CN115247975A - Plasma treatment low-radioactivity waste flue gas cooling device - Google Patents

Abstract

The invention discloses a flue gas cooling device for plasma treatment of low radioactive waste, relates to the technical field of radioactive waste treatment, and solves the problems of poor cooling effect, low device integration and high investment cost of conventional flue gas cooling devices. It includes a cylinder, which is divided into an upper cylinder, a lower cylinder and an ash hopper from top to bottom. The upper cylinder is provided with a water-cooling cooling device, and the lower cylinder is provided with a tube heat exchange device. The bottom of the ash hopper passes through The valve is controlled to open and close; the cylinder is connected with a flue gas intake pipe located above the water-cooled cooling device and a flue gas exhaust pipe located below the tube heat exchanger. water wall. Adjusting the heat exchange area according to the amount of flue gas can reduce the flue gas from 1150 ℃ to about 200 ℃, which achieves the effect of less floor space, low investment cost, automatic cleaning of radioactive fly ash, simple and convenient operation, and high degree of device integration.

Description

A flue gas cooling device for plasma treatment of low-level radioactive waste

technical field

The invention relates to the technical field of radioactive waste treatment, in particular to a flue gas cooling device for plasma treatment of low-level radioactive waste.

Background technique

At present, domestic nuclear power plants will generate a large amount of low-level radioactive waste during operation and maintenance. Low-level waste mainly includes plastic cloth, plastic bags, absorbent paper, waste wood, rags, waste metal parts, and building materials. Most of the low-level waste is combustible waste; a small part is non-combustible waste. Plasma gasification and melting technology has the characteristics of high temperature, high energy density and strong compatibility. It can dispose of all low-level radioactive waste and completely destroy dioxins. Heavy metals and nuclides are solidified in molten glass, and plasma gasification and melting The technology has the advantages of more thorough harmlessness, a high degree of volume reduction, and a small footprint. The ash produced by traditional incineration still needs to be solidified and stabilized (compatibilization), while the glass body produced by plasma melting treatment has stable physical and chemical properties and can be directly landfilled.

However, the flue gas generated during the plasma treatment of low-level radioactive waste has a high temperature (the temperature of the flue gas at the outlet of the second combustion chamber is generally around 1150°C), and the flue gas contains a large amount of radionuclides and particulate matter. In the hazardous waste industry, the high-temperature flue gas is often cooled first and then the pollutants in the flue gas are treated. However, conventional flue gas cooling devices often have poor cooling effects, low device integration, high investment costs, difficulty in cleaning fly ash, and flue gas Issues such as volume increase. Therefore, there is an urgent need for a new flue gas cooling device, which can effectively reduce the flue gas temperature, and has the characteristics of small footprint, low investment cost, simple and convenient cleaning of fly ash, and high degree of device integration.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a flue gas cooling device for plasma treatment of low-level radioactive waste, and propose a flue gas cooling method that combines "multi-circle membrane water-cooled cooling structure + tube heat exchanger". Adjusting the heat exchange area can reduce the flue gas from 1150°C to about 200°C, which has a good cooling effect; and has the advantages of small footprint, low investment cost, automatic cleaning of radioactive fly ash, simple and convenient operation, and high degree of device integration. Features, the temperature of the exhausted flue gas is low, which brings convenience for the removal of pollutants in the subsequent flue gas.

The above-mentioned technical purpose of the present invention is achieved through the following technical solutions:

A flue gas cooling device for plasma treatment of low-level radioactive waste, including a cylinder body, which is divided into an upper cylinder body, a lower cylinder body, and an ash hopper from top to bottom. There is a tube heat exchange device in the cylinder, and the bottom of the ash hopper is opened and closed by valve control;

The cylinder body is connected with a flue gas inlet pipe located above the water cooling device and a flue gas exhaust pipe located below the tube heat exchanger. The water cooling device includes a plurality of cylindrical membrane water walls nested inside and outside in sequence.

Furthermore, the water-cooling device reduces the temperature of the flue gas to 500-600°C, and then the tube-and-tube heat exchanger reduces the temperature of the flue gas to no higher than 200°C within <1s.

Furthermore, the membrane water wall includes several vertical cooling water pipes and fins welded to each other.

Furthermore, the membrane water wall includes spiral cooling water coils and fins welded to each other.

