JPS62176501A - Operation of centrifugal film dryer - Google Patents

Abstract

PURPOSE:To prevent generation of temperature gradient in the device caused by warming up and to carry out continuous operation, by guiding water or hot water from the inside before guiding waste liquid and starting continuous warming up for a specific period of time. CONSTITUTION:An open/close valve 8 is closed before operation of waste liquid treatment, and water is guided into a dryer 4 from a water supply tube 11. A thin film is formed with supplied water on a heat transfer surface 25 by centrifugal force of a rotor blade 23, and heated up by the heat from a heat jacket 24 to form steam to heat up the inside of dryer uniformly. After said specified warming up, a valve 15 is closed to stop supply of water, and then the valve 8 is opened to supply waste liquid 2 into dryer to carry out a continuous waste liquid treatment operation. By such warming up from the inside, temperature difference is not generated between the outer body and inner main shaft, and a specific clearance (a clearance between the inner circumference of outer body and the rotor blade of shaft) is maintained.

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention relates to centrifugal thin film drying in which radioactive waste liquid discharged from, for example, nuclear power generation equipment is made into a thin film, heated and dried, and separated into steam and non-steam components. Concerning how to operate the machine.

[Technical Background of the Invention] Generally, a centrifugal thin film dryer is operated with a supply amount determined depending on the properties of the supplied waste liquid and the purpose of treatment, and a constant rotation speed of a rotating shaft equipped with rotary blades. There are many types of control devices, including those to keep the amount of waste liquid supplied constant, those to keep the concentration conditions of the device constant, and those to control the amount of waste liquid supplied to obtain a constant concentration of evaporation residue. There is something.

[Problems with yellow steel technology] According to the above configuration, regarding waste liquid treatment during steady operation,
Various operational improvements have been made and good results have been obtained, but these are only for waste liquid treatment in a steady state, and no special measures have been taken for unsteady situations, such as when starting waste liquid treatment. In reality, the dryer itself was only slightly warmed up using an external heating method.

The external heating method here refers to, for example, a method in which heated steam is circulated through the heating jacket of the outer body of a centrifugal 1111 dryer to dry the dryer from the outside. When such an external heating method is adopted, a temperature difference occurs between the outer shell and the inner main shaft, and this temperature difference causes a difference in the degree of thermal deformation between the outer shell and the main shaft. In some cases, it may not be possible to maintain the gap between the inner peripheral surface of the shell and the rotor of the main shaft, and they may come into contact with each other. Also aJ! If waste liquid treatment is performed immediately after drying, the motor current for driving the dryer may become overloaded before the dryer reaches a steady state. Therefore, in the past, the device had to be stopped and the operation interrupted after the start of operation, which posed a problem in improving the operating rate.

[Purpose of the Invention] The present invention has been made based on the above points, and its purpose is to enable stable waste liquid treatment operation to be carried out continuously over a long period of time, and to improve the operating rate. It is an object of the present invention to provide a method of operating a centrifugal thin film dryer that can achieve the following objectives.

[Summary of the Invention 1] That is, the method of operating a centrifugal thin film dryer according to the present invention includes disposing a rotating shaft having rotary blades inside a cylinder, and introducing waste liquid into the cylinder while rotating the rotating shaft. In the operating method of a centrifugal thin film dryer, in which 1lll is formed on the heat transfer surface of the surface, heated and evaporated to discharge steam and scrape off the evaporation residue with the rotary blade, waste liquid is introduced and waste liquid treatment operation is started. This is characterized in that water or hot water is first introduced to perform warm-up operation for a predetermined period of time.

That is, before starting the waste liquid treatment operation, water or hot water is introduced and heated not only from the outside but also from the inside to perform warm-up operation for a predetermined time, and then the waste liquid treatment operation is performed.

