Seawater desalination device and offshore hydrogen production system

Abstract

According to the sea water desalination device and the offshore hydrogen production system, the structure of the sea water desalination device is improved, the sea water desalination efficiency is improved, the system cost is reduced, and meanwhile it is ensured that the sea water desalination device can stably operate in the deep and far sea environment. The seawater desalination device comprises an evaporation tank, a collection device and a suction device, the evaporation tank is used for containing seawater, the evaporation tank is provided with an exhaust port, the suction device is provided with a turbine structure and a suction fan which are in transmission connection, the suction fan is matched with the exhaust port, and the collection device is used for collecting seawater. The turbine structure is used for being matched with an oxygen outlet of an oxygen side gas-liquid separator of the offshore hydrogen production system, and the turbine structure drives the suction fan to rotate so as to extract gas in the evaporation tank into the collecting device.

Description

Technical Field

[0001] The present invention relates to the technical field of offshore hydrogen production, and in particular to a seawater desalination device and an offshore hydrogen production system. Background Art

[0002] With the acceleration of global energy transformation, offshore wind power, as an important component of clean energy, is expanding in scale of development and utilization. However, the power consumption and transmission problems of offshore wind power, especially the high power transmission cost and low energy utilization efficiency of deep-sea wind power projects, have become key factors restricting the further development of offshore wind power. In order to solve these problems, the offshore hydrogen production system came into being. The system can not only effectively utilize the electricity generated by offshore wind power, but also realize the storage and transportation of hydrogen energy by passing desalinated seawater and alkaline solution into the electrolyzer for electrolysis and hydrogen production, providing a new way to optimize and diversify the energy structure.

[0003] In the offshore hydrogen production system, seawater desalination is a vital link. At present, the negative pressure distillation of seawater is one of the common means of seawater desalination. The key lies in how to form a negative pressure environment in the evaporation tank to promote the rapid evaporation and desalination of seawater. There are two common ways to form negative pressure: one is to use an ejector to achieve negative pressure, but the ejector method has the problem of low seawater desalination efficiency; the other is to use a negative pressure pump. During the process of using a vacuum pump to pump the seawater evaporation tank, water vapor that has not yet condensed into fresh water will be discharged into the air by the huge suction force of the vacuum pump, resulting in a reduction in the amount of condensed fresh water and a reduction in the efficiency of seawater desalination; in addition, the maintenance cost of the vacuum pump equipment is high. Summary of the invention

[0004] The purpose of the present invention is to provide a seawater desalination device and an offshore hydrogen production system, which improves the efficiency of seawater desalination and reduces system costs by improving the structure of the seawater desalination device, while ensuring stable operation in deep sea environments.

[0005] To achieve the above-mentioned purpose, the present invention provides a seawater desalination device, which includes an evaporation tank, a collecting device, and a suction device. The evaporation tank is used to contain seawater. The evaporation tank is provided with an exhaust port. The suction device has a turbine structure and a suction fan connected in a transmission manner. The suction fan is adapted to the exhaust port. The turbine structure is adapted to the oxygen outlet of the oxygen-side gas-liquid separator of the offshore hydrogen production system. The turbine structure drives the suction fan to rotate to extract the gas in the evaporation tank into the collecting device.

[0006] In the technical solution of the present application, a suction device is provided at the exhaust port of the evaporator, and the suction device includes a suction fan for extracting air from the evaporator. At the same time, the suction device is also equipped with a turbine structure for driving the suction fan, and the turbine structure drives the suction fan to form a negative pressure in the evaporator. The rotation of the turbine structure is based on the adaptation to the oxygen outlet of the oxygen-side gas-liquid separator of the offshore hydrogen production system, and the high-pressure oxygen discharged from the oxygen-side gas-liquid separator drives the turbine structure to drive the suction fan; thereby improving the efficiency of seawater desalination, reducing system costs, and ensuring stable operation in deep sea environments.

[0007] Optionally, the suction device includes a shell, the shell includes a first air cavity and a second air cavity that are isolated from each other; the turbine structure is located in the first air cavity, and the suction fan is located in the second air cavity.

[0008] Optionally, the turbine structure includes a plurality of turbine blades and a turbine shaft, the suction fan includes a fan shaft, and the fan shaft is coaxially arranged with the turbine shaft; the first air cavity is axially distributed with the second air cavity.

[0009] Optionally, the first air cavity is provided with a first inlet and a first outlet, the first inlet is used to communicate with the oxygen outlet, the first outlet is used to communicate with the outside of the suction device, the first inlet is arranged on the side of the first air cavity and radially opposite to the turbine shaft, and the first outlet is axially located at an end of the first air cavity away from the second air cavity.

