阅读说明：本技术 一种处理放射性废水的工艺 (Process for treating radioactive wastewater ) 是由 唐娜 黄传峰 田桂英 程鹏高 项军 张蕾 杜威 王松博 于 2020-08-04 设计创作，主要内容包括：本发明公开一种处理放射性含盐废水的工艺,其包括以下工序：加热工序、膜蒸馏工序、蒸发结晶工序、固废处理工序和回收利用工序；具体包括以下步骤：(1)将放射性含盐废水引入加热器进行加热工序；(2)加热后的放射性含盐废水进入膜蒸馏工序,得到浓缩液和第一冷凝水；(3)将步骤(2)得到的浓缩液引入蒸发集盐装置进行蒸发结晶,产生蒸汽和固体废物,得到的固体废物进行固废处理工序,后收集放射性固体；(4)将步骤(2)得到的第一冷凝水引入回收利用工序。本发明工艺利用集热板提高太阳能利用率,膜蒸馏加快废水蒸发速率,最后经蒸发集盐装置实现固液分离。本工艺大大提高自然蒸发速率,加快废水处理,利用太阳能将能耗大大降低。(The invention discloses a process for treating radioactive salt-containing wastewater, which comprises the following steps: a heating process, a membrane distillation process, an evaporation crystallization process, a solid waste treatment process and a recycling process; the method specifically comprises the following steps: (1) introducing the radioactive salt-containing wastewater into a heater for heating; (2) the heated radioactive salt-containing wastewater enters a membrane distillation process to obtain a concentrated solution and first condensed water; (3) introducing the concentrated solution obtained in the step (2) into an evaporation salt collecting device for evaporation crystallization to generate steam and solid waste, performing a solid waste treatment process on the obtained solid waste, and then collecting radioactive solid; (4) and (3) introducing the first condensate water obtained in the step (2) into a recycling process. The process of the invention utilizes the heat collecting plate to improve the solar energy utilization rate, the membrane distillation accelerates the wastewater evaporation rate, and finally the solid-liquid separation is realized by the evaporation salt collecting device. The process greatly improves the natural evaporation rate, accelerates the wastewater treatment and greatly reduces the energy consumption by utilizing solar energy.)

1. The process for treating radioactive salt-containing wastewater is characterized by comprising the following steps of: a heating process, a membrane distillation process, an evaporation crystallization process, a solid waste treatment process and a recycling process;

the method for treating radioactive salt-containing wastewater by using the procedures comprises the following steps:

(1) introducing the radioactive salt-containing wastewater into a heater for heating;

(2) the heated radioactive salt-containing wastewater enters a membrane distillation process and is further concentrated to obtain concentrated solution and first condensed water;

(3) and (3) introducing the concentrated solution obtained in the step (2) into an evaporation salt collecting device for evaporation crystallization to generate steam and solid waste, performing a solid waste treatment process on the obtained solid waste, and then collecting radioactive solid.

(4) And (3) introducing the first condensate water obtained in the step (2) into a recycling process.

Wherein, the step (3) and the step (4) are not in sequence and can be carried out simultaneously.

2. The process for treating radioactive saline wastewater according to claim 1, further comprising a preheating step, wherein the radioactive saline wastewater before entering the heating step is preheated by the steam generated in the step (3), and the steam is converted into second condensate water and introduced into the recycling step.

3. The process for treating radioactive saline wastewater according to claim 1, wherein the radioactive wastewater is sodium nitrate wastewater with radioactivity generated after radioactive elements are extracted through nitric acid treatment.

4. The process for treating radioactive salt-containing wastewater according to claim 1, wherein the heater in the step (1) is a solar heater, and the radioactive wastewater is heated to 65-75 ℃ by using solar energy.

5. The process for treating radioactive salt-containing wastewater according to claim 1, wherein the evaporation salt collecting device used in the evaporation crystallization process comprises an evaporation chamber (1), an evaporation salt collecting device (2) and a condensation liquid collecting device (3);

the evaporation chamber (1) comprises a side wall surrounded by a surrounding plate (11) and a top cover formed by a cover plate (12), wherein the surrounding plate (11) is provided with an air inlet (111), an air inlet (112) and a waste water inlet (113);

the evaporation salt collecting device (2) is positioned in the evaporation chamber (1) and comprises a water absorbing part cross beam (21), a water absorbing part (22), a heat collecting plate (23) and a heat insulating plate (24); the heat insulation plate (24) is positioned below the cover plate (12) and is tightly attached to the cover plate (12), and the heat collection plate (23) is positioned below the heat insulation plate (24) and is tightly attached to the heat insulation plate (24); the water absorbing component cross beam (21) is positioned below the heat collecting plate (23), and the water absorbing component (22) is hung on the water absorbing component cross beam (21);

the condensation liquid collecting device (3) comprises an induced draft fan (31) and a heat exchange pipe (32); draught fan (3) one end is passed through on bounding wall (11) induced air mouth (111) with evaporating chamber (1) gas intercommunication, ambient air passes through air intake (112) and gets into evaporating chamber (1), draught fan (31) other end with heat exchange tube (32) one end intercommunication, the heat exchange tube (32) other end is condensate outlet (321) and air discharge mouth (322), condensate outlet (321) department has tap switch.

