JP2999080B2 - Waste liquid evaporator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a waste liquid evaporating apparatus used for treating waste liquid used for treating used resin in a nuclear power plant, for example.

[0002]

2. Description of the Related Art In a nuclear power plant, an ion exchange resin is used as a means for removing radioactive contaminants from waste liquid. The used ion exchange resin is usually stored in a storage tank. In order to reduce the volume of such high-level radioactive waste, radionuclides are eluted from the used ion-exchange resin with an eluent such as sulfuric acid, and the eluted waste is concentrated and reduced in volume by a waste liquid evaporator to reduce radioactivity. A method of solidifying cement after damping has been adopted. On the other hand, the resin that has become the eluted low-level radioactive waste is disposed of by a predetermined method. In addition, as a device for concentrating and reducing the volume of the eluted waste liquid, the eluted waste liquid is heated and evaporated by an evaporator to be separated into a vapor and a concentrated liquid, and the vapor is cooled to form a condensate, which is discharged out of the system. Is used.

FIG. 2 is a diagram showing a conventional example of an apparatus for performing such processing as evaporation, concentration, and condensation of a waste liquid. That is, this device is roughly divided into an evaporator 10, a main steam condenser 20, a vent condenser 30, and a condensed water cooler 4.
0, and operates as follows.
The processing waste liquid X is supplied to the evaporator 10 from the solution system 11. The steam Y generated by the heater 12 is supplied to the steam conduit 1
3 and into the main steam condenser 20.

[0004] The treated liquid in the evaporator 10 is concentrated by the heater 12 and transferred to the outside of the system by the concentrated liquid transfer pump 14 via the concentrated liquid transfer system 15. In the concentration process, the processed liquid is returned to the evaporator 10 through the solution circulation system 16, and is recycled to a predetermined concentration. Note that reference numeral 17 denotes a pressure detector, and reference numeral 18 denotes a control signal line.

The steam Y guided to a main steam condenser 20 having a steam flow path 21 and a condensed water reservoir 22 is cooled and condensed by a main cooling water heat transfer pipe 24 supplied with cooling water from a main cooling water system 23. . A part of the non-condensable gas such as air and oxygen gas and the steam contained in the steam Y are sent to the vent condenser 30 through the steam communication pipe 25. The condensed water W collected in the condensed water pool 22 is pumped out by a pump 26 and guided to a condensed water cooler 40 via a pipe 27.
On the other hand, the pressure detector 17 via the control signal line 18
The main cooling water control valve 28 supplied with a signal from the main cooling water system 23 maintains the internal pressure of the evaporator 10 constant.
Is adjusted.

The non-condensable gas and the steam, which are led to the vent condenser 30 having the steam flow path 31 and the condensed water reservoir 32, pass through a cooling water heat transfer pipe 34 to which cooling water is supplied from a cooling water system 33. Cools and condenses. The non-condensed gas condensed and separated in the vent condenser 30 is discharged to the outside through an exhaust hole (vent) 35.
Further, the condensed water in the condensed water pool 32 is returned to the main steam condenser 20 through a pipe 37 having a U-shaped seal pipe 36. The U-shaped seal tube 36 uses the height difference of the position, self-balances with the head difference, and prevents the backflow by causing precipitation.

The flow path 41 of the condensed water W and the condensed water discharge hole 4
The condensed water W guided to the condensed water cooler 40 having the cooling water 2 is cooled to a predetermined temperature by a cooling water heat transfer pipe 44 supplied with cooling water from a cooling water system 43. Cooled condensed water W
Is discharged out of the system by the condensed water discharge system 45. A temperature signal detected by a condensed water temperature detector 48 is supplied to a cooling water control valve 46 of the cooling water system 43 via a control signal line 47 via a controller (not shown). The condensed water discharged in this way is adjusted to the set temperature.

[0008]

In the above-mentioned conventional waste liquid evaporating apparatus, the evaporating capacity is 50 to 100 kg / h.
When the size is relatively small, the internal volumes of the main steam condenser 20, the condensed water cooler 40, and the vent condenser 30 are small. For this reason, the absorption mitigation action for each device, that is, the buffer function is insufficient. Therefore, when the operating temperature, pressure, flow rate, and the like of each system fluctuate, each control system works too sensitively to cause an unstable phenomenon, which causes a reduction in the performance of the apparatus and a trouble.

