JPS5819599A - Heating device for recombiner of radioactive gaseous waste processing system - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention The present invention provides a heating device for a recombiner in a radioactive gaseous waste treatment system for recombining and removing oxygen and hydrogen in gaseous waste in the main condenser system of a nuclear power plant. Regarding.

Generally, air leaks into the main condenser of a boiling water reactor nuclear power plant, and this air must be disposed of.

However, oxygen and hydrogen generated by radiolysis of a portion of the cooling water by neutrons, and rare gases generated as nuclear fission products from the fuel rods of the nuclear reactor are mixed into the steam and mixed with the air. For this reason, a device for disposing of air is provided with a device for treating gas extracted from the main condenser. This processing equipment includes a hydrogen oxidation processing equipment that recombines hydrogen and oxygen from the extracted steam and the mixed gas, a condenser that removes the steam and the recombined steam, and a nuclear fission product processing equipment. It consists of a hold-up device, etc.

A conventional radioactive gas waste treatment apparatus will be explained below with reference to FIG.

The gaseous waste extracted from the main condenser 1 by the air extractor 2 (
Gaseous radionuclides such as oxygen, hydrogen, rare gases, and air) and steam flow into the preheater 3 from the preheating section inlet pipe 2a via the valve V1. The preheater 3 is preheated by a separate steam line, as shown in FIG. 2, and flows into the recombiner 4'.

Oxygen and hydrogen are recombined into water vapor by the catalyst filled in the recombiner 4. The treated water vapor is cooled in a condenser 5 together with the extracted steam, and is condensed and drained as water.

Drain water is returned to the main condenser 1 through the drain acid pipe.

5b indicates the direction of flow of cooling water. On the other hand, the remaining air and radioactive nuclides such as rare gas are transferred from the outlet pipe 7 of the condenser 5 to the rare gas hold up tower 6. In the rare gas hold up tower 6, the rare gas is adsorbed and desorbed onto the activated carbon, and the radioactivity is attenuated for a certain period of time (30 days for xenon Xe). After attenuating the radioactivity of the rare gas and making it below the emission standard, the rare gas is passed through the vacuum pump 7 to the exhaust stack 8.
released into the atmosphere. It should be noted that each of the above-mentioned devices consists of two lines, one of which is reserved.

As described above, in the conventional processing apparatus, the preheater 3 is provided in order to improve the processing efficiency in the recombiner 4, and a separate steam line 3a is required as a heat source for this preheating. The recombiner is equipped with a heater that can maintain the temperature and raise the temperature.

When switching the system to standby, it is necessary to maintain the recombiner at the optimum temperature for chemical reactions, and it is also necessary to prevent the recombiner from repeatedly drying out and getting wet after the operation ends. There is. Furthermore, it is necessary to quickly reach the required temperature and to maintain a uniform internal temperature.

However, in conventional devices, the temperature of the catalyst in the recombiner rises abnormally, causing oxidation, shortening the lifespan, and making it difficult to withstand long-term operation, so it cannot be said to be efficient.

The present invention has been made in order to eliminate the above-mentioned disadvantages, and is efficient in that it eliminates the need for a steam line in a separate system 3a that serves as a heat source for the preheater 3, and also makes it possible to control the temperature in the recombiner to prevent oxidation of the catalyst. An object of the present invention is to provide a heating device for a recombiner in a radioactive gas waste treatment system with good performance.

That is, the present invention controls the temperature in the recombiner by providing a preheater for preheating extracted gaseous waste and steam using reaction heat generated in the recombiner, and a passage bypassing the preheater. This is a heating device for a recombiner in a radioactive gas waste treatment system, which is characterized by the following.

Hereinafter, an embodiment of the present invention will be explained with reference to FIGS. 3 and 4.

In Fig. 3, hydrogen extracted from the reactor main condenser 1,
Gaseous wastes such as oxygen, air, rare gases, etc. and steam are sent to the gas inlet pipe 2a by a blower.

A temperature control valve 10 is connected to the gas inlet pipe 2a, and a downstream pipe 11 of the temperature control valve 10 is connected to the inlet pipe 17 of the recombiner 4.
connected to. A temperature controller 12 is provided in the inlet pipe 17, and the temperature controller 12 and the temperature control valve 10 are connected by instrumentation wiring 13. Further, both sides of the temperature control valve 10 are branched to connect pipes 15 and 16, and the pipe 1
5.16 is connected to the heat exchanger 14. The downstream piping 4a of the recombiner 4 is connected to the upstream side of the heat exchanger 14,
The downstream pipe 4b of the heat exchanger 14 is connected to the upstream side of the exhaust gas condenser 5. The gas treated in the recombiner 4 passes through the heat exchanger 14 and the condenser 5, and then flows into the inlet pipe 5C of the rare gas hold up tower 6. 9 is a cooling pipe of the condenser 5, an arrow indicates the flow direction of the cooling water, and 1.5d is a drain pipe. The temperature control valve 10 is connected to the temperature controller 12 attached to the inlet pipe 17 of the recombiner 4, and the instrumentation wiring 13
controlled via.

