CN111508631A - External circulation type high-level radioactive waste liquid continuous evaporation concentration denitrator - Google Patents

External circulation type high-level radioactive waste liquid continuous evaporation concentration denitrator Download PDF

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CN111508631A
CN111508631A CN202010333501.7A CN202010333501A CN111508631A CN 111508631 A CN111508631 A CN 111508631A CN 202010333501 A CN202010333501 A CN 202010333501A CN 111508631 A CN111508631 A CN 111508631A
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denitration
concentration
evaporation
waste liquid
kettle
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CN111508631B (en
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徐聪
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Tsinghua University
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    • GPHYSICS
    • G21NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21FPROTECTION AGAINST X-RADIATION, GAMMA RADIATION, CORPUSCULAR RADIATION OR PARTICLE BOMBARDMENT; TREATING RADIOACTIVELY CONTAMINATED MATERIAL; DECONTAMINATION ARRANGEMENTS THEREFOR
    • G21F9/00Treating radioactively contaminated material; Decontamination arrangements therefor
    • G21F9/04Treating liquids
    • G21F9/06Processing
    • G21F9/08Processing by evaporation; by distillation
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D45/00Separating dispersed particles from gases or vapours by gravity, inertia, or centrifugal forces
    • B01D45/12Separating dispersed particles from gases or vapours by gravity, inertia, or centrifugal forces by centrifugal forces
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D50/00Combinations of methods or devices for separating particles from gases or vapours

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Abstract

The invention discloses an external circulation type high-level radioactive waste liquid evaporation concentration denitrator, which comprises: concentrated denitration cauldron of evaporation, external circulating pipe, heater, backpressure overheat district and defoaming purifying column, wherein, the concentrated denitration cauldron of evaporation one side bottom opening links to each other with the external circulating pipe, and the external circulating pipe links to each other with the heater, and heater upper portion links to each other with the backpressure overheat district, and the backpressure overheat district links to each other with the another side opening of the concentrated denitration cauldron of evaporation, and the concentrated denitration cauldron top of evaporation links to each other with defoaming purifying column. The evaporation concentration denitrator can not generate a large amount of sediment, effectively separates small liquid drops and breaks foam, prevents bumping, and is suitable for evaporation concentration denitration treatment of high-level radioactive waste liquid generating sediment and/or bumping.

Description

外循环式高放废液连续蒸发浓缩脱硝器External circulation type high-level waste liquid continuous evaporation concentration and denitrification device

技术领域technical field

本发明涉及核能乏燃料后处理技术领域,特别涉及一种外循环式高放废液连续蒸发浓缩脱硝设备。The invention relates to the technical field of post-processing of nuclear energy spent fuel, in particular to an external circulation type high-level waste liquid continuous evaporation, concentration and denitrification equipment.

背景技术Background technique

核反应堆在运行一定时间后,对内燃料燃耗在达到一定程度成为乏燃料后需要卸出并进行后处理,回收其中的铀、钚以及其它贵重核素。目前乏燃料后处理广泛采用PUREX流程。在PUREX流程以及其它类似流程中,乏燃料均是被硝酸溶解形成料液,然后再通过液液萃取操作实现硝酸溶液中铀钚的提取和分离。上述硝酸溶液在提取铀钚后,里面仍含有高放射性、长寿命周期的其它核素,被称为高放废液。高放废液通常需要通过蒸发-浓缩-脱硝处理来减少废液体积,以便进行后续的临时贮存并继续进行玻璃固化或者进一步的分离减容等操作。因此,在乏燃料后处理主工艺流程和高放废液辅助工艺流程之间,高放废液的蒸发浓缩脱硝操作是关键的衔接环节。After a nuclear reactor runs for a certain period of time, the internal fuel burnup reaches a certain level and becomes spent fuel, which needs to be unloaded and reprocessed to recover uranium, plutonium and other precious nuclides. At present, the PUREX process is widely used for spent fuel reprocessing. In the PUREX process and other similar processes, spent fuel is dissolved by nitric acid to form a feed liquid, and then the extraction and separation of uranium and plutonium in the nitric acid solution is achieved by liquid-liquid extraction. After the uranium and plutonium are extracted from the above-mentioned nitric acid solution, it still contains other nuclides with high radioactivity and long life cycle, which is called high-level radioactive waste liquid. High-level waste liquid usually needs to be reduced by evaporation-concentration-denitrification treatment for subsequent temporary storage and continued vitrification or further separation and volume reduction. Therefore, between the main process of spent fuel reprocessing and the auxiliary process of high-level waste liquid, the evaporation, concentration and denitrification of high-level waste liquid is the key link.

对于高放废液蒸发浓缩脱硝来说,其3个基本操作过程为:加热溶液、过热溶液沸腾蒸发、甲醛(或甲酸)脱硝反应。目前上述步骤采用的典型设备是加热室和汽液分离室分开设置的外加热式蒸发器。该设备的一个显著特点是将上述3个基本操作过程都集中在加热室中完成,在操作方法上则普遍采用分段蒸发浓缩-脱硝(首先加热蒸发溶液使硝酸浓缩至一定浓度,而后停止加热,加入甲醛或甲酸脱硝使硝酸浓度降至一定数值,然后再次加热溶液进行蒸发浓缩并重复上述过程,直至溶液体积和硝酸浓度符合要求为止)或者清蒸(一次性地将溶液加热蒸发浓缩至所需体积,而后停止加热,再逐渐地加入甲醛或甲酸一次性地脱硝至所需酸度)的操作方法对料液进行处理。对外加热式蒸发器的结构特点分析可知,对于蒸发浓缩脱硝过程产生沉淀的料液,由于3个基本操作过程都集中在加热室内完成,因此如有沉淀产生,则沉淀必然会沉积在加热室中,严重时将引起管道堵塞从而导致操作无法正常进行。对应燃耗较深的动力反应堆乏燃料,高放废液中锆含量相对较高,在对该废液进行蒸发浓缩脱硝的过程中,当硝酸浓度降至一定程度时,锆离子和钼离子将以钼酸锆沉淀的形式沉积出来,因此普遍采用的外加热式蒸发器以及其它类似的,如夹套釜式蒸发器等都不适用。此外,现有类型的高放废液蒸发浓缩脱硝设备均存在容易爆沸的问题,即高放废液产生大量泡沫并溢流出设备进入后续管路的问题,这将导致设备状态失稳和放射性泄漏等严重问题。综合上述,目前尚没有可解决沉淀析出、爆沸问题的高放废液蒸发浓缩脱硝设备。For the evaporative concentration and denitration of high-level waste liquid, its three basic operation processes are: heating solution, boiling evaporation of superheated solution, and formaldehyde (or formic acid) denitration reaction. At present, the typical equipment used in the above steps is an externally heated evaporator with the heating chamber and the vapor-liquid separation chamber set separately. A notable feature of this equipment is that the above three basic operation processes are concentrated in the heating chamber, and the operation method generally adopts the staged evaporation concentration-denitrification (first heating the evaporation solution to concentrate the nitric acid to a certain concentration, and then stop heating , add formaldehyde or formic acid for denitration to reduce the concentration of nitric acid to a certain value, then heat the solution again for evaporation and concentration and repeat the above process until the volume of the solution and the concentration of nitric acid meet the requirements) or steam (one-time heating, evaporation and concentration of the solution to the required level) Volume, then stop heating, and then gradually add formaldehyde or formic acid to denitrify to the desired acidity at one time) to process the feed liquid. Analysis of the structural characteristics of the externally heated evaporator shows that, for the feed liquid produced by the evaporation, concentration and denitration process, the three basic operation processes are concentrated in the heating chamber. Therefore, if precipitation occurs, the precipitation will inevitably be deposited in the heating chamber. , in severe cases, the pipeline will be blocked and the operation cannot be carried out normally. For the spent fuel of the power reactor with deep burnup, the content of zirconium in the high-level waste liquid is relatively high. It is deposited in the form of a zirconium molybdate precipitate, so the commonly used externally heated evaporators and other similar ones, such as jacketed kettle evaporators, are not suitable. In addition, the existing types of high-level waste liquid evaporation, concentration and denitrification equipment all have the problem of easy bumping, that is, the high-level waste liquid produces a large amount of foam and overflows the equipment into the subsequent pipeline, which will lead to equipment instability and radioactivity. serious problems such as leakage. To sum up the above, there is currently no high-level waste liquid evaporation concentration and denitrification equipment that can solve the problems of precipitation and bumping.

发明内容SUMMARY OF THE INVENTION

本发明旨在至少在一定程度上解决相关技术中的技术问题之一。The present invention aims to solve one of the technical problems in the related art at least to a certain extent.

为此,本发明的目的在于提出一种外循环式高放废液蒸发浓缩脱硝器。Therefore, the purpose of the present invention is to propose an external circulation type high-level waste liquid evaporation concentration denitrifier.

为达到上述目的,本发明实施例提出了外循环式高放废液蒸发浓缩脱硝器,包括:蒸发浓缩脱硝釜、外部循环管、加热器,背压过热区和除沫净化塔,其中,所述蒸发浓缩脱硝釜一侧底部开口与所述外循环管相连,所述外循环管与所述加热器相连,所述加热器上部与所述背压过热区相连,所述背压过热区与所述蒸发浓缩脱硝釜的另一侧面开口相连,所述蒸发浓缩脱硝釜顶部与所述除沫净化塔相连;所述蒸发浓缩脱硝釜包括脱硝剂分布器、隔板、溢流区和旋风分离器,其中,所述脱硝剂分布器设置在所述蒸发浓缩脱硝釜的底部,所述旋风分离器设置在所述蒸发浓缩脱硝釜的顶部,所述蒸发浓缩脱硝釜侧面靠近底部开口一侧通过所述隔板形成与蒸发浓缩脱硝区相隔离的溢流区。In order to achieve the above purpose, the embodiment of the present invention proposes an external circulation type high-level waste liquid evaporative concentration and denitrification device, including: an evaporation concentration denitrification kettle, an external circulation pipe, a heater, a back pressure superheating zone and a defoaming purification tower. The bottom opening on one side of the evaporation concentration and denitration kettle is connected with the outer circulation pipe, the outer circulation pipe is connected with the heater, the upper part of the heater is connected with the back pressure overheating zone, and the back pressure overheating zone is connected with the heater. The other side opening of the evaporation concentration and denitration kettle is connected with the opening, and the top of the evaporation concentration and denitration kettle is connected with the defoaming purification tower; the evaporation concentration and denitration kettle includes a denitration agent distributor, a partition, an overflow area and a cyclone separation wherein, the denitration agent distributor is arranged at the bottom of the evaporative concentration and denitration kettle, the cyclone separator is arranged on the top of the evaporative concentration and denitration kettle, and the side of the evaporative concentration and denitration kettle passes through the side close to the bottom opening. The separator forms an overflow area isolated from the evaporative concentration and denitration area.

本发明实施例的外循环式高放废液蒸发浓缩脱硝器,通过采用加热区和蒸发浓缩脱硝区相分离、蒸发浓缩脱硝区和外循环管入口相分隔、外循环管中流速足够大的策略,使蒸发浓缩脱硝区产生的沉淀不会大量进入并沉积在加热室中,同时,采用旋风分离器对进入除沫净化塔前的蒸汽进行处理,有效分离其中的小液滴并破除泡沫,可以有效地防止爆沸发生,尤其适用于产生沉淀和/或易爆沸的高放废液的蒸发浓缩脱硝处理,可广泛应用放射性核化工领域。The external circulation type high-level waste liquid evaporative concentration and denitrification device in the embodiment of the present invention adopts the strategy of phase separation between the heating zone and the evaporative concentration and denitrification zone, separation of the evaporative concentration and denitrification zone from the inlet of the external circulation pipe, and a sufficiently large flow rate in the external circulation pipe. , so that the precipitation generated in the evaporation concentration and denitrification zone will not enter and deposit in the heating chamber in large quantities. At the same time, the steam before entering the defoaming purification tower is treated with a cyclone separator, which can effectively separate the small droplets and break the foam. It can effectively prevent the occurrence of bumping, especially suitable for the evaporative concentration and denitration treatment of high-level radioactive waste liquid that produces precipitation and/or bumping, and can be widely used in the field of radionuclear chemical industry.

另外,根据本发明上述实施例的外循环式高放废液蒸发浓缩脱硝器还可以具有以下附加的技术特征:In addition, the external circulation type high-level waste liquid evaporation concentration denitrifier according to the above-mentioned embodiment of the present invention may also have the following additional technical features:

进一步地,在本发明的一个实施例中,所述蒸发浓缩脱硝釜中的液体高于所述隔板,使液体溢流入所述溢流区。Further, in an embodiment of the present invention, the liquid in the evaporative concentration and denitration tank is higher than the separator, so that the liquid overflows into the overflow area.

进一步地,在本发明的一个实施例中,蒸发浓缩脱硝过程中产生的沉淀受重力作用不会进入所述溢流区。Further, in an embodiment of the present invention, the precipitate generated in the process of evaporative concentration and denitrification will not enter the overflow area under the action of gravity.

进一步地,在本发明的一个实施例中,所述加热器与所述蒸发浓缩脱硝釜通过所述背压过热区相分隔,所述蒸发浓缩脱硝釜与所述外部循环管通过溢流区相分隔,所述蒸发浓缩脱硝釜与所述除沫净化塔通过旋风分离器相分隔。Further, in an embodiment of the present invention, the heater is separated from the evaporative concentration and denitrification kettle through the back pressure superheating zone, and the evaporative concentration and denitration kettle is separated from the external circulation pipe through the overflow zone. Separation, the evaporation concentration denitration kettle and the defoaming purification tower are separated by a cyclone.

进一步地,在本发明的一个实施例中,所述背压过热区的高度大于理论值,以保证经过所述加热器的高放废液在进入所述蒸发浓缩脱硝釜后才开始沸腾蒸发。Further, in an embodiment of the present invention, the height of the back pressure superheating zone is greater than the theoretical value, so as to ensure that the high-level waste liquid passing through the heater starts to boil and evaporate after entering the evaporative concentration and denitration kettle.

本发明附加的方面和优点将在下面的描述中部分给出,部分将从下面的描述中变得明显,或通过本发明的实践了解到。Additional aspects and advantages of the present invention will be set forth, in part, from the following description, and in part will be apparent from the following description, or may be learned by practice of the invention.