Therefore, the present invention provides a waste liquid evaporating apparatus which can exhibit stable performance even if the evaporating processing capacity is small, and has a simple structure and can be manufactured at a small size and at a low cost. It is intended to be.

[0010]

Means for Solving the Problems In order to solve the above problems and achieve the object, the present invention has taken the following means. An evaporator that heats the waste liquid and separates it into steam and a concentrated liquid; and a condensing cooler that receives and cools the steam and separates it into condensed water and non-condensed gas and cools the condensed water. The shell portion is composed of a vertical cylindrical main container and a sub-container mounted on the main container and internally communicating with the main container, and the inside of the main container extends upward from the bottom of the main container. A through-flow cooling water heat transfer tube extending through the inside of the main container, a condensate discharge system extending from the bottom of the main vessel, a recirculation line is provided in parallel, and a condensate water level control system is formed. did.

[0011]

The following effects are obtained as a result of taking the above measures. The steam introduced into the main container of the condensing cooler is condensed by a once-through cooling water heat transfer tube provided inside the main container, and the inside of the main container is occupied by steam by the level of condensed water generated by the condensation. It is functionally divided into a gas phase for cooling and condensing the vapor and a liquid phase for cooling the condensed water occupied by the condensed water. And, for the once-through cooling water heat transfer tube inserted and arranged in series in the internal space of the main container consisting of the gas phase part and the liquid phase part and the sub-container directly connected to the upper part, the set pressure of the evaporating part A corresponding amount of cooling water is flowed by the cooling water control valve. For this reason, the condensation capacity of the once-through cooling water heat transfer tube is adjusted, and the evaporation load is settled so as to keep the internal pressure of the evaporator constant.

On the other hand, the condensed water in the main container is discharged outside the system by the condensed water discharge system in an amount corresponding to the evaporation load.
Since the condensed water level control system provided with the recirculation line is controlled in accordance with the temperature, the flow rate of the condensed water returned from the condensed water discharge system into the main vessel is adjusted. For this reason, the water level of the condensed water changes, the cooling capacity of the liquid phase changes, and the temperature of the condensed water discharged is adjusted. At this time, the heat transfer surface height (Hc) of the gas phase portion and the heat transfer surface height (Hw) of the liquid phase portion correspond to the stabilization of the evaporation load by the cooling water control valve.
Will be balanced by self-balancing.

Thus, the heat transfer area of the gas phase portion and the liquid phase portion can be freely determined by adjusting the water level in the main vessel by the cooling water control valve for controlling the evaporation load and the condensate water level control system for controlling the condensate water level. Can be adjusted and set.

As described above, the main container and the sub-container, whose internal spaces communicate with each other via the steam discharge pipe provided at the upper part of the main container, have a so-called integrated form. For this reason, even if the evaporation processing capacity is small, a sufficient buffer function convenient for absorbing and mitigating fluctuations in pressure and flow rate can be obtained. Therefore, an excessive response can be avoided, and stable operation can be expected. Then, a series of once-through cooling water heat transfer tubes are inserted in series in the internal space formed by the integral body, and the cooling water system is unified. Therefore, in combination with the fact that the container is formed as an integral body, the configuration is simplified, and the container can be manufactured in a small size and at low cost.

[0015]

FIG. 1 is a view showing a configuration of a waste liquid evaporating apparatus according to an embodiment of the present invention. That is, this apparatus comprises an evaporator 10 for heating and evaporating the processing waste liquid X, and an evaporator 1
A condensing cooling unit 50 for condensing the steam generated in step S0 and cooling and discharging the condensed water; a vent condenser 60 for recondensing a part of the steam not condensed in the condensing cooling unit 50; The condensed water is condensed and cooled in accordance with the temperature.
And a condensed water level control system 70 that returns to the

A solution system 11 for introducing the processing waste liquid X is connected to the evaporator 10, and a heater 12 for heating the processing waste liquid X is provided. Further, an upper part of the evaporator 10 is connected to a steam conduit 13 for sending out steam to the main steam condenser 20, and a lower part of the evaporator 10 is provided with a concentrated liquid transfer pump 14 for sending concentrated waste liquid out of the system. A concentrate transfer system 15 is connected. A solution circulation system 16 is branched from a concentrated liquid transfer system 15 on the outlet side of the pump 14 and connected to the evaporator 10. The evaporator 10 is provided with a pressure detector 17. The pressure detector 17 is connected via a control signal line 18 to a cooling water control valve 67 described later.

