CN117210874A - Device for preparing hydrogen by electrolyzing water and method for preparing hydrogen by electrolyzing water - Google Patents
Device for preparing hydrogen by electrolyzing water and method for preparing hydrogen by electrolyzing water Download PDFInfo
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- CN117210874A CN117210874A CN202311181552.2A CN202311181552A CN117210874A CN 117210874 A CN117210874 A CN 117210874A CN 202311181552 A CN202311181552 A CN 202311181552A CN 117210874 A CN117210874 A CN 117210874A
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 title claims abstract description 342
- 239000001257 hydrogen Substances 0.000 title claims abstract description 101
- 229910052739 hydrogen Inorganic materials 0.000 title claims abstract description 101
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 title claims abstract description 99
- 238000000034 method Methods 0.000 title claims abstract description 32
- 239000012153 distilled water Substances 0.000 claims abstract description 93
- 238000004821 distillation Methods 0.000 claims abstract description 88
- 238000004519 manufacturing process Methods 0.000 claims abstract description 38
- 238000005868 electrolysis reaction Methods 0.000 claims abstract description 35
- 239000007788 liquid Substances 0.000 claims abstract description 35
- 150000003839 salts Chemical class 0.000 claims abstract description 35
- 239000003792 electrolyte Substances 0.000 claims abstract description 10
- 238000011049 filling Methods 0.000 claims abstract description 9
- 239000002994 raw material Substances 0.000 claims abstract description 8
- 239000000203 mixture Substances 0.000 claims description 34
- 238000005292 vacuum distillation Methods 0.000 claims description 32
- 239000003513 alkali Substances 0.000 claims description 29
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 24
- 239000001301 oxygen Substances 0.000 claims description 24
- 229910052760 oxygen Inorganic materials 0.000 claims description 24
- 238000010992 reflux Methods 0.000 claims description 16
- 238000012856 packing Methods 0.000 claims description 15
- 238000011033 desalting Methods 0.000 claims description 14
- 239000012267 brine Substances 0.000 claims description 12
- HPALAKNZSZLMCH-UHFFFAOYSA-M sodium;chloride;hydrate Chemical compound O.[Na+].[Cl-] HPALAKNZSZLMCH-UHFFFAOYSA-M 0.000 claims description 12
- 238000009833 condensation Methods 0.000 claims description 10
- 230000005494 condensation Effects 0.000 claims description 10
- 238000001704 evaporation Methods 0.000 claims description 6
- 238000000926 separation method Methods 0.000 claims description 5
- 150000002431 hydrogen Chemical class 0.000 claims description 4
- 238000010612 desalination reaction Methods 0.000 claims description 2
- 230000008020 evaporation Effects 0.000 claims description 2
- 239000007791 liquid phase Substances 0.000 claims description 2
- 238000001816 cooling Methods 0.000 claims 1
- 239000002918 waste heat Substances 0.000 abstract description 4
- 230000000052 comparative effect Effects 0.000 description 5
- 238000001223 reverse osmosis Methods 0.000 description 5
- 238000010977 unit operation Methods 0.000 description 4
- 239000007789 gas Substances 0.000 description 3
- 238000010438 heat treatment Methods 0.000 description 3
- 239000012071 phase Substances 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000003809 water extraction Methods 0.000 description 2
- 230000002411 adverse Effects 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 238000005115 demineralization Methods 0.000 description 1
- 230000002328 demineralizing effect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 238000004064 recycling Methods 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 238000009834 vaporization Methods 0.000 description 1
- 230000008016 vaporization Effects 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
Classifications
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/30—Hydrogen technology
- Y02E60/36—Hydrogen production from non-carbon containing sources, e.g. by water electrolysis
Landscapes
- Electrolytic Production Of Non-Metals, Compounds, Apparatuses Therefor (AREA)
Abstract
The invention relates to the field of hydrogen production, and discloses a device for producing hydrogen by water electrolysis and a method for producing hydrogen by water electrolysis. The device comprises: the system comprises a demineralized water system, an electrolytic hydrogen production system and a distillation condensing system which are communicated with each other; wherein, the desalted water outlet of the desalted water system is communicated with the raw material inlet of the electrolytic hydrogen production system; the salt-containing concentrated water outlet of the desalted water system is communicated with the raw material inlet of the distillation condensing system; the liquid discharge outlet of the electrolytic hydrogen production system is communicated with the inlet of the heat source pipeline of the distillation condensing system; the outlet of the heat source pipeline of the distillation condensing system is communicated with the electrolyte filling port of the electrolytic hydrogen production system, and the condensate outlet of the distillation condensing system is optionally communicated with the raw water inlet of the demineralized water system. The invention adopts the waste heat of the electrolysis process to exchange heat with the salt-containing concentrated water and distill and condense the salt-containing concentrated water to obtain distilled water, thereby improving the utilization rate of the water.