6. The apparatus for separating and recovering solid and liquid waste according to claim 1, wherein the surrounding plate (11) and the cover plate (12) are transparent and are selected from a glass plate or an acrylic plate.

7. The apparatus for separating and recovering solid and liquid waste according to claim 1, wherein the water absorbing member beam (21) is made of corrosion resistant material, and the water absorbing member beam (21) is a round rod made of polymethyl methacrylate; the water absorbing component (22) is a water absorbing material selected from natural cellulose, polypropylene fiber compound, cotton cloth, filter paper, sponge or absorbent paper; the insulating plate (24) is selected from transparent silicone rubber materials.

8. The apparatus for separating and recycling solid and liquid wastes according to claim 3, wherein said heat collecting plate (23) is made of metal and is selected from aluminum plate, copper plate and alloy plate, said heat collecting plate (23) is coated with solar photo-thermal conversion coating selected from black chromium coating, blue titanium coating or carbon black coating.

9. The apparatus for separating and recycling solid and liquid wastes according to claim 3, wherein the photothermal conversion coating is black chrome, blue titanium or carbon black coating, and the solar light absorption rate of the heat collecting plate (23) is more than 90% and the reflectivity is less than 8%.

10. The apparatus for separating and recovering solid-liquid waste according to claim 1, wherein the heat exchange pipe (32) is a copper pipe or a stainless steel pipe.

Technical Field

The invention belongs to the technical field of radioactive salt-containing wastewater treatment, and particularly relates to a novel process for treating radioactive wastewater, in particular to a process for treating radioactive salt-containing wastewater after uranium and plutonium are extracted through acid treatment.

Background

Since the discovery of x-rays by roentgen in 1895, people opened the door to explore the atomic world. In the period of more than 100 years, the nuclear industry has leaped forward and made remarkable contribution to the economic construction of human society. Also, a large amount of radioactive waste is generated. Among radioactive wastes, radioactive waste water is particularly the main component. The volume of the waste water is large, the storage occupied area is large, and the total amount of radioactive substances is large, so that the waste water becomes the key point of radioactive waste treatment.

The ore is treated by nitric acid, a large amount of radioactive salt-containing wastewater is left after uranium and plutonium are extracted, the radioactive salt-containing wastewater contains a large amount of radioactive substances and high-concentration sodium nitrate, the industrial wastewater which is forbidden to be discharged by the country must be strictly controlled and discharged after reaching the standard, and serious environmental pollution can be caused by the situation that whether the uranium and the plutonium are extracted or not.

The radioactive waste water treating process includes mainly precipitation, ion exchange, adsorption, biological treatment, membrane treatment, evaporation, concentration and other steps. Wherein, the evaporation concentration method is widely applied, the volume reduction multiple is large, and the complex water quality is often treated. But the evaporation concentration method has higher energy consumption and large investment, and has great resistance for further popularization. Therefore, a process for treating radioactive salt-containing wastewater needs to be developed, so that the purposes of recovering radioactive solids and discharging the wastewater after reaching standards are achieved, but because the radioactive wastewater contains a large amount of radioactive substances and high-concentration sodium nitrate, the radioactive substances are discharged to harm animals and plants due to slight improper sealing in the treatment process. Aiming at the harsh environment, how to simply, efficiently and safely treat the radioactive wastewater is more critical, the energy consumption is low, the investment is low, and the applicable device is designed in a targeted manner, so that the requirement of practical application is met.

The present invention has been made to solve the above problems.

Disclosure of Invention

Aiming at the problems of the existing evaporation concentration method for treating radioactive salt-containing wastewater, the invention aims to provide a process method for treating radioactive salt-containing wastewater. The process can not only reduce energy consumption, but also improve the rate of natural evaporation.