[Embodiment of the Invention] A first embodiment of the present invention will be described below with reference to FIGS. 1 to 4. FIG. 1 is a diagram schematically showing an apparatus for carrying out the operating method of a centrifugal thin film dryer according to this embodiment, and reference numeral 1 in the figure is a storage tank for storing waste liquid 2. In FIG. A centrifugal thin film dryer is connected to this storage tank 1 via a waste liquid pipe 3. A waste liquid pump 5 and a waste liquid control valve 6 are sequentially inserted into the waste liquid piping 3 from the storage tank 2 side, and the waste liquid pump 5 pumps the waste liquid 2 in the storage tank 1 into the centrifugal thin film dryer.

Further, a waste liquid flow rate detector 7 and an on-off valve 8 are inserted into the waste liquid pipe 3. A waste liquid control device 9 controls the waste liquid control valve 6, and this waste liquid control device 9 adjusts the opening degree of the waste liquid control valve 6 based on the flow threat detection signal S7 from the waste liquid flow rate detector 7. Thereby, the waste liquid stream fed to the centrifugal membrane dryer A- is controlled.

In addition to the waste liquid line, a water (or hot water) line is connected to the centrifugal membrane dryer Ia4. In this embodiment, a case will be described in which water is supplied. In other words, reference numeral 11 in the figure
is a water supply pipe, and this water supply pipe 11 has a water supply pump 1.
2, water supply control valve 13, water supply flow rate detector 14, on-off valve 15
are inserted sequentially. The water supply control valve 13 is controlled by a water supply control lI device 16. That is, the water supply control m+ device 16 adjusts the opening degree of the water supply control valve 13 based on the detection signal S14 from the water supply flow rate detector 14, thereby adjusting the flow rate of the water supply supplied onto the centrifugal thin film dryer. Further, the water supply pipe 11 and the waste liquid pipe 3 are connected via a pipe 17, and an on-off valve 18 is inserted into the pipe 17.

Next, the configuration of the centrifugal thin film dryer will be described with reference to FIGS. 2 and 3. FIG. 2 is a partially cutaway perspective view of the top of the centrifugal thin film dryer, and FIG. 3 is a longitudinal sectional view. Reference numeral 21 in the figure is a cylindrical body, and a rotating shaft 22 is accommodated within this cylindrical body 21. A plurality of rotary blades 23 are attached to this rotary shaft 22 at equal intervals in the axial direction.

The cylindrical body 21 has a double-walled structure, has a heating jacket 24 formed therein, and has a heat transfer surface 25 on the inner circumferential surface of the cylindrical body 21 . Heating steam is supplied into the heating jacket 24 to heat the inside of the cylindrical body 21 from the outside. The upper part of the cylindrical body 21 has a waste liquid 2 from the waste liquid line.
Alternatively, a liquid supply nozzle 26 for introducing water from a water supply line into the interior is connected. A distribution ring 27 is arranged within the cylinder 21 at the same position in the axial direction as the liquid supply nozzle 26 . This distribution ring 27 causes the waste liquid 2 or water introduced from each liquid supply nozzle 26 to flow down uniformly along the heat transfer surface 25. A vapor outlet 28 is connected above the liquid supply nozzle 26 of the cylindrical body 21, and the evaporated waste liquid 2 is discharged through the vapor outlet 28. On the other hand, a discharge port 29 is formed at the lower end of the cylindrical body 21, and the evaporation residue of the waste liquid 2 is discharged through the discharge port 29.