The condensing / cooling unit 50 is provided with a steam introduction hole 5 for introducing steam from the steam conduit 13 into a vertical main container 51 having a cylindrical shape.
2 and a short tube-shaped steam discharge pipe 53 protruding outside the upper side wall.
And a condensed water discharge hole 54 provided on the bottom and a condensed water return hole 55 provided on the side wall.
The main cooling portion 56 a of the once-through cooling water heat transfer tube 56 formed of a coil-type snake tube is provided inside the main container 51.

The vent condenser 60 includes a steam discharge pipe 53
A cylindrical sub-container 61 disposed around the periphery of the main container 51 has a flange portion 62 formed at the end and joined to the outer surface of the upper wall of the main container 51 in a liquid-tight manner, an exhaust hole 63 provided at an upper portion, and one end. A U-shaped seal tube 64 is provided so as to be located in the gap between the steam discharge pipe 53 and the sub-container 61, and the other end is located in the condensing cooling section 50. The sub-cooling portion 56b of the once-through cooling water heat transfer tube 56 formed of a coil-type snake tube is provided inside the sub-container 61.

On the other hand, the main cooling portion 5 of the once-through cooling water heat transfer tube 56
6 a and the sub-cooling section 56 b are integrally connected through a steam discharge pipe 53. A cooling water system 68 having a cooling water control valve 67 is connected to the once-through cooling water heat transfer tube 56. The cooling water control valve 67 is supplied with a signal from the pressure detector 17 via a control signal line 18.

The condensed water level control system 70 is provided with a pump 7 connected to a condensed water discharge hole 54 provided at the bottom of the main vessel 51.
1 and a recirculation line 74 provided with a return water amount regulating valve 73 branched from the condensed water discharge system 72 at the outlet side of the pump 71. A condensed water temperature detector 75 is provided in the condensed water discharge system 72, and the condensed water temperature detector 75 is connected to a feedback water amount control valve 73 via a control signal line 76.

The waste liquid evaporating apparatus of this embodiment having the above-mentioned structure operates as follows. The processing waste liquid X supplied quantitatively into the evaporator 10 from the solution system 11 is supplied to the heater 12
To generate steam Y. Generated steam Y
Is sent into the condensing cooling section 50 through the steam conduit 13.

On the other hand, the treated liquid in the evaporator 10 is concentrated to a predetermined concentration by the heating and evaporating operation by the heater 11, and is transferred out of the system by the concentrated liquid transfer pump 14 via the concentrated liquid transfer system 15. In the concentration process, the processed liquid is returned to the evaporator 10 through the solution circulation system 16 and recirculated.

The steam Y introduced into the condensing cooling section 50 from the steam introducing hole 52 is supplied to the main cooling section 5 of the once-through cooling water heat transfer tube 56.
It is cooled and condensed by the Hc portion of 6a. The condensed water W generated by this condensation collects at the bottom of the main container 51. According to the level of the condensed water W, the inside of the condensing cooling section 50 is functionally divided into a gas phase portion (Hc portion) occupied by the vapor Y and a liquid phase portion (Hw portion) occupied by the condensed water W. Will be.

A part of the steam guided to the condensing cooling section 50 is mixed with a non-condensable gas such as air or oxygen gas, guided to the vent condenser 60 through the steam discharging pipe 53, and passed through the cooling water. Cooled and condensed by the sub-cooling portion 56b of the heat transfer tube 56. The condensed water W generated by this condensation accumulates in the gap between the outer periphery of the steam discharge pipe 53 and the inner peripheral wall of the sub-container 61, and
It is returned into the condensing cooling section 50 through the U-shaped seal tube 64. The U-shaped seal tube 64 uses the height difference of the position, self-balances with the head difference, and prevents the backflow by causing precipitation. The condensed water W collected in the condensing cooling section 50 is pumped out by a pump 71 and discharged out of the system via a condensed water discharging system 72.

