CN-121976250-A - Gradient enrichment heavy water method and system for producing hydrogen by coupling electrolysis of seawater

CN121976250ACN 121976250 ACN121976250 ACN 121976250ACN-121976250-A

Abstract

The invention relates to a gradient enrichment heavy water method and system for producing hydrogen by coupling electrolysis of seawater, belonging to the technical field of seawater resource utilization. The gradient enrichment heavy water method comprises the following steps of preprocessing natural seawater to obtain preprocessed seawater, performing ALK electrolysis or AEM electrolysis on the preprocessed seawater to initially enrich deuterium in the preprocessing to form deuterium-enriched alkali liquor while preparing hydrogen, evaporating the deuterium-enriched alkali liquor under the heat drive of primary electrolysis heat carried by the deuterium-enriched alkali liquor to remove alkali and salt to obtain primary deuterium-enriched pure water, performing PEM electrolysis on the primary deuterium-enriched pure water to form secondary deuterium-enriched pure water, and rectifying the secondary deuterium-enriched pure water carrying secondary electrolysis heat to obtain a heavy water product. The gradient enrichment heavy water method combines the coupling of different seawater electrolysis hydrogen production modes with rectification treatment, realizes the gradient enrichment of heavy water, has low energy consumption and high enrichment efficiency, and can meet the extraction requirement of large-scale heavy water.

Inventors

TANG BO
LI JIAWEI
QIN JIANGUANG
YU QIANG
CHENG YONGQIANG
CAI ZHENGWEI

Assignees

崂山国家实验室

Dates

Publication Date: 20260505
Application Date: 20260120

Claims (10)

1. The gradient enrichment heavy water method for producing hydrogen by coupling electrolysis of seawater is characterized by comprising the following steps of: pretreatment, namely pretreating natural seawater to obtain pretreated seawater meeting the electrolysis water inlet requirement of an alkaline system; An alkaline system electrolysis step, namely performing ALK electrolysis or AEM electrolysis on the pretreated seawater to initially enrich deuterium in the pretreated seawater to form deuterium-enriched alkali liquor while preparing hydrogen, wherein the deuterium-enriched alkali liquor carries primary electrolysis heat generated by ALK electrolysis or AEM electrolysis; The dealkalization and desalination step, namely evaporating the deuterium-enriched alkali liquor under the heat drive of primary electrolysis heat carried by the deuterium-enriched alkali liquor to remove alkali and salt, so as to obtain primary deuterium-enriched pure water; a PEM electrolysis step, namely carrying out PEM electrolysis on the primary deuterium-enriched pure water so as to further enrich deuterium in the primary deuterium-enriched pure water to form secondary deuterium-enriched pure water while producing hydrogen, wherein the secondary deuterium-enriched pure water carries secondary electrolysis heat generated by PEM electrolysis; And rectifying the secondary deuterium-enriched pure water carrying the secondary electrolytic heat to ensure that the heavy water content in the heavy component exceeds 99 percent and obtain a heavy water product.
2. The gradient enrichment heavy water method for producing hydrogen by coupling electrolysis of seawater according to claim 1, wherein in the alkaline system electrolysis step, when ALK electrolysis is adopted, the temperature of the ALK electrolysis is 60-85 ℃, the current density is 0.2-0.6A/cm 2 , and when AEM electrolysis is adopted, the temperature of the AEM electrolysis is 60-85 ℃ and the current density is 0.5-2A/cm 2 .
3. The gradient heavy water enrichment method for producing hydrogen by coupling electrolysis of seawater according to claim 1, wherein the evaporation method adopted in the dealkalization and desalination step is any one selected from the group consisting of flash evaporation, vacuum evaporation and multiple effect evaporation.
4. The gradient heavy water enrichment method for producing hydrogen by coupling electrolysis of seawater according to claim 1 or 3, wherein in the dealkalization and desalination step, the conductivity of the primary deuterium-enriched pure water obtained after evaporation is controlled to be not higher than 1 μs/cm.
5. The gradient enriched heavy water method for producing hydrogen by coupling electrolysis of seawater according to claim 1, wherein in the PEM electrolysis step, the temperature of the PEM electrolysis is 50-80 ℃ and the current density is 0.5-2.5A/cm 2 .
6. The gradient heavy water enrichment method for producing hydrogen by coupling electrolysis of seawater according to claim 1 or 5, wherein in the PEM electrolysis step, the primary deuterium-enriched pure water is sequentially subjected to multistage PEM electrolysis, the produced water of the previous stage PEM electrolysis is used as the feed of the next stage PEM electrolysis, the produced water of the final stage PEM electrolysis is used as the secondary deuterium-enriched pure water, and the temperature and current density of the multistage PEM electrolysis are increased step by step.
7. The gradient heavy water enrichment method for producing hydrogen by coupling electrolysis of seawater according to claim 6, further comprising an alkali liquor reflux treatment step, wherein the alkali liquor reflux treatment step specifically comprises taking residual alkali liquor evaporated in the dealkalization and desalination step as reflux alkali liquor, and the reflux alkali liquor is refluxed to maintain the alkali liquor concentration of the ALK electrolysis or AEM electrolysis in the alkaline system electrolysis step.
8. The gradient heavy water enrichment method for producing hydrogen by coupling electrolysis of seawater according to claim 1, further comprising a rectifying light component reflux treatment step, wherein the rectifying light component reflux treatment step specifically comprises the step of taking a light component produced by rectifying in the rectifying step as a light component reflux liquid, wherein the light component reflux liquid is refluxed to repeat the dealkalization and desalination step or the light component reflux liquid is refluxed to repeat the alkaline system electrolysis step.
9. A gradient enriched heavy water system for producing hydrogen from coupling electrolyzed seawater, characterized by operating the gradient enriched heavy water method for producing hydrogen from coupling electrolyzed seawater according to any one of claims 1 to 8, comprising: the pretreatment unit is used for pretreating the natural seawater to obtain pretreated seawater; An alkaline system electrolysis unit for performing ALK electrolysis or AEM electrolysis on the pretreated seawater to initially enrich deuterium in the pretreated seawater while producing hydrogen to form deuterium-enriched alkaline solution, wherein the alkaline system electrolysis unit comprises an ALK electrolysis tank or an AEM electrolysis tank; the dealkalization and desalination unit is used for evaporating the deuterium-enriched alkali liquor to obtain primary deuterium-enriched pure water and comprises an evaporation device connected with the ALK electrolytic tank or the AEM electrolytic tank; A PEM electrolysis cell for subjecting the primary deuterium-enriched pure water to PEM electrolysis to further enrich deuterium in the primary deuterium-enriched pure water while producing hydrogen to form secondary deuterium-enriched pure water, comprising a PEM electrolysis cell connected to the evaporation device; And the rectification unit is used for rectifying the secondary deuterium-enriched pure water and comprises a rectification tower connected with the PEM electrolytic tank.
10. The gradient enriched heavy water system for producing hydrogen by coupling electrolysis of seawater of claim 9, wherein a plurality of PEM electrolytic cells are provided in the PEM electrolytic cell, and a plurality of the PEM electrolytic cells are connected in series in sequence.