Furthermore, dust cleaning devices are provided above the upper cylinder and the lower cylinder.

Furthermore, the dust removal device includes a shock wave dust removal device.

Furthermore, both ends of the water-cooling device and the tube-and-tube heat exchange device are respectively connected to the cooling water inlet pipe and the cooling water outlet pipe.

Furthermore, the ash hopper is conical with a large top and a small bottom, and the bottom is opened and closed by electric double gate valves.

Furthermore, the ash hopper is connected to the ash bucket through a flange connection.

Furthermore, an air hammer or a mechanical rapping device is also provided at the ash hopper.

In summary, the present invention has the following beneficial effects:

(1) The flue gas cooling method combined with "membrane water cooling structure + tube heat exchanger" is adopted, and the cooling effect of the whole device is obvious; the membrane water cooling structure can reduce the flue gas temperature from about 1150 ℃ to 500-600 ℃, while the tube-and-tube heat exchange structure can not only reduce the temperature of the flue gas from 500 ℃ to 200 ℃, but also control the time of the 500 ℃ - 200 ℃ cooling period < 1s, so as to avoid the re-synthesis of dioxin during the cooling process, thus To achieve the purpose of controlling the concentration of pollutants in the outlet flue gas;

(2) The membrane water-cooling structure is composed of multiple membrane water-cooling walls superimposed and nested inside and outside (a single membrane water-cooling wall can be composed of two ways: "vertical cooling water pipes welded with fins" or "spiral cooling water Coil and fins are welded together"); the membrane structure can effectively reduce the deposition of fly ash, and there is an appropriate gap between the membrane walls to facilitate ash cleaning; the upper end of the tube heat exchange device is equipped with an online cleaning system. The ash device is convenient for cleaning the fly ash adhering to the pipe wall on a regular basis; an air hammer or a mechanical vibrating device is also installed at the conical ash hopper to regularly beat the area to prevent the fly ash from falling on the electric double ram. There is a phenomenon that the bridge is hardened above the valve and cannot fall, so as to realize the effect of simple and convenient dust removal of the device;

(3) The entire set of inverted cone cylinder device is made of heat-resistant and corrosion-resistant metal materials; it not only has better heat resistance, but also can withstand the corrosion of acid gases such as SO ₂ and HCl in the flue gas, ensuring that the flue gas is treated The device will not be cracked, damaged, corroded and deformed during the process;

(4) The diameter and height of the inverted cone cylinder are determined by the actual heat exchange and cooling effect. The design of the flue gas flow rate, cylinder diameter, and cylinder height should be properly selected to improve the cooling effect of the flue gas and reduce the pressure loss.

Description of drawings

Fig. 1 is the overall structure schematic diagram of embodiment one among the present invention;

Fig. 2 is the top view of membrane type water cooling structure in Fig. 1;

Fig. 3 is a structural side view of the shell and tube heat exchanger part;

Fig. 4 is a schematic diagram of the overall structure of Embodiment 2 of the present invention;

Fig. 5 is a top view of the membrane water cooling structure in Fig. 4 .

In the figure, 1. Cylinder body; 2. Water cooling device; 3. Flue gas inlet pipe; 4. Flue gas exhaust pipe; 5. Cooling water inlet pipe; 6. Cooling water outlet pipe; 8. Shock wave ash cleaning device ; 9. Mechanical rapping device; 10. Tube heat exchange device; 11. Electric double gate valve; 12. Connecting ash bucket.

Detailed ways

The specific implementation manners of the present invention will be further described below in conjunction with the accompanying drawings, and this embodiment does not constitute a limitation to the present invention.

Example 1:

A flue gas cooling device for plasma treatment of low-level radioactive waste, as shown in Figure 1, includes a cylinder 1, which is divided into an upper cylinder 1, a lower cylinder 1 and a conical ash hopper from top to bottom, The upper cylinder body 1 is equipped with a water cooling device 2, and the lower cylinder body 1 is equipped with a tube heat exchange device 10, and the bottom of the ash hopper is opened and closed by valve control;

The cylinder 1 is connected with a flue gas inlet pipe 3 located above the water cooling device 2 (on the wall of the upper cylinder 1), and a flue gas exhaust pipe 4 located below the tube heat exchanger (on the wall of the lower cylinder 1). ), the flue gas inlet pipe 3 and the flue gas exhaust pipe 4 are respectively located on opposite sides of the cylinder body 1, and are connected to the upstream and downstream equipment through flanges, the cylinder body 1, the flue gas inlet pipe 3 and the flue gas exhaust pipe 4 They are all made of the same high temperature and corrosion resistant metal material and welded together.

