CN111883279A - Partitioned heating method for treating radioactive waste liquid by rotary calcining furnace - Google Patents

Abstract

The invention provides a subarea heating method for treating radioactive waste liquid by a rotary calciner, which comprises the following steps: (1) starting the rotary calcining furnace, and setting the rotation speed and the inclination angle of the rotary calcining furnace; (2) the temperature heating zone is divided into two sections, and the first zone and the second zone respectively occupy the furnace body lengths of 2/4-3/4 and 2/4-1/4; (3) after the feeding is stopped, the heating mechanism is closed; (4) and after the temperature of the furnace tube is reduced to the room temperature, the main power supply is closed. The zoned heating method for treating the radioactive waste liquid by the rotary calciner provided by the invention can improve the treatment capacity on the basis of successfully finishing the evaporation/calcination treatment of the radioactive waste liquid.

Description

Partitioned heating method for treating radioactive waste liquid by rotary calcining furnace

Technical Field

The invention belongs to the technical field of radioactive waste liquid treatment, and particularly relates to a partition heating method for treating radioactive waste liquid by a rotary calcining furnace.

Background

The technical route of high-level radioactive liquid waste treatment is determined to be a glass curing technology in China at present. The cold crucible glass solidification technology is a novel glass solidification technology for radioactive waste treatment in the world at present, and high frequency (10) is generated by utilizing a power supply⁵～10⁶Hz) current, and then the current is converted into electromagnetic current through the induction coil to permeate into the material to be heated, so that eddy current is formed to generate heat, and the material to be treated is directly heated and melted. The cold crucible glass solidification device mainly comprises a high-frequency induction power supply, a cold crucible furnace body and other auxiliary systems, wherein the cold crucible furnace body is a container (the shape of the container is mainly circular or oval) formed by metal arc blocks or tubes filled with cooling water, the cooling water is continuously filled into the metal tube during working, the temperature of a melt in the crucible can reach more than 2000 ℃, but the crucible wall still keeps a lower temperature (generally less than 200 ℃) so that a layer of solid glass shell (cold wall) with the thickness of 2-3 cm is formed in a low-temperature region of the furnace body close to a sleeve in the operation process, and the cold crucible furnace body is called as a cold crucible. Compared with other glass solidification technologies, the cold crucible technology has the main advantages of high melting temperature, wide waste treatment type, long service life (more than 20a) of the melting furnace and easy decommissioning.

The cold crucible glass curing technology has the advantages that the treatment temperature is high, the service life of a smelting furnace is long and the like which cannot be compared with other curing technologies, is a more advanced glass curing technology, is more suitable for the requirement of long-term continuous operation of a post-treatment plant, is determined as the development direction of the high-level waste liquid glass curing technology in future in China, and is listed as one of ten bottleneck technologies in the nuclear industry. The spent fuel reprocessing demonstration factory of China also takes the technology as one of the alternative technologies of high-level waste liquid glass curing treatment.

A relatively complete industrial system is basically established in the front stage of the nuclear fuel cycle in China, but the rear stage (including high-level waste treatment and disposal and the like) of the nuclear fuel cycle cannot form autonomous industrial production capacity so far. The high-level radioactive waste liquid glass curing treatment technology covers the specialties and subjects of nuclear chemical industry, radiochemistry, high-temperature chemistry, mechanical design and manufacturing, silicate material science, automatic control, electromagnetism and the like, is high-tech crystals and reflects the scientific and industrial level of a country. Because of the strong radioactivity and high temperature operation, the requirements on materials and equipment are high, the requirements on the reliability, stability and safety of the equipment are far higher than the requirements of the common industry, and more manpower and material resources are required to be invested. The glass curing technology is a link with great technical difficulty in closed circulation of nuclear fuel, and the glass curing of high-level radioactive waste liquid becomes a weak link in the circulation of the nuclear fuel in China due to insufficient technical storage for many years. The two-step cold crucible glass solidification related technology is about to be further broken through and developed.

