JPS6263897A - Recombiner for exhaust gas - Google Patents

Abstract

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

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention mainly relates to radioactive gaseous waste treatment equipment for boiling water nuclear power plants, and is used to remove hydrogen and oxygen produced by radiolysis of reactor water. The present invention relates to an exhaust gas recombination device.

[Conventional technology]

The flow of the radioactive gas waste treatment system in a boiling water nuclear power plant is shown in Figure 1.

Hydrogen and oxygen gases generated by radiolysis of reactor water are extracted together with leaked air from the main condenser 2 by an air extractor 3.
Air is extracted from the main condenser and driven by steam from the air extractor.
After being diluted to below the detonation gas limit, the exhaust gas preheater 4 adjusts the temperature using in-house steam to be about 30° C. higher than the saturation temperature of the process gas. The treated gas that has exited the exhaust gas preheater is turned into water vapor by the catalyst in the exhaust gas recombiner 5. The water vapor is condensed and removed together with the driving steam by the exhaust gas condenser 6. The radioactive exhaust gas from which hydrogen, oxygen, and water vapor have been removed has a long half-life, and 'tXe is attenuated by the activated carbon adsorption tower 7, and then released into the atmosphere from the exhaust stack 8.

Since the catalyst filled in the exhaust gas recombiner has the disadvantage that the recombination reaction worsens when moisture flows into it, conventionally, before starting the device, air is injected from the air supply device 9.
The air heated by the exhaust gas preheater warms the piping between the exhaust gas preheater and the exhaust gas recombiner to prevent condensate from flowing into the exhaust gas recombiner.

Note that the technology related to the present invention is disclosed in Japanese Patent Application Laid-open No. 55-15
There is one described in Publication No. 8600.

[Problem to be interpreted by the invention]

However, since it is not possible to flow a large amount of air from downstream processing vessels such as activated carbon adsorption towers, the flow rate is about 1/200 of the rated value even through an exhaust gas preheater, so it is difficult to heat the pipes due to poor heat exchange. The disadvantage is that it takes time to heat up and the temperature cannot be raised sufficiently. In addition, the exhaust gas preheater, exhaust gas recombiner, and exhaust gas condenser are composed of two systems with 100% capacity, one in operation and one in timing. When switching the operating system to the standby side, there is air leakage from the main condenser.
Due to the capacity of the activated carbon adsorption tower, it is not possible to flow much air to raise the temperature. Therefore, when switching to the standby side,
Since the temperature of the piping between the exhaust gas preheater and the exhaust gas recombination cannot be kept elevated, some of the water vapor condenses and flows into the recombination, resulting in a temporary drop in performance.

The object of the present invention is to provide a method for solving the above drawbacks of the prior art.6 [Means for Solving the Problems] In order to achieve the above object, the present invention has an exhaust gas recombination device configured as follows. .

That is, in an apparatus in which exhaust gas containing hydrogen gas and oxygen gas is introduced and the hydrogen gas and oxygen gas are recombined into water vapor in a reaction vessel filled with a catalyst, the exhaust gas introduced into the reaction vessel is preheated to a temperature higher than the saturation temperature. a temperature detector provided on a pipe wall of a pipe connecting the preheater and the reaction vessel; and a temperature detector provided outside the pipe between the preheater and the reaction vessel.

and a means for heating the pipe based on the output of the detector, the lower limit temperature of which is set to be slightly higher than the saturation temperature of steam during normal operation, and the upper limit temperature is set to be slightly higher than the saturation temperature of the steam during normal operation. The above objective is achieved by providing a heater whose temperature is slightly lower than the outlet gas temperature.

[For production]

Detects the temperature of the pipe wall of the piping between the preheater and the reaction vessel,
The piping is heated by a heater so that this temperature is higher than the saturation temperature of the steam when the process gas is introduced, so condensate does not flow into the catalytic recombination, and the catalytic recombiner reaction decreases. It can be prevented. Further, since the upper limit temperature of the heater temperature adjustment is set lower than the gas temperature at the outlet of the exhaust gas preheater, heating by the heater during normal operation becomes unnecessary.

〔Example〕

The details of the present invention will be explained with reference to the embodiment shown in FIG.

A heater 11 is attached to the outer surface of the pipe 10 between the exhaust gas preheater and the exhaust gas recombiner, and a temperature detector is provided on the distribution wall, and the heater is regulated by this thermometer. A heat insulating material 15 is wrapped around the heater.

Before the process gas flows into the exhaust gas recombination device, the heater is turned on to raise the temperature of the piping. The temperature of the pipe surface is detected and controlled so that this temperature is equal to or higher than the saturation temperature of the steam when the processing gas is flowing.

According to the present invention, the temperature of the piping can be easily raised within a short period of time, and no condensed water is generated even when the process gas is vented, so that the performance of the catalyst does not deteriorate.

Processing gas containing oxygen and hydrogen gas is processed by an exhaust gas preheater.
Since the temperature is controlled by in-house steam to be several tens of degrees higher than the saturated temperature of the steam, by setting the upper limit temperature of the heater temperature control to be lower than the exhaust gas preheater outlet gas temperature mentioned above. , the heater does not need to be energized during normal operation.

〔Effect of the invention〕

According to the present invention, it is possible to obtain an exhaust gas recombination device that can be easily activated and switched to the standby side without deteriorating the performance of the catalyst in the recombiner.

[Brief explanation of the drawing]

FIG. 1 is a flow diagram of a radioactive gas waste treatment system which is the main subject of the present invention, FIG. 2 is a detailed explanatory diagram of the present invention, and FIG. 3 is a detailed diagram of the present invention. 3... Air extractor, 4... Exhaust gas preheater, 5...
Exhaust gas recombiner, 10... Piping, 11... Heater,
12...Power source, 13...Temperature detector, 14...Switch, 15...Heat insulation material, 16...Temperature detector,
17...Temperature adjustment valve.

Claims (1)

[Claims] 1. In an apparatus for introducing exhaust gas containing hydrogen gas and oxygen gas and recombining the hydrogen gas and oxygen gas into water vapor in a reaction vessel filled with a catalyst, the exhaust gas introduced into the reaction vessel. a preheater for preheating to a saturation temperature or higher; a temperature detector provided on the pipe wall of a pipe connecting the preheater and the reaction vessel; a temperature detector provided outside the pipe between the preheater and the reaction vessel; A means for heating the piping based on the output of the detector, the lower limit temperature of which is set to be slightly higher than the saturation temperature of steam during normal operation, and the upper limit temperature is set to be slightly higher than the steam saturation temperature during normal operation. An exhaust gas recombination device comprising: a heater whose temperature is slightly lower than that of the exhaust gas recombiner;