A thermal energy coupling and water saving system for hydrogen production by electrolysis of water

Abstract

The application discloses a heat energy coupling and water saving system for hydrogen production by water electrolysis, which comprises a lye cooler, a hydrogen cooling separator, an oxygen cooling separator, a precooling separator, and a waste heat utilization refrigerating unit for providing refrigerated water for the hydrogen cooling separator, the oxygen cooling separator and the precooling separator, a high-temperature intermediate hot water circulating main loop is arranged on the lye cooler for cooling the lye cooler, a first high-temperature intermediate hot water circulating branch loop for providing a driving heat source for the waste heat utilization refrigerating unit is arranged on the high-temperature intermediate hot water circulating main loop and connected with the waste heat utilization refrigerating unit, a refrigerated water circulating main loop is arranged on the waste heat utilization refrigerating unit, and the hydrogen cooling separator, the oxygen cooling separator and the precooling separator are connected with the refrigerated water circulating main loop through refrigerated water circulating branch loops. The application reduces the consumption of electric energy and water resources for hydrogen production by water electrolysis.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of hydrogen production by water electrolysis, and particularly relates to a heat energy coupling and water saving system for hydrogen production by water electrolysis. BACKGROUND

[0002] The equipment for hydrogen production by alkaline water electrolysis in industry mainly comprises an electrolytic cell, an alkali solution cooler, an alkali solution circulating pipeline connected between the electrolytic cell and the alkali solution cooler, a hydrogen gas separator and a hydrogen gas scrubber connected in sequence with a hydrogen gas output end of the electrolytic cell, an oxygen gas separator and an oxygen gas scrubber connected in sequence with an oxygen gas output end of the electrolytic cell, and a hydrogen gas cooling separator and an oxygen gas cooling separator for dehumidification. The working principle of hydrogen production by alkaline water electrolysis is that water molecules will generate oxygen at an anode and generate hydrogen at a cathode through loading of electric current between the two electrodes of the electrolytic cell; the oxygen containing alkali solution and the hydrogen containing alkali solution are treated by the gas separator and the gas scrubber respectively, and then dehumidified by the cooling separator to obtain corresponding oxygen and hydrogen. Since pure water is a weak electrolyte, the degree of ionization and the conductivity are poor, and therefore a certain concentration of KOH or NaOH solution is added as an electrolyte in the process of hydrogen production by water electrolysis to increase the conductivity of the electrolyte. In order to improve the purity of hydrogen production by water electrolysis, a deoxygenation tower heater for deoxygenation is also provided in the equipment for hydrogen production by alkaline water electrolysis, and the process medium (hydrogen containing trace oxygen) is subjected to oxygen and hydrogen chemical reaction in the deoxygenation tower heater to remove oxygen.

[0003] The hydrogen production process is mainly to obtain hydrogen, and the generated oxygen can be treated, collected or emptied and discharged.

[0004] The existing hydrogen production process by alkaline water electrolysis has the following deficiencies:

[0005] Firstly, in the process of hydrogen production by alkaline water electrolysis, electric energy is consumed to heat the process medium in the deoxygenation tower heater from 14.99℃ to 150℃, and the existing process is to heat the process medium by electric energy, which consumes a large amount of electric energy.

[0006] Secondly, in the electrolysis process, the alkali solution in the alkali solution cooler needs to be cooled (the alkali solution is a kind of high-temperature waste heat), and the existing hydrogen production process by alkaline water electrolysis is to take away the heat by 32-42℃ circulating water, which causes great waste of heat.

[0007] Thirdly, the gas cooling separator in the electrolysis process needs to be cooled by low-temperature refrigerant (12-7℃), and the existing hydrogen production process by alkaline water electrolysis is to cool the process medium by 12-7℃ low-temperature cold water prepared by electric refrigeration, which also consumes a large amount of electric energy.

[0008] Fourthly, the cooling tower used in the existing hydrogen production process by alkaline water electrolysis consumes a large amount of water resources. SUMMARY

[0009] To solve the above problems, the application provides a heat energy coupling and water saving system for hydrogen production by water electrolysis, which aims to reduce the power consumption in the process of hydrogen production by water electrolysis and reduce the consumption of water resources.

[0010] The heat energy coupling and water saving system for hydrogen production by water electrolysis comprises a hydrogen gas cooling separator, an oxygen gas cooling separator and a pre-cooling separator arranged in a hydrogen production by water electrolysis system respectively, and a waste heat utilization refrigerating unit for providing refrigerated water for the hydrogen gas cooling separator, the oxygen gas cooling separator and the pre-cooling separator, wherein a refrigerated water circulation main loop is arranged on the waste heat utilization refrigerating unit, and the hydrogen gas cooling separator, the oxygen gas cooling separator and the pre-cooling separator are connected with the refrigerated water circulation main loop through refrigerated water circulation branch loops respectively.