Description
Technical Field
The invention relates to the field of hydrogen production, in particular to a device for producing hydrogen by electrolyzing water and a method for producing hydrogen by electrolyzing water.
Background
The hydrogen production by electrolysis of water is a necessary link in the development of hydrogen energy, 9kg of water is needed to be added in the theoretical electrolysis to obtain 1kg of hydrogen, but the actual water consumption is higher than the value, one of the main reasons is that pure water is needed to be adopted in an electrolytic tank, generally source water is obtained through a reverse osmosis and other demineralized water system, after qualified demineralized water is obtained (the conductivity of 25 ℃ is less than 1 mu s/cm), a stream of concentrated water (called salty concentrated water) which is 3-8 times higher than the salt content of the source water is formed, and the stream of water is generally discharged directly, so that the water resource utilization rate is only 70-85%, and the water resource is basically not recycled in the industry; the bottleneck of water resource recycling restricts the development of hydrogen energy to a certain extent. Therefore, a process for producing hydrogen by electrolyzing water, which can improve the utilization rate of water resources, is needed.
Disclosure of Invention
The invention aims to solve the problem of low water resource utilization rate in the process of producing hydrogen by electrolyzing water in the prior art, and provides a device and a method for producing hydrogen by electrolyzing water.
In order to achieve the above object, a first aspect of the present invention provides an apparatus for producing hydrogen by electrolyzing water, wherein the apparatus comprises: the system comprises a demineralized water system, an electrolytic hydrogen production system and a distillation condensing system which are communicated with each other; wherein,
the desalted water outlet of the desalted water system is communicated with the raw material inlet of the electrolytic hydrogen production system;
the salt-containing concentrated water outlet of the desalted water system is communicated with the raw material inlet of the distillation condensing system;
the liquid discharge outlet of the electrolytic hydrogen production system is communicated with the inlet of the heat source pipeline of the distillation condensing system;
the outlet of the heat source pipeline of the distillation condensing system is communicated with the electrolyte filling port of the electrolytic hydrogen production system, and the condensate outlet of the distillation condensing system is optionally communicated with the raw water inlet of the demineralized water system.
In a second aspect, the present invention provides a method for producing hydrogen by electrolysis of water, wherein the method comprises:
s1, desalting raw water to obtain desalted water and salty concentrated water;
s2, electrolyzing the desalted water to obtain a mixture of hydrogen, oxygen and alkali water;
and S3, distilling and condensing at least part of the brine mixture serving as a heat source to obtain distilled water.
Through the technical scheme, the invention has the beneficial effects that:
the conventional preparation process of distilled water adopts steam heating, the steam temperature of a heating source is higher than the vaporization temperature of water, and the prior art does not apply the steam heating source in industry because of the need of additional energy. The process for obtaining distilled water by adopting a vacuum distillation system has not been studied, and the operation conditions and parameters of the process are not selected systematically.
The invention uses the waste heat of the electrolysis process, takes the alkaline water mixture with the waste heat in the electrolysis hydrogen production system as the heat source of the distillation condensing system to indirectly exchange heat with the salt-containing concentrated water, and continuously returns the distilled water obtained by evaporating and condensing the salt-containing concentrated water to the desalted water system to produce desalted water or directly enters the electrolysis tank for use, thereby improving the water utilization rate.
In some preferred embodiments of the invention, by selecting an appropriate distillation pressure; when the salt-containing concentrated water is distilled and condensed, selecting proper distilled water to be extracted to occupy the proportion of the salt-containing concentrated water; the proper height of the filling section in the vacuum distillation system and the proper reflux ratio of distilled water during distillation and condensation are selected, the water resource utilization rate is improved to 90% -98%, the water consumption is greatly reduced, and the waste heat of the electrolytic tank is utilized.
Drawings
FIG. 1 is a schematic diagram of an apparatus for producing hydrogen by electrolysis of water in accordance with an embodiment of the present invention.
