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Passivation method of metal sodium

A technology of metal sodium and caustic soda, applied in alkali metal hydroxides, chemical instruments and methods, cleaning methods using liquids, etc., can solve the problems of difficult control and acceleration of deactivation

Inactive Publication Date: 2019-01-22
NIPPON SODA CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0009] The method of perfusing water to deactivate it is difficult to control the generated hydrogen, and the metal sodium heated by the reaction heat of metal sodium and water melts at once, and the reaction may be accelerated continuously, and the control of deactivation may become difficult

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment approach 1

[0054] In one embodiment of the cleaning method described above, first, the state of the storage tank is checked. As a storage tank, the metal sodium dispersion storage tank is mentioned, for example. The state of adhesion of metallic sodium to the inner surface of the storage tank was investigated using a surveillance camera or the like. In addition, it was checked whether there was a pipe for discharging the metal sodium dispersion out of the system in the storage tank. When there is no pipe for discharge, temporarily install a discharge pipe in the storage tank. Since hydrogen gas is produced when sodium metal is converted to caustic soda, check for the presence of a vent line in the storage tank for letting off the hydrogen gas. When there is no exhaust pipe, temporarily install the exhaust pipe in the storage tank. It is preferable to install a mist eliminator and a water washing tower on the exhaust pipe. Since the inert oil mist may contain metallic sodium particles...

Embodiment approach 2

[0064] When the amount of the sodium metal dispersion remaining in the dead space is large, the following operation can be performed in order to empty the storage tank.

[0065] Fill the storage tank with new inactive oil, and wash out the sodium metal dispersion remaining in the dead corners with the inactive oil. Then, the washed sodium metal dispersion is withdrawn from the storage tank. The extraction of the inert oil containing the eluted sodium metal dispersion can be carried out by supplying an inert gas or the like to a storage tank and applying pressure. It should be noted that the concentration of sodium metal in the extracted sodium metal dispersion was measured, and if it was higher than the specified value, washing and extraction could be performed repeatedly using inert oil. The temperature of the inactive oil is preferably 0°C to 98°C, more preferably 0 to 60°C, even more preferably 0 to 40°C.

[0066] When the sodium metal concentration in the extracted sodiu...

Embodiment approach 3

[0068] When the sodium metal attached to the storage tank becomes lumps, the following operations can be performed in order to passivate effectively.

[0069] First, remove the tank from the other equipment. Removal can be performed by inserting a blind flange or the like into the pipe. Since the metal sodium dispersion remaining in the piping, gaps between connecting flanges, etc. may fall when the flange bolts are loosened, it is preferable to place a metal container or the like under the flange to catch the metal sodium dispersion. The received metal sodium dispersion can be passivated with methanol or the like. Reduce the internal pressure of the storage tank to atmospheric pressure and open the blind flange or sight glass of the preliminary nozzle. The interior is observed with an endoscope or the like to check the adhesion state of the metallic sodium dispersion.

[0070] Fill the tank with non-reactive oil until the bottom of the tank is covered. Put a metal jig fro...

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PUM

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Abstract

A method for cleaning a storage tank with metallic sodium, comprising the following steps: making inactive oil overflow the storage tank with metallic sodium, then adding water, water vapor or humidified inactive gas to the inactive oil, Install an exhaust pipe in the storage tank to measure the hydrogen concentration of the exhaust pipe, adjust the amount of water, water vapor, or humidifying inert gas added per unit time according to the hydrogen concentration level, and adjust the temperature of the inert oil 0°C to 98°C, and in parallel with the addition of water, steam or humidified inert gas to the inert oil, the metal sodium is converted into caustic soda while changing the liquid level of the inert oil.

Description

technical field [0001] The invention relates to a passivation method of metal sodium and a cleaning method of a device or a storage tank attached with metal sodium. [0002] This application claims priority based on Japanese Patent Application No. 2014-115803 for which it applied in Japan on June 4, 2014, and Japanese Patent Application No. 2015-081912 for which it applied in Japan on April 13, 2015, and uses the content here. Background technique [0003] Sodium metal dispersion (hereinafter, sometimes referred to as SD drug) is obtained by dispersing sodium metal particles in inert oil. Sodium metal dispersions are used to remove PCBs, etc. During storage of the SD drug in the storage tank, metallic sodium may accumulate on the top surface or the inner side surface of the tank to form sodium lumps such as icicles. If the sodium block is left as it is, cracks will appear in the storage tank, and there is a risk of explosion and fire due to the reaction between water and m...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): B08B3/08B08B3/10C01D1/04
CPCC01D1/04Y02E60/36B08B9/08B09C1/00C01B3/06A62D3/38A62D2101/40B08B1/165B08B9/083
Inventor 伊藤英明荒川彻相羽孝弘
Owner NIPPON SODA CO LTD