[0011] As one of the further improved schemes of the application, an alkali solution cooler is arranged in the hydrogen production by water electrolysis system, a high-temperature intermediate hot water circulation main loop for cooling the alkali solution cooler is arranged on the alkali solution cooler, a first high-temperature intermediate hot water circulation branch loop for providing a driving heat source for the waste heat utilization refrigerating unit is arranged on the high-temperature intermediate hot water circulation main loop and connected with the waste heat utilization refrigerating unit, an air cooler instead of a cooling tower is arranged in the hydrogen production by water electrolysis system, and the high-temperature intermediate hot water circulation main loop is connected between the alkali solution cooler and the air cooler.

[0012] Preferably, a deoxidizing tower heater for deoxidizing and purifying the hydrogen gas containing trace oxygen separated through the hydrogen gas cooling separator is arranged in the hydrogen production by water electrolysis system, a hot water pre-heater is further arranged in the hydrogen production by water electrolysis system, a second high-temperature intermediate hot water circulation branch loop for providing a heat source for the hot water pre-heater is further arranged on the high-temperature intermediate hot water circulation main loop and connected with the hot water pre-heater, and the hydrogen gas containing trace oxygen enters the hot water pre-heater and the deoxidizing tower heater through a hydrogen deoxidizing and heating pipeline to realize twice heating.

[0013] The hydrogen deoxidizing and heating pipeline comprises a hydrogen deoxidizing and heating input pipeline connected with the hot water pre-heater, a hydrogen deoxidizing and heating intermediate pipeline connected between the hot water pre-heater and the deoxidizing tower heater, and a hydrogen deoxidizing and heating output pipeline arranged on the deoxidizing tower heater.

[0014] As a second further improvement of the present application, the electrolytic water hydrogen production system does not have an alkali solution cooler, and an alkali solution cooling circulation main loop for cooling alkali solution of the electrolytic cell is arranged on the electrolytic cell of the electrolytic water hydrogen production system, a first alkali solution cooling circulation branch loop for providing driving heat source for the waste heat utilization refrigerating unit is arranged on the alkali solution cooling circulation main loop and connected with the waste heat utilization refrigerating unit, and an air cooler instead of a cooling tower is arranged in the electrolytic water hydrogen production system, and the alkali solution cooling circulation main loop is connected between the electrolytic cell and the air cooler.

[0015] Preferably, a deoxidizing tower heater for heating hydrogen containing trace oxygen separated by the hydrogen cooling separator is arranged in the electrolytic water hydrogen production system, an alkali solution preheater is also arranged in the electrolytic water hydrogen production system, a second alkali solution cooling circulation branch loop for providing heat source for the alkali solution preheater is arranged on the alkali solution cooling circulation main loop and connected with the alkali solution preheater, and the hydrogen containing trace oxygen enters the alkali solution preheater and the deoxidizing tower heater in sequence through a hydrogen deoxidizing heating pipeline to realize twice heating.

[0016] Preferably, the hydrogen deoxidizing heating pipeline comprises a hydrogen deoxidizing heating input pipeline connected with the alkali solution preheater, a hydrogen deoxidizing heating intermediate pipeline connected between the alkali solution preheater and the deoxidizing tower heater, and a hydrogen deoxidizing heating output pipeline arranged on the deoxidizing tower heater.

[0017] In the present application, the deoxidizing tower heater is provided with an electric energy heating heat supply pipeline for heating the hydrogen containing trace oxygen.

[0018] In the present application, the electrolytic water hydrogen production system comprises an electrolytic cell, an alkali solution cooling loop arranged between the electrolytic cell and the alkali solution cooler, the alkali solution cooling loop comprises a hydrogen-containing alkali solution branch pipeline output from a cathode chamber of the electrolytic cell, an oxygen-containing alkali solution branch pipeline output from an anode chamber of the electrolytic cell, an electrolytic cell alkali solution output pipeline connected between a confluence node of the hydrogen-containing alkali solution branch pipeline and the oxygen-containing alkali solution branch pipeline and the alkali solution cooler, and an electrolytic cell alkali solution recovery pipeline connected between the alkali solution cooler and the electrolytic cell; a hydrogen separator is arranged on the hydrogen-containing alkali solution branch pipeline, an oxygen separator is arranged on the oxygen-containing alkali solution branch pipeline, the hydrogen separator is connected with a hydrogen scrubber, and the oxygen separator is connected with an oxygen scrubber; and an alkali solution circulating pump is arranged on the electrolytic cell alkali solution recovery pipeline.

[0019] In the application, the hydrogen output end of the hydrogen scrubber is connected to the hydrogen cooling separator through a pipeline; the oxygen output end of the oxygen scrubber is connected to the oxygen cooling separator through a pipeline; the hydrogen output end of the hydrogen cooling separator is connected to the deoxidation tower heater through a pipeline, and the hydrogen output end of the deoxidation tower heater is connected to the pre-cooling separator through a pipeline.

[0020] Preferably, the pre-cooling separator comprises a pre-cooling separator A, a pre-cooling separator B and a pre-cooling separator C, which are respectively connected to the dryers A, B and C.

[0021] Preferably, the waste heat utilization refrigerating unit is one of a hot water type refrigerating unit, a caustic lye direct-in refrigerating unit and a multi-energy source refrigerating unit; wherein the multi-energy source refrigerating unit is one of a steam-hot water dual energy source lithium bromide refrigerating unit, a steam-caustic lye refrigerating unit and a steam-hot water-caustic lye refrigerating unit.

[0022] The heat energy coupling and water saving system for electrolyzing water to produce hydrogen can be applied to one set of electrolysis water hydrogen production system, and can also be applied to multiple sets of electrolysis water hydrogen production systems. When applied to one set of electrolysis water hydrogen production system, it is a set of heat energy coupling and water saving system matched with one set of electrolysis water hydrogen production system; when applied to multiple sets of electrolysis water hydrogen production systems, it is a set of heat energy coupling and water saving system shared by multiple sets of electrolysis water hydrogen production systems.

[0023] In the application, the heat energy coupling and water saving process of the heat energy coupling and water saving system for electrolyzing water to produce hydrogen is as follows:

[0024] (1) Selection of cold source in the electrolysis water hydrogen production system: the chilled water sent into the hydrogen cooling separator, the oxygen cooling separator and the pre-cooling separator in the electrolysis water hydrogen production system is generated by the waste heat utilization refrigerating unit;

[0025] (2) Selection of driving heat source of the waste heat utilization refrigerating unit: the driving heat source of the waste heat utilization refrigerating unit can use primary energy sources including steam and natural gas, or can use hot water or caustic lye; wherein the steam as the driving heat source is derived from the steam in the plant pipe network, the hot water as the driving heat source is derived from the high-temperature intermediate hot water prepared after heat exchange with the caustic lye cooler, and the caustic lye as the driving heat source is derived from the electrolytic cell caustic lye; when working, the waste heat utilization refrigerating unit preferentially utilizes the heat of the driving hot water or caustic lye to prepare chilled water, and when the heat of the driving hot water or caustic lye is insufficient, the driving steam is used as a supplementary energy source to prepare chilled water;

[0026] (3) The process parameters of the waste heat utilization refrigeration unit are set as follows: the temperature of the hot water or alkali solution sent into the waste heat utilization refrigeration unit is 70-95°C, the temperature of the hot water or alkali solution out of the waste heat utilization refrigeration unit is 50-70°C, and the temperature of the chilled water out of the refrigeration end of the waste heat utilization refrigeration unit is ≤12°C, and the temperature of the chilled water after heat exchange and temperature rise with the hydrogen cooling separator, oxygen cooling separator and pre-cooling separator is ≤20°C;

[0027] (4) Heat energy coupling and water saving process:

[0028] When hot water is used as the driving heat source of the waste heat utilization refrigeration unit, the heat energy coupling and water saving process is as follows:

[0029] The high-temperature intermediate hot water with a temperature of 50-70°C is sent into the alkali solution cooler instead of the circulating cooling water, and the high-temperature intermediate hot water is used to cool the high-temperature alkali solution with a temperature of ≥80°C sent into the alkali solution cooler, so that the alkali solution is cooled to ≤70°C. The temperature of the high-temperature intermediate hot water used to cool the alkali solution in the alkali solution cooler is between 50°C and 70°C, and the temperature of the high-temperature intermediate hot water after heat exchange in the alkali solution cooler is between 70°C and 95°C.

[0030] The high-temperature intermediate hot water with a temperature of 70-95°C after heat exchange with the alkali solution cooler is branched into two high-temperature intermediate hot water circulation branch circuits, i.e., a first high-temperature intermediate hot water circulation branch circuit and a second high-temperature intermediate hot water circulation branch circuit. The first high-temperature intermediate hot water circulation branch circuit sends the high-temperature intermediate hot water into the waste heat utilization refrigeration unit, and the second high-temperature intermediate hot water circulation branch circuit sends the high-temperature intermediate hot water into the newly set hot water pre-heater in front of the deoxidization heater. The remaining high-temperature intermediate hot water is sent into the air cooler through the high-temperature intermediate hot water circulation main circuit and is cooled by the ambient air to a temperature of 50-70°C. By using the air cooler instead of the traditional cooling tower to cool the high-temperature intermediate hot water, 100% water saving effect is achieved compared with the traditional cooling tower.

[0031] The high-temperature intermediate hot water sent into the waste heat utilization refrigeration unit is used as the driving heat source to produce chilled water, which is sent into the hydrogen cooling separator, oxygen cooling separator and pre-cooling separator for use, thereby saving the power consumption of the traditional electric refrigeration. The high-temperature intermediate hot water after temperature drop in the waste heat utilization refrigeration unit is also sent into the air cooler and is cooled by the ambient air to a temperature of 50-70°C.

[0032] By adding a hot water preheater before the original deoxygenation tower heater, the hydrogen containing trace amounts of oxygen from the hydrogen cooling separator is preheated to above 60°C by the high-temperature intermediate hot water in the hot water preheater before being sent to the deoxygenation tower heater. The preheated hydrogen containing trace amounts of oxygen is then sent to the deoxygenation tower heater for heating, which can save the power consumption of the deoxygenation tower heater. After being cooled in the hot water preheater, the high-temperature intermediate hot water is also sent to the air cooler to be cooled to between 50°C and 70°C by the ambient air.

[0033] When alkaline solution is used as the driving heat source for waste heat recovery chiller, its heat energy coupling and water-saving process is basically the same as when hot water is used as the driving heat source for waste heat recovery chiller. The difference is that alkaline solution replaces hot water and directly enters any or all of the equipment in the waste heat recovery chiller, alkaline solution preheater, and air cooler, thereby achieving heat energy coupling and water-saving effects.

[0034] The beneficial effects of this invention are:

[0035] First, the present invention provides a thermal energy coupling and water-saving system for hydrogen production by water electrolysis, which uses a waste heat utilization refrigeration unit to replace the traditional electric refrigeration, thereby reducing the system's power consumption.

[0036] Secondly, the present invention provides a thermal energy coupling and water-saving system for hydrogen production by electrolysis of water. By using an air cooler instead of a traditional cooling tower to cool the high-temperature intermediate hot water, it achieves 100% water saving compared to the traditional cooling tower.

[0037] Third, the present invention provides a thermal energy coupling and water-saving system for hydrogen production by electrolysis of water. A hot water preheater is added before the heater of the deoxygenation tower, and intermediate high-temperature hot water is used instead of circulating water to cool the high-temperature alkaline solution, so that the heat of the high-temperature alkaline solution can be reused, thereby further reducing the energy consumption of the system.

[0038] Fourth, the present invention provides a thermal energy coupling and water-saving system for hydrogen production by water electrolysis. The high-temperature intermediate hot water not only provides a driving heat source for the waste heat utilization refrigeration unit, but also preheats the process medium (hydrogen containing trace amounts of oxygen) sent to the deoxygenation tower heater. At the same time, it provides the water temperature required for cooling in the air cooler, so that the air cooler can cool the circulating water by relying solely on air, thus playing a good role in saving electricity. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of a thermal energy coupling and water-saving system for hydrogen production by water electrolysis according to the present invention;

[0040] Figure 2 It is aimed at Figure 1 A schematic diagram of the modified structure based on the thermal energy coupling and water-saving system;

[0041] Figure 3 This is a schematic diagram of a water electrolysis hydrogen production system. Detailed Implementation

[0042] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings and examples. The following examples are only used to more clearly illustrate the technical solutions of the present invention and should not be construed as limiting the scope of protection of the present invention.

[0043] like Figures 1 to 3 The illustration shows an embodiment of a thermal energy coupling and water-saving system for hydrogen production by water electrolysis according to the present invention. It includes a hydrogen cooling separator, an oxygen cooling separator, and a pre-cooling separator respectively installed in the water electrolysis hydrogen production system, and a waste heat utilization chiller unit for providing chilled water to the hydrogen cooling separator, oxygen cooling separator, and pre-cooling separator. The waste heat utilization chiller unit is provided with a chilled water circulation main loop. The hydrogen cooling separator, oxygen cooling separator, and pre-cooling separator are respectively connected to the chilled water circulation main loop through chilled water circulation branch loops.

[0044] As a further improvement of the present invention, the water electrolysis hydrogen production system is provided with an alkaline cooler, and the alkaline cooler is provided with a high-temperature intermediate hot water circulation main loop for cooling the alkaline cooler. The high-temperature intermediate hot water circulation main loop is provided with a first high-temperature intermediate hot water circulation branch loop connected to the waste heat utilization refrigeration unit for providing a driving heat source for the waste heat utilization refrigeration unit. The water electrolysis hydrogen production system is provided with an air cooler instead of a cooling tower, and the high-temperature intermediate hot water circulation main loop is connected between the alkaline cooler and the air cooler.

[0045] Preferably, the water electrolysis hydrogen production system is equipped with a deoxygenation tower heater for deoxygenating and purifying hydrogen containing trace amounts of oxygen separated by the hydrogen cooling separator. The water electrolysis hydrogen production system is also equipped with a hot water preheater. A second high-temperature intermediate hot water circulation branch circuit is also provided on the main high-temperature intermediate hot water circulation circuit, which is connected to the hot water preheater and provides a heat source for the hot water preheater. The hydrogen containing trace amounts of oxygen enters the hot water preheater and the deoxygenation tower heater successively through the hydrogen deoxygenation heating pipeline to achieve two heating processes.

[0046] The hydrogen deoxygenation heating pipeline includes a hydrogen deoxygenation heating input pipeline connected to the hot water preheater, a hydrogen deoxygenation heating intermediate pipeline connected between the hot water preheater and the deoxygenation tower heater, and a hydrogen deoxygenation heating output pipeline installed on the deoxygenation tower heater.

[0047] As a further improvement of the present invention, the water electrolysis hydrogen production system does not include an alkali cooler. Instead, the electrolyzer of the water electrolysis hydrogen production system is equipped with an alkali cooling circulation main loop for cooling the alkali solution in the electrolyzer. The alkali cooling circulation main loop is equipped with a first alkali cooling circulation branch loop connected to the waste heat utilization refrigeration unit for providing a driving heat source for the waste heat utilization refrigeration unit. The water electrolysis hydrogen production system is equipped with an air cooler instead of a cooling tower. The alkali cooling circulation main loop is connected between the electrolyzer and the air cooler.

[0048] Preferably, the water electrolysis hydrogen production system is equipped with a deoxygenation tower heater for deoxygenating and purifying hydrogen containing trace amounts of oxygen separated by the hydrogen cooling separator. The water electrolysis hydrogen production system is also equipped with an alkali preheater. The alkali cooling circulation main loop is also equipped with a second alkali cooling circulation branch loop connected to the alkali preheater for providing a heat source for the alkali preheater. The hydrogen containing trace amounts of oxygen enters the alkali preheater and the deoxygenation tower heater successively through the hydrogen deoxygenation heating pipeline to achieve two heating processes.

[0049] The hydrogen deoxygenation heating pipeline includes a hydrogen deoxygenation heating input pipeline connected to the alkali preheater, a hydrogen deoxygenation heating intermediate pipeline connected between the alkali preheater and the deoxygenation tower heater, and a hydrogen deoxygenation heating output pipeline installed on the deoxygenation tower heater.

[0050] In this invention, the deoxygenation tower heater is equipped with an electrically powered heating pipeline for deoxygenating and purifying the hydrogen containing trace amounts of oxygen.

[0051] In this invention, the water electrolysis hydrogen production system includes an electrolyzer, an alkali cooling circuit disposed between the electrolyzer and the alkali cooler, the alkali cooling circuit including a hydrogen-containing alkali branch pipe output from the cathode chamber of the electrolyzer, an oxygen-containing alkali branch pipe output from the anode chamber of the electrolyzer, an electrolyzer alkali output pipe connecting the junction of the hydrogen-containing and oxygen-containing alkali branch pipes to the alkali cooler, and an electrolyzer alkali recovery pipe connecting the alkali cooler and the electrolyzer; a hydrogen separator is disposed on the hydrogen-containing alkali branch pipe, and an oxygen separator is disposed on the oxygen-containing alkali branch pipe, the hydrogen separator being connected to a hydrogen scrubber, and the oxygen separator being connected to an oxygen scrubber; an alkali circulation pump is disposed on the electrolyzer alkali recovery pipe.

[0052] In this invention, the hydrogen output end of the hydrogen scrubber is connected to the hydrogen cooling separator via a pipeline; the oxygen output end of the oxygen scrubber is connected to the oxygen cooling separator via a pipeline; the hydrogen output end of the hydrogen cooling separator is connected to the deoxygenation tower heater via a pipeline; and the hydrogen output end of the deoxygenation tower heater is connected to the precooling separator via a pipeline.

[0053] Preferably, the precooling separator includes precooling separator A, precooling separator B and precooling separator C, and the precooling separator A, precooling separator B and precooling separator C are respectively connected to dryer A, dryer B and dryer C.

[0054] Preferably, the waste heat utilization refrigeration unit is one of the following: a hot water refrigeration unit, an alkaline solution direct-inlet refrigeration unit, and a multi-energy refrigeration unit; wherein, the multi-energy refrigeration unit is one of the following: a steam-hot water dual-energy lithium bromide refrigeration unit, a steam alkaline solution refrigeration unit, and a steam-hot water alkaline solution refrigeration unit.

[0055] This invention provides a thermal energy coupling and water-saving system for hydrogen production via water electrolysis. It can be applied to a single water electrolysis hydrogen production system or multiple systems. When applied to a single system, it means that one thermal energy coupling and water-saving system is used in conjunction with that system; when applied to multiple systems, it means that multiple systems share the same thermal energy coupling and water-saving system.

[0056] In this invention, the thermal energy coupling and water-saving process for the electrolysis hydrogen production system is as follows:

[0057] (1) Selection of cold source in water electrolysis hydrogen production system: The chilled water fed into the hydrogen cooling separator, oxygen cooling separator and pre-cooling separator in water electrolysis hydrogen production system is generated by waste heat utilization refrigeration unit.

[0058] (2) Selection of driving heat source for waste heat utilization chiller: The driving heat source for waste heat utilization chiller can be primary energy including steam and natural gas, or hot water or alkaline solution; among them, the steam used as driving heat source comes from the steam in the plant pipeline network, the hot water used as driving heat source comes from the high-temperature intermediate hot water produced after heat exchange with the alkaline solution cooler, and the alkaline solution used as driving heat source comes from the alkaline solution in the electrolytic cell; during operation, the waste heat utilization chiller prioritizes the use of the heat of the driving hot water or alkaline solution to produce chilled water. When the heat of the driving hot water or alkaline solution is insufficient, driving steam is used as a supplementary energy source to produce chilled water.

[0059] (3) Setting of process parameters for waste heat utilization chiller: The temperature of hot water or alkaline solution fed into the waste heat utilization chiller is 70-95℃, and the temperature of hot water or alkaline solution coming out of the waste heat utilization chiller is 50-70℃; the temperature of chilled water coming out of the cooling end of the waste heat utilization chiller is ≤12℃, and the temperature of chilled water after heat exchange with the hydrogen cooling separator, oxygen cooling separator and precooling separator is ≤20℃;

[0060] (4) Thermal energy coupling and water-saving process:

[0061] When hot water is used as the driving heat source for waste heat recovery chillers, the thermal energy coupling and water-saving process is as follows:

[0062] High-temperature intermediate hot water at a temperature of 50-70℃ is used to replace circulating cooling water in the alkali cooler. The high-temperature intermediate hot water is used to cool down the high-temperature alkali solution with a temperature of ≥80℃ sent from the electrolytic cell to the alkali cooler, so that the alkali solution is cooled down to ≤70℃. The temperature of the high-temperature intermediate hot water sent to the alkali cooler to cool the alkali solution is between 50℃ and 70℃. The high-temperature intermediate hot water exchanges heat and heats up in the alkali cooler, and its temperature is between 70℃ and 95℃.

[0063] The high-temperature intermediate hot water, with a temperature between 70℃ and 95℃ after heat exchange with the alkali cooler, will split into two high-temperature intermediate hot water circulation branch loops from the main high-temperature intermediate hot water circulation loop: a first high-temperature intermediate hot water circulation branch loop and a second high-temperature intermediate hot water circulation branch loop. The first high-temperature intermediate hot water circulation branch loop sends the high-temperature intermediate hot water to the waste heat utilization refrigeration unit, and the second high-temperature intermediate hot water circulation branch loop sends the high-temperature intermediate hot water to the hot water preheater newly installed before the deaerator heater. The remaining high-temperature intermediate hot water is sent to the air cooler through the main high-temperature intermediate hot water circulation loop and cooled by the ambient air to between 50℃ and 70℃. By using the air cooler instead of the traditional cooling tower to cool the high-temperature intermediate hot water, a 100% water-saving effect is achieved compared to the traditional cooling tower.

[0064] The high-temperature intermediate hot water fed into the waste heat utilization chiller unit is used as a driving heat source to produce chilled water. The chilled water is then sent to the hydrogen cooling separator, oxygen cooling separator, and pre-cooling separator for use, which saves on the power consumption of traditional electric refrigeration. After being cooled in the waste heat utilization chiller unit, the high-temperature intermediate hot water is also sent to the air cooler to be cooled by the ambient air to between 50°C and 70°C.

[0065] By adding a hot water preheater before the original deoxygenation tower heater, the hydrogen containing trace amounts of oxygen from the hydrogen cooling separator is preheated to above 60°C by the high-temperature intermediate hot water in the hot water preheater before being sent to the deoxygenation tower heater. The preheated hydrogen containing trace amounts of oxygen is then sent to the deoxygenation tower heater for heating, which can save the power consumption of the deoxygenation tower heater. After being cooled in the hot water preheater, the high-temperature intermediate hot water is also sent to the air cooler to be cooled to between 50°C and 70°C by the ambient air.

[0066] When alkaline solution is used as the driving heat source for waste heat recovery chiller, its heat energy coupling and water-saving process is basically the same as when hot water is used as the driving heat source for waste heat recovery chiller. The difference is that alkaline solution replaces hot water and directly enters any or all of the equipment in the waste heat recovery chiller, alkaline solution preheater, and air cooler, thereby achieving heat energy coupling and water-saving effects.

[0067] Example 2:

[0068] The thermal coupling and water-saving system of Example 1 was used to retrofit the water electrolysis hydrogen production system (where the waste heat utilization chiller's driving heat source is hot water, and the specific retrofit scheme adopts...). Figure 1 The data on electricity consumption and water consumption were compared with two previous water electrolysis hydrogen production systems (one using a wet cooling tower with electric refrigeration, and the other using a combined wet and dry cooling tower with electric refrigeration) before the modification. The results are shown in the table below.

[0069]

[0070] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A thermal energy coupling and water-saving system for hydrogen production by water electrolysis, characterized in that, The system includes a hydrogen cooling separator, an oxygen cooling separator, and a pre-cooling separator, each installed in a water electrolysis hydrogen production system. It also includes a waste heat recovery chiller unit for providing chilled water to the hydrogen cooling separator, oxygen cooling separator, and pre-cooling separator. The waste heat recovery chiller unit has a main chilled water circulation loop. The hydrogen cooling separator, oxygen cooling separator, and pre-cooling separator are each connected to the main chilled water circulation loop via a chilled water circulation branch loop. The water electrolysis hydrogen production system also includes an alkali cooler with a high-temperature intermediate hot water circulation main loop for cooling the alkali cooler. This main loop has a first high-temperature intermediate hot water circulation branch loop connected to the waste heat recovery chiller unit to provide a driving heat source for the unit. The system also includes an air cooler, replacing a cooling tower. The high-temperature intermediate hot water circulation main loop is connected between the alkali cooler and the air cooler.

2. The thermal energy coupling and water-saving system for hydrogen production by water electrolysis according to claim 1, characterized in that, The water electrolysis hydrogen production system is equipped with a deoxygenation tower heater for deoxygenating and purifying hydrogen containing trace amounts of oxygen separated by the hydrogen cooling separator. The water electrolysis hydrogen production system is also equipped with a hot water preheater. A second high-temperature intermediate hot water circulation branch circuit is also provided on the main high-temperature intermediate hot water circulation circuit, which is connected to the hot water preheater and provides a heat source for the hot water preheater. The hydrogen containing trace amounts of oxygen enters the hot water preheater and the deoxygenation tower heater successively through the hydrogen deoxygenation heating pipeline to achieve two heating processes.

3. The thermal energy coupling and water-saving system for hydrogen production by water electrolysis according to claim 1, characterized in that, The water electrolysis hydrogen production system does not have an alkali cooler. Instead, the electrolyzer of the system is equipped with a main alkali cooling circulation loop for cooling the alkali solution. This main loop has a first alkali cooling circulation branch loop connected to the waste heat recovery refrigeration unit to provide a driving heat source for the unit. The system also includes an air cooler that replaces the cooling tower. The main alkali cooling circulation loop connects the electrolyzer to the air cooler.

4. A thermal energy coupling and water-saving system for hydrogen production by water electrolysis according to claim 3, characterized in that, The water electrolysis hydrogen production system is equipped with a deoxygenation tower heater for deoxygenating and purifying hydrogen containing trace amounts of oxygen separated by the hydrogen cooling separator. The water electrolysis hydrogen production system is also equipped with an alkali preheater. The main alkali cooling circulation loop is also equipped with a second alkali cooling circulation branch loop connected to the alkali preheater to provide a heat source for the alkali preheater. The hydrogen containing trace amounts of oxygen enters the alkali preheater and the deoxygenation tower heater successively through the hydrogen deoxygenation heating pipeline to achieve two heating processes.

5. A thermal energy coupling and water-saving system for hydrogen production by water electrolysis according to claim 2, characterized in that, The deoxygenation tower heater is equipped with an electrically powered heating pipeline for deoxygenating and purifying the hydrogen containing trace amounts of oxygen.

6. A thermal energy coupling and water-saving system for hydrogen production by water electrolysis according to claim 1, characterized in that, The water electrolysis hydrogen production system includes an electrolyzer, an alkali cooling circuit disposed between the electrolyzer and the alkali cooler, the alkali cooling circuit including a branch pipe for hydrogen-containing alkali solution output from the cathode chamber of the electrolyzer, a branch pipe for oxygen-containing alkali solution output from the anode chamber of the electrolyzer, an electrolyzer alkali solution output pipe connecting the junction of the hydrogen-containing and oxygen-containing alkali solution branch pipes to the alkali cooler, and an electrolyzer alkali solution recovery pipe connecting the alkali cooler and the electrolyzer; a hydrogen separator is installed on the hydrogen-containing alkali solution branch pipe, and an oxygen separator is installed on the oxygen-containing alkali solution branch pipe, the hydrogen separator being connected to a hydrogen scrubber, and the oxygen separator being connected to an oxygen scrubber; an alkali solution circulation pump is installed on the electrolyzer alkali solution recovery pipe.

7. A thermal energy coupling and water-saving system for hydrogen production by water electrolysis according to claim 6, characterized in that, The hydrogen output of the hydrogen scrubber is connected to the hydrogen cooling separator via a pipeline; the oxygen output of the oxygen scrubber is connected to the oxygen cooling separator via a pipeline; the hydrogen output of the hydrogen cooling separator is connected to the deoxygenation tower heater via a pipeline; and the hydrogen output of the deoxygenation tower heater is connected to the precooling separator via a pipeline.