Description of the reference numerals
1 electrolytic tank 2 hydrogen gas-liquid separator 3 oxygen gas-liquid separator
4 alkali liquor circulating pump 5 distillation condensing system
Detailed Description
The endpoints and any values of the ranges disclosed herein are not limited to the precise range or value, and are understood to encompass values approaching those ranges or values. For numerical ranges, one or more new numerical ranges may be found between the endpoints of each range, between the endpoint of each range and the individual point value, and between the individual point value, in combination with each other, and are to be considered as specifically disclosed herein.
The first aspect of the invention provides a device for producing hydrogen by electrolyzing water, wherein the device comprises: the system comprises a demineralized water system, an electrolytic hydrogen production system and a distillation condensing system which are communicated with each other; wherein,
the desalted water outlet of the desalted water system is communicated with the raw material inlet of the electrolytic hydrogen production system;
the salt-containing concentrated water outlet of the desalted water system is communicated with the raw material inlet of the distillation condensing system;
the liquid discharge outlet of the electrolytic hydrogen production system is communicated with the inlet of the heat source pipeline of the distillation condensing system;
the outlet of the heat source pipeline of the distillation condensing system is communicated with the electrolyte filling port of the electrolytic hydrogen production system, and the condensate outlet of the distillation condensing system is optionally communicated with the raw water inlet of the demineralized water system.
In the invention, the desalted water obtained by separating raw water by the desalted water system is subjected to electrolytic hydrogen production in the electrolytic hydrogen production system, and meanwhile, the alkali water mixture discharged by the electrolytic hydrogen production system is sent into the distillation condensing system to be used as a heat source for evaporating the salty concentrated water discharged by the desalted water system, and the distilled water obtained by evaporating and condensing the salty concentrated water is optionally returned to the desalted water system.
According to the present invention, preferably, the electrolytic hydrogen production system includes: an electrolytic tank, an oxygen gas-liquid separator and a hydrogen gas-liquid separator; wherein,
the oxygen gas-liquid separator is communicated with the electrolytic tank and is used for separating anode products from the electrolytic tank to obtain oxygen and alkaline water-1;
the hydrogen gas-liquid separator is communicated with the electrolytic tank and is used for separating a cathode product from the electrolytic tank to obtain hydrogen and alkaline water-2;
the oxygen gas-liquid separator is communicated with the hydrogen gas-liquid separator and the distillation condensing system, and is used for taking the alkaline water-1 and the alkaline water-2 as heat sources of the distillation condensing system.
In the invention, the electrolytic cell is an alkaline electrolytic cell.
According to the invention, the outlet of the heat source pipeline of the distillation condensing system is communicated with the electrolytic tank and is used for returning the alkaline water-1 and the alkaline water-2 to the electrolytic tank as electrolyte after being cooled.
According to the invention, preferably, an alkali liquor circulating pump is arranged between the outlet of the heat source pipeline of the distillation condensing system and the electrolytic tank, and is used for sending effluent from the outlet of the heat source pipeline to the electrolytic tank.
According to the present invention, preferably, the distillation system is a vacuum distillation system, and the vacuum distillation system may be a single-effect vacuum distillation system or a multi-effect vacuum distillation system. The multi-effect vacuum distillation system is used for distillation, so that when the distilled water extraction amount is high, the distilled water can still be ensured to have lower conductivity, and the water resource utilization rate can be further improved.
According to the present invention, preferably, the distillation and condensation system further comprises a condenser for condensing the water vapor obtained by evaporating the brine to obtain distilled water fed into the demineralization water system.
According to the present invention, preferably, a packing section having a height of 1m or more is provided in the vacuum distillation system. The inventor finds that the electric conductivity of distilled water can be reduced by arranging the filling section in the vacuum distillation system, and the electric conductivity of distilled water can be effectively reduced by measuring that the height of the filling section is more than or equal to 1 m; if it is less than 1m, the electric conductivity of distilled water is high; the packing may be conventional packing in the art, such as random packing and structured packing, wherein the structured packing may be plate corrugated structured packing, wire mesh structured packing, and the like.
In a second aspect, the present invention provides a method for producing hydrogen by electrolysis of water, wherein the method comprises:
s1, desalting raw water to obtain desalted water and salty concentrated water;
s2, electrolyzing the desalted water to obtain a mixture of hydrogen, oxygen and alkali water;
and S3, distilling and condensing at least part of the brine mixture serving as a heat source to obtain distilled water.