As shown in Figures 1 and 2, the water-cooling cooling device 2 includes a plurality of cylindrical membrane-type water-cooled walls nested inside and outside in sequence (the distance between adjacent water-cooled walls is equal, which is convenient for the design of automatic cleaning robots to clean in it in the future), The membrane water wall includes several vertical cooling water pipes and fins welded to each other. The fins are arc-shaped, vertically arranged, and welded between adjacent cooling water pipes;

Both ends of the water cooling device 2 and the tube heat exchange device 10 are respectively connected to the cooling water inlet pipe 5 and the cooling water outlet pipe 6; in this embodiment, the water cooling device 2 also includes a plurality of concentric The circular water distribution pipe, the cooling water inlet pipe 5 feeds water into the top part of the water pipe, and the top part of the water pipe feeds water into each cooling water pipe in the membrane water cooling wall with the same diameter; similarly, corresponding to each cooling water pipe in the membrane water cooling wall Through the water distribution pipe at the bottom, it is collected to the cooling water outlet pipe 6 for drainage, and the flow rate is fast and the cooling effect is good.

As shown in Figure 3, the cooling water pipes of the tube-and-tube heat exchange device 10 are made of high-temperature-resistant and corrosion-resistant metal materials; dust removal devices are provided above the upper cylinder body 1 and the lower cylinder body 1, and in this embodiment, the dust removal The device includes a shock wave cleaning device 8, and the outer periphery of the upper cylinder 1 can also be provided with a number of openings and closing ports located above the water cooling device 2. The openings and closing ports are closed during work, and are opened and passed into the cleaning device (such as a blowing pipe) when cleaning the dust. , spray pipe or knocking device, etc.) or put into the cleaning robot, etc.

As shown in Figure 1, the ash bucket is conical with a large top and a small bottom, and the bottom is connected to the ash bucket 12 through a flange, and the electric double gate valve 11 is connected between the two flanges to control the opening and closing;

A material level transmitter is set on the wall of the ash hopper and is linked with the opening and closing of the electric double gate valve 11. When a certain amount of fly ash is deposited in the ash hopper and the material level reaches a certain height, the electric double gate valve 11 automatically Open, otherwise when the material level of the ash hopper drops below the detection value, the electric double gate valve 11 is automatically closed.

As shown in Figure 1, an air hammer or a mechanical rapping device 9 is also connected to the outside of the ash hopper. The device should be tapped regularly to prevent the fly ash from being hardened and bridging above the gate valve and unable to fall.

work process:

When the flue gas cooling device is in operation, the high-temperature flue gas at about 1150°C (generally not exceeding 1200°C) will enter the cylinder body 1 horizontally through the intake pipe on the wall of the upper cylinder body 1, and when the downwardly moving flue gas passes through Membrane water-cooling cooling device 2, through the convection of cold and hot fluid on the wall, heat exchange between high-temperature flue gas and cooling water is realized;

The temperature of the flue gas in this heat exchange section is reduced from 1150°C to about 500°C-600°C through the cooling liquid speed and the length of the membrane water cooling device 2;

When the flue gas moves to the lower cylinder 1, the flue gas will contact the tube heat exchanger, and the flue gas will exchange heat with the cooling water of the heat exchanger again. The heat exchange structure of the tubes can not only reduce the temperature of the flue gas from 500 600°C is lowered to 200°C, and the time of the 500°C-200°C cooling section is controlled <1s to avoid re-synthesis of dioxins during the cooling process, so as to achieve the purpose of controlling the concentration of pollutants in the outlet flue gas. After a certain time, the online ash cleaning device will be activated to clean the fly ash adhering to the pipe wall;

Finally, the cooled flue gas will be discharged from the exhaust pipe on the wall of the lower cylinder 1, and the fly ash falling to the bottom of the cylinder 1 will accumulate above the electric double slide valve along the conical ash hopper. When the fly ash is deposited and the material level reaches a certain height, the electric double gate valve 11 is automatically opened, and when the material level drops, the electric double gate valve 11 is automatically closed, and the fly ash will eventually all fall into the ash receiving bucket 12 to complete the process. The collection of fly ash by the whole device;

After the high-temperature flue gas is treated by the flue gas cooling method combining "membrane water cooling cooling structure + tube heat exchanger", the final flue gas is discharged at a relatively low temperature, and the device has completed a significant cooling of the high-temperature flue gas At the same time, the device cleans and collects the fly ash stuck on the pipe wall in an efficient and simple way, and has the advantages of small footprint, low investment cost, automatic cleaning of radioactive fly ash, simple and convenient operation, and device integration The characteristics of high degree of purification and the low temperature of the exhausted flue gas bring convenience to the removal of pollutants in the subsequent flue gas.

Embodiment 2:

This embodiment is roughly the same in structure as Embodiment 1, the difference is:

As shown in Figure 4 and Figure 5, the membrane water wall includes spiral cooling water coils and fins that are welded to each other. The cooling water coil can be welded from the end to the end of multiple pipe fittings. Between the upper and lower pipe fittings, a water-cooled wall is formed; the cooling water inlet pipe 5 is located on one side of the cylinder body 1, and communicates with the water inlets on the top of the spiral cooling water coils with different diameters, and the cooling water outlet pipe 6 is located on the other side of the cylinder body 1. Connected to the water outlets at the bottom of the spiral cooling water coils with different diameters. Its structure and connection method are simpler, and the amount of welding on site is small.

The above are only preferred embodiments of the present invention, and are not intended to limit the present invention. Those skilled in the art can make various modifications or equivalent replacements to the present invention within the essence and protection scope of the present invention. Or an equivalent replacement should also be deemed to fall within the protection scope of the technical solution of the present invention.

Claims (10)

1. The utility model provides a plasma treatment low radioactive waste flue gas cooling device which characterized in that: the cooling device comprises a barrel, wherein the barrel is sequentially divided into an upper barrel, a lower barrel and a dust hopper from top to bottom, a water-cooling device is arranged in the upper barrel, a tube array heat exchange device is arranged in the lower barrel, and the bottom of the dust hopper is controlled to be opened and closed through a valve;

the tube body is connected with a flue gas inlet pipe positioned above the water-cooling device and a flue gas exhaust pipe positioned below the tube heat exchanger, and the water-cooling device comprises a plurality of cylindrical membrane type water-cooling walls which are nested inside and outside in sequence.

2. The plasma processing low radioactive waste flue gas cooling apparatus of claim 1, wherein: the water-cooling device reduces the temperature of the flue gas to 500-600 ℃, and then the tube-in-tube heat exchanger reduces the temperature of the flue gas to not higher than 200 ℃ within the time of <1 s.

3. A plasma processing low radioactive waste flue gas cooling apparatus according to claim 1 or 2, wherein: the membrane water-cooled wall comprises a plurality of vertical cooling water pipes and fins which are welded with each other.

4. A plasma processing low radioactive waste flue gas cooling apparatus according to claim 1 or 2, wherein: the membrane water wall comprises a spiral cooling water coil and fins which are welded with each other.

5. A plasma processing low radioactive waste flue gas cooling apparatus according to claim 1 or 2, wherein: and ash cleaning devices are arranged above the upper barrel and the lower barrel.

6. The plasma processing low radioactive waste flue gas cooling device of claim 5, wherein: the ash removal device comprises a shock wave ash removal device.

7. The plasma processing low radioactive waste flue gas cooling apparatus of claim 1, wherein: and the two ends of the water-cooling temperature-reducing device and the two ends of the tube array heat exchange devices are respectively connected to a cooling water inlet pipe and a cooling water outlet pipe.

8. The plasma processing low radioactive waste flue gas cooling device of claim 1, wherein: the ash falling hopper is in a conical shape with a large upper part and a small lower part, and the bottom of the ash falling hopper is opened and closed through an electric double-gate valve.

9. The plasma processing low radioactive waste flue gas cooling device according to claim 1 or 8, wherein: the ash falling hopper is connected with the ash receiving barrel through a flange.

10. The plasma processing low radioactive waste flue gas cooling device according to claim 1 or 8, wherein: and an air hammer or a mechanical rapping device is also arranged at the ash falling hopper.

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