The invention provides a process for treating radioactive salt-containing wastewater, which comprises the following steps: a heating process, a membrane distillation process, an evaporation crystallization process, a solid waste treatment process and a recycling process;

the method for treating radioactive salt-containing wastewater by using the procedures comprises the following steps:

(1) introducing the radioactive salt-containing wastewater into a heater for heating;

(2) the heated radioactive salt-containing wastewater enters a membrane distillation process and is further concentrated to obtain concentrated solution and first condensed water;

(3) and (3) introducing the concentrated solution obtained in the step (2) into an evaporation salt collecting device for evaporation crystallization to generate steam and solid waste, performing a solid waste treatment process on the obtained solid waste, and then collecting radioactive solid.

(4) And (3) introducing the first condensate water obtained in the step (2) into a recycling process.

Wherein, the step (3) and the step (4) are not in sequence and can be carried out simultaneously. In addition, the first condensed water recycled in the step (4) is discharged or can be recycled after meeting the standard, for example, water is also needed in the process of treating the uranium remolde ore, so that the condensed water can be directly recycled, the use of tap water is reduced, and the effects of water saving and emission reduction are achieved.

Preferably, the method further comprises a preheating process, wherein the radioactive saline wastewater before entering the heating process is preheated by the steam generated in the step (3), and the steam is converted into second condensed water and introduced into the recycling process. In addition, the second condensate water recycled in the step (3) is discharged or can be recycled after meeting the standard, for example, water is also needed in the uranium ore treatment process, so that the condensate water can be directly recycled, the use of tap water is reduced, and the effects of water saving and emission reduction are achieved.

Preferably, the radioactive wastewater is sodium nitrate wastewater with radioactivity generated after extracting radioactive elements such as uranium, plutonium and the like through nitric acid treatment.

Preferably, the heater in the step (1) is a solar heater, and the radioactive wastewater is heated to 60-80 ℃ by using solar energy.

Preferably, the membrane distillation process in the step (2) utilizes a hollow fiber membrane module to carry out membrane distillation on the heated radioactive saline wastewater. Of course, the present invention is not limited to the center control fiber membrane, and other membrane distillation methods commonly used in the art may be used, such as: air gap type membrane distillation and contact type membrane distillation.

The evaporation salt collecting device used in the evaporation crystallization process comprises an evaporation chamber 1, an evaporation salt collecting device 2 and a condensation liquid collecting device 3;

the evaporation chamber 1 comprises a side wall enclosed by a surrounding plate 11 and a top cover formed by a cover plate 12, wherein the surrounding plate 11 is provided with an air induction opening 111, an air inlet 112 and a waste water inlet 113;

the evaporation salt collecting device 2 is positioned inside the evaporation chamber 1 and comprises a water absorption part cross beam 21, a water absorption part 22, a heat collecting plate 23 and a heat insulating plate 24; the heat insulation plate 24 is positioned below the cover plate 12 and is tightly attached to the cover plate 12, and the heat collection plate 23 is positioned below the heat insulation plate 24 and is tightly attached to the heat insulation plate 24; the water absorbing component cross beam 21 is positioned below the heat collecting plate 23, and the water absorbing component 22 is hung on the water absorbing component cross beam 21;

the condensation liquid collecting device 3 comprises an induced draft fan 31 and a heat exchange tube 32; draught fan 3 will through air intake 112 gas in the evaporating chamber 1 exchanges and discharges through induced air opening 111 with the dry air in the environment, the draught fan 31 other end with heat exchange tube 32 one end intercommunication, the heat exchange tube 32 other end is condensate outlet 321 and air discharge port 322, condensate outlet 321 department has tap switch.

Preferably, the surrounding plate 11 and the cover plate 12 are transparent and are made of high-transmittance materials such as glass plates or acrylic plates.

Preferably, the heat collecting plate 23 is made of a metal material, and is selected from commercially available materials with high photothermal conversion characteristics, such as an aluminum plate, a copper plate, and an alloy plate, and the solar photothermal conversion coating is plated on the heat collecting plate 23, and is selected from a black chromium coating, a blue titanium coating, or a carbon black coating.

Preferably, the photothermal conversion coating is a black chromium, blue titanium or carbon black coating, and the solar light absorption rate of the heat collecting plate 23 is more than 90%, and the reflectivity is less than 8%.

Preferably, the water absorption part beam 21 is made of corrosion-resistant materials, and the water absorption part beam 21 is a round rod made of polymethyl methacrylate; the water absorption part 22 is a water absorption material selected from porous loose materials such as natural cellulose, polypropylene fiber compound, cotton cloth, filter paper, sponge or water absorption paper and the like; the heat insulation board 24 is selected from high-transmittance heat insulation materials such as transparent silicon rubber materials.