According to the present invention, preferably, the method further comprises: and (3) returning the distilled water obtained in the step (S3) to the step (S1) for the desalination.
According to the present invention, preferably, the process of desalting includes: and (3) performing reverse osmosis treatment on the raw water.
In the invention, the conductivity of the raw water at 25 ℃ is 80-1500 mu s/cm; the conductivity of desalted water obtained after desalting at 25 ℃ is 0.1-15 mu s/cm.
According to the present invention, preferably, in S2, the alkali-water mixture is a mixture of liquid phase products obtained by gas-liquid separation of the anode product and the cathode product obtained by electrolysis, respectively.
According to the present invention, preferably, the method further comprises: the alkali water mixture is cooled to 50-100 ℃, more preferably 65-90 ℃ after being distilled, and is returned to the electrolysis as electrolyte of the electrolysis. The temperature is reduced to the range and then returns to the electrolysis, which is more beneficial to the electrolytic hydrogen production.
According to the invention, preferably, in S3, the pressure of the distillation is from 10 to 60kPa, preferably from 15 to 50kPa, more preferably from 20 to 40kPa. Wherein pressure refers to absolute pressure. Too low distillation pressure can lead to higher conductivity of the obtained distilled water, but has little influence on the water resource utilization rate; however, too high a pressure of distillation has little effect on the conductivity of distilled water, but it may result in a decrease in the water resource utilization rate.
According to the invention, preferably, the temperature of the alkaline water mixture is 80-95 ℃.
According to the present invention, preferably, in S3, the distilled water obtained by the distillation and condensation is in an amount of 50 to 98wt% based on the total weight of the brine.
In principle, the salt-containing concentrated water can be distilled and condensed to obtain the corresponding distilled water, but the inventor finds that when the amount of distilled water produced satisfies the above range, the distilled water can be obtained to the greatest extent, the scale ratio can be greatly reduced, and the conductivity of the obtained distilled water can be further reduced,
since the distilled water is produced in a low amount, which has a certain adverse effect on the water resource utilization ratio, the distilled water obtained by distillation and condensation is more preferably 70 to 95wt% based on the total weight of the brine in order to obtain distilled water having a low conductivity and to improve the water resource utilization ratio while avoiding scaling.
According to the invention, the distillation preferably has a reflux ratio of 0.05-1.5:1. The reflux ratio of distillation refers to the ratio of the amount of distilled water returned to the distillation condensing system at the time of distillation condensation to the amount of distilled water distilled off. When the reflux ratio of distillation is low, the conductivity of the obtained distilled water is high; the distillation reflux ratio is high, which results in energy waste, and further preferably, the distillation reflux ratio is 0.1-0.4:1.
By controlling the distillation pressure, the amount of distilled water extracted, the reflux ratio of distillation and the height of a filling section in a vacuum distillation system, the electric conductivity of distilled water can be controlled to be 1-30 mu s/cm, further can be controlled to be 1.5-20 mu s/cm, further can be controlled to be 2-10 mu s/cm, distilled water with the electric conductivity less than or equal to 10 mu s/cm can directly enter an electrolytic tank for use, and distilled water with the electric conductivity more than 10 mu s/cm returns to a desalting water system at the front end for reverse osmosis treatment to prepare pure water required by the electrolytic tank.
According to one embodiment of the present invention, the method for producing hydrogen by electrolysis of water in the apparatus of FIG. 1 comprises the steps of:
s1, raw water is sent into a desalted water system for desalting, and desalted water and salty concentrated water are respectively obtained;
s2, sending the desalted water into an electrolytic tank 1 for electrolytic hydrogen production to obtain an anode product and a cathode product respectively; wherein the anode product comprises an oxygen and anode alkali water mixture, and the cathode product comprises a hydrogen and cathode alkali water mixture;
s3, respectively sending an anode product and a cathode product in the electrolytic tank 1 into the oxygen gas-liquid separator 3 and the hydrogen gas-liquid separator 2 for gas-liquid separation, and respectively enabling the obtained oxygen and hydrogen to flow out from gas phase outlets of the oxygen gas-liquid separator 3 and the hydrogen gas-liquid separator 2 and enter downstream for storage or use; the obtained anode alkali water mixture and cathode alkali water mixture are mixed to obtain an alkali water mixture with the temperature of 80-95 ℃, then the alkali water mixture is sent into a distillation condensing system 5 to serve as a heat source, at least part of the salt-containing concentrated water is distilled and condensed, distilled water obtained by the distillation condensing system 5 is sent into a desalted water system to be used for preparing desalted water, the alkali water mixture serves as the heat source to distill the at least part of the salt-containing concentrated water, the temperature is reduced to 50-100 ℃, and the distilled water is returned to an electrolytic tank 1 through an alkali liquor circulating pump 4 to be used as electrolyte.
The present invention will be described in detail below by way of examples and comparative examples. In the following examples, unless otherwise specified, the methods are conventional; the reagents and materials used, unless otherwise indicated, are all those commercially available.
In the following examples and comparative examples, a hydrogen production of 1000Nm was used 3 An electrolyzer of/h and a desalting water system matched with the electrolyzer.
Example 1
In the apparatus shown in fig. 1, the water electrolysis is performed to produce hydrogen gas according to the following steps:
s1, feeding raw water with the conductivity of 520 mu S/cm at 25 ℃ into a desalting system for desalting, wherein the water inflow (raw water) per hour is 1020kg, and respectively obtaining desalted water with the flow rate of 802kg/h and the conductivity of 6 mu S/cm at 25 ℃ and salt-containing concentrated water with the flow rate of 216kg/h through reverse osmosis treatment of the desalting system;
s2, sending desalted water obtained in the step S1 into an electrolytic tank 1 for electrolytic hydrogen production to obtain an anode product and a cathode product respectively; wherein the anode product comprises an oxygen and anode alkali water mixture, and the cathode product comprises a hydrogen and cathode alkali water mixture;
s3, respectively sending an anode product and a cathode product in the electrolytic tank 1 into the oxygen gas-liquid separator 3 and the hydrogen gas-liquid separator 2 for gas-liquid separation, and respectively enabling the obtained oxygen and hydrogen to flow out from gas phase outlets of the oxygen gas-liquid separator 3 and the hydrogen gas-liquid separator 2 and enter the downstream; the obtained anode alkali water mixture and cathode alkali water mixture are mixed to obtain an alkali water mixture with the temperature of 87 ℃, and then the alkali water mixture is sent into a distillation condensing system 5 (a single-effect vacuum distillation unit) to be used as a heat source, wherein the flow is 200m 3 /h; distilling the salt-containing concentrated water obtained in the step S1, wherein the absolute pressure of the operation of a distillation unit is 40kPa, the packing height of the distillation unit is 2m, and the reflux ratio is 0.15; the flow rate of distilled water at the top of the vacuum distillation unit is 198kg/h (the distilled water amount is 91.7wt percent based on the total weight of the salt-containing concentrated water, namely 91.7wt percent of the salt-containing concentrated water is extracted), and the electric conductivity of the distilled water at 25 ℃ is 28 mu s/cm; distilled water is sent into a desalted water system for preparing desalted water, the temperature of the alkali water mixture is reduced to 86.4 ℃ after passing through a vacuum distillation unit, and the alkali water mixture is sent back to the electrolytic tank 1 through an alkali liquor circulating pump 4 for continuous use as electrolyte.
The raw water consumption is 9.3kg, and the water resource utilization rate is 97% according to the hydrogen yield of 1 kg.
Example 2
Water electrolysis to produce hydrogen was performed in the same manner as in example 1 except that in S3, a distillation unit was operated at an absolute pressure of 30kPa; the packing height of the distillation unit is 1.5m; reflux ratio of 0.25 "replacement" distillation unit operating absolute pressure of 40kPa; the packing height of the distillation unit is 2m; the reflux ratio was 0.15". The top of the vacuum distillation unit distills out distilled water with the flow rate of 151.2kg/h (the distilled water is 70wt percent based on the total weight of the salt-containing concentrated water, namely 70wt percent of the salt-containing concentrated water is extracted), and the electric conductivity of the distilled water is 6 mu s/cm at 25 ℃, and the distilled water is directly sent to an electrolytic tank for hydrogen production.
The raw water consumption was 9.6kg and the water resource utilization was 94% based on the hydrogen yield of 1 kg.
Example 3
The electrolysis of water to produce hydrogen was performed in the same manner as in example 1 except that the reflux ratio of the vacuum distillation unit was changed and "0.15" was replaced with "0.8". The top of the vacuum distillation unit distills out distilled water with the flow rate of 198kg/h (the distilled water amount is 91.7wt percent based on the total weight of the salt-containing concentrated water, namely 91.7wt percent of the extracted salt-containing concentrated water) and the electric conductivity of 11 mu s/cm at 25 ℃, and the distilled water is sent into a desalted water system for preparing desalted water.
The raw water consumption is 9.3kg, and the water resource utilization rate is 97% according to the hydrogen yield of 1 kg.
Example 4
The electrolysis of water to produce hydrogen was performed as in example 1, except that the amount of distilled water produced in S3 was different. The flow rate of distilled water at the top of the vacuum distillation unit is 129.6kg/h (the distilled water is 60wt percent based on the total weight of the salt-containing concentrated water, namely 60wt percent of the salt-containing concentrated water is extracted), and the electric conductivity of the distilled water at 25 ℃ is 1.2 mu s/cm, and the obtained distilled water is directly introduced into an electrolytic cell to prepare hydrogen gas for use.
The raw water consumption is 9.8kg and the water resource utilization rate is 91.5% according to the hydrogen yield of 1 kg.
Example 5
The electrolysis of water to produce hydrogen was performed in the same manner as in example 1 except that in S3, the distillation condensing system was a three-effect vacuum distillation unit, the packing height of each vacuum distillation unit was 2m, and the reflux ratio was 0.15. The top of the third-stage vacuum distillation unit distills distilled water with the flow rate of 205.2kg/h (the distilled water is 95wt percent based on the total weight of the salt-containing concentrated water, namely 95wt percent of the produced salt-containing concentrated water) and the electric conductivity of 15 mu s/cm at 25 ℃, and the distilled water is sent into a desalted water system for preparing desalted water.
The raw water consumption is 9.1kg, and the water resource utilization rate is 99% according to the hydrogen yield of 1 kg.
Example 6
The electrolysis of water to produce hydrogen was carried out in the same manner as in example 1 except that the distillation pressure was varied, and the "distillation unit operation absolute pressure was 15kPa" was used instead of the "distillation unit operation absolute pressure was 40kPa". The top of the vacuum distillation unit distills out distilled water with the flow rate of 203kg/h (the distilled water is 94wt percent based on the total weight of the salt-containing concentrated water, namely 94wt percent of the produced salt-containing concentrated water) and the electric conductivity of 86 mu s/cm at 25 ℃, and the distilled water is sent into a desalted water system for preparing desalted water.
The raw water consumption is 9.3kg, and the water resource utilization rate is 97% according to the hydrogen yield of 1 kg.
Example 7
The electrolysis of water to produce hydrogen was carried out in the same manner as in example 1 except that the distillation pressure was varied, and the "distillation unit operation absolute pressure was replaced with" 51kPa "and the" distillation unit operation absolute pressure was 40kPa ". The evaporation capacity of vacuum distillation is reduced, the flow rate of distillation from the top of the unit is only 52kg/h (the distilled water amount is 24wt% based on the total weight of the salt-containing concentrated water, namely 24wt% of the produced salt-containing concentrated water), and the electric conductivity of the distilled water is 28 mu s/cm at 25 ℃, and the distilled water is sent into a desalted water system for preparing desalted water.
The raw water consumption is 10.5kg, and the water resource utilization rate is 85% according to the hydrogen yield of 1 kg.
Example 8
The electrolysis of water to produce hydrogen was performed as in example 1, except that in S3, the vacuum distillation unit did not perform reflux. The top of the vacuum distillation unit distills out distilled water with a flow rate of 198kg/h (the distilled water is 91.7wt% based on the total weight of the brine, namely 91.7wt% of the brine is produced), and the electric conductivity of the distilled water is 472 mu s/cm at 25 ℃ and is sent to a desalted water system for preparing desalted water, and the distilled water has scaling at the top of the tower after running for about 15 days.
The raw water consumption is 9.6kg, and the water resource utilization rate is 93% according to the hydrogen yield of 1 kg.
Example 9
The electrolysis of water to produce hydrogen was performed as in example 1, except that in S3, the distillation unit packing height was replaced with "0.4 m" for 2m ". The top of the vacuum distillation unit distills out distilled water with the flow rate of 198kg/h (the distilled water amount is 91.7wt percent based on the total weight of the salt-containing concentrated water, namely 91.7wt percent of the extracted salt-containing concentrated water) and the electric conductivity of 107 mu s/cm at 25 ℃, and the distilled water is sent into a desalted water system for preparing desalted water.
The raw water consumption is 9.4kg and the water resource utilization rate is 96% according to the hydrogen yield of 1 kg.
Example 10
The electrolysis of water to produce hydrogen was performed in the same manner as in example 1 except that the amount of distilled water produced was different. In S3, distilled water with flow rate of 213.8kg/h (the distilled water amount is 99wt% based on the total weight of the salt-containing concentrated water, namely 99wt% of the produced salt-containing concentrated water) and electric conductivity of 143 mu S/cm at 25 ℃ is distilled out from the top of the vacuum distillation unit, and the distilled water is sent into a desalted water system for preparing desalted water.
The raw water consumption is 9.1kg, and the water resource utilization rate is 99% according to the hydrogen yield of 1 kg. Meanwhile, scaling is obvious after the bottom part runs for 125 hours, the distilled water is reduced, and the device can not run continuously.
Comparative example 1
The process of example 1 was followed to produce hydrogen by electrolysis of water, except that the apparatus did not contain a vacuum distillation unit, and the brine was directly discharged without distillation and condensation. Specifically, the method comprises the following steps of:
s1, feeding raw water with the conductivity of 520 mu S/cm at 25 ℃ into a desalting system for desalting, wherein the water inflow (raw water) amount per hour is 1020kg, and performing reverse osmosis treatment on the raw water by the desalting system to obtain desalted water with the flow rate of 802kg/h and the conductivity of 6 mu S/cm at 25 ℃ and salty concentrated water with the flow rate of 216kg/h, and discharging the salty concentrated water decontaminated water;
s2, sending desalted water obtained in the step S1 into an electrolytic tank 1 for electrolytic hydrogen production to obtain an anode product and a cathode product respectively; wherein the anode product comprises an oxygen and anode alkali water mixture and the cathode product comprises a hydrogen and cathode alkali water mixture. The anode product and the cathode product in the electrolytic tank 1 are respectively sent into an oxygen gas-liquid separator 3 and a hydrogen gas-liquid separator 2 for gas-liquid separation, and the obtained oxygen and hydrogen respectively flow out from gas phase outlets of the oxygen gas-liquid separator 3 and the hydrogen gas-liquid separator 2 and enter downstream.
The raw water consumption is 11.4kg and the water resource utilization rate is 79 percent according to the hydrogen yield of 1 kg.
From the results of each example and comparative example, it can be seen that the device and method according to the invention can produce hydrogen by electrolysis of water, the water resource utilization rate is more than 85%, while the salt-containing concentrated water in the process of producing hydrogen by electrolysis of water in comparative example 1 is directly discharged without distillation and condensation, the water resource utilization rate is only 79%, which indicates that the device and method according to the invention can effectively improve the water resource utilization rate by electrolysis of water to produce hydrogen.
In example 4, the distilled water was reduced in the amount of distilled water to be distilled, and the conductivity of the distilled water was reduced as compared with example 1, but the water resource utilization was also reduced; example 10 increased distilled water distillate, and compared with example 1, although water resource utilization was improved, conductivity of the resulting distilled water was increased, scaling was evident after 125 hours of operation of the distillation apparatus, and the apparatus was not sustainable; when the distilled water distillate satisfies a certain range, the scale ratio can be reduced while the water resource utilization rate is higher, and the conductivity of the obtained distilled water can be further reduced. In example 5, the three-effect vacuum distillation unit is used for distillation, and compared with example 1, the water resource utilization rate is improved, and the conductivity of the obtained distilled water is reduced, which shows that when the multi-effect vacuum distillation system is used for distillation, the distilled water can still be ensured to have lower conductivity when the distilled water extraction amount is higher, and the water resource utilization rate can be further improved. Example 6 reduced the pressure of distillation, compared to example 1, with no change in water resource utilization, but increased the conductivity of the resulting distilled water; example 7 increased the distillation pressure and reduced the water resource utilization compared to example 1, but the conductivity of the resulting distilled water was unchanged. The vacuum distillation unit of example 8 did not perform reflux, and the water resource utilization was reduced and the conductivity of the obtained distilled water was increased as compared with example 1. Example 9 reduced the packing height in the distillation unit, reduced the water resource utilization and increased the conductivity of the resulting distilled water as compared to example 1. The results show that only if the distillation pressure, the distilled water distillation amount, the distilled reflux ratio and the filling height in the distillation unit meet a certain range, the distilled water with lower conductivity can be obtained, and the water resource utilization rate is improved while scaling is avoided.
