METHOD FOR INACTIVATING SODIUM METAL

Abstract

A method for cleaning a storage tank to which sodium metal is adherent, the method containing: filling, with an inert oil, the storage tank to which sodium metal is adherent; subsequently adding water, water vapor, or a humidified inert gas to the inert oil; providing a gas discharge line to the storage tank and measuring the hydrogen gas concentration in the gas discharge line; regulating the amount of the water, water vapor, or humidified inert gas to be added per hour in accordance with the level of the hydrogen gas concentration; regulating the temperature of the inert oil to 0-98 C.; and converting the sodium metal into caustic soda while changing the liquid surface level of the inert oil in parallel with addition of the water, water vapor, or humidified inert gas to the inert oil.

Claims

1. A method for inactivating sodium metal, comprising: immersing a sodium metal in an inert oil; and subsequently adding a moisture to the inert oil to convert the sodium metal into a caustic soda.

2. The inactivating method according to claim 1, further comprising changing a liquid surface level of the inert oil in parallel with the addition of the moisture.

3. The inactivating method according to claim 1, further comprising regulating a temperature of the inert oil to 0 C. to 98 C.

4. The inactivating method according to claim 1, wherein at least one of the moisture and the inert oil comprises a surfactant.

5. A method for cleaning an apparatus to which a sodium metal is adherent, comprising: immersing, in an inert oil, the apparatus to which a sodium metal is adherent, and subsequently adding a moisture to the inert oil to convert the sodium metal into a caustic soda.

6. A method for cleaning a storage tank to which a sodium metal is adherent, comprising: putting an inert oil in the storage tank to which a sodium metal is adherent, and subsequently adding a moisture to the inert oil to convert the sodium metal into a caustic soda.

7. The cleaning method according to claim 5, further comprising scraping the adherent sodium metal into the inert oil.

8. The cleaning method according to claim 5, wherein a hydrogen gas concentration is measured, and an amount of the moisture to be added per unit time is regulated in accordance with the measured hydrogen gas concentration.

9. The cleaning method according to claim 5, further comprising changing a liquid surface level of the inert oil in parallel with the addition of the moisture.

10. The cleaning method according to claim 5, further comprising regulating a temperature of the inert oil to 0 C. to 98 C.

11. The cleaning method according to claim 5, wherein at least one of the moisture and the inert oil comprises a surfactant.

12. The cleaning method according to claim 6, further comprising scraping the adherent sodium metal into the inert oil.

13. The cleaning method according to claim 6, wherein a hydrogen gas concentration is measured, and an amount of the moisture to be added per unit time is regulated in accordance with the measured hydrogen gas concentration.

14. The cleaning method according to claim 6, further comprising changing a liquid surface level of the inert oil in parallel with the addition of the moisture.

15. The cleaning method according to claim 6, further comprising regulating a temperature of the inert oil to 0 C. to 98 C.

16. The cleaning method according to claim 6, wherein at least one of the moisture and the inert oil comprises a surfactant.

Description

EXAMPLES

Example 1

[0075] A 100 ml container that could be sealed was filled with an inert oil having a temperature of 19 C., and then 4 pieces of sodium metal each having a size of 6 mm6 mm6 mm were put therein. The container was sealed, and the inert oil in the container was stirred with a stirrer bar while supplying the container with a nitrogen gas at 40 ml/min. 4.3 ml of water was added thereto at 0.6 ml/hour for 1 hour, 1.2 ml/hour for 0.5 hours, and 2.4 ml/hour for 1.3 hours. The added water was present in the inert oil in a drop shape. A large size of droplets sometimes contacted with sodium metal intermittently, and thereby the inactivating reaction sometimes rapidly and intermittently progressed. When the water addition was ended, all of the put sodium metal was inactivated. It is preferable that the amount of water added be approximately regulated, since the concentration of generated hydrogen gas sometimes significantly changes.

Example 2

[0076] An aqueous solution containing 5% dodecyl sodium sulfate (quenching agent A) was prepared. A 100 ml container that could be sealed was filled with an inert oil having a temperature of 17 C., and then 4 pieces of sodium metal each having a size of 6 mm6 mm6 mm were put therein. The container was sealed, and the inert oil in the container was stirred with a stirrer bar while supplying the container with a nitrogen gas at 40 ml/min. 4.8 ml of the quenching agent A was added thereto at 0.6 ml/hour for 1 hour, 1.2 ml/hour for 0.5 hours, and 2.4 ml/hour for 1.5 hours. The added quenching agent A was present in the inert oil in a micelle shape. The micelles contacted with sodium metal without interruption, and thereby the inactivating reaction progressed mildly and continuously. When the addition of the quenching agent A was completed, about two-thirds of the put sodium metal was inactivated. The concentration of the generated hydrogen gas gradually changed in accordance with the amount of the added quenching agent A, and thereby the amount of the quenching agent A to be added could be easily regulated by detecting the concentration of the hydrogen gas.

Example 3

[0077] An aqueous solution containing 10% polyoxyalkylenealkyl (C11-15) ether (quenching agent B) was prepared. A 100 ml container that could be sealed was filled with an inert oil having a temperature of 21 C., and then 4 pieces of sodium metal each having a size of 6 mm6 mm6 mm were put therein. The container was sealed, and the inert oil in the container was stirred with a stirrer bar while supplying the container with a nitrogen gas at 40 ml/min. 4.3 ml of the quenching agent B was added thereto at 0.6 ml/hour for 1 hour, 1.2 ml/hour for 0.5 hours, and 2.4 ml/hour for 1.3 hours. The added quenching agent B was emulsified in the inert oil and present in a micelle shape. The micelles contacted with sodium metal without interruption, and thereby the inactivating reaction progressed mildly and continuously. When the addition of the quenching agent B was completed, about two-thirds of the put sodium metal was inactivated. The concentration of the generated hydrogen gas gradually changed in accordance with the amount of the added quenching agent B, and thereby the amount of the quenching agent B to be added could be easily regulated by detecting the concentration of the hydrogen gas.

[0078] Although the present invention is typified by the above-mentioned embodiments, the present invention is not limited by the embodiments, and may be carried out by adding suitable modifications within a range that is compatible with the gist of the present invention, and all such modifications are also included within the technical scope of the present invention.

INDUSTRIAL APPLICABILITY

[0079] The method for inactivating sodium metal according to the present invention makes it possible to inactivate sodium metal industrially and safely.

[0080] The cleaning method according to the present invention makes it possible to clean a storage tank safely at a position where the storage tank is placed without moving the storage tank, even if the amount of sodium metal adherent to the storage tank or in an apparatus is unclear. In addition, the cleaning method makes it possible to inactivate sodium metal in a stepwise manner and to remove sodium metal safely even if the sodium metal is adherent to the inner surface to form lumps. The inactivating method and the cleaning method according to the present invention may be applied in a wide range from the small scale of a laboratory level to the large scale of a factory level.