附图说明Description of drawings

本发明上述的和/或附加的方面和优点从下面结合附图对实施例的描述中将变得明显和容易理解,其中:The above and/or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of embodiments taken in conjunction with the accompanying drawings, wherein:

图1为根据本发明一个实施例的外循环式高放废液蒸发浓缩脱硝器的总体结构示意图;1 is a schematic diagram of the overall structure of an external circulation type high-level waste liquid evaporative concentration denitrifier according to an embodiment of the present invention;

图2为根据本发明一个实施例的蒸发浓缩脱硝器内部结构和原理示意图;2 is a schematic diagram of the internal structure and principle of an evaporative concentration denitrifier according to an embodiment of the present invention;

图3为根据本发明一个具体实施例的高放废液蒸发浓缩脱硝流程图。FIG. 3 is a flow chart of high-level waste liquid evaporation concentration and denitration according to a specific embodiment of the present invention.

附图标记说明:Description of reference numbers:

1-蒸发浓缩脱硝釜,2-外部循环管;3-加热器;4-背压过热区;5-除沫净化塔;6-旋风分离器;7-蒸发浓缩脱硝区;8-隔板;9-溢流区;10-脱硝剂分布器;11-背压过热区出口;12-外部循环管入口;13-蒸发浓缩脱硝釜排料口;14-旋风分离器进口;15-旋风分离器液封;16-旋风分离器水相排出口;A-蒸发浓缩脱硝区液位;B-脱硝反应区;C-脱硝反应产生的沉淀。1- Evaporation concentration and denitrification kettle, 2- External circulation pipe; 3- Heater; 4- Back pressure superheat zone; 5- Defoaming purification tower; 6- Cyclone separator; 7- Evaporation concentration and denitrification zone; 8- Clapboard; 9- Overflow area; 10- Denitration agent distributor; 11- Outlet of back pressure superheating area; 12- Inlet of external circulation pipe; 13- Evaporation concentration and denitrification kettle discharge port; 14- Inlet of cyclone separator; 15- Cyclone separator Liquid seal; 16-water phase discharge port of cyclone separator; A-liquid level of evaporation concentration and denitrification zone; B-denitration reaction zone; C-precipitation produced by denitration reaction.

具体实施方式Detailed ways

下面详细描述本发明的实施例,所述实施例的示例在附图中示出,其中自始至终相同或类似的标号表示相同或类似的元件或具有相同或类似功能的元件。下面通过参考附图描述的实施例是示例性的,旨在用于解释本发明,而不能理解为对本发明的限制。The following describes in detail the embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals refer to the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary, and are intended to explain the present invention and should not be construed as limiting the present invention.

下面参照附图描述根据本发明实施例提出的外循环式高放废液蒸发浓缩脱硝器。The external circulation type high-level waste liquid evaporative concentration and denitrifier proposed according to the embodiment of the present invention will be described below with reference to the accompanying drawings.

图1是本发明一个实施例的外循环式高放废液蒸发浓缩脱硝器的结构示意图。FIG. 1 is a schematic structural diagram of an external circulation type high-level waste liquid evaporation concentration denitrator according to an embodiment of the present invention.

如图1所示,该蒸发浓缩脱硝器包括:蒸发浓缩脱硝釜1、外部循环管2、加热器3,背压过热区4和除沫净化塔5。As shown in FIG. 1 , the evaporative concentration denitrification device includes: an evaporative concentration denitrification kettle 1 , an external circulation pipe 2 , a heater 3 , a back pressure superheating zone 4 and a defoaming purification tower 5 .

其中,如图2所示,蒸发浓缩脱硝釜1一侧底部开口12与外部循环管2相连,外部循环管2在U型弯转后与加热器3相连,加热器3上部与具有预设高度的背压过热区4相连,背压过热区4与蒸发浓缩脱硝釜侧面开口11相连,蒸发浓缩脱硝釜1顶部与除沫净化塔5相连。Among them, as shown in FIG. 2 , the bottom opening 12 of the evaporation concentration denitration kettle 1 is connected to the external circulation pipe 2, and the external circulation pipe 2 is connected to the heater 3 after U-shaped bending, and the upper part of the heater 3 has a preset height. The back pressure superheating zone 4 is connected with the back pressure superheating zone 4, which is connected with the side opening 11 of the evaporation concentration denitration kettle, and the top of the evaporation concentration denitration kettle 1 is connected with the defoaming purification tower 5.

进一步地,蒸发浓缩脱硝釜1包括旋风分离器6、蒸发浓缩脱硝区7、隔板8、溢流区9和脱硝剂分布器10,具体地,旋风分离器6设置在蒸发浓缩脱硝釜1的内部顶部,蒸发浓缩脱硝釜1侧面通过隔板8形成与蒸发浓缩脱硝区7相隔离的溢流区9,溢流区9底部设有开口12与外循环管2相连,脱硝剂分布器10设置在蒸发浓缩脱硝釜1内的底部。Further, the evaporative concentration and denitration kettle 1 includes a cyclone 6, an evaporative concentration and denitration zone 7, a baffle 8, an overflow zone 9 and a denitration agent distributor 10. Inside the top, the side of the evaporation concentration denitration kettle 1 forms an overflow area 9 isolated from the evaporation concentration denitration area 7 through the partition plate 8, and the bottom of the overflow area 9 is provided with an opening 12 to be connected with the outer circulation pipe 2, and the denitration agent distributor 10 is provided. At the bottom of the evaporative concentration denitration kettle 1.

进一步地,加热区3通过背压过热区4与蒸发浓缩脱硝区7相分隔,蒸发浓缩脱硝区7与外循环管2通过溢流区9相分隔,蒸发浓缩脱硝区7通过旋风分离器6与顶部除沫净化塔5相分隔。Further, the heating zone 3 is separated from the evaporation concentration and denitrification zone 7 by the back pressure superheat zone 4, the evaporation concentration denitration zone 7 and the external circulation pipe 2 are separated by the overflow zone 9, and the evaporation concentration denitration zone 7 is separated from the cyclone separator 6 and The top defoaming purification tower 5 is separated.

需要说明的是,蒸发浓缩脱硝区7的液位A超过隔板8的高度,可以溢流入溢流区9;蒸发浓缩脱硝过程中产生的沉淀C由于重力作用不会进入溢流区9;外循环管2中流速足够快,可防止沉淀在其中沉积;背压过热区4高度需足够高,要大于理论值,进而可以保证经过加热器3的高放废液在进入蒸发浓缩脱硝区7后才开始沸腾蒸发。It should be noted that the liquid level A of the evaporation concentration and denitrification zone 7 exceeds the height of the partition plate 8 and can overflow into the overflow zone 9; the precipitate C generated during the evaporation concentration and denitration process will not enter the overflow zone 9 due to the action of gravity; The flow velocity in the circulation pipe 2 is fast enough to prevent the sediment from depositing in it; the height of the back pressure superheating zone 4 must be high enough, which is greater than the theoretical value, so as to ensure that the high-level waste liquid passing through the heater 3 enters the evaporation concentration and denitrification zone 7. Just started to boil and evaporate.

可以理解的是,本发明实施例的外循环式高放废液蒸发浓缩脱硝器的工作流程为:将高放废液放入蒸发浓缩脱硝釜1中,使用加热器3对高放废液进行加热,被加热的高放废液经过背压过热区后,在蒸发浓缩脱硝釜1内沸腾蒸发,脱硝剂分布器10释放脱硝剂,发生脱硝反应,沸腾过程中蒸发产生大量水蒸气、产生的氮氧化物气体会夹带部分小液滴、泡沫进入旋风分离器6,密度大的小液滴在分离后重新回到釜内,水蒸汽、氮氧化物气体和少量泡沫进入顶部的除沫净化塔5,除沫净化塔5进行彻底除沫和挥发性核素的回收,蒸发浓缩脱硝过程的持续进行,但金属元素的浓度不断增大,酸度较低,则会有部分金属元素形成沉淀,沉积在蒸发浓缩脱硝釜1底部,其中,控制外部循环管2流速足够快,防止沉淀在外部循环管2中沉积。It can be understood that the working process of the external circulation type high-level waste liquid evaporative concentration and denitrification device in the embodiment of the present invention is: put the high-level waste liquid into the evaporation concentration and denitration kettle 1, and use the heater 3 to carry out the high-level waste liquid. After heating, the heated high-level waste liquid passes through the back pressure overheating zone, and boils and evaporates in the evaporative concentration and denitration kettle 1. The denitration agent distributor 10 releases the denitration agent, and a denitration reaction occurs. The nitrogen oxide gas will entrain some small droplets and foam into the cyclone separator 6, and the small droplets with high density will return to the kettle after separation, and the water vapor, nitrogen oxide gas and a small amount of foam will enter the top defoaming purification tower 5. The defoaming purification tower 5 performs thorough defoaming and recovery of volatile nuclides, and the process of evaporative concentration and denitrification continues, but the concentration of metal elements continues to increase and the acidity is low, and some metal elements will form precipitation and deposition. At the bottom of the evaporative concentration and denitration kettle 1 , the flow rate of the external circulation pipe 2 is controlled to be fast enough to prevent sediment from depositing in the external circulation pipe 2 .

下面结合一个具体实施例对本发明实施例的外循环式高放废液蒸发浓缩脱硝器进一步说明。The following is a further description of the external circulation type high-level waste liquid evaporative concentration denitrifier in accordance with an embodiment of the present invention with reference to a specific embodiment.

外循环式高放废液蒸发浓缩脱硝器中的蒸发浓缩脱硝釜1内径为410mm,中间直段高度为1770mm,下部渐缩段高度为370mm,外部循环管内径为60mm,加热器3采用列管式蒸汽加热器,换热面积为3.2m2,背压过热区4高度为2.5m。蒸发浓缩脱硝区7底部设置脱硝剂甲醛分布器10,侧面靠近外循环管2进口12一侧通过高度为610mm的隔板8设置溢流区9,顶部设置旋风分离器6。蒸发浓缩脱硝釜1顶部连接有除沫净化塔5,内径为60mm,高度为990mm,内部设置有5块筛板。The inner diameter of the evaporative concentration and denitrification kettle 1 in the external circulation type high-level waste liquid evaporative concentration and denitrification device is 410mm, the height of the middle straight section is 1770mm, the height of the lower tapered section is 370mm, the inner diameter of the external circulation pipe is 60mm, and the heater 3 adopts a column tube. type steam heater, the heat exchange area is 3.2m 2 , and the height of the back pressure superheating zone 4 is 2.5m. Evaporation, concentration and denitrification zone 7 is provided with a denitration agent formaldehyde distributor 10 at the bottom, an overflow zone 9 is provided on the side close to the inlet 12 of the outer circulation pipe 2 through a partition 8 with a height of 610 mm, and a cyclone separator 6 is provided at the top. The top of the evaporative concentration and denitration kettle 1 is connected with a defoaming purification tower 5, the inner diameter is 60mm, the height is 990mm, and 5 sieve plates are arranged inside.

如图3所示,以上述的外循环式高放废液蒸发浓缩脱硝器为例,具体地高放废液蒸发浓缩脱硝流程为:As shown in Figure 3, taking the above-mentioned external circulation type high-level waste liquid evaporation concentration and denitrification device as an example, specifically the high-level waste liquid evaporation concentration and denitrification process is:

采用37-40%的甲醛溶液作为脱硝剂,在进料量为10L/h、105℃的条件下,连续地将含有16.5g-NaNO3/L、0.45g-Cs/L、0.44g-Ce/L的2.5mol/L硝酸溶液中的硝酸浓度蒸发浓缩脱硝至1.0mol/L。在脱硝反应区B发生如下的脱硝反应:Using 37-40% formaldehyde solution as denitrification agent, under the condition of feeding amount of 10L/h and 105℃, continuously containing 16.5g-NaNO 3 /L, 0.45g-Cs/L, 0.44g-Ce The nitric acid concentration in the 2.5mol/L nitric acid solution of /L was evaporated, concentrated and denitrified to 1.0mol/L. The following denitration reaction occurs in the denitration reaction zone B:

Figure BDA0002465785200000041
Figure BDA0002465785200000041

蒸发导致大量水份蒸发为水蒸气,导致料液被浓缩,同时上述脱硝反应不断降低硝酸浓度,保证酸度不会过高,防止设备严重腐蚀。生成的水蒸气、产生的氮氧化物气体会夹带部分小液滴、泡沫进入旋风分离器6。在旋风分离器6中,密度较大的小液滴被甩到外壁并向下通过液封15、排出口16重新回到釜内,其中,泡沫由于外面包裹的液膜被破坏同时起到了消除泡沫的效果,而蒸汽、气体和少量泡沫则进入顶部的除沫净化塔5。除沫净化塔顶部连接有蒸汽冷凝器,塔内上行的汽体与塔顶回流的冷凝液接触实现彻底的除沫和挥发性核素的回收。从蒸汽冷凝液排出的不凝气体则进一步进入后面的尾气吸收环节,对其中的氮氧化物进行吸收,排出的冷凝液则进入储罐进行回收。随着蒸发浓缩脱硝的不断进行,蒸发浓缩脱硝釜1中溶液中的酸度虽然始终保持在1.0mol/L左右,但金属元素的浓度不断增大,且由于酸度较低,会有部分金属元素形成沉淀沉积在脱硝区B下部的渐缩段中。当溶液中金属氧化物总浓度达到200g/L时,停止进料和蒸发浓缩脱硝操作,并通过底部排料口13将料液(含沉淀)排出。在排料完毕后再重新进行蒸发浓缩脱硝操作。按照上面的条件和操作步骤操作,最终完成蒸发浓缩脱硝的料液酸度在0.9~1.1mol-HNO3/L,产生的沉淀没有发现在外循环管2和加热器3中沉积并可由蒸发浓缩脱硝釜1底部排料口13顺利排出,没有发生明显的泡沫溢出事故。Evaporation causes a large amount of water to evaporate into water vapor, resulting in the concentration of the feed liquid. At the same time, the above denitration reaction continuously reduces the concentration of nitric acid to ensure that the acidity will not be too high and prevent serious corrosion of equipment. The generated water vapor and the generated nitrogen oxide gas will entrain some small droplets and foam into the cyclone separator 6 . In the cyclone separator 6, the denser droplets are thrown to the outer wall and go down through the liquid seal 15 and the discharge port 16 to return to the kettle, where the foam is destroyed due to the liquid film wrapped around it and eliminates the The effect of foam, and steam, gas and a small amount of foam enter the top of the defoaming purification tower 5. The top of the defoaming purification tower is connected with a steam condenser, and the upward vapor in the tower contacts the condensate refluxing at the top of the tower to achieve complete defoaming and recovery of volatile nuclides. The non-condensable gas discharged from the steam condensate will further enter the tail gas absorption link to absorb the nitrogen oxides therein, and the discharged condensate will enter the storage tank for recovery. With the continuous progress of evaporative concentration and denitrification, although the acidity of the solution in the evaporative concentration and denitrification kettle 1 is always maintained at about 1.0mol/L, the concentration of metal elements continues to increase, and due to the low acidity, some metal elements may form The precipitation is deposited in the tapered section in the lower part of the denitrification zone B. When the total concentration of metal oxides in the solution reaches 200g/L, the feeding and evaporative concentration and denitration operations are stopped, and the feed liquid (including the precipitate) is discharged through the bottom discharge port 13. After the discharge is completed, the evaporative concentration and denitrification operation is performed again. According to the above conditions and operation steps, the acidity of the feed liquid that finally completes the evaporative concentration and denitrification is 0.9-1.1 mol-HNO 3 /L, and the resulting precipitate is not found to be deposited in the outer circulation pipe 2 and the heater 3 and can be obtained by the evaporative concentration and denitrification kettle. 1. The bottom discharge port 13 is discharged smoothly, and there is no obvious foam overflow accident.

上述实施例的实验结果表明:本发明实施例可有效的解决高放废液蒸发浓缩脱硝过程中的沉淀生成和爆沸问题。The experimental results of the above embodiments show that the embodiments of the present invention can effectively solve the problems of precipitation formation and bumping in the process of high-level waste liquid evaporation, concentration and denitration.

根据本发明实施例提出的外循环式高放废液蒸发浓缩脱硝器,通过采用加热区和蒸发浓缩脱硝区相分离、蒸发浓缩脱硝区和外循环管入口相分隔、外循环管中流速足够大的策略,使蒸发浓缩脱硝区产生的沉淀不会大量进入并沉积在加热室中,同时,采用旋风分离器对进入除沫净化塔前的蒸汽进行处理,有效分离其中的小液滴并破除泡沫,可以有效地防止爆沸发生,尤其适用于产生沉淀和/或易爆沸的高放废液的蒸发浓缩脱硝处理,可广泛应用放射性核化工领域。The external circulation type high-level waste liquid evaporative concentration and denitrification device proposed according to the embodiment of the present invention adopts the phase separation between the heating zone and the evaporative concentration and denitrification zone, the separation between the evaporative concentration and denitrification zone and the entrance of the external circulation pipe, and the flow velocity in the external circulation pipe is large enough. The strategy of the evaporative concentration and denitrification zone prevents a large amount of precipitates from entering and depositing in the heating chamber. At the same time, a cyclone separator is used to treat the steam before entering the defoaming purification tower to effectively separate the small droplets and break the foam. , can effectively prevent the occurrence of bumping, especially suitable for the evaporative concentration and denitration treatment of high-level radioactive waste liquids that produce precipitation and/or bumping, and can be widely used in the field of radionuclear chemical industry.

此外,术语“第一”、“第二”仅用于描述目的,而不能理解为指示或暗示相对重要性或者隐含指明所指示的技术特征的数量。由此,限定有“第一”、“第二”的特征可以明示或者隐含地包括至少一个该特征。在本发明的描述中,“多个”的含义是至少两个,例如两个,三个等,除非另有明确具体的限定。In addition, the terms "first" and "second" are only used for descriptive purposes, and should not be construed as indicating or implying relative importance or implying the number of indicated technical features. Thus, a feature delimited with "first", "second" may expressly or implicitly include at least one of that feature. In the description of the present invention, "plurality" means at least two, such as two, three, etc., unless otherwise expressly and specifically defined.

在本说明书的描述中,参考术语“一个实施例”、“一些实施例”、“示例”、“具体示例”、或“一些示例”等的描述意指结合该实施例或示例描述的具体特征、结构、材料或者特点包含于本发明的至少一个实施例或示例中。在本说明书中,对上述术语的示意性表述不必须针对的是相同的实施例或示例。而且,描述的具体特征、结构、材料或者特点可以在任一个或多个实施例或示例中以合适的方式结合。此外,在不相互矛盾的情况下,本领域的技术人员可以将本说明书中描述的不同实施例或示例以及不同实施例或示例的特征进行结合和组合。In the description of this specification, description with reference to the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples", etc., mean specific features described in connection with the embodiment or example , structure, material or feature is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the particular features, structures, materials or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, those skilled in the art may combine and combine the different embodiments or examples described in this specification, as well as the features of the different embodiments or examples, without conflicting each other.

尽管上面已经示出和描述了本发明的实施例,可以理解的是,上述实施例是示例性的,不能理解为对本发明的限制,本领域的普通技术人员在本发明的范围内可以对上述实施例进行变化、修改、替换和变型。Although the embodiments of the present invention have been shown and described above, it should be understood that the above-mentioned embodiments are exemplary and should not be construed as limiting the present invention. Embodiments are subject to variations, modifications, substitutions and variations.

Claims (5)

1.一种外循环式高放废液蒸发浓缩脱硝器,其特征在于,包括:蒸发浓缩脱硝釜、外部循环管、加热器,背压过热区和除沫净化塔,其中,1. an external circulation type high-level waste liquid evaporation concentration denitrification device is characterized in that, comprising: evaporation concentration denitration still, external circulation pipe, heater, back pressure superheat zone and defoaming purification tower, wherein, 所述蒸发浓缩脱硝釜的一侧底部开口与所述外循环管相连,所述外循环管与所述加热器相连,所述加热器上部与所述背压过热区相连,所述背压过热区与所述蒸发浓缩脱硝釜的另一侧面开口相连,所述蒸发浓缩脱硝釜顶部与所述除沫净化塔相连;The bottom opening on one side of the evaporation, concentration and denitration kettle is connected with the outer circulation pipe, the outer circulation pipe is connected with the heater, the upper part of the heater is connected with the back pressure superheating zone, and the back pressure superheating zone is connected The area is connected with the other side opening of the evaporation concentration and denitration still, and the top of the evaporation concentration and denitration still is connected with the defoaming purification tower; 所述蒸发浓缩脱硝釜包括脱硝剂分布器、隔板、溢流区、蒸发浓缩脱硝区和旋风分离器,其中,所述脱硝剂分布器设置在所述蒸发浓缩脱硝釜的底部,所述旋风分离器设置在所述蒸发浓缩脱硝釜的顶部,所述蒸发浓缩脱硝釜侧面靠近底部开口一侧通过所述隔板形成与所述蒸发浓缩脱硝区相隔离的溢流区。The evaporative concentration and denitration kettle includes a denitration agent distributor, a baffle, an overflow area, an evaporative concentration and denitration zone and a cyclone separator, wherein the denitration agent distributor is arranged at the bottom of the evaporative concentration and denitration kettle, and the cyclone The separator is arranged on the top of the evaporative concentration and denitration kettle, and the side of the evaporative concentration and denitration kettle is close to the bottom opening to form an overflow area isolated from the evaporative concentration and denitration zone through the separator. 2.根据权利要求1所述的外循环式高放废液蒸发浓缩脱硝器,其特征在于,所述蒸发浓缩脱硝釜中的液体需高于所述隔板,使液体溢流入所述溢流区。2. The external circulation type high-level waste liquid evaporative concentration and denitrification device according to claim 1 is characterized in that, the liquid in the evaporative concentration and denitrification still needs to be higher than the partition plate, so that the liquid overflows into the overflow Area. 3.根据权利要求1所述的外循环式高放废液蒸发浓缩脱硝器,其特征在于,蒸发浓缩脱硝过程中产生的沉淀受重力作用不会进入所述溢流区。3 . The external circulation type high-level waste liquid evaporative concentration and denitrification device according to claim 1 , wherein the sediment produced in the evaporative concentration and denitrification process will not enter the overflow area under the action of gravity. 4 . 4.根据权利要求1所述的外循环式高放废液蒸发浓缩脱硝器,其特征在于,所述加热器与所述蒸发浓缩脱硝釜通过所述背压过热区相分隔,所述蒸发浓缩脱硝釜与所述外部循环管通过溢流区相分隔,所述蒸发浓缩脱硝釜与所述除沫净化塔通过旋风分离器相分隔。4. The external circulation type high-level waste liquid evaporation concentration denitrification device according to claim 1, is characterized in that, the heater and the evaporation concentration denitration still are separated by the back pressure superheat zone, and the evaporation concentration The denitration kettle and the external circulation pipe are separated by an overflow area, and the evaporation concentration denitration kettle and the defoaming purification tower are separated by a cyclone separator. 5.根据权利要求1所述的外循环式高放废液蒸发浓缩脱硝器,其特征在于,所述背压过热区的高度大于理论值,以保证经过所述加热器的高放废液在进入所述蒸发浓缩脱硝釜后才开始沸腾蒸发。5. The external circulation type high-level waste liquid evaporative concentration denitrifier according to claim 1, characterized in that, the height of the back pressure superheat zone is greater than the theoretical value, to ensure that the high-level waste liquid passing through the heater is at Boiling evaporation starts only after entering the evaporation concentration denitration kettle.
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