[0010] Optionally, a plurality of the turbine blades are arranged around the turbine shaft, and a power flow channel is formed between two adjacent turbine blades and the cavity wall of the first air cavity. The power flow channel is offset at a certain angle relative to the central axis of the turbine shaft, and one end of the power flow channel is connected to the first inlet, and the other end is connected to the first outlet.

[0011] Optionally, the second air cavity is connected with an air inlet channel and an air outlet channel; the air inlet channel and the air outlet channel are arranged on both sides of the suction fan along the radial direction of the fan shaft;

[0012] The suction fan also includes fan blades, which are distributed circumferentially around the fan shaft. Two adjacent fan blades and a partial area of ​​the second air cavity form an air supply space, and the air supply space can be rotated to a position connected to the air inlet channel and a position connected to the air outlet channel.

[0013] Optionally, the collecting device is provided with a liquid discharge port, and the liquid discharge port is used to communicate with a liquid replenishment port of an electrolysis module of the offshore hydrogen production system.

[0014] An offshore hydrogen production system comprises an electrolysis module and an oxygen-side gas-liquid separator connected to the electrolysis module, wherein the oxygen-side gas-liquid separator is provided with an oxygen outlet;

[0015] It also includes the above-mentioned seawater desalination device, wherein the oxygen outlet is adapted to the turbine structure to drive the turbine structure to rotate.

[0016] Optionally, the oxygen-side gas-liquid separator further comprises an alkali liquid outlet, and the alkali liquid outlet is connected to the medium flow channel of the heat exchanger of the seawater desalination device.

[0017] Optionally, it also includes a heat exchanger and a seawater supply module, the heat exchanger has a heat exchange channel and a medium channel, the inlet of the heat exchange channel is connected to the seawater supply module, the outlet of the heat exchange channel is connected to the evaporation tank, and the medium channel is used to connect to the alkali liquid outlet of the oxygen side gas-liquid separator.

[0018] Other features and advantages of the present specification will become apparent from the following detailed description of exemplary embodiments of the present specification with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the specification and, together with the description, serve to explain the principles of the specification.

[0020] Figure 1 is a schematic structural diagram of an offshore hydrogen production system according to an embodiment of the present invention;

[0021] Figure 2 is a schematic structural diagram of a seawater desalination device according to an embodiment of the present invention;

[0022] Figure 3 is a schematic diagram of the structure of the suction device;

[0023] Figure 4 yes Figure 3 sectional view of

[0024] Figure 5 It is a partial structural schematic diagram of the suction device.

[0025] Reference numerals:

[0026] 1- holding box;

[0027] 21-evaporation tank; 22-collection device;

[0028] 3-suction device; 31-turbine structure; 311-turbine blades; 311a-power airflow channel; 312-turbine shaft; 32-suction fan; 321-fan blades; 321a-air supply space; 322-fan shaft; 323-middle section of shaft; 33-housing; 331a-first shell; 331b-first sealing plate; 332-transition part; 333a-second shell; 333b-second sealing plate; 33a-first air cavity; 33a1-first inlet; 33a2-first outlet; 33b-second air cavity; 33b1-second inlet; 33b2-second outlet; 33b3-inlet channel; 33b4-outlet channel;

[0029] 41- oxygen side gas-liquid separator; 41a- oxygen outlet; 42- hydrogen side gas-liquid separator; 43- alkali liquid outlet;

[0030] 5-heat exchanger; 61-filter device; 62-seawater pump; 63-water supply circulation pump;

[0031] 71-alkaline solution tank; 72-electrolytic cell. DETAILED DESCRIPTION

[0032] The present invention provides a seawater desalination device and an offshore hydrogen production system, which improves the efficiency of seawater desalination and reduces system costs by improving the structure of the seawater desalination device, while ensuring stable operation in a deep sea environment.

[0033] In order to enable those skilled in the art to better understand the solution of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0034] Relational terms such as “first” and “second” and the like are merely used to distinguish one component from another having the same name, but do not necessarily require or imply any such actual relationship or order between these components.

[0035] In the traditional technical solution using ejectors, the power gas of the ejector needs to be mixed with the sucked water vapor and discharged. The subsequent process needs to set up a gas-liquid separator to separate the power gas and water vapor, which increases the volume and weight of the equipment. At the same time, the mechanical efficiency of the ejector is low, generally only about 30%, and it is impossible to effectively use the energy in the power gas to extract fresh water.

[0036] Please refer to Figures 1 to 5 , Figure 1 is a schematic structural diagram of an offshore hydrogen production system according to an embodiment of the present invention; Figure 2 is a schematic structural diagram of a seawater desalination device according to an embodiment of the present invention; Figure 3 is a schematic diagram of the structure of the suction device; Figure 4 yes Figure 3 sectional view of Figure 5It is a partial structural schematic diagram of the suction device.

