JPH0226757B2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention is a method of drying radioactive waste liquid slurry such as chemical regeneration waste liquid, laundry waste liquid, etc., which is mainly composed of spent resin and sodium sulfate discharged from a nuclear power plant, and The present invention relates to a radioactive waste processing apparatus that evaporates water and converts solid content into dry powder.

[Technical background of the invention and its problems]

Conventionally, cement solidification methods have been used to solidify radioactive waste slurry.

However, this cement solidification method involved filling a drum with radioactive waste liquid slurry and cement and solidifying it, which had the disadvantage of poor volume reduction.

For this reason, a treatment method has been proposed, as disclosed in Japanese Patent Publication No. 55-33559, in which a radioactive waste slurry is dried, the water is evaporated, and the solid content is obtained as a dry powder having a constant moisture content.

However, in the processing method and processing apparatus described in the above publication, the temperature of the dry powder is detected in order to know the moisture content of the dry powder, but the temperature between the heating jacket and the rotor of the dryer is not heated by the heating jacket. The method detects the temperature of the radioactive liquid waste, which is decreasing as it is heated, and processes the detected temperature to match the set temperature, so it has the following drawbacks.

1. The detected temperature is the temperature of the radioactive liquid waste that is still being heated by the heating jacket, and is not the temperature of the dried powder after drying is completed.

Also, if the state of the steam supplied to the heating jacket changes, such as an increase in flow rate or a rise in temperature,
Since the detection part is also the heating jacket part,
The detector detects not only the temperature of the radioactive liquid waste itself, but also changes in the state of the supplied vapor that cause disturbances.

Therefore, since it does not detect the actual temperature of radioactive liquid waste, there is a high risk that the state of the dry powder obtained will not be the specified state, making it impossible to perform stable processing and further reducing reliability. It was also inferior.

2. In order to detect the temperature of the radioactive liquid waste that descends between the heating jacket and the rotor, the detector must be installed in an extremely narrow space, and the structure must be designed so that it can accurately detect the temperature. becomes complicated. Furthermore, since heat is directly transmitted to the detector from the heating jacket, thermal stress, which causes detection errors, is generated in the detector and its surrounding components.

[Purpose of the invention]

The present invention has been made in view of these points, and is capable of detecting the temperature of the dried powder itself obtained after drying is completed, and moreover, is able to accurately detect the temperature of the dried powder itself without being affected by changes in the state of the heating steam. The temperature of the dry powder itself can be detected, and the detected temperature, that is, the temperature of the dry powder, can be reliably matched to the set temperature, and the control operation is stable and reliable, and the structure is simple. The purpose is to provide a certain radioactive waste treatment equipment.

[Summary of the invention]

In order to accurately detect the temperature of the dried powder itself after drying is completed without being affected by the state of the heating steam, the present invention provides a temperature sensor in the cone section below the heater of the dryer, and detects the temperature. A control device is provided to match the detected temperature accurately measured by the detector to the set temperature.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a system diagram of a radioactive waste treatment apparatus according to the present invention, and in the figure, reference numeral 1 indicates a vertically long dryer. The details of this dryer 1 are shown in FIG. 2, and a cylindrical heater 2 is provided inside the middle part. In order to supply heating steam as a heat source to this heater 2, there is a heating steam flow rate regulating valve 3 in the middle.
A heating steam supply pipe 4 is connected thereto, and a discharge pipe 5 for discharging the heated steam provided for heating
is connected. A rotating rotor 7 is provided inside the heater 2 and is driven to rotate by a motor 6 provided at the top of the dryer 1 . Also,
The dryer 1 is provided with an inlet 8 through which radioactive waste slurry is supplied above the heater 2 and an outlet 9 through which steam generated during drying is discharged. A funnel-shaped cone portion 10 is provided below to collect and discharge dry powder, that is, solid content in the radioactive waste slurry, that falls between the heater 2 and the rotating rotor 7.

A radioactive waste slurry supply device 11 that supplies radioactive waste slurry into the dryer 1 through the inlet 8 includes a liquid supply tank 12, a liquid supply pump 13 on the way, and a radioactive waste slurry supply amount adjustment valve 1.
A supply channel 15 having 4 is provided.

