JP-7856306-B2 - Water production method, adsorbent regeneration method, and water production apparatus

JP7856306B2JP 7856306 B2JP7856306 B2JP 7856306B2JP-7856306-B2

Inventors

江口晃哉
小野勇次

Assignees

株式会社タカギ

Dates

Publication Date: 20260511
Application Date: 20220801

Claims (14)

A method for producing water in which the content of the isotopically substituted molecule is reduced, from raw water containing water molecules and molecules in which at least one of the hydrogen atoms constituting the water molecules is replaced with an isotopic element of hydrogen, A first step involves supplying raw material steam from raw water to an adsorbent, adsorbing at least a portion of the raw material steam onto the adsorbent, and recovering steam containing water molecules that preferentially desorb from the adsorbent due to differences in the strength of hydrogen bonds formed between the adsorbent and the adsorbent. The first step is followed by a second step of supplying a gas containing water vapor to the adsorbent, thereby diffusing at least a portion of the molecules adsorbed on the adsorbent into the gas, and restoring the separation performance of the adsorbent. In the second step, The relative humidity of the gas supplied to the adsorbent is adjusted to be between 0.0005% and 2.5% RH at the temperature of the gas supplied to the adsorbent. A manufacturing method wherein the content of the molecule substituted with an isotopic element in the gas supplied to the adsorbent is less than the content of the molecule in the raw material vapor.
The manufacturing method according to claim 1, wherein the content of the molecule in the gas supplied to the adsorbent in the second step is 140 atoms ppm or less.
The manufacturing method according to claim 1 or 2, wherein the temperature of the gas supplied to the adsorbent in the second step is 60°C or higher.
The process further includes a third step of preparing water in which the molecular content is reduced by condensing a portion of the steam recovered in the first step, The manufacturing method according to claim 1 or 2, wherein in the third step, a portion of the vapor that was not condensed is used as the gas supplied to the adsorbent in the second step.
The manufacturing method according to claim 1 or 2, wherein the first step and the second step are repeated alternately to continuously produce water with a reduced molecular content.
The manufacturing method according to claim 1 or 2, wherein the adsorbent is at least one selected from the group consisting of polymer sorbents, activated carbon, and zeolites.
The manufacturing method according to claim 1 or 2, wherein the adsorbent is contained in an adsorbent layer provided on at least a portion of the surface of the cylindrical body.
The manufacturing method according to claim 1 or 2, wherein the adsorbent is filled into a cylindrical body.
A method for regenerating an adsorbent used to reduce the content of molecules substituted with isotopes, from raw water containing water molecules and molecules in which at least one of the hydrogen atoms constituting the water molecules is substituted with an isotope of hydrogen, This includes supplying a gas containing water vapor to the adsorbent and diffusing at least a portion of the molecules adsorbed on the adsorbent into the gas, thereby restoring the separation performance of the adsorbent. The relative humidity of the gas supplied to the adsorbent is adjusted to be between 0.0005% and 2.5% RH at the temperature of the gas supplied to the adsorbent. A regeneration method wherein the content of the molecule substituted with an isotopic element in the gas supplied to the adsorbent is less than the content of the molecule in the raw material steam generated from the raw material water.
The regeneration method according to claim 9, wherein the content of the molecule in the gas supplied to the adsorbent is 140 atoms ppm or less.
The regeneration method according to claim 9 or 10, wherein the temperature of the gas supplied to the adsorbent is 60°C or higher.
A manufacturing apparatus for producing water in which the content of the isotopically substituted molecules is reduced, from raw water containing water molecules and molecules in which at least one of the hydrogen atoms constituting the water molecules is replaced with an isotopic element of hydrogen, An adsorption and desorption unit for raw material vapor generated from the raw material water, having an adsorbent, A raw material supply unit that supplies the raw material steam to the adsorption/desorption unit, A recovery unit that recovers steam containing water molecules preferentially detached from the adsorbent due to differences in the strength of hydrogen bonds formed between the adsorbent and the adsorbent, The system includes a gas supply unit that supplies gas with adjusted molecular content and humidity to the adsorption/desorption unit, A manufacturing apparatus that adjusts the humidity of the gas supply unit so that the relative humidity at the temperature at which it is supplied to the adsorbent is 0.0005 to 2.5% RH, and supplies a gas to the adsorption/desorption unit in which the content of the molecules substituted with isotopic elements in the gas is less than the content of the molecules in the raw material vapor, thereby diffusing at least a portion of the molecules substituted with isotopic elements adsorbed on the adsorbent into the gas, and restoring the separation performance of the adsorbent.
The recovery unit has means for condensing the recovered steam, The manufacturing apparatus according to claim 12, wherein the gas supply unit supplies the steam that was not condensed in the recovery unit as the gas to the adsorption/desorption unit.
The raw material supply unit supplies steam of the raw material water in a direction parallel to the extending direction of the adsorption/desorption unit. The manufacturing apparatus according to claim 12 or 13, wherein the gas supply unit supplies the gas in the opposite direction to the steam of the raw water.

