CN117815817A - A wet purification system for radioactive tail gas treatment - Google Patents

Abstract

The invention discloses a wet purification system applied to radioactive tail gas treatment, which comprises a jet scrubber and a washing liquid circulation loop, wherein: the jet scrubber comprises a tower kettle, a tower column and a mixing chamber, wherein the tower column is arranged above the tower kettle, the bottom of the tower column is communicated with the tower kettle, the top of the tower column is provided with an air outlet, the mixing chamber is arranged above the tower column and is communicated with the tower column, a radioactive tail gas inlet is arranged on the mixing chamber, and a washing liquid inlet is arranged at the top of the mixing chamber; the washing liquid circulation pipeline comprises a circulation pipeline and a circulation pump, the circulation pump is arranged on the circulation pipeline, the tail end of the circulation pipeline is communicated with the top of the tower kettle, the head end of the circulation pipeline is communicated with a washing liquid inlet at the top of the mixing chamber, and the head end of the circulation pipeline is connected with a nozzle so as to atomize the washing liquid. The invention has good purifying effect, simple structure, no vulnerable parts such as tower plates or fillers in the interior, small pressure drop and capability of meeting the long-term operation requirement of radioactive environment.

Description

A wet purification system for radioactive tail gas treatment

Technical Field

The invention belongs to the technical field of nuclear industry, and in particular relates to a wet purification system used for treating radioactive tail gas.

Background technique

In the process of recycling spent fuel produced in nuclear power plants, a large amount of high-level liquid waste is inevitably produced. The current internationally accepted method for treating high-level liquid waste is vitrification technology. Vitrification technology refers to evaporating and calcining high-level liquid waste into oxides or single substances under high temperature conditions exceeding 1000°C, melting and bonding into a glass matrix to form a stable radioactive solid waste that meets disposal requirements. The vitrification process of high-level liquid waste will produce a large amount of radioactive tail gas, which contains not only water vapor produced by the evaporation of waste liquid, NO _x produced by the calcination of nitrates, and air introduced during the vitrification process, but also a large amount of radioactive particles. If it cannot be effectively treated, it will have an immeasurable impact on the safety of personnel and the environment. Therefore, radioactive tail gas treatment technology is one of the key links in radioactive waste management projects.

At present, plate towers are mostly used to leach the exhaust gas in the radioactive exhaust gas treatment process. The structure of the plate tower is complex, and the equipment such as the float valve or bubble cap on the plate tower is easy to corrode. The equipment pressure drop is large and the purification effect is poor. Therefore, it is necessary to optimize the radioactive exhaust gas treatment process system to ensure the continuous and stable operation of the facility and the exhaust gas emission meets the standards.

Summary of the invention

The technical problem to be solved by the present invention is to provide a wet purification system for radioactive tail gas treatment in view of the above-mentioned deficiencies in the prior art, which has good purification effect, simple structure, no vulnerable parts such as tower plates or fillers inside, small pressure drop, and can meet the long-term operation requirements of radioactive environments.

The technical solution of the present invention to solve the above technical problems is:

According to one aspect of the present invention, there is provided a wet purification system for treating radioactive tail gas, comprising a jet scrubber and a scrubbing liquid circulation loop, wherein:

The jet scrubber comprises a tower kettle, a tower column and a mixing chamber, wherein the tower column is arranged above the tower kettle, and the bottom of the tower column is connected to the tower kettle, and the top of the tower column is provided with an air outlet, the mixing chamber is arranged on the upper side of the tower column and is connected to the tower column, a radioactive tail gas inlet is provided on the mixing chamber, and a scrubbing liquid inlet is provided on the top of the mixing chamber;

The washing liquid circulation pipeline includes a circulation pipeline and a circulation pump. The circulation pump is arranged on the circulation pipeline. The tail end of the circulation pipeline is connected to the top of the tower kettle, and the head end is connected to the washing liquid inlet at the top of the mixing chamber. A nozzle is connected to the head end to atomize the washing liquid.

Preferably, the bottom of the mixing chamber is connected to the lower side of the tower column through an L-shaped mixing tube for preliminary gas-liquid separation of the tail gas.

Preferably, the washing liquid circulation pipeline further includes a cooler, and the cooler is arranged on the circulation pipeline for cooling the washing liquid.