Preferably, the heat exchange tube 32 is made of corrosion-resistant material with high heat transfer rate, such as copper tube, stainless steel tube, etc., and has a tube diameter of 5-10 mm.

Wherein the induced draft fan 31 is a commercial LH-50S-shaped nine-blade wind mini-pipeline induced draft fan. The pipe diameter of the interface is 5-10mm, and the air quantity is 36m³H, air pressure 330 Pa. The pipe diameter of the interface is matched with that of the heat exchange pipe.

Based on the above expression, the method for performing evaporative crystallization on membrane-distilled (high-concentration salt-containing wastewater after membrane distillation) in the evaporative crystallization process comprises the following steps:

(1) introducing the concentrated solution after membrane distillation into the evaporation salt collecting device along a waste water inlet 113, so that the enclosing plate 11, the water absorbing part 22 and the heat exchange tube 32 are at least partially immersed in the concentrated solution, the water vapor in the evaporation chamber 1 can be discharged only through an induced draft opening 111, and ambient air enters the evaporation chamber 1 through an air inlet 112 to supplement ambient dry air into the evaporation chamber 1;

(2) the water absorption component 22 is in contact with the concentrated solution, the concentrated solution is absorbed by utilizing the capillary action, the solar energy is converted into heat energy by the heat collection plate 23, the concentrated solution in the water absorption component 22 is heated and evaporated, solid salt formed after evaporation is concentrated on the water absorption component 22, and water vapor formed after evaporation is emitted into the evaporation chamber 1;

(3) draught fan 31 exchanges the inside steam of evaporating chamber 1 with the dry air that air intake 112 got into, and the inside steam of evaporating chamber 1 discharges through induced air port 111 to get into heat exchange tube 32, heat exchange tube 32 is at least partly soaked in the concentrate, and the concentrate is right vapor in the heat exchange tube 32 condenses, and the condensate that obtains passes through condensate export 321 discharges, and the heat transfer of vapor is to in the heat exchange tube 32 the concentrate.

In the step (1), the enclosing plate 11 is provided with the induced draft opening 111 and the air inlet 112, the induced draft opening 111 is in gas communication with the induced draft fan 31, and the air inlet 112 is in communication with the environment. Therefore, the closed environment in the evaporation chamber 1 is not absolutely sealed, but due to the suction action of the induced draft fan 31, the other places in the evaporation chamber 1 except the air inlet 112 of the induced draft opening 111 are sealed, the water vapor in the evaporation chamber 1 can only be discharged along the induced draft opening 111 and enter the heat exchange tube 32, so the evaporation chamber 1 is a relatively sealed environment, after the water vapor in the evaporation chamber 1 is discharged, the ambient air enters the evaporation chamber 1 through the air inlet 112, and the purpose of exchanging the vapor in the evaporation chamber 1 with the dry air entering from the air inlet 112 is achieved.

In the step (3), after the vapor in the evaporation chamber 1 is discharged through the air inducing port 111, the vapor is not directly discharged into the environment, but enters the heat exchange tube 32, at least part of the heat exchange tube 32 is immersed in the concentrated solution, the concentrated solution condenses the vapor in the heat exchange tube 32, the obtained condensate is discharged through the condensate outlet 321, and the air is discharged from the air discharge port 322. The latent heat of the water vapor is recovered to heat the water body so as to improve the evaporation rate, and the recovered condensate can be continuously recycled in the processes of dissolution and separation of ores and the like. In addition, a small condensate seal (indicated by the dashed line in the heat exchange tube 32 in fig. 3) is left at the condensate outlet 321 to prevent air from being discharged from the condensate outlet 321. The heat exchange pipe 32 has a gas-liquid separation function, and effectively prevents radioactive substances from being discharged into the environment.

In the invention, the periphery and the top of the device are covered by the heat collecting plates 23 plated with the solar photo-thermal conversion coating, so that the heat absorption area is increased. The internal water absorption crystalline material with capillary action is fixed with the internal water absorption part beam, and the lower end of the immersed water body distributes water through capillary action. The entire suspension structure increases the evaporation area in a limited space. The draught fan discharges the saturated vapor inside in time, reduces the air humidity inside, increases the evaporation rate. The discharged water vapor is subjected to heat exchange with a water body through the spiral heat exchange coil to form condensed water. The vapor with the concentrated solution is smoothly recycled and treated, and the latent heat of the vapor can be utilized by heat exchange to heat the water body so as to enhance the evaporation rate.

Compared with the prior art, the process for treating the radioactive salt-containing wastewater has the following beneficial effects:

1. according to the invention, the solar heater is firstly utilized to heat the radioactive salt-containing wastewater, the heated radioactive salt-containing wastewater is concentrated by combining membrane distillation, and compared with the previous evaporation concentration, the energy consumption is reduced by utilizing solar energy and membrane distillation.

2. The invention improves the evaporation rate by utilizing the solar heat collector and the membrane distillation, reduces the treatment period, improves the treatment efficiency and has obvious utilization value.

3. In a preferred embodiment of the invention, the process for treating radioactive salt-containing wastewater further comprises a preheating process, wherein the radioactive salt-containing wastewater before entering the heating process is preheated by the steam generated in the step (3), and the steam is converted into second condensed water and introduced into the recycling process. According to the invention, the radioactive salt-containing wastewater is preheated by using the water vapor generated in the evaporation salt collecting device, so that the latent heat of the water vapor is recycled, and the condensed water can be collected and recycled for a series of processes such as dissolution and separation of nuclear raw materials.

4. The method for treating the radioactive salt-containing wastewater has the advantages of simple process flow, low cost and simple industrial amplification.

Aiming at the process, the invention specifically designs an evaporation salt collecting device for an evaporation crystallization process, and the evaporation salt collecting device has the following beneficial effects:

1. in the evaporation salt collecting device, the solar heat collecting plate 23 with good light absorption performance and low emissivity is used as a photo-thermal conversion material, so that the absorptivity of solar energy is increased.

2. In the evaporation salt collecting device, the capillary water absorption part 22 in the evaporation chamber 1 adopts a suspension type arrangement structure on the water absorption part beam 21, thereby greatly increasing the evaporation area and improving the utilization rate of solar energy.

3. In the method for separating and recovering solid and liquid wastes by using the evaporative salt collecting device evaporative concentrated solution, the concentrated solution enters the evaporative salt collecting device along a waste water inlet 113, so that the enclosing plate 11, the water absorbing part 22 and the heat exchange tube 32 are at least partially immersed in the concentrated solution, the concentrated solution is absorbed by using the capillary action of the water absorbing part 22, the heat collecting plate 23 converts solar energy into heat energy, the concentrated solution in the water absorbing part 22 is heated and evaporated, solid salt formed after evaporation is concentrated on the water absorbing part 22, and water vapor formed after evaporation is emitted into the evaporation chamber 1; the concentrated solution which is not introduced into the evaporation chamber 1 does not participate in the evaporation process, and radioactive substances are not released, and the serious harm to the environment, animals and plants is avoided. In addition, ambient dry air enters the inside of the evaporation chamber 1 through an air inlet 112 to exchange with water vapor and is exhausted through an air induction port 111; the closed type of evaporation process has better guaranteed that radioactive solid waste is at the inside crystallization of evaporating chamber 1, and can not blown away the polluted environment by wind, endangers animals and plants, that is to say that the concentrate that lets in evaporating chamber 1 can not release radioactive substance yet, guarantees in two respects that can not cause the problem that the concentrated solution releases radioactive substance polluted environment.

4. In the use process of the device, at least part of the heat exchange tube 32 is immersed in the concentrated solution, the concentrated solution condenses the water vapor in the heat exchange tube 32, the obtained condensate is discharged through the condensate outlet 321, the air is discharged from the air discharge port 322, and the heat of the water vapor in the heat exchange tube 32 is transferred into the concentrated solution, namely, the concentrated solution is used for cooling and recovering the water vapor through the draught fan 31, so that the water vapor is well recovered, the environmental pollution is prevented, the latent heat of the water vapor is recovered, the utilization rate of solar energy is increased, and the use of additional coolant is avoided.

Drawings

FIG. 1 is an industrial flow diagram of the present invention for treating radioactive saline wastewater;

FIG. 2 is a schematic view of the structure of an evaporative salt collecting device used in the evaporative crystallization process of the present invention;

FIG. 3 is a schematic view showing the structure of a heat exchange tube 32 in the evaporative salt collecting apparatus used in the evaporative crystallization process of the present invention;

the notation in the figure is:

1-an evaporation chamber, 2-an evaporation salt collecting device, 3-a condensation liquid collecting device, 11-enclosing plates, 12-covering plates, 21-a water absorption part cross beam, 22-a water absorption part, 23-a heat collecting plate, 24-a heat insulating plate, 31-an induced draft fan, 32-a heat exchange tube, 111-an induced draft port, 112-an air inlet, 113-a waste water inlet, 321-a condensate outlet and 322-an air outlet.

Detailed Description

In order to better understand the present invention, the following examples are further provided to illustrate the content of the present invention, but the content of the present invention is not limited to the following examples.