In the waste liquid evaporating apparatus of this embodiment, the evaporator 1
The evaporation load of 0 is controlled as follows. That is, the evaporating unit 10 is connected to the condensing cooling unit 50 composed of a gas phase part and a liquid phase part, and the cooling heat transfer tube 56 inserted and arranged in series in the internal space of the vent condenser 60 directly connected to the condensing cooling part 50.
The amount of cooling water corresponding to the set pressure of
Swept away by For this reason, the condensing capacity of the once-through cooling water heat transfer tube 56 is adjusted, and the evaporation load is settled so that the internal pressure of the evaporator 10 is kept constant.

On the other hand, the amount of the condensed water W in the condensing cooling section 50 is discharged out of the system by the pump 71 in accordance with the evaporation load. The flow rate of the condensed water W returned from the condensed water discharge system 72 into the condensed cooling unit 50 via the valve 73 is adjusted. For this reason, the water level of the condensed water W changes, the cooling capacity of the liquid phase changes, and the temperature of the condensed water W discharged is adjusted. At this time, the ratio between the heat transfer surface height (Hc) of the gas phase portion and the heat transfer surface height (Hw) of the liquid phase portion is self-balanced in accordance with the staticization of the evaporation load by the cooling water control valve 67. Will be balanced.

Thus, the cooling water control valve 6 for controlling the evaporation load.
By adjusting the water level in the condensing cooling section 50 with the return water amount adjusting valve 73 for adjusting the water level of the condensed water W and the condensed water W, the heat transfer areas of the gas phase portion and the liquid phase portion can be arbitrarily adjusted and set.

As described above, in the present embodiment, the condensing and cooling unit 50 is formed as a so-called integral body because the internal space communicates with the vent condenser 60 via the vapor discharge pipe 53 provided at the upper part. It forms an aspect. Therefore, even if the evaporation processing capacity is small, a buffer function sufficient to absorb and mitigate fluctuations in pressure and flow rate can be obtained. Therefore, an excessive response can be avoided, and stable operation can be expected. A series of cooling heat transfer tubes 56 are inserted in series in the internal space of the condensing cooling unit 50 and the vent condenser 60, which are formed as an integral body, so that the cooling water system is unified. Combined with the fact that the container is formed as an integral body, the configuration is simplified, and the container can be manufactured small and inexpensively. Also, since the arrangement of the condenser cooler is relatively free, the evaporator for processing high-level radioactivity can be installed separately,
Maintenance becomes easy.

The present invention is not limited to the embodiment described above. That is, although the cooling heat transfer tube 56 is formed of a coil-type snake tube, a plate-type or fin-type cooling heat transfer tube may be used. Further, the present invention is not limited to the above-described embodiments, and it goes without saying that various modifications can be made without departing from the spirit of the present invention.

[0030]

According to the present invention, even if the evaporation processing capacity is small, a buffer function sufficient to absorb and mitigate pressure fluctuations and the like can be obtained, so that an excessive response can be avoided. Since stable operation can be expected, the container is formed as an integral body, and the cooling water system is unified, a waste liquid evaporating apparatus that is simple in configuration and can be manufactured at low cost can be provided.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a waste liquid evaporating apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of a waste liquid evaporating apparatus according to a conventional example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Evaporator 50 ... Condensing cooling part 51 ... Main container 56 ... Through-flow cooling water heat transfer tube 60 ... Vent condenser 61 ... Subcontainer 63 ... Exhaust hole 64 ... U-shaped seal tube 70 ... Condensed water level control system 72 ... Condensed water discharge System 74: Recirculation line

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G21F 9/08 C02F 1/04

Claims (1)

(57) [Claims] 1. An evaporator for heating a waste liquid to separate it into a vapor and a concentrated liquid, and a condensing cooler for receiving and cooling the vapor and dividing it into condensed water and non-condensed gas and cooling the condensed water. The shell of the condensing cooler is composed of a vertical cylindrical main container and a sub-container mounted on the main container and internally communicating with the main container,
A once-through cooling water heat transfer tube extending upward from the bottom of the main container and extending through the inside of the sub container is provided therein, and a recirculation line is provided for a condensed water discharge system extending from the bottom of the main container. A waste liquid evaporating apparatus characterized in that a condensed water level control system is formed in parallel therewith.