Preferably, the tower kettle, the tower column and the mixing chamber are all provided with spray ring pipes for replenishing washing liquid and cleaning and decontamination.

Preferably, a drain pipe is provided on the tower kettle for outputting and emptying the liquid in the tower kettle.

Preferably, the tower bottom is further provided with a stirring device, which is a compressed air stirring device for preventing impurities from depositing.

Preferably, the pump body of the circulating pump includes a pump casing and a pump core, the pump casing is fixed by a bracket, the inlet pipe and the outlet pipe of the circulating pump are fixed on the pump casing, and the pump core is detachably installed in the pump casing; the main terminal box of the circulating pump is detachably connected to the power supply cable by a quick-release connector.

Preferably, a hanging ring is provided on the top of the pump core.

Preferably, the number of the circulating pumps is two, and the two circulating pumps are arranged in parallel, one for use and the other for backup.

Preferably, a pressure measuring instrument is provided on the circulation pipeline for detecting the pressure of the washing liquid at the outlet of the circulation pump, and the pressure measuring instrument is connected to an automatic controller for transmitting the detected pressure value to the automatic controller;

The automatic controller is electrically connected to each circulation pump respectively. A pressure threshold is preset in the automatic controller. The automatic controller is used to receive the pressure value detected by the pressure measuring instrument and compare it with the pressure threshold. When the pressure value is lower than the pressure threshold, the automatic control switches to the spare circulation pump.

Beneficial effects:

The wet purification system for radioactive tail gas treatment of the present invention can remove fine particles and aerosols carried in the radioactive tail gas, and at the same time, can absorb a small amount of NO _x , with good purification effect. Moreover, compared with the prior art, the jet scrubber has no vulnerable parts such as tower plates or fillers, has a simple structure, reliable operation, small system pressure drop, high cleaning efficiency, and can meet the long-term operation requirements of a radioactive environment.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a schematic structural diagram of a wet purification system for treating radioactive tail gas according to an embodiment of the present invention.

In the figure: 1-tower kettle; 2-tower column; 3-mixing chamber; 4-L-shaped mixing tube; 5-circulating pump; 6-cooler; 7-air inlet; 8-air outlet; 9-liquid discharge pipe; 10-circulating liquid outlet; 11-washing liquid inlet; 12-nozzle; 13-third washing liquid inlet pipe; 14-third spray ring pipe; 15-second spray ring pipe; 16-first spray ring pipe; 17-compressed air inlet pipe;

18 - cooling water inlet; 19 - cooling water outlet; 20 - first washing liquid inlet pipe; 21 - circulation pipe; 22 - cone bottom; 23 - second washing liquid inlet pipe.

Detailed ways

In order to enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings in the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the protection scope of the present invention.

In the description of the present invention, it should be noted that the term "on" and the like to indicate orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience and simplification of description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

In the description of the present invention, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

In view of the problems existing in the prior art, such as complex equipment structure, easy corrosion of equipment such as float valves or bubble caps on commonly used plate towers, large equipment pressure drop, and poor purification effect, the present invention discloses a wet purification system for radioactive tail gas treatment, including a jet scrubber and a washing liquid circulation loop, wherein:

The jet scrubber comprises a tower kettle, a tower column and a mixing chamber, wherein the tower column is arranged above the tower kettle, and the bottom of the tower column is connected to the tower kettle, and the top of the tower column is provided with an air outlet, the mixing chamber is arranged on the upper side of the tower column and is connected to the tower column, a radioactive tail gas inlet is provided on the mixing chamber, and a scrubbing liquid inlet is provided on the top of the mixing chamber;

The washing liquid circulation pipeline includes a circulation pipeline and a circulation pump. The circulation pump is arranged on the circulation pipeline. The tail end of the circulation pipeline is connected to the top of the tower kettle, and the head end is connected to the washing liquid inlet at the top of the mixing chamber. A nozzle is connected to the head end to atomize the washing liquid.

Example 1

As shown in FIG1 , this embodiment discloses a wet purification system for treating radioactive tail gas, including a jet scrubber and a scrubbing liquid circulation loop, wherein:

The jet scrubber includes a tower kettle 1, a tower column 2 and a mixing chamber 3. The tower kettle 1 is used to hold liquid (such as washing liquid and washing residual liquid after washing). The tower column 2 is arranged above the tower kettle 1, and the bottom of the tower column 2 is connected to the tower kettle 1. The top of the tower column 2 is provided with an air outlet 8. The mixing chamber 3 is arranged on the upper side of the tower column 2 and is connected to the tower column 2. The side wall of the mixing chamber 3 is provided with a radioactive tail gas inlet 7, and the top of the mixing chamber 3 is provided with a washing liquid inlet 11;

The washing liquid circulation pipeline includes a circulation pipe 21 and a circulation pump 5. The circulation pump 5 is arranged on the circulation pipe 21. The tail end of the circulation pipe 21 is connected to the circulation liquid outlet 10 at the top of the tower kettle 1, and the head end is connected to the washing liquid inlet 11 at the top of the mixing chamber 3. The head end of the circulation pipe 21 is connected to the nozzle 12 to atomize the washing liquid.

In some embodiments, the bottom of the mixing chamber 3 is preferably a conical bottom 22, and the taper is preferably 55-65°, which can accelerate the discharge of liquid to the tower kettle and prevent liquid accumulation. The nozzle 12 should select a high-pressure nozzle whose spray range can cover the conical bottom of the mixing chamber. The pressure at the outlet of the high-pressure nozzle is controlled at 0.2-0.6MPa, which can ensure the liquid flushing force. At the same time, a positive pressure environment is created inside the equipment to prevent excessive pressure drop in the tail gas treatment line. The upper part of the mixing chamber 3 is a cylindrical section, and the air inlet 7 is arranged on the cylindrical section of the mixing chamber, and the air inlet 7 is preferably arranged in a horizontal direction so that the radioactive tail gas can be introduced from the horizontal direction.

In some embodiments, the bottom of the mixing chamber 3 is connected to the lower side of the tower column 2 through an L-shaped mixing pipe 4 for performing preliminary gas-liquid separation on the tail gas.

Specifically, the L-shaped mixing tube 4 includes a vertical section and a horizontal section, the vertical section is connected to the bottom of the mixing chamber 3, one end of the horizontal section is connected to the bottom of the vertical section, and the other end is connected to the lower side wall of the tower column 2. The L-shaped mixing tube can ensure that the gas-liquid mixture collides at the corner, thereby achieving gas-liquid separation.

In some embodiments, considering that the temperature of the washing liquid will rise after flowing through the circulation pump 5 due to the influence of the motor, the washing liquid circulation pipeline also includes a cooler 6. The cooler 6 is arranged on the circulation pipeline 21, preferably downstream of the circulation pump 5, between the circulation pump 5 and the washing liquid inlet 11 pipeline at the top of the mixing chamber 3, and is used to cool the washing liquid to prevent the washing liquid from continuing to heat up.

Specifically, the cooler 6 can be a shell and tube heat exchanger or a double-tube heat exchanger or other forms of heat exchangers.

In this embodiment, the cooler 6 preferably adopts a shell and tube heat exchanger, and because the washing liquid contains radioactivity, in order to prevent the washing liquid from leaking into the environment, the tube side of the shell and tube heat exchanger passes the washing liquid, and the shell side passes the cooling water, and the shell side inlet 18 is located at one end of the washing liquid inlet near the top of the mixing chamber 3, and the shell side outlet 19 is located at one end near the circulating pump 5, and the two are in countercurrent heat exchange.

In some embodiments, the tower kettle 1, the tower column 2, and the mixing chamber 3 are all provided with a washing device, and the washing device is preferably a spray ring pipe, which is located at the top of the tower kettle 1, the tower column 2, and the mixing chamber 3, and is sequentially a first spray ring pipe 16, a second spray ring pipe 15, and a third spray ring pipe 14. The first spray ring pipe 16 is connected to the first washing liquid inlet pipe 20, the second spray ring pipe 15 is connected to the second washing liquid inlet pipe 23, and the third spray ring pipe 14 is connected to the third washing liquid inlet pipeline 13. Washing liquid (such as deionized water or acid-base solution) is passed through each spray ring pipe for replenishing washing liquid and cleaning and decontamination.

In some embodiments, a drain pipe 9 is provided on the tower kettle 1 for outputting and draining the liquid in the tower kettle so as to replace the washing liquid. The drain pipe 9 is preferably provided with a non-active conveying device such as a steam jet pump. Through the drain pipe 9, the liquid can be regularly transported to other equipment such as a glass solidification device using a non-active conveying device such as a steam jet pump to avoid continuous accumulation of radioactive substances and particulate matter. It can also be used to drain the liquid in the tower kettle. When the liquid in the tower kettle is insufficient, deionized water is introduced through each spray ring pipe as a washing liquid supplement.

In some embodiments, the bottom of the tower 1 is further provided with a stirring device, the type of which is not limited, and is used to prevent impurities from depositing.

In this embodiment, the stirring device is preferably a compressed air stirring device, which specifically includes a compressed air inlet pipe 17 and a compressor (not shown in the figure). The compressor is connected to the top of the tower bottom 1 through the compressed air inlet pipe 17, and the liquid in the tower bottom 1 is stirred by passing compressed air into the tower bottom 1.

In some embodiments, the pump body of the circulation pump 5 includes a fixed pump housing and a pump core (not shown in the figure), wherein:

The pump casing is fixed by a bracket and cannot be replaced. The inlet and outlet pipes of the circulating pump are fixed to the pump casing by welding or other methods. The pump core (including the motor and impeller part) is detachably installed in the pump casing by bolts or other quick-release structures and can be replaced as a whole.

The main terminal box of the circulation pump and the power supply cable are detachably connected by a quick-release connector (such as a pluggable connector) to facilitate remote operation.

In some embodiments, a lifting ring is provided on the top of the pump core for lifting and replacement at a distance, thereby reducing the radiation risk to the workers.

When the pump core needs to be replaced over a long distance, the electrical connector (such as a pluggable connector) between the main terminal box and the power supply cable is unplugged by a power hand or a manipulator, and the liquid in the circulation pump is pumped out by a steam jet pump. The bolts between the pump core and the pump housing are loosened by a power hand and an electric impact wrench, and the top ring of the old pump core is hung with a power hand auxiliary hook and lifted out to be loaded into a barrel. The installation method of the new pump core is opposite to the lifting method of the old pump core, so it will not be repeated here.

In some embodiments, to ensure continuous operation of the equipment, the number of the circulation pumps 5 is at least two, preferably two, and the two circulation pumps are arranged in parallel, one for use and one for backup.

In some embodiments, a pressure measuring instrument (not shown in the figure) is provided on the circulation pipeline 21 for detecting the pressure of the washing liquid at the outlet of the circulation pump, and the pressure measuring instrument is connected to an automatic controller (not shown in the figure) for transmitting the detected pressure value to the automatic controller;

The automatic controller is electrically connected to each circulation pump 5 respectively. A pressure threshold is preset in the automatic controller. The automatic controller is used to receive the pressure value detected by the pressure measuring instrument and compare it with the pressure threshold. When the pressure is lower than the pressure threshold, that is, the pressure does not meet the process requirements, the automatic control switches to the spare circulation pump 5.

The working process of the wet purification system for treating radioactive tail gas in this embodiment is described in detail below, as follows:

The radioactive tail gas enters the mixing chamber 3 horizontally through the air inlet 7. At the same time, the circulating pump 5 is turned on to transport the washing liquid in the tower kettle 1 to the top of the mixing chamber 3 through the washing liquid circulation pipeline, and then sprayed vertically downward through the high-pressure nozzle to form mist droplets. The spraying direction of the washing liquid is perpendicular to the radioactive tail gas flow entering horizontally. The sprayed mist droplets are fully contacted and mixed with the radioactive tail gas in the mixing chamber 3, so as to remove the fine particles and aerosols carried by the radioactive tail gas. In addition, the washing liquid can also absorb a small amount of NO _x to obtain washed tail gas and washing residual liquid.

Afterwards, the washed exhaust gas and the washing residual liquid enter the vertical section of the L-shaped mixing tube 4 through the conical bottom 22 of the mixing chamber 3, and then enter the tower column 2 through the horizontal section of the L-shaped mixing tube 4, and are sprayed on the side wall of the washing tower column 2 in a tangential straight-impact manner. Under the action of gravity and rotational force, the washed exhaust gas and the washing residual liquid are separated into gas and liquid, and the separated washed exhaust gas flows upward and is discharged to the next treatment process through the gas outlet 8 at the top of the tower column 2. The separated washing residual liquid falls into the tower kettle 1. Afterwards, the liquid in the tower kettle 1 is extracted by the circulation pump 5, and is transported to the top of the mixing chamber 3 again after pressurization for spraying, thereby realizing the circulation of the washing liquid.

The tail gas discharged from the gas outlet 8 at the top of the tower column 2 was detected and calculated, and it was found that the radioactive purification coefficient after treatment by the system of this embodiment was about 15-25, achieving a good radioactive purification effect and meeting the tail gas emission standards.

The wet purification system applied to radioactive tail gas treatment of this embodiment can remove fine particles and aerosols carried in the radioactive tail gas, and can absorb a small amount of NO _x , with good purification effect. Moreover, compared with the prior art, the jet scrubber has no vulnerable parts such as tower plates or fillers, and has a simple structure, reliable operation, small system pressure drop, high cleaning efficiency, and can meet the long-term operation requirements of radioactive environments.

It is to be understood that the above embodiments are merely exemplary embodiments used to illustrate the principles of the present invention, but the present invention is not limited thereto. For those of ordinary skill in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims (10)

1. The utility model provides a be applied to wet purification system of radioactive tail gas treatment which characterized in that includes jet scrubber, washing liquid circulation circuit, wherein:

the jet scrubber comprises a tower kettle (1), a tower column (2) and a mixing chamber (3), wherein the tower column is arranged above the tower kettle, the bottom of the tower column is communicated with the tower kettle, the top of the tower column is provided with an air outlet (8), the mixing chamber is arranged above the tower column and is communicated with the tower column, a radioactive tail gas inlet (7) is arranged on the mixing chamber, and a washing liquid inlet (11) is arranged at the top of the mixing chamber;

the washing liquid circulation pipeline comprises a circulation pipeline (21) and a circulation pump (5), wherein the circulation pump is arranged on the circulation pipeline, the tail end of the circulation pipeline is communicated with the top of the tower kettle, the head end of the circulation pipeline is communicated with a washing liquid inlet at the top of the mixing chamber, and the head end of the circulation pipeline is connected with a nozzle so as to atomize the washing liquid.

2. The wet purification system for radioactive tail gas treatment according to claim 1, wherein the bottom of the mixing chamber is communicated with the lower side of the tower column through an L-shaped mixing pipe (4) for preliminary gas-liquid separation of the tail gas.

3. The wet purification system for radioactive tail gas treatment according to claim 2, wherein the washing liquid circulation line further comprises a cooler (6),

the cooler is arranged on the circulating pipeline and used for cooling the washing liquid.

4. The wet purification system for radioactive tail gas treatment according to claim 3, wherein the tower kettle, the tower column and the mixing chamber are provided with spray ring pipes for supplementing washing liquid and cleaning and decontaminating.

5. The wet purification system for radioactive tail gas treatment according to claim 4, wherein a liquid discharge pipe (9) is arranged on the tower kettle and is used for outputting and evacuating liquid in the tower kettle.

6. The wet purification system for radioactive tail gas treatment according to claim 5, wherein the tower still further comprises a stirring device, wherein the stirring device is a compressed air stirring device for preventing deposition of impurities.

7. The wet purification system for radioactive tail gas treatment according to any one of claims 1 to 6, wherein the pump body of the circulating pump comprises a pump shell and a pump core, the pump shell is fixed by a bracket, an inlet pipeline and an outlet pipeline of the circulating pump are fixedly arranged on the pump shell, and the pump core is detachably arranged in the pump shell;

the body terminal box of the circulating pump is detachably connected with the power supply cable through a quick-release connector.

8. The wet purification system for radioactive tail gas treatment of claim 7, wherein a hanging ring is arranged at the top of the pump core.

9. The wet purification system for radioactive tail gas treatment according to claim 8, wherein the number of the circulating pumps (5) is two, and the two circulating pumps are arranged in parallel and are one by one.

10. The wet purification system for radioactive tail gas treatment according to claim 9, wherein a pressure measuring instrument is provided on the circulation pipe for detecting the washing liquid pressure at the outlet of the circulation pump,

the pressure measuring instrument is connected with an automatic controller and is used for transmitting the detected pressure value to the automatic controller;

the automatic controller is electrically connected with each circulating pump respectively, a pressure threshold value is preset in the automatic controller, the automatic controller is used for receiving the pressure value detected by the pressure measuring instrument and comparing the pressure value with the pressure threshold value, and when the pressure value is lower than the pressure threshold value, the automatic controller is automatically controlled to switch to the standby circulating pump.