8. A thermal energy coupling and water-saving system for hydrogen production by water electrolysis according to claim 1, characterized in that, The waste heat utilization refrigeration unit is one of the following: a hot water refrigeration unit, an alkaline solution direct-inlet refrigeration unit, and a multi-energy refrigeration unit; wherein, the multi-energy refrigeration unit is one of the following: a steam-hot water dual-energy lithium bromide refrigeration unit, a steam alkaline solution refrigeration unit, and a steam-hot water alkaline solution refrigeration unit.

9. A thermal energy coupling and water-saving system for hydrogen production by water electrolysis according to any one of claims 1 to 8, characterized in that, The thermal energy coupling and water-saving process for the electrolytic hydrogen production system is as follows: (1) Selection of cold source in water electrolysis hydrogen production system: The chilled water fed into the hydrogen cooling separator, oxygen cooling separator and precooling separator in water electrolysis hydrogen production system is generated by waste heat utilization refrigeration unit. (2) Selection of driving heat source for waste heat utilization chiller: The driving heat source for waste heat utilization chiller is hot water or alkaline solution; the hot water used as driving heat source comes from the high-temperature intermediate hot water produced after heat exchange with the alkaline solution cooler, and the alkaline solution used as driving heat source comes from the alkaline solution of the electrolytic cell; during operation, the waste heat utilization chiller prioritizes the use of the heat of the driving hot water or alkaline solution to produce chilled water. (3) Setting of process parameters for waste heat utilization chiller: The temperature of hot water or alkaline solution fed into the waste heat utilization chiller is 70-95℃, and the temperature of hot water or alkaline solution coming out of the waste heat utilization chiller is 50-70℃; the temperature of chilled water coming out of the cooling end of the waste heat utilization chiller is ≤12℃, and the temperature of chilled water after heat exchange with the hydrogen cooling separator, oxygen cooling separator and precooling separator is ≤20℃; (4) Thermal energy coupling and water-saving process: When hot water is used as the driving heat source for waste heat recovery chillers, the thermal energy coupling and water-saving process is as follows: High-temperature intermediate hot water at a temperature of 50-70℃ is used to replace circulating cooling water in the alkali cooler. The high-temperature intermediate hot water is used to cool down the high-temperature alkali solution with a temperature of ≥80℃ sent from the electrolytic cell to the alkali cooler, so that the alkali solution is cooled down to ≤70℃. The temperature of the high-temperature intermediate hot water sent to the alkali cooler to cool the alkali solution is between 50℃ and 70℃. The high-temperature intermediate hot water exchanges heat and heats up in the alkali cooler, and its temperature is between 70℃ and 95℃. The high-temperature intermediate hot water, with a temperature between 70℃ and 95℃ after heat exchange with the alkali cooler, will split into two high-temperature intermediate hot water circulation branch loops from the main high-temperature intermediate hot water circulation loop: a first high-temperature intermediate hot water circulation branch loop and a second high-temperature intermediate hot water circulation branch loop. The first high-temperature intermediate hot water circulation branch loop sends the high-temperature intermediate hot water to the waste heat utilization refrigeration unit, and the second high-temperature intermediate hot water circulation branch loop sends the high-temperature intermediate hot water to the hot water preheater newly installed before the deaerator heater. The remaining high-temperature intermediate hot water is sent to the air cooler through the main high-temperature intermediate hot water circulation loop and cooled to between 50℃ and 70℃ by the ambient air. By using the air cooler instead of the traditional cooling tower to cool the high-temperature intermediate hot water, a 100% water-saving effect is achieved compared to the traditional cooling tower. The high-temperature intermediate hot water fed into the waste heat utilization chiller unit is used as a driving heat source to produce chilled water. The chilled water is then sent to the hydrogen cooling separator, oxygen cooling separator, and pre-cooling separator for use, which saves on the power consumption of traditional electric refrigeration. After being cooled in the waste heat utilization chiller unit, the high-temperature intermediate hot water is also sent to the air cooler to be cooled by the ambient air to between 50°C and 70°C. By adding a hot water preheater before the original deoxygenation tower heater, the hydrogen containing trace amounts of oxygen from the hydrogen cooling separator is preheated to above 60°C by the high-temperature intermediate hot water in the hot water preheater before being sent to the deoxygenation tower heater. The preheated hydrogen containing trace amounts of oxygen is then sent to the deoxygenation tower heater for heating, which can save the power consumption of the deoxygenation tower heater. After being cooled in the hot water preheater, the high-temperature intermediate hot water is also sent to the air cooler to be cooled to between 50°C and 70°C by the ambient air.

Images