Next, the driving method will be explained. First, before the waste liquid 2 is introduced into the centrifugal thin film dryer A- to perform a waste liquid treatment operation, water is introduced into the centrifugal 1111 dryer A- and warmed up for a predetermined period of time. In other words, in the past, the top of the dryer was heated only from the outside using an external heating method to warm up the dryer, but in this embodiment, in addition to the external heating method, the top of the dryer A- The heating operation is performed by heating the fuel. This will be explained in detail below. That is, the on-off valve 8 is closed and water is supplied via the water supply pipe 11. At that time, it is also possible to open the on-off valve 18 and supply hot water from two directions. The water thus supplied is distributed by opening the liquid supply nozzle 26 and the distribution ring 27, and at the same time
As a result of the centrifugal force 123 acting, a thin film is formed on the heat transfer surface 25. Then, it is heated by the heat from the heating jacket 24 and evaporates into steam. As a result, the inside of the centrifugal thin film drying m4- is uniformly heated from the inside. The water supply flow rate at this time is set in advance, and the water supply control device 1
Let me remember it in 6. Water supply control! The l device 16 adjusts the opening degree of the water supply control valve 130 based on the water supply flow rate detection signal 814 from the water supply flow layer detector 14, and controls the water supply flow rate to a set water flow rate. The situation is shown in the middle diagram a in FIG. In addition, Fig. 4 shows the time change on the horizontal axis and the steam temperature in the heating jacket 24, the rotation speed of the rotation shaft 22, and the flow rate of the liquid supplied (water or waste liquid) on the vertical axis. It is.

After performing the warm-up operation for a predetermined time in this manner, the on-off valve 15 is closed to stop the supply of water. Next, the on-off valve 8 is opened and the waste liquid 2 stored in the storage tank 1 is pumped to the waste liquid pump 5.
is fed to the centrifugal thin film dryer A-.

The waste liquid 2 can be supplied from two directions by opening the on-off valve 18 as in the case of water supply. The waste liquid 2 supplied onto the centrifugal IIA dryer is supplied to the liquid supply nozzle 26.
The heat transfer surface 2
5 flows down in a thin film.

At that time, it is heated through the heating jacket 24 and evaporated.

The steam is then discharged through the paper outlet 28, and the evaporation residue of the waste liquid 2 adhering to the heat transfer surface 25 is removed from the rotary blade 23.
It is removed by the scraping action of , and is discharged from the discharge port 29 in the form of slurry or powder. Note that the supply amount of the waste 12 is set in advance in consideration of the properties of the waste liquid 2, etc., and is stored in the waste liquid control device 9. The waste liquid control device 9 adjusts the opening degree of the waste liquid control valve 6 based on the waste liquid flow rate detection signal S7 from the waste liquid flow rate detector 7, and controls the waste liquid flow rate to be a preset waste liquid flow rate. This situation is shown in the middle diagram of FIG. The waste liquid treatment operation is then carried out continuously.

According to this embodiment, the following effects can be achieved. That is, before starting the waste liquid treatment operation, water is supplied into the centrifugal thin film dryer m4- to perform warm-up operation, and the waste liquid treatment operation is started immediately after the warm-up operation is completed, so that the waste liquid treatment operation is smooth. can be done. In particular, unlike the conventional external heating method, the top of the centrifugal thin film dryer is uniformly heated from the inside during warm-up operation, which prevents temperature gradients from occurring during warm-up operation. It can be effectively prevented and
It is also possible to avoid interruptions in operation, enabling continuous operation and improving the operating rate.

Next, a second embodiment will be explained. The apparatus used in this second embodiment is the same as the apparatus used in the first embodiment, and its explanation will be omitted. In this second embodiment, as shown by lines C and d in FIG. 5, after the warm-up operation is completed, the water supply is gradually reduced and at the same time, the waste liquid 2 is gradually supplied, until the water supply flow rate reaches zero. This is done so that the waste liquid flow rate reaches a predetermined amount when the Similarly to FIG. 4, FIG. 5 is a diagram showing changes in steam temperature per revolution and feed liquid flow rate over time.

First, with the on-off valve 18 closed, water is supplied to the water supply control valve 1.
3 to a centrifugal thin film dryer.

The supplied water is introduced into the cylinder 21 through the liquid supply nozzle 26, and the uniform distribution action of the dispersion ring 27 and the rotation 1123
It flows down on the heat transfer surface 25 in the form of a thin film due to the action of centrifugal force.

Then, it is heated through the heating jacket 24 and evaporated. The steam generated at this time uniformly heats the inside of the centrifugal i1Ng dryer from the inside.