[0037] As shown in the figure, the offshore hydrogen production system includes an electrolysis module, which includes an alkali liquid tank 71 and an electrolytic tank 72. The alkali liquid tank 71 and the electrolytic tank 72 are connected by a pipeline, and an alkali liquid circulation pump is provided to pump the liquid to be electrolyzed in the alkali liquid tank 71 into the electrolytic tank 72. The electrolytic tank 72 is connected to the hydrogen side gas-liquid separator 42 and the oxygen side gas-liquid separator 41. After electrolysis, the cathode side of the electrolytic tank 72 is connected to the hydrogen side gas-liquid separator 42 and discharges a mixture of hydrogen and alkali liquid to the hydrogen side gas-liquid separator 42, and the anode side is connected to the oxygen side gas-liquid separator 41 and discharges a mixture of oxygen and alkali liquid to the oxygen side gas-liquid separator 41. Subsequently, the mixtures on both sides enter the hydrogen side gas-liquid separator 42 and the oxygen side gas-liquid separator 41 respectively for gas-liquid two-phase separation, and the hydrogen separated by the hydrogen side gas-liquid separator 42 is stored and utilized after washing, deoxygenation, drying and other process flows. The oxygen-side gas-liquid separator 41 is provided with an oxygen outlet 41 a to transport the separated oxygen to the outside.

[0038] In an optional example, the offshore hydrogen production system further includes a heat exchanger 5 , a seawater supply module and a seawater desalination device, wherein the seawater supply module is used to supply seawater to the seawater desalination device. The seawater supply module includes a filter device 61 and a seawater pump 62 , and the seawater pump 62 pumps seawater into the filter device 61 .

[0039] In the example shown in the figure, the seawater desalination device specifically includes an evaporation tank 21, a collecting device 22 and a suction device 3. The evaporation tank 21 is used to contain seawater and evaporate the seawater.

[0040] The heat exchanger 5 has a heat exchange flow channel and a medium flow channel. The inlet of the heat exchange flow channel is connected to the seawater supply module. Specifically, the inlet of the heat exchange flow channel is connected to the outlet of the filter device 61. The outlet of the heat exchange flow channel is connected to the evaporation tank 21. In this way, the seawater from the heat exchanger 5 enters the evaporation tank 21. The collecting device 22 is used to collect the water vapor discharged from the evaporation tank 21, and the suction device 3 is used to form a set negative pressure in the evaporation tank 21.

[0041] The oxygen-side gas-liquid separator 41 and the hydrogen-side gas-liquid separator 42 both include an alkali liquid outlet 43, and the medium flow channel is used to communicate with the alkali liquid outlet 43 of the oxygen-side gas-liquid separator 41. The inlet of the medium flow channel is simultaneously connected to the alkali liquid outlet 43 of the oxygen-side gas-liquid separator 41 and the alkali liquid outlet 43 of the hydrogen-side gas-liquid separator 42.

[0042] In this way, the alkali liquid from the oxygen side gas-liquid separator 41 and the hydrogen side gas-liquid separator 42 enters the medium flow channel and exchanges heat with the seawater in the heat exchange flow channel to heat the seawater entering the evaporation tank 21. The cooled alkali liquid flows out through the medium flow channel outlet to the alkali liquid tank 71 for further use.

[0043] In this way, the waste heat of the alkaline solution after electrolysis can be used to heat the seawater, so that the waste heat resources of the offshore hydrogen production system can be further utilized, thereby further improving the efficiency of seawater desalination.

[0044] The specific manner in which the evaporation tank 21 in the present application performs negative pressure distillation is described below. In this embodiment, the suction device 3 has a turbine structure 31 and a suction fan 32 that are transmission-connected. The evaporation tank 21 is provided with an exhaust port, and the suction fan 32 is adapted to the exhaust port. The turbine structure 31 is adapted to the oxygen outlet 41a of the oxygen-side gas-liquid separator 41 of the offshore hydrogen production system, that is, the oxygen outlet 41a is adapted to the turbine structure 31 to drive the turbine structure 31 to rotate.

[0045] The turbine structure 31 drives the suction fan 32 to rotate so as to extract the gas in the evaporation tank 21 into the collection device 22 .

[0046] In the technical solution of the present application, the exhaust port of the evaporation tank 21 is provided with a suction device 3, which includes a suction fan 32 for extracting air from the evaporation tank 21, and is also equipped with a turbine structure 31 for driving the suction fan 32, and the turbine structure 31 drives the suction fan 32 to form a negative pressure in the evaporation tank 21. The rotation of the turbine structure 31 is based on the adaptation with the oxygen outlet 41a of the oxygen-side gas-liquid separator 41 of the offshore hydrogen production system, and the high-pressure oxygen discharged from the oxygen-side gas-liquid separator 41 is used to drive the turbine structure 31 to drive the suction fan 32; thereby improving the efficiency of seawater desalination, reducing system costs, and ensuring stable operation in deep sea environments.