Description

This disclosure relates to a method for producing water, a method for regenerating adsorbents, and a water production apparatus. Tap water and natural spring water may contain semi-heavy water and heavy water, and water used for reactor cooling may contain tritium water. These semi-heavy water, heavy water, and tritium water differ from light water in physical properties such as solubility, electrical conductivity, and degree of ionization, as well as reaction rates. Therefore, if living organisms ingest large amounts of water containing semi-heavy water, heavy water, and tritium water, it can adversely affect biological reactions. To avoid such situations, various methods are being investigated for preparing water with reduced semi-heavy water, heavy water, and tritium water content. For example, a method is known for producing deuterium-reduced water by utilizing the slight difference in adsorption and desorption performance between light water, semi-heavy water, and heavy water on an adsorbent. This method involves adsorbing raw water onto an adsorbent with a porous structure, and then desorbing a portion of the adsorbed raw water (e.g., Patent Documents 1 and 2). These techniques are useful in reducing the content of semi-heavy water and heavy water. However, as the proportion of semi-heavy water and heavy water adsorbed onto the adsorbent increases, the ability to separate light water from semi-heavy water and heavy water in the raw water gradually decreases. This raises concerns about unstable water quality, such as a gradual increase in the semi-heavy water and heavy water content in the resulting deuterium-reduced water. Therefore, generally, replacement of the adsorbent is required, leading to an increase in the production cost of deuterium-reduced water. Studies are also being conducted to regenerate and reuse used adsorbents. Such regeneration methods primarily involve removing molecules adsorbed on the adsorbent by heating and volatilizing them. Furthermore, for example, Patent Document 3 discloses a method for activating and regenerating adsorbents used in hydrogen isotope concentration and separation. This method involves heating and regenerating the adsorbent used for the separation and concentration of various hydrogen isotopes in water, and then bringing the water vapor-encompassing gas of hydrogen isotopes with lighter masses than the heavier components remaining in the heat-regenerated adsorbent into countercurrent contact with the heat-regenerated adsorbent in an activation and regeneration zone at near the adsorbent's regeneration temperature, thereby transferring the heavier components of the hydrogen isotopes remaining in the heat-regenerated adsorbent into the gas. International Publication No. 2017/209227International Publication No. 2019/004102Japanese Unexamined Patent Publication No. 53-093294 Figure 1 is a schematic diagram showing an example of a manufacturing apparatus.Figure 2 is a schematic diagram of the evaluation apparatus used for evaluation in the embodiment.Figure 3 is a graph showing the relationship between the deuterium concentration and yield in the deuterium-reduced water produced in the examples.Figure 4 is a graph showing the relationship between the content of deuterium-containing components in the deuterium-reduced water in the examples and the content of deuterium-containing components in the water vapor used to regenerate the adsorbent.Figure 5 is a graph showing the relationship between the content of deuterium-containing components in the deuterium-reduced water in the example and the relative humidity of the water vapor used to regenerate the adsorbent.Figure 6 is a graph showing the relationship between the content of deuterium-containing components in the deuterium-reduced water in the examples and the relative humidity of the water vapor used to regenerate the adsorbent.Figure 7 is a graph showing the relationship between the deuterium concentration and yield in the deuterium-reduced water produced in the examples. The embodiments of this disclosure will be described below, with reference to the drawings as appropriate. However, the following embodiments are illustrative examples for illustrating this disclosure and are not intended to limit this disclosure to the following. Unless otherwise specified, positional relationships such as top, bottom, left, and right are based on those shown in the drawings. The dimensional ratios of each element are not limited to those shown in the drawings. Unless otherwise specified, the materials exemplified herein may be used individually or in combination of two or more. The content of each component in a composition refers to the total amount of any multiple substances present in the composition, unless otherwise specified, if multiple substances corresponding to each component exist in the composition. One embodiment of a production method for obtaining water with a reduced content of isotopically substituted mole