Note that the water supply flow rate at this time is set in advance and stored in the water supply control device [16]. The water supply control device al16 adjusts the opening degree of the water supply control valve 13 based on the water supply flow l detection signal S14 from the water supply flow rate detector 14, and controls the water supply flow rate to a preset water flow rate. Next, after a predetermined period of warm-up operation, the water supply control valve 13 is gradually closed, the water supply flow rate is gradually decreased, and the waste liquid 2 is gradually supplied. Then, when the water supply control valve 13 is fully opened and the water supply flow rate reaches zero, the waste liquid 2 flow is set to a predetermined flow rate. At this time, as is clear from FIG. 5', the supply liquid flow rate is always constant. Note that the waste liquid flow rate is set in consideration of the properties of the waste liquid 2, etc., and is stored in the waste liquid control device 9. Then, the opening degree of the waste liquid control valve 6 is adjusted by the waste liquid control device 19 to obtain the target flow rate. Thereafter, waste liquid treatment operation will be carried out continuously. The treatment of the waste liquid 2 is the same as in the first embodiment, and its explanation will be omitted.

As described above, according to the second embodiment, it is possible to not only achieve the same effects as the first embodiment, but also to provide a smoother operating state. In other words, if the waste liquid 2 is supplied after a while after the water supply is stopped, the inside of the dryer A- will be in a dry state because the dryer A- is always heated via the heating jacket 24. Therefore, even if the waste liquid 2 is supplied in such a state, it is predicted that a stable operating state cannot be obtained.

In the case of the first embodiment, this problem is avoided by supplying the waste liquid 2 immediately after completely stopping the supply of water. On the other hand, in the case of this second embodiment, a constant fluid (water, waste liquid, or a mixture of both) is always supplied into the centrifugal thin film dryer, and from the viewpoint of so-called wettability. Since the inside of the dryer is always in a wet state, stable operating conditions can be provided.

[Effects of the Invention] As detailed above, according to the operating method of a centrifugal thin film dryer according to the present invention, it is possible to perform smooth waste liquid treatment operation continuously, and the operating rate can be improved, etc. is large.

[Brief explanation of drawings]

1 to 4 are diagrams showing a first embodiment of the present invention,
Fig. 1 is a diagram showing the configuration of the centrifugal 11111 dryer and peripheral equipment, Fig. 2 is a partially cutaway perspective view of the centrifugal thin film dryer, Fig. 3 is a vertical sectional view of the centrifugal thin film dryer, and Fig. 4 FIG. 5 is a diagram showing changes over time in the rotation speed of the steam temperature 3 rotation shaft and the feed liquid flow rate, and FIG. It is. 2... Waste liquid, 3... Waste liquid piping, 4... Centrifugal thin film dryer, 11... Water supply piping, 21... Cylindrical body, 22...
... Rotating shaft, 23 rotor blade, 25... heat transfer surface. Applicant's Representative Patent Attorney Takehiko Suzue No. 1 TgJ Iso Figure 2 Figure 3 Figure 4 Figure 5

Claims (3)

[Claims] (1) A rotating shaft with rotary blades is placed inside the cylinder, and while the rotating shaft is rotating, waste liquid is introduced into the cylinder to form a thin film on the heat transfer surface of the inner surface of the cylinder, and is heated and evaporated. In the method of operating a centrifugal thin film dryer in which steam is discharged by the rotor and the evaporation residue is scraped off by the rotary blade, water or hot water is introduced and warm-up operation is performed for a predetermined period of time before introducing waste liquid and starting the waste liquid treatment operation. A method of operating a centrifugal thin film dryer, characterized in that: (2) A patent claim characterized in that water or hot water is introduced, warm-up operation is performed for a predetermined period of time, and after the introduction of water or hot water is completely stopped, waste liquid is introduced and waste liquid treatment operation is started. A method of operating a centrifugal thin film dryer according to item 1. (3) Water or hot water is introduced and warm-up operation is performed for a predetermined period of time, and then the introduction of water or hot water is gradually reduced, and at the same time waste liquid is gradually introduced and waste liquid treatment operation is started. A method for operating a centrifugal thin film dryer according to claim 1.