Further, the cone portion 10 is provided with a plurality of temperature detectors 16, 16 for detecting the temperature of the dry powder falling from between the heater 2 and the rotating rotor 7 and emitting a detected temperature signal 16a. There is. The moisture content of the dry powder can be determined by detecting the atmospheric temperature of the part where the dry powder flows down using the temperature detector 16 and knowing the temperature of the dry powder itself. When the relationship between the detected temperature of the dry powder and the moisture content of the dry powder was measured using the Karl Fischer method, it was found that the relationship between the detected temperature of the dry powder and the moisture content of the dry powder was determined to be constant as shown in the diagram for used resin and concentrated waste liquid shown in Figure 3. It was requested because of the relationship. Therefore, in order to keep the moisture content of the dry powder constant, the temperature detected by the dry powder temperature detector 16 may be maintained within the set temperature range.

The present invention is provided with a control device 19 that maintains the temperature of the dry powder at a set temperature in order to maintain the moisture content of the dry powder constant. This control device 19 is
Detected temperature signal 1 sent from temperature detector 16
6a and the set temperature, and sends an opening/closing signal 19a to open and close the radioactive waste slurry supply amount adjustment valve 14 and the heating steam flow rate adjustment valve 3 so that the difference becomes zero and the temperature of the dry powder matches the set temperature. emanate. That is, in order to control the temperature of the dry powder, the amount of radioactive waste liquid slurry supplied to the dryer 1 is controlled, and the heating steam flow rate is controlled to control the heating temperature by the heater 2. be.

The dry powder discharged from the cone section 10 of the dryer 1 is stored in a collection hopper 18 by a transfer device 17, and then transferred to a radioactive waste solidification processing section and a drum filling processing section (both not shown). sent to ).

Further, from the upper outlet 9, the water in the radioactive waste slurry is discharged as steam through the discharge channel 20, and is condensed in the condenser 21.

Next, the operation of this embodiment will be explained.

The radioactive waste liquid slurry stored in the liquid supply tank 12 is fed to the dryer 1 through the supply path 15 by opening the radioactive waste liquid slurry supply amount adjustment valve 14 and driving the liquid supply pump 13. Can be fed to the top. At this time, in the dryer 1, the heated steam flow rate adjustment valve 3 is opened to supply heated steam into the heater 2 from the heated steam supply pipe 4, and the rotating rotor 7 is rotated by the motor 6. Therefore, the radioactive waste liquid slurry supplied into the dryer 1 flows down between the heater 2 and the rotating rotor 7 in order. During the flow, the radioactive waste liquid slurry is heated by the heater 2, water is evaporated,
It is discharged from the outlet 9 to the discharge channel 20 . As the solid content in the radioactive waste slurry flows down as it dries, its moisture content gradually decreases.
At the lowest part between the heater 2 and the rotating rotor 7, drying is almost completed and the powder is a dry powder.

This dry powder falls freely into the cone portion 10 from between the heater 2 and the rotating rotor 7. and,
Inside the cone section 10, temperature detectors 16 detect the temperature of the falling dry powder. At this time, since the cone portion 10 is separated from the heater 2, the temperature detector 16 can detect the true temperature of the dry powder itself without being affected by the temperature state of the heater 2. Further, the cone portion 10 is connected to the heater 2
Since the diameter is smaller, the temperature of the dry powder can be accurately detected using a smaller number of temperature detectors 16.