Therefore, in the recombiner heating device described above, the gaseous waste and steam extracted from the main condenser 1 are sent to the gas inlet pipe 15 of the heat exchanger 14, flow into the heat exchanger 14, and enter the recombiner 4. Heated by the heat of the hydrogen oxidation reaction. The heat exchanger 14 is also provided with a pipe 11 that bypasses the heat exchanger 14 and a valve 10 that controls the amount of gas flowing through the pipe 11. This is a temperature control device for maintaining the optimum operating temperature (generally 450° C.) at which the recombination process of oxygen and hydrogen is carried out most efficiently. The gaseous waste and steam heated in the heat exchanger 14 are sent to the recombiner 4 containing a catalyst containing palladium or platinum supported on alumina pellets or a metal carrier, and the oxygen in the gaseous waste and steam is and hydrogen are recombined into water vapor. By operating the recombiner 4 at an optimal operating temperature (generally 450'C) below the permissible temperature at which the catalyst oxidizes, a device with high treatment efficiency and prevention of catalyst oxidation is created.

On the other hand, the treated gas is sent to the exhaust gas condenser 5, where it is condensed and drained, and the remaining gas, a rare gas, is sent to the hold-up tower 6, where it is exhausted in the conventional manner.

Next, an enlarged perspective view of the apparatus according to the present invention is shown in FIG. 2 and FIG. In FIG. 4, the recombiner 4 and the heat exchanger 14 in FIG.
This shows an example in which the catalyst is integrated into a cylindrical container 20, and is composed of a catalyst 21 filled in the upper half and a heat exchanger 14 housed in the lower half. This heat exchanger 14 can be freely removed by means of a flange 22, and has a structure that allows easy maintenance.

Further, in FIG. 4, the operating temperature is detected by a temperature detector 18 provided in the upper half of the catalyst 21, and
controlled by The lower end side of the container 20 is connected to the condenser inlet pipe 4a. In this embodiment, by removing the bypass line and installing a temperature control valve upstream of the recombiner 4 to reduce the amount of gaseous waste and steam supplied to the recombiner 4, the recombiner 4 temperature rise can be suppressed. However, the amount of gaseous waste fed to the recombiner is reduced, and the amount of oxygen and hydrogen reacted is reduced. This will reduce the efficiency of the recombination reaction.

In this embodiment, the total amount of gaseous waste supplied to the recombiner 4 does not change even before and after adjusting the opening degree of the temperature control valve 10, and the recombination reaction of hydrogen and oxygen is efficiently carried out.

In the above embodiment, the gas flow rate is controlled by detecting the gas temperature at the inlet of the recombiner 4, but it is also possible to control the gas flow rate by directly detecting the temperature of the recombiner. be.

As explained above, according to the present invention, it is possible to prevent the oxidation of the catalyst in the recombiner, and to efficiently recombine oxygen and hydrogen without requiring a separate steam line that serves as a heat source for the preheating section. It is possible to provide a heating device for a recombiner that can perform well.

[Brief explanation of drawings]

Figure 1 is a system diagram showing a conventional radioactive gas waste treatment system.
FIG. 2 is a system diagram showing the recombiner in FIG. It is a perspective view showing a piping system. 1... Main condenser, 2... Air extractor, 3... Preheater, 4... Recombiner, 5... Condenser, 6... Activated carbon hold up tower, 7 ...Vacuum pump, 8kawa Star γ
tower, 9... cooling pipe, 10... temperature control valve, 11.
... Piping, 12... Temperature controller, 13... Instrumentation wiring, 14... Heat exchanger, 15.16.17... Piping, 18... Temperature detector, 20... Cylindrical container, 21.
...Catalyst, 22...Flange. Application agent Patent attorney Gobe Kikuchi

Claims (1)

[Scope of Claims] (υ In a radioactive gas waste treatment system formed by sequentially connecting an exhaust gas extractor, a preheater, a recombiner, an exhaust gas condenser, and an activated carbon hold-up tower, the exhaust gas is removed by the preheater, A temperature control valve is interposed in the flow path between the extractor and the recombiner, and a temperature controller is provided, and a heat exchanger is provided that branches from and communicates with piping on both sides of the temperature control valve, and the heat exchanger is provided. A heating device for a recombiner in a radioactive waste treatment system, characterized in that the recombiner is provided with a flow path through which exhaust gas flowing out from the recombiner flows and flows into a predistribution exhaust gas condenser. The heater was a cylindrical container with a temperature detector at the upper end, a catalyst was filled in approximately the upper half of the container, and a heat exchanger was housed in approximately the lower half of the container, and the catalyst was heated by flowing the catalyst through the container. A patent characterized in that a vibrator in the heat exchanger is heated by gas, and the gas flowing in the heated pipe passes through the catalyst and forms a flow path to flow to an exhaust gas condenser. A heating device for a recombiner in a radioactive gas waste treatment system according to claim 1.