At present, the countries in the world in which the development of the cold crucible glass solidification technology is performed are france, uk, usa, india, korea, china, and the like. The French high-level radioactive waste liquid cold crucible glass solidification technology develops fastest, and the two-step cold crucible glass solidification industrial operation production of U-Mo high-level radioactive waste is realized in 2012 and 2013. Because the cold crucible furnace has a small volume, a rotary calciner is usually equipped to convert the high-level radioactive waste liquid into powder, so the main key equipment of the cold crucible glass solidification technology comprises the rotary calciner and a cold crucible body. At present, the rotary calcining furnace in France and England has the longest length of 3250mm and the diameter of 250mm, and is heated in four regions. The length of the Indian furnace is 2000mm, and the heating is carried out in three zones. In the four-zone and three-zone heating operation, four zones or three zones need to be respectively set with temperature rise programs, and the treatment capacity of the rotary calcining furnace is limited due to the zone length. At present, no zoned heating mode of a rotary calciner for radioactive waste liquid treatment is reported in China.

Disclosure of Invention

Aiming at the defects in the prior art, the invention provides a subarea heating method for treating radioactive waste liquid by a rotary calciner, which can improve the treatment capacity on the basis of successfully finishing the evaporation/calcination treatment of the radioactive waste liquid.

In order to achieve the above purposes, the invention adopts a technical scheme that: a method for rotary calciner multipoint thermometry for radioactive liquid waste treatment, the method comprising the steps of:

(1) starting the rotary calcining furnace, and setting the rotation speed and the inclination angle of the rotary calcining furnace;

(2) the temperature heating zone is divided into two sections, and the first zone and the second zone respectively occupy the furnace body lengths of 5/8-3/4 and 3/8-1/4;

(3) after the feeding is stopped, the heating mechanism is closed;

(4) and after the temperature of the furnace tube is reduced to the room temperature, the main power supply is closed.

Further, the rotation speed of the rotary calcining furnace in the step (1) is 20-30rpm, and the inclination angle is 2-5%.

Further, the step (2) further comprises:

the temperature of the first zone and the second zone is respectively raised to the set temperature ranges of 780-850 ℃ and 500-600 ℃.

Further, the stop of the feeding in the step (3) means that the feeding unit is closed and the calcined material is not discharged.

The invention has the following effects: (1) the evaporation/calcination treatment process of the radioactive waste liquid can be smoothly completed; (2) the operation process is simple to control because the number of the partitions is two; (3) the processing capacity is improved, and the original four-section partition processing capacity can be improved by at least 30 percent; (4) the heating mode has simple process and is convenient for industrial production.

Drawings

FIG. 1 is a schematic view showing the relationship between the temperature distribution in the furnace and the flow rate during four-zone heating.

Detailed Description

In order to make the technical problems solved, the technical solutions adopted, and the technical effects achieved by the present invention clearer, the technical solutions of the embodiments of the present invention will be further described in detail with reference to the accompanying drawings. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.

The invention provides a method for multipoint temperature measurement of a rotary calcining furnace for radioactive waste liquid treatment, which comprises the following steps:

(1) starting the rotary calcining furnace, and setting the rotation speed and the inclination angle of the rotary calcining furnace;

it should be noted that step (1) also includes adjusting other parts of the rotary calciner to set process parameters, such as also adjusting the heating temperature and the flow rate of the fed simulation waste liquid.

In a specific embodiment, the calciner rotation rate is 20-30rpm with an inclination angle of 2-5%.

(2) The temperature heating zone is divided into two sections, and the first zone and the second zone respectively occupy the furnace body lengths of 5/8-3/4 and 3/8-1/4;

in one specific embodiment, the side close to the mouth of the rotary calciner is a first zone which occupies the furnace body length of 5/8-3/4.

The temperature of the first zone and the second zone is respectively raised to the set temperature ranges of 780-850 ℃ and 500-600 ℃.

(3) After the feeding is stopped, the heating mechanism is closed, and the rotation rate of the furnace body is reduced;

in a specific embodiment, the feeding unit is closed, the calcined substance is not discharged, the heating mechanism is closed, and the rotation rate of the furnace body is reduced.

(4) And after the temperature of the furnace tube is reduced to the room temperature, the main power supply is closed.

In a specific embodiment, the temperature of the furnace tube is reduced to the room temperature, which means about 30 ℃

The following description is given with reference to specific examples, and a zone heating method for treating radioactive waste liquid by a rotary calciner specifically includes the following steps:

and starting the rotary calcining furnace to set the rotation rate, the inclination angle and the heating temperature of the furnace body, and feeding the simulated waste liquid. Taking a rotary calcining furnace with a heating zone of about 3 meters and an inner diameter of 250mm as an example, the first zone length is about 5/8-3/4(1.9-2.4 meters), the temperature is about 780-850 ℃, the second zone length is about 3/8-1/4(1.1-0.6 meters), and the temperature is about 500-600 ℃. And feeding the waste liquid for initial 30L/h, and after the waste liquid is stabilized, increasing the speed of the waste liquid to 40L/h or 50L/h, so that a calcined product meeting the requirements of the subsequent process can be obtained from the tail end of the calciner.

Referring to fig. 1, fig. 1 is a schematic diagram showing the relationship between the temperature distribution in the furnace and the flow rate during four-zone heating. In the figure, the line a is the feeding amount of 30L/h, and the line b is the feeding amount of 40L/h. FIG. 1 shows the four-zone heating, in which the lowest temperature was around the position 4/12 in the furnace length when the amount of waste liquid fed was 30L/h, and around the position 6/12 in the furnace length when the amount of waste liquid was increased to 40L/h. Because the temperature of the second two areas is higher, the evaporation process of the first two areas cannot be completed in time when the temperature is increased, and therefore the highest processing capacity is about 40L/h when the four areas are heated. After the temperature partition is changed into two partitions, the first partition is 3/4 length of the total heating length of the furnace tube, the lowest temperature can be shifted to about 8/12 position of the furnace body length after feeding, namely the waste liquid amount can be increased to more than 50L/h, and the maximum treatment capacity of the rotary calciner for treating the waste liquid is improved by about 30 percent.

Different from the prior art, the invention provides a subarea heating method for treating radioactive waste liquid by a rotary calciner, which comprises the following steps: (1) the evaporation/calcination treatment process of the radioactive waste liquid can be smoothly completed; (2) the operation process is simple to control because the number of the partitions is two; (3) the processing capacity is improved, and the original four-section partition processing capacity can be improved by at least 30 percent; (4) the heating mode has simple process and is convenient for industrial production.

It will be appreciated by persons skilled in the art that the method of the present invention is not limited to the examples described in the specific embodiments, and that the above detailed description is for the purpose of illustrating the invention only and is not intended to limit the invention. Other embodiments will be apparent to those skilled in the art from the following detailed description, which is intended to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.

Claims (4)

1. A zoned heating method for a rotary calciner to treat radioactive liquid waste, characterised in that the method comprises the steps of:

(1) starting the rotary calcining furnace, and setting the rotation speed and the inclination angle of the rotary calcining furnace;

(2) the temperature heating zone is divided into two sections, and the first zone and the second zone respectively occupy the furnace body lengths of 5/8-3/4 and 3/8-1/4;

(3) after the feeding is stopped, the heating mechanism is closed;

(4) and after the temperature of the furnace tube is reduced to the room temperature, the main power supply is closed.

2. The process of claim 1, wherein the rotary calciner rotation rate in step (1) is 20-30rpm with an inclination angle of 2-5%.

3. The method of claim 1, wherein step (2) further comprises:

the temperature of the first zone and the second zone is respectively raised to the set temperature ranges of 780-850 ℃ and 500-600 ℃.

4. The method according to claim 1, wherein the stop of the feeding in step (3) means that the feeding unit is closed and the calcined material is not discharged.

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