Description

Gradient enrichment heavy water method and system for producing hydrogen by coupling electrolysis of seawater Technical Field The invention belongs to the technical field of seawater resource utilization, and particularly relates to a gradient enrichment heavy water method and system for producing hydrogen by coupling electrolysis of seawater. Background Heavy water is used as an important strategic isotope resource and has an irreplaceable effect in the fields of nuclear energy, fine chemical engineering and the like. The existing industrial heavy water production mainly comprises an ammonia-hydrogen isotope exchange method, a sulfide exchange method and a multistage rectification method, and the problems of complex flow, large equipment scale, high energy consumption, high operation cost and the like generally exist in the processes, and a special production system is usually required to be independently configured, so that the process is difficult to cooperatively operate with other energy processes. In recent years, along with the rapid development of proton exchange membrane electrolysis hydrogen production technology, electrolysis methods such as PEM and the like can not only produce high-purity hydrogen, but also bring along with electrochemical distribution effect of hydrogen isotopes in the electrolysis process, so that deuterium content in produced water is improved compared with that of original water. For example, chinese patent No. 118461029A discloses an offshore platform PEM water electrolysis hydrogen production and heavy water production system, which adopts two-stage PEM electrolysis to realize the extraction of heavy water while producing hydrogen, but the deuterium content in the PEM electrolysis produced water is still relatively low, and high-concentration heavy water is difficult to obtain only by adopting an electrolysis mode, and the patent is further combined with a rectification mode, so that the heavy water in the PEM electrolysis produced water is further purified by utilizing rectification. However, the higher water intake requirements of PEM electrolysis, especially on the salinity of the water intake, result in higher pretreatment costs, and the PEM electrolysis throughput is generally smaller, making it difficult to meet the large-scale heavy water extraction requirements. Therefore, how to fully utilize the enrichment effect of hydrogen production by seawater electrolysis on deuterium to realize low-energy consumption, high-efficiency and large-scale heavy water enrichment is a technical problem which needs to be solved currently. Disclosure of Invention Aiming at the technical problems, the invention provides the gradient enrichment heavy water method and system for producing hydrogen by coupling electrolytic seawater, which combines coupling and rectification treatment of different seawater electrolytic hydrogen production modes, realizes gradient enrichment of deuterium generated in the electrolytic seawater hydrogen production process while producing hydrogen, has low energy consumption and high enrichment efficiency, and can meet the extraction requirement of large-scale heavy water. The invention provides a gradient enrichment heavy water method for producing hydrogen by coupling electrolysis of seawater, which comprises the following steps: pretreatment, namely pretreating natural seawater to obtain pretreated seawater meeting the electrolysis water inlet requirement of an alkaline system; An alkaline system electrolysis step, namely performing ALK electrolysis or AEM electrolysis on the pretreated seawater to initially enrich deuterium in the pretreated seawater to form deuterium-enriched alkali liquor while preparing hydrogen, wherein the deuterium-enriched alkali liquor carries primary electrolysis heat generated by ALK electrolysis or AEM electrolysis; the dealkalization and desalination step, namely evaporating deuterium-enriched alkali liquor under the heat drive of primary electrolysis heat carried by the deuterium-enriched alkali liquor to remove alkali and salt, thus obtaining primary deuterium-enriched pure water; A PEM electrolysis step, namely carrying out PEM electrolysis on the primary deuterium-enriched pure water so as to further enrich deuterium in the primary deuterium-enriched pure water to form secondary deuterium-enriched pure water while producing hydrogen, wherein the secondary deuterium-enriched pure water carries secondary electrolysis heat generated by PEM electrolysis; And rectifying the secondary deuterium-enriched pure water carrying the secondary electrolytic heat to ensure that the heavy water content in the heavy component exceeds 99 percent and obtain a heavy water product. In some embodiments, in the alkaline system electrolysis step, when ALK electrolysis is adopted, the temperature of ALK electrolysis is 60-85 ℃, the current density is 0.2-0.6A/cm 2, and when AEM electrolysis is adopted, the temperature of AEM electrolysis is 60-85