[0047] In addition, the turbine structure 31 is not affected by the vaporization degree of seawater, but only by the input power gas oxygen, which ensures the stability of fresh water production and provides a stable material source for the electrolyzer 72. During the operation of the turbocharger, the power gas oxygen and the water vapor generated by negative pressure boiling are circulated in separate pipelines, and there is no need to connect a gas-liquid separator to separate the mixture. Compared with the ejector device and subsequent processing technology, the turbine structure 31 optimizes the independent negative pressure distillation module from the perspective of space and weight, saving the volume of the gas-liquid separator, and can be compatible with the traditional offshore hydrogen production system to achieve plug-and-play.

[0048] As a specific embodiment, the suction device 3 includes a housing 33, and the housing 33 includes a first air cavity 33a and a second air cavity 33b that are isolated from each other; the turbine structure 31 is located in the first air cavity 33a, and the suction fan 32 is located in the second air cavity 33b. In this way, the high-pressure oxygen of the turbine structure 31 can flow in the first air cavity 33a as the power gas for the turbine rotation, that is, the first air cavity 33a is connected to the oxygen outlet 41a, and the second air cavity 33b is connected to the exhaust port of the evaporation tank 21.

[0049] In the initial stage of desalination, the suction fan 32 draws out the air in the evaporation tank 21 to form a set negative pressure in the evaporation tank 21. After the negative pressure value in the evaporation tank 21 reaches the set value, the seawater boils and evaporates to form water vapor. At this time, under the action of high-pressure oxygen, the turbine structure 31 always keeps rotating to drive the suction fan 32. During the rotation process, the suction fan 32 can draw the water vapor in the evaporation tank 21 outward through the exhaust port to the collection device 22, and the water vapor condenses into fresh water in the collection device 22. The remaining seawater can be discharged into the sea through the evaporation tank 21.

[0050] Specifically, the turbine structure 31 includes a turbine shaft 312, and the suction fan 32 includes a fan shaft 322, and the fan shaft 322 is coaxially arranged with the turbine shaft 312, and the two can be a split structure or an integrated structure. The first air cavity 33a is axially distributed with the second air cavity 33b. The shell 33 includes a first shell portion 331a, a transition portion 332, and a second shell portion 333a. The first shell portion 331a, the transition portion 332, and the second shell portion 333a are arranged in sequence, and the arrangement direction of the three is defined as the first set direction.

[0051] In the example shown in the figure, the suction device 3 includes a rotating shaft portion, which is arranged in the housing 33, and the central axis of the rotating shaft portion is the arrangement direction of the first shell portion 331a, the transition portion 332 and the second shell portion 333a. The rotating shaft portion has a shaft middle section 323, and the shaft middle section 323 is rotatably adapted to the bearing arranged in the transition portion 332. One end of the rotating shaft portion, defined as the "turbine section", extends into the first shell portion 331a and forms a closed first air cavity 33a with the inner wall of the first shell portion 331a. The other end of the rotating shaft portion, defined as the "fan section", extends into the second shell portion 333a and forms a closed second air cavity 33b with the inner wall of the second shell portion 333a.

[0052] Specifically, the first shell 331a is in the shape of a volute, and an annular first sealing plate 331b is provided at the position where the first shell 331a and the transition part 332 meet. The annular first sealing plate 331b extends radially, and has a socket on its inner ring side, which can be connected with the transition part 332. The turbine section is the aforementioned turbine shaft 312, and the turbine shaft 312 is in an approximately trapezoidal structure, with a large end face and a small end face. In the axial direction, the large end face is closer to the side where the transition part 332 is located than the small end face, that is, the large end face is pressed against the surface of the first sealing plate 331b constituting the first air cavity 33a in the axial direction. The middle section 323 of the shaft can extend into the transition section through the socket, and the radial dimension of the middle section 323 of the shaft is smaller than the radial dimension of the turbine shaft 312, but the central axis of the two and the central axis of the outer shell coincide.

[0053] The turbine structure 31 also includes a plurality of turbine blades 311, and the plurality of turbine blades 311 are arranged around the turbine shaft 312. In the example shown in the figure, the turbine blades 311 are arranged on the trapezoidal hypotenuse surface of the turbine shaft 312, and extend from the large end face of the turbine shaft 312 to the small end face of the turbine shaft 312. At the same time, each turbine blade 311 is deflected in the same direction relative to the axial direction at a certain angle. In other words, the walls of the first air cavity 33a and the two adjacent turbine blades 311 form a power flow channel 311a, and the power flow channel 311a is deflected at a certain angle relative to the central axis of the turbine shaft 312.

