and guide holes (5-6) evenly distributed above it. The atomizing disc (5-4) is a rotary thin sheet structure with a downward tilt angle of 10°. The water outlet (5-7) is located above its root, and the water collection atomizing disc (5-5) is located below it. The water collection atomizing disc (5-5) is a rotary thin sheet structure with a downward tilt angle of 10°. The water return hole (5-8) is located at its root. There is a gap between the atomizing disc (5-4) and the water collection atomizing disc (5-5). The root of the atomizing core is connected to the base. The base and the atomizing core amplitude rod are integrally formed. The multi-stage atomizing structure is welded to the amplitude rod.

4. An ultrasonic atomizing nozzle for cooling flue gas from radioactive waste incineration according to claim 1, characterized in that, The multiple cooling water inlets (7) are evenly distributed in a ring along the side wall of the outer shell (1).

5. An ultrasonic atomizing nozzle for cooling flue gas from radioactive waste incineration according to claim 4, characterized in that, The height of the cooling water inlet (7) is located 2 mm above the edge of the water collection tank (5-3) of the atomizer.

6. An ultrasonic atomizing nozzle for cooling flue gas from radioactive waste incineration according to claim 1, characterized in that, The air inlet (8) is located above the nozzle, and the cooling water mist outlet is located below the nozzle.

7. An ultrasonic atomizing nozzle for cooling flue gas from radioactive waste incineration according to claim 1, characterized in that, The outer shell (1) is configured as a gradually expanding rotating body.

8. An ultrasonic atomizing nozzle for cooling flue gas from radioactive waste incineration according to claim 7, characterized in that, The outer casing (1) is provided with a mounting flange for mounting and fixing the nozzle.

9. An ultrasonic atomizing nozzle for cooling flue gas from radioactive waste incineration according to any one of claims 1-8, characterized in that, The outer shell (1), the inner shell (3), the pre-tightening bolt (2), and the atomizing body (5) are made of corrosion-resistant stainless steel.

10. An ultrasonic atomizing nozzle for cooling flue gas from radioactive waste incineration according to any one of claims 1-8, characterized in that, The piezoelectric ceramic sheet (4) is made of lead zirconate titanate.

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