Then, the control device 19 compares the detected temperature signal 16a sent from the temperature detector 16 with the set temperature, and if the detected temperature is low, the water content is too high, so the heated steam flow rate regulating valve 3 is The opening/closing signal 19a that increases the opening degree is sent to increase the heating capacity of the heater 2, and the opening/closing signal 19a that decreases the opening degree is sent to the radioactive waste liquid slurry supply amount adjustment valve 14 to prevent the radioactive waste liquid from flowing into the dryer 1. Reduce the amount of slurry supplied. As a result, the temperature of the dry powder gradually rises, and when the detected temperature matches the set temperature, the control device 19 controls both the regulating valves 3,
Opening/closing signal 1 that maintains the valve opening degree of 14 in the current state
Send 9a each. On the other hand, if the detected temperature is higher than the set temperature, the water content is too low, so contrary to the above, an opening/closing signal 19a is sent to reduce the valve opening of the heated steam flow rate adjustment valve 3, and the supply amount of radioactive waste slurry is adjusted. An opening/closing signal is sent to increase the opening degree of the valve 14.

In this manner, dry powder having a constant moisture content is obtained by the operation of the control device 19.

This dry powder then flows out of the cone section 10,
It falls onto the transfer device 17 and is sent towards the collection hopper 18.

If the temperature is set to 125 to 135°C as a control method using the control device 19, the moisture content of the used resin will be 5% by weight as shown in Fig. 3.
Therefore, the water content in the case of concentrated waste liquid is 0.3% by weight, indicating that it is in a sufficiently dry state.

〔Effect of the invention〕

Since the present invention is configured in this manner, it produces the following effects.

1. Since the temperature sensor is installed in the cone of the dryer, it is possible to detect the temperature of the dry powder itself falling from between the heater and the rotating rotor. Therefore,
The detected temperature accurately becomes the temperature of the dry powder without disturbances such as the temperature of the heater, and is compared with the set temperature by the controller, ensuring that the dry powder temperature matches the set temperature and maintains a constant temperature. A dry powder with a high moisture content can be obtained.

2 Even if the heating temperature changes suddenly due to a sudden change in the amount of heating steam supplied to the heater, the temperature of the dry powder itself can be detected without being affected by the change, so the temperature of the dry powder itself can be detected without being affected by the change. Moisture content can be easily controlled by changing the amount.

3. Moisture content of dry powder can be stably controlled by temperature control, increasing operational reliability.

4 The temperature detector is not installed in the narrow area between the heater and rotating rotor as in the past, but is installed in the wide cone area, and furthermore, the temperature of the dry powder can be accurately detected even if the number of sensors is small. Since it is a product, it has a simple structure and can be easily repaired.

[Brief explanation of drawings]

The drawings show an embodiment of the radioactive waste processing apparatus of the present invention, in which Fig. 1 is a system diagram, Fig. 2 is a vertical side view of the dryer, and Fig. 3 is a graph showing the relationship between detected temperature and moisture content of dry powder. It is a characteristic diagram showing a relationship. 1... Dryer, 2... Heater, 3... Heated steam flow rate adjustment valve, 7... Rotating rotor, 8... Inflow port,
9... Outlet, 10... Cone part, 11... Radioactive waste slurry supply device, 14... Radioactive waste slurry supply amount adjustment device, 16... Temperature detector, 1
9...control device.

Claims (1)

[Claims] 1. The radioactive waste slurry supplied from the upper inlet is passed downward between a heater and a rotating rotor provided in the middle to dry it, and the moisture in the radioactive waste slurry is vaporized. a radioactive waste slurry for supplying the radioactive waste slurry to the inlet of the dryer; a waste liquid slurry supply device; a temperature detector provided in the cone of the dryer to detect the temperature of the dry powder falling from the heater; the temperature detected by the temperature detector and the set temperature of the dry powder. a control device that adjusts the heating state of the heater and the amount of radioactive waste slurry supplied by the radioactive waste slurry supply device so that the detected temperature matches the set temperature; . 2 The heater uses heated steam as a heat source and has a heated steam flow rate adjustment valve that adjusts the flow rate of the heated steam, and the radioactive waste slurry supply device has a radioactive waste slurry supply amount adjustment valve that adjusts the amount of radioactive waste slurry supplied. The control device includes a comparator that compares the detected temperature and a set temperature, and a command device that sends an opening/closing signal to the heated steam flow rate adjustment valve and the radioactive waste slurry supply amount adjustment valve to make the difference between the two temperatures zero. A radioactive waste treatment apparatus according to claim 1, characterized in that it comprises: