JPH0644962B2 - Centrifugal thin film dryer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a centrifuge which heats and dries radioactive waste liquid discharged from a nuclear power plant or the like to form a thin film, and disperses it into a vapor component and a non-vapor component. Regarding thin film dryers.

(Prior Art) Generally, in a nuclear power plant such as a nuclear power plant,
A centrifugal thin film dryer is installed in order to efficiently treat the radioactive liquid waste discharged therefrom.

In this centrifugal thin film dryer, a rotary shaft equipped with rotary blades is arranged in the cylinder, and the waste liquid is introduced into the cylinder while the rotary shaft is rotated, and is heated and evaporated to leave the evaporation residue on the inner surface of the cylinder. A thin film is formed, vapor is discharged, and evaporation residue is scraped off by the rotary blade.The supply amount determined according to the property of the waste liquid supplied and the processing purpose, and the rotation speed of the rotary shaft are always constant. Is being driven as.

In the centrifugal thin film dryer with the above-mentioned configuration, various operational measures have been taken for waste liquid treatment during steady operation, and good results have been obtained, but at non-steady state, for example, preparation before the start of waste liquid treatment. Regarding the process, the actual condition is that no special measures have been taken, and the dryer itself was only warmed up by a slightly external heating method. Here, the external heating method is a method in which heating steam is circulated through a heating jacket of a tubular body of a centrifugal thin film dryer to heat and dry the dryer from the outside.

(Problems to be Solved by the Invention) When this external heating method is adopted, a temperature difference occurs between the cylindrical body and the internal rotating shaft, and the temperature difference causes thermal deformation of the cylindrical body and the rotating shaft. Because of different degrees, it is not possible to maintain a predetermined clearance (gap between the inner peripheral surface of the cylindrical body and the rotary blade of the main shaft), and there is a risk of contact.

Moreover, the clearance between the processable cylinder and the rotary blade is the fifth
As shown in the figure, it takes 2 hours for a small device and 4-6 hours for a large device, because it takes time for the rotor blades to reach a predetermined temperature. In the case of a large-sized apparatus whose time is about 10 hours, nearly half of the operating time is spent on warm-up operation, which is a problem in improving the operation rate of waste liquid treatment.

Also, regarding the management of the gap between the cylinder and the rotary shaft, conventionally, only a fixed interval can be set, and when several kinds of waste liquids are processed by one centrifugal thin film dryer, It was impossible to set the gap according to the property. Therefore, there is a problem that even if the optimum setting is made for a waste liquid whose viscosity increases during the drying process such as a concentrated waste liquid, it is not optimum for a waste liquid having a solid substance containing water such as a granular resin waste liquid. .

The present invention has been made to eliminate the above-mentioned drawbacks in the prior art, and provides a centrifugal thin film dryer that enables stable treatment of various waste liquids and can improve the operation rate. With the goal.

[Structure of the Invention] (Means for Solving the Problems) The centrifugal thin film dryer according to the present invention has a rotary shaft having rotary blades arranged in the cylinder, and waste liquid in the cylinder while the rotary shaft is rotated. To form a thin film on the heat transfer surface inside the cylinder,
In a centrifugal thin film dryer configured to heat and evaporate to discharge steam and to evaporate residue by scraping with the above-mentioned rotary blades, the structure is characterized in that heating steam is introduced into the rotary shaft to heat. Is.

(Operation) In the centrifugal thin film dryer configured as described above, the temperature of the tubular body and that of the rotary shaft can be made the same by heating not only from the outside of the tubular body but also from the inside of the rotary shaft. Since the rotary shaft is heated directly, the warm-up time is also very short.

Further, since the heating steam temperature of the cylinder and the rotating shaft is controlled, the clearance between the cylinder and the rotating shaft can be arbitrarily changed and set according to the concentration of the waste liquid even during the operation of the centrifugal thin film dryer. be able to.

(Example) Hereinafter, the Example of this invention is described based on drawing.

FIG. 1 is a longitudinal sectional view showing an embodiment of a centrifugal thin film dryer of the present invention, and FIG. 2 is a schematic view of an example of a waste liquid treatment apparatus to which the centrifugal thin film dryer of the present invention is applied.

In these figures, the centrifugal thin film dryer 1 has a double-structured cylindrical body 2 composed of an inner cylinder 2a and a jacket 2b,
A hollow rotating shaft 3 is rotatably arranged.

A steam inlet 4 is provided above the rotary shaft 3 so that the heated steam flowing from the main shaft heating nozzle 5 can flow into the rotary shaft 3. After heating the rotating shaft, the heating steam flowing into the rotating shaft 3 is discharged into the inner cylinder 2a from a steam outlet 6 provided in the lower part of the rotating shaft 3 and rises in the inner cylinder 2a, and the vapor outlet in the upper part of the inner cylinder. It is discharged to the outside of the cylindrical body 2 from 7.

Rotor blades 8 are provided on the outer periphery of the rotary shaft 3 with a slight distance from the inner cylinder 2a. Also, the cylindrical body 2
The heated steam is supplied to the double-walled space through the main body heating nozzle 9 to heat the inner cylinder 2 a and then discharged from the outlet nozzle 10.

As shown in FIG. 2, an electric motor 11 is connected to the rotary shaft 3 of the centrifugal thin film dryer 1 configured as described above, and the treatment liquid is connected to the waste liquid nozzle 12 via the waste liquid pump 13. A storage tank 15 that stores 14 is connected.

A spindle temperature detector 16 and a body temperature detector 17 are attached to the inner cylinder 2a and the jacket 2b, respectively.
A main shaft steam control valve 18 and a main body steam control valve 19 are connected to the main shaft heating nozzle 5 and the main body heating nozzle 9, respectively.

A control device 20 controls the main shaft steam control valve 18 and the main body steam control valve 19, and this control device performs necessary calculation based on the temperature signals from the main shaft temperature detector 16 and the main body temperature detector 17. Then, the opening degrees of the main body steam control valve 19 and the main shaft steam control valve 18 are adjusted, and the rotating shaft 3 and the inner cylinder 2a are controlled so as to reach a preset temperature.

The operation will be described based on the above configuration.

When an operation instruction is input to the centrifugal thin film dryer 1, the control device 20 monitors the temperature signals from the main body temperature detector 17 and the main spindle temperature detector 16, and at the same time, opens the main body steam control valve 19 and the main spindle steam control valve 18. Is adjusted, and heating steam is gradually supplied so that the tubular body 2 and the rotating shaft 3 reach a preset temperature.

Here, the heating steam supplied to heat the rotating shaft 3 flows into the rotating shaft 3 through the main shaft heating nozzle 5 and the steam inlet 4, and heats the rotating shaft 3 from the inside of the rotating shaft 3, The same thermal deformation as that of the cylindrical body 2 occurs. Further, the heating steam that has heated the rotating shaft 3 flows out from the steam outlet 6 and the vapor outlet 7
Is discharged from the cylindrical body 2 while heating the rotor 8 during that period.
The gap between the rotor and the rotor 8 is always maintained in the same state.

Therefore, in the conventional apparatus, the warm-up time of about 4 hours was required, but in the present invention, as shown in FIG. 3, the processing can be performed in about 1/6 of the conventional time. .

In the present invention, the temperature of the heating steam supplied to the tubular body and the temperature of the rotary shaft are changed to provide a temperature difference, thereby making the gap smaller than the standard gap as shown in FIG. It is also possible to set the gap according to the properties of the processing liquid.

[Effects of the Invention] As described above, according to the centrifugal thin film dryer of the present invention, it is possible to arbitrarily set the gap between the cylindrical body and the rotating blades corresponding to various waste liquids, and the warm-up operation time before treatment can be set. It can be greatly shortened and the operating rate can be improved.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of a centrifugal thin film dryer of the present invention, FIG. 2 is a schematic view of an example of a waste liquid treatment apparatus equipped with the centrifugal thin film dryer of the present invention, and FIG. 3 is an apparatus of the present invention. Fig. 4 is a characteristic diagram showing the change over time in the gap between the cylindrical body and the rotary blade in Fig. 4, Fig. 4 is a characteristic diagram showing the change over time in the gap between the cylindrical body and the rotary blade in another embodiment of the present invention, and Fig. 5 is a conventional method. FIG. 7 is a characteristic diagram showing a change over time in the gap between the cylindrical body and the rotary blade due to. 1 ... Centrifugal thin film dryer 2 ... Cylindrical body 3 ... Rotating shaft 8 ... Rotating blade 16 ... Main shaft temperature detector 17 ... Main body temperature detector 18 ... Main shaft steam control valve 19 ... Main body steam control valve 20 ... Control device

Claims (2)

[Claims] 1. A rotary shaft having rotary blades is arranged in a cylinder,
Introduce the waste liquid into the cylinder while rotating this rotating shaft,
In a centrifugal thin film dryer configured to heat and evaporate to form a thin film of an evaporation residue on the inner surface of the cylindrical body, and to exhaust the vapor and scrape the evaporation residue with the rotary blade.
A centrifugal thin film dryer, wherein the rotary shaft is hollow, and steam for heating the rotary shaft can be introduced into the hollow portion. 2. The temperature of a rotating shaft is detected by a main shaft temperature detector, the temperature of a cylinder is detected by a main body temperature detector, and these temperature signals are introduced to a control device to make a main shaft steam control valve and a main body steam control valve. The centrifugal thin film dryer according to claim 1, wherein the centrifugal thin film dryer is configured to control