The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, a number of simple variants of the technical solution of the invention are possible, including combinations of the individual technical features in any other suitable way, which simple variants and combinations should likewise be regarded as being disclosed by the invention, all falling within the scope of protection of the invention.
Claims (18)
1. An apparatus for producing hydrogen by electrolysis of water, the apparatus comprising: the system comprises a demineralized water system, an electrolytic hydrogen production system and a distillation condensing system which are communicated with each other; wherein,
the desalted water outlet of the desalted water system is communicated with the raw material inlet of the electrolytic hydrogen production system;
the salt-containing concentrated water outlet of the desalted water system is communicated with the raw material inlet of the distillation condensing system;
the liquid discharge outlet of the electrolytic hydrogen production system is communicated with the inlet of the heat source pipeline of the distillation condensing system;
the outlet of the heat source pipeline of the distillation condensing system is communicated with the electrolyte filling port of the electrolytic hydrogen production system, and the condensate outlet of the distillation condensing system is optionally communicated with the raw water inlet of the demineralized water system.
2. The apparatus of claim 1, wherein the electrolytic hydrogen production system comprises: an electrolytic tank, an oxygen gas-liquid separator and a hydrogen gas-liquid separator; wherein,
the oxygen gas-liquid separator is communicated with the electrolytic tank and is used for separating anode products from the electrolytic tank to obtain oxygen and alkaline water-1;
the hydrogen gas-liquid separator is communicated with the electrolytic tank and is used for separating a cathode product from the electrolytic tank to obtain hydrogen and alkaline water-2;
the oxygen gas-liquid separator is communicated with the hydrogen gas-liquid separator and the distillation condensing system, and is used for taking the alkaline water-1 and the alkaline water-2 as heat sources of the distillation condensing system.
3. The apparatus of claim 2, wherein the heat source pipeline outlet of the distillation condensing system is communicated with the electrolytic tank and is used for returning the alkaline water-1 and the alkaline water-2 to the electrolytic tank as electrolyte after being cooled.
4. A device according to claim 3, characterized in that an alkali liquor circulation pump is arranged between the outlet of the heat source pipe of the distillation condensation system and the electrolytic cell for feeding the effluent from the outlet of the heat source pipe into the electrolytic cell.
5. The apparatus of any one of claims 1-4, wherein the distillation condensing system is a vacuum distillation system.
6. The apparatus according to claim 5, wherein a packing section having a height of 1m or more is provided in the vacuum distillation system.
7. The apparatus of claim 1, wherein the distillation condensing system further comprises a condenser for condensing water vapor from the evaporation of the brine to distilled water fed to the demineralized water system.
8. A method for producing hydrogen by electrolysis of water, the method comprising:
s1, desalting raw water to obtain desalted water and salty concentrated water;
s2, electrolyzing the desalted water to obtain a mixture of hydrogen, oxygen and alkali water;
and S3, distilling and condensing at least part of the brine mixture serving as a heat source to obtain distilled water.
9. The method of claim 8, wherein the method further comprises: and (3) returning the distilled water obtained in the step (S3) to the step (S1) for the desalination.
10. The method according to claim 8 or 9, wherein in S2, the alkaline water mixture is a mixture of liquid phase products obtained by gas-liquid separation of the anode product and the cathode product, respectively, obtained by electrolysis.
11. The method of claim 8, wherein the method further comprises: and cooling the alkali water mixture after distillation, and returning the alkali water mixture to the electrolysis to be used as electrolyte of the electrolysis.
12. The process of claim 8, wherein in S3, the distillation is carried out at a pressure of 10 to 60kPa.
13. The process according to claim 12, wherein in S3 the distillation is carried out at a pressure of 15-50kPa.
14. The process of claim 13, wherein in S3, the distillation is at a pressure of 20-40kPa.
15. The method of claim 8, wherein the temperature of the alkaline water mixture is 80-95 ℃.
16. The method according to claim 8, wherein in S3, the distilled water is obtained by distillation and condensation in an amount of 50 to 98wt%, based on the total weight of the brine.
17. The method according to claim 16, wherein in S3, the distilled water is obtained by distillation and condensation in an amount of 70 to 95wt% based on the total weight of the brine.
18. The process of claim 8, wherein the distillation has a reflux ratio of 0.05 to 1.5:1.
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