[0054] The first air cavity 33a is provided with a first inlet 33a1 and a first outlet 33a2, wherein the first inlet 33a1 is used to communicate with the oxygen outlet 41a, and the first outlet 33a2 is used to communicate with the outside of the suction device 3, the first inlet 33a1 is provided at the side of the first air cavity 33a and is radially opposite to the turbine shaft 312, and the first outlet 33a2 is axially located at an end of the first air cavity 33a away from the second air cavity 33b. That is, the first outlet 33a2 is located on the same side as the small end face of the turbine shaft 312. One end of the power air channel 311a is connected to the first inlet 33a1, and the other end is connected to the first outlet 33a2.

[0055] In this way, high-pressure oxygen enters the power flow channel 311a through the first inlet 33a1, thereby forming a high-pressure side inside the power flow channel 311a, and a low-pressure side outside the power flow channel 311a. Since the extension direction of the power flow channel 311a enables the high-pressure oxygen to flow through the power flow channel 311a and be discharged from the first outlet 33a2, it can drive the turbine blades 311 to rotate around the central axis of the shaft, thereby driving the exhaust fan to rotate.

[0056] As a result, the high-pressure oxygen produced by the existing offshore hydrogen production system can be used as power gas, avoiding the waste of high-pressure oxygen and improving the energy utilization efficiency of the offshore hydrogen production system.

[0057] The position where the second shell portion 333a and the transition portion 332 meet is fixedly connected with an annular second sealing plate 333b, and the second sealing plate 333b is arranged parallel to the first sealing plate 331b, that is, it extends radially to enclose the second air cavity 33b with the second shell portion 333a. The inner ring side of the second sealing plate 333b is used to insert the fan section of the rotating shaft portion, that is, the fan shaft 322, and the radial dimension of the fan shaft 322 is greater than the radial dimension of the middle section 323 of the shaft. The axial clearance of the end face of the fan shaft 322 facing the turbine shaft 312 is matched with the surface of the second sealing plate 333b that constitutes the second air cavity 33b. The suction fan 32 also includes fan blades 321, which are distributed circumferentially around the fan shaft 322 and extend axially. The two adjacent fan blades 321 and a partial area of ​​the second air cavity 33b form an air supply space 321a, and the air supply space 321a can be rotated to a position connected to the air inlet channel 33b3 and a position connected to the air outlet channel 33b4.

[0058] The second air cavity 33b is provided with a second inlet 33b1 and a second outlet 33b2. The second air cavity 33b is a cylindrical structure. The second inlet 33b1 and the second outlet 33b2 are provided on the side wall of the second air cavity 33b and are arranged opposite to each other in the radial direction. The second air cavity 33b is connected with an air inlet channel 33b3 and an air outlet channel 33b4; the air inlet channel 33b3 and the air outlet channel 33b4 are arranged on both sides of the suction fan 32 in the radial direction of the fan shaft 322; the second inlet 33b1 and the second outlet 33b2 are connected with the air inlet channel 33b3 and the air outlet channel 33b4 in a one-to-one correspondence. Thus, it can be connected with the exhaust port and the collecting device 22.

[0059] In this embodiment, as the fan blades 321 rotate around the central axis, the second inlet 33b1 can be sequentially connected to the air supply space 321a between two adjacent fan blades 321, and at the same time, the second outlet 33b2 can also be sequentially connected to the air supply space 321a between two adjacent fan blades 321. Negative pressure can be formed in the collection device 22, so that a set negative pressure value can be formed in the evaporation tank 21 to make the filtered seawater boil and evaporate.

[0060] In the above-mentioned embodiments, the collecting device 22 is provided with a liquid discharge port, and the liquid discharge port is used to communicate with the liquid replenishment port of the electrolysis module of the offshore hydrogen production system. Specifically, the liquid replenishment port is provided in the alkali liquid tank 71, so that the collecting device 22 can pump fresh water into the alkali liquid tank 71.

[0061] The present application also provides an offshore hydrogen production system, including an electrolysis module and an oxygen-side gas-liquid separator 41 connected to the electrolysis module, wherein the oxygen-side gas-liquid separator 41 is provided with an oxygen outlet 41a; and also includes the above-mentioned seawater desalination device, wherein the oxygen outlet 41a is adapted to the turbine structure 31 to drive the turbine structure 31 to rotate. The efficiency of seawater desalination and supply of the offshore hydrogen production system is improved, the system cost is reduced, and stable operation is ensured in a deep sea environment. As an optional embodiment, the seawater desalination device also includes a container 1, which can be airtight or watertight with the outside, and the container 1 contains various components such as a seawater pump 62, a filter device 61, a collection device 22, an evaporation tank 21, a water replenishment circulation pump 63, and a turbine structure 31, so that the seawater desalination device in the present application can be placed in water for use. Thereby, the adaptation environment of the seawater desalination device is improved.

[0062] In the example shown in the figure, the filter device 61 and the collection device 22 are arranged inside the containing box 1 along the first direction, and the evaporation tank 21 is arranged between the filter device 61 and the collection device 22 .

[0063] The second direction is defined as the direction perpendicular to the first direction in the same plane, and the third direction is defined as the direction perpendicular to the plane where the first direction and the second direction are located. The third direction may be the height direction in the figure. In the third direction, the suction device 3 is disposed on the upper side of the evaporation tank 21, and its height is higher than the highest position of the collection device 22.

[0064] In the third direction, the turbine structure 31 is located on a side of the suction fan 32 that is away from the evaporation can 21 .

[0065] In the third direction, a seawater pump 62 is integrated on the upper side of the filter device 61, and the seawater pump 62 can pump seawater into the seawater transition device. The liquid inlet of the filter device 61 is arranged on its upper surface, so as to facilitate communication with the seawater pump 62. In the second direction, the evaporation tank 21 and the collection device 22 are distributed front and back, thereby improving the further utilization of the space in the container box 1.

[0066] In this embodiment, a through hole is provided at the top of the container box 1, and the turbine structure 31 discharges oxygen to the outside of the container box 1. Specifically, the container box 1 is provided with a through hole, and the first outlet 33a2 is connected to an exhaust pipe, and the exhaust pipe extends to the outside of the container box 1 through the hole, and the outlet of the exhaust pipe extends beyond the sea surface, so that oxygen can be discharged. Of course, this is only a specific description of the exhaust method, and does not constitute a limitation of the present application. As long as the oxygen is discharged, those skilled in the art can choose it according to the specific layout position of the seawater desalination device in the present application.

[0067] The side wall of the containing box 1 is provided with corresponding openings so that high-pressure oxygen can be delivered to the turbine structure 31 through pipelines, seawater can be pumped into the seawater pump 62 through pipelines, the filtered seawater can be delivered to the heat exchanger 5, and fresh water can be added to the alkali solution tank 71.

[0068] Compared with the prior art, the advantages of this application are:

[0069] First, the evaporation tank 21 is evacuated without using conventional vacuum instruments, vacuum pumps, ejectors and other devices. Instead, a suction device 3 is used to use high-pressure oxygen as kinetic energy to drive a simple mechanical structure to move, thereby sucking out the gas in the evaporation tank 21 to form a negative pressure condition.

[0070] Second, the seawater pump 62, the filter device 61, the collection device 22, the evaporation tank 21, the water replenishment circulation pump 63, the suction device 3, etc. are integrated together according to the process flow as a separate fresh water production module, which has no effect on the original electrolyzer 72 system. In the deep sea hydrogen production scenario, it serves as a fresh water source supply device to provide fresh water for the electrolyzer 72 system. It has a simple structure and flexible device, which greatly saves space and cost.

[0071] Third, during the operation of the suction device 3, the power gas oxygen and the water vapor generated by negative pressure boiling are circulated in separate pipes, and there is no need to connect a gas-liquid separator to separate the mixture. Compared with the traditional ejector device and subsequent processing technology, the suction device 3 optimizes the independent negative pressure distillation module from the perspective of space and weight.

[0072] Fourthly, the amount of fresh water produced by the seawater desalination device in the present application exceeds the amount of fresh water required by the electrolyzer 72, thus generating additional economic benefits other than hydrogen production.

[0073] In each of the above-mentioned embodiments, multiple groups of suction devices 3 and evaporation tanks 21 can be added to perform multiple distillations on the seawater and make more effective use of oxygen and waste heat.

[0074] The technical effects of this application are illustrated below with specific examples.

[0075] First, waste heat utilization:

[0076] Taking the example that the alkali solution can be cooled down from 90°C to 70°C and the temperature of seawater can be increased from 25°C to 40°C by adopting the technical solution of the present application, in the technical solution of the present application, the heat exchanger 5 is connected to the alkali solution outlet 43 of the oxygen side gas-liquid separator 41 and the alkali solution outlet 43 of the hydrogen side gas-liquid separator 42 to heat the filtered seawater flowing therethrough.

[0077] Without considering heat loss, according to the law of conservation of heat, the heat required to heat the seawater through the heat exchanger 5 is theoretically equal to the heat dissipated by the alkali solution through the heat exchanger 5. Assumptions Electrolytic cell 72 (200Nm 3 / h) the actual water consumption of the reaction is 180L / h, and the hydrogen production is 200Nm 3 / h, oxygen output 100Nm 3 / h. The hydrogen output of the electrolyzer 72 is 200Nm 3 / h, oxygen output 100Nm 3 / h, according to GB32311-2015 water electrolysis hydrogen production system energy efficiency limit value and energy efficiency level, the electrolytic cell 72 is designed according to this requirement: the current density is 3000A / m 3 , assuming that the diameter of the electrolytic cell 72 is 1 m.

[0078] Electrolytic cell 72 current: I = 3000 × (3.14 × 0.5 * 0.5) = 2355A

[0079] According to the overall reaction formula of water electrolysis, 2 mol of electrons are needed to produce 1 mol of hydrogen. The charge of 2 mol of electrons is 2 mol*96485C / mol. Then the unit of these charges is converted from C to Ah, which is (2 mol*96485C / mol / 3600s)Ah. Under standard conditions, the volume of 1 mol of hydrogen is 22.4L, which is 0.00224m3.

[0080] In summary, the amount of electricity Q0 required to produce 1Nm3 of hydrogen is: Q0 = (2mol*96485C / mol / 3600s) / 0.00224m3 = 2390Ah / Nm3. The amount of electricity required to produce 200 standard cubic meters of hydrogen is 478,000Ah.

[0081] Assuming that the electrolyzer 72 runs for 1 hour at a current of 2355A, the power consumed is 2355Ah. Under standard conditions, the charge required to produce 1m3 of hydrogen is 2390Ah. Then the hydrogen production of a single chamber is:

[0082] V=2355 / 2390=0.99Nm 3 / h≈1Nm 3 / h

[0083] Then the 200 standard cubic electrolytic cell 72 requires about 200 small chambers. In this case, in order to verify whether the alkali solution and gas waste heat for heating seawater are sufficient, it is assumed that the electrolytic cell 72 has a high efficiency and good control technology, and the number of small chambers does not take the design margin. Under this condition, the energy used to heat the alkali solution is less.

[0084] The total voltage of 200 electrolysis chambers is 400 V, calculated based on a 2 V voltage per chamber. The chamber voltage of 2 V is an empirical value for industrial hydrogen production by electrolysis of water, so the total power including the conversion into chemical energy and thermal energy is:

[0085] P=V*I=2355A*400V=942Kw

[0086] The system produces 200Nm of hydrogen. 3 / h, belongs to large and medium-sized hydrogen production system, energy efficiency level 1 requires that the energy efficiency value of the hydrogen production system shall not be less than 82%. According to the energy efficiency value of 82%, the power used for heating is: P = 942KW*(1-82%) = 169.56KW = 169.56KJ / s

[0087] The power transmitted to the seawater by the gas-liquid two-phase flow must be less than or equal to the power of the alkali solution electric heating. According to practical experience, the temperature difference before and after the gas-liquid two-phase flow enters the heat exchanger 5 is 10°C, which is about 75°C to 85°C.

[0088] The following is the calculation of the heat generated by the alkali solution: 1000Nm 3 / h electrolytic cell 72 corresponds to 60m3 / h of alkali solution, 200Nm 3 / h electrolytic cell 72 corresponds to 12m 3 / h of alkali solution. The density of alkali solution is 1.29g / cm 3 =1290kg / m 3 , the mass flow rate of alkali solution m3 = 12 / 3600*1290 = 4.3 kg / s;

[0089] Specific heat capacity: c = 3.3KJ / (kg.K);

[0090] Temperature difference: 10℃;

[0091] Q3=m3*c3*T03=4.3*3.3*10=141.9KJ / s;

[0092] 141.9KJ / s<169.56KJ / s

[0093] Therefore 200Nm 3 / h The waste heat generated in the electrolytic cell 72 is enough to be supplied to the seawater by the gas-liquid two-phase flow of the heat exchanger 5, thereby reducing the requirement of 10℃. The heat absorption of seawater: The initial temperature of seawater is 25℃. Assuming that the temperature after heat exchange in the heat exchanger 5 is 40℃, the mass flow rate of heated seawater Qabsorption = Qtotal, that is, m4*c4*T0 = m4*4*15 = 141.9KJ / s, and the mass flow rate of seawater m40℃ = 2.37kg / s is obtained.

[0094] Latent heat of vaporization of seawater

[0095] Electrolyzer 72 (200Nm 3 / h) is 180L / h=0.05*10-3=0.05kg / s. To meet the water replenishment rate of 0.05kg / s, the evaporation rate of seawater in the evaporation tank 21 should be greater than or equal to 0.05kg / s. In actual situations, some water vapor may be lost during the condensation and separation process. In this analysis, the water vapor utilization rate is temporarily considered to be 100%.

[0096] Since the suction device 3 changes the air pressure and causes the boiling point to drop, the seawater in the evaporation tank 21 will boil and vaporize. The seawater will continuously flow in and out of the evaporation tank 21. The vaporization amount of the seawater can be controlled by controlling the residence time of the seawater in the evaporation tank 21. The vaporization heat absorption can be calculated by monitoring the inlet and outlet temperature difference of the evaporation tank 21 to determine whether the vaporized water volume can just replenish the consumed water volume.

[0097] The inlet temperature of the evaporation tank 21 is 40°C, then the heat released by the seawater at 40°C = the heat of phase change of the seawater. The specific heat capacity of water: 4.185KJ / (kg.K), the latent heat of vaporization of the seawater at 40°C H = 2430KJ / kg;

[0098] Q heat generation = Q heat absorption

[0099] Q heat generation = m*c*T = 4.185*2.37*ΔT

[0100] Q heat absorption = m2*H = 0.05*2430,

[0101] The temperature difference ΔT is 12.2°C, so the outlet temperature of the evaporator 21 is 40-12.2=27.8°C. Second, negative pressure

[0102] (1) Negative pressure required for seawater to boil

[0103] According to the above calculations, please refer to the following Table 1, the temperature at the inlet of the evaporation tank 21 is 40°C (technical personnel in the field can further increase it according to actual needs), the temperature at the outlet of the seawater is 27.8°C, and assuming that the structure inside the evaporation tank 21 is uniform, the average temperature inside the evaporation tank 21 is 33.9°C, which is approximately equal to 34°C. If the average temperature of the seawater in the evaporation tank 21 is 34°C, the vacuum pressure to be generated is -95.8kpa, and the actual pressure is:

[0104] 101.325kpa-95.8kpa=5.525kPa

[0105] Table 1 Correspondence between boiling point of water and vacuum degree

[0106]

[0107] Note: A vacuum degree of -81.2 kPa means it is 81.2 kPa lower than the standard atmospheric pressure.

[0108] Assume that the volume of the evaporation tank 21 is 2m 3 , the pumping time is about 60s, 200Nm 3 / hThe amount of fresh water required by electrolytic cell 72 is 0.05kg / s, i.e. 0.13m 3 / s.

[0109] T=V / S*In(P1 / P2)

[0110] Wherein, T is the pumping time, V is the volume of the evaporation tank 21, S is the pumping rate, P1 is the initial pressure 100 kPa, and P2 is the target pressure.

[0111] Substitute the relevant data for calculation, 60=2 / 0.13*In(100 / P2), P2 is 2.024kPa.

[0112] 2.024kPa<5.525kPa, which meets the pressure required for 34℃ seawater.

[0113] The principles and implementation methods of the present invention are described in this article using specific examples. The description of the above embodiments is only used to help understand the core idea of ​​the present invention. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present invention, the present invention can also be improved and modified, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A seawater desalination device, characterized in that: The invention comprises an evaporation tank (21), a collecting device (22), and a suction device (3), wherein the evaporation tank (21) is used to contain seawater, the evaporation tank (21) is provided with an exhaust port, the suction device (3) comprises a turbine structure (31) and a suction fan (32) which are connected in a transmission manner, the suction fan (32) is adapted to the exhaust port, the turbine structure (31) is adapted to be adapted to an oxygen outlet (41a) of an oxygen-side gas-liquid separator (41) of an offshore hydrogen production system, and the turbine structure (31) drives the suction fan (32) to rotate so as to extract the gas in the evaporation tank (21) into the collecting device (22).

2. The seawater desalination device according to claim 1, characterized in that: The suction device (3) comprises a shell (33), wherein the shell (33) comprises a first air cavity (33a) and a second air cavity (33b) which are isolated from each other; the turbine structure (31) is located in the first air cavity (33a), and the suction fan (32) is located in the second air cavity (33b).

3. The seawater desalination device according to claim 2, characterized in that: The turbine structure (31) includes a plurality of turbine blades (311) and a turbine shaft (312); the suction fan (32) includes a fan shaft (322); the fan shaft (322) is coaxially arranged with the turbine shaft (312); the first air cavity (33a) is axially distributed with the second air cavity (33b).

4. The seawater desalination device according to claim 3, characterized in that: The first air cavity (33a) is provided with a first inlet (33a1) and a first outlet (33a2); the first inlet (33a1) is used to communicate with the oxygen outlet (41a); the first outlet (33a2) is used to communicate with the outside of the suction device (3); the first inlet (33a1) is provided at a side of the first air cavity (33a) and is radially opposite to the turbine shaft (312); the first outlet (33a2) is axially located at an end of the first air cavity (33a) away from the second air cavity (33b).

5. The seawater desalination device according to claim 4, characterized in that: A plurality of turbine blades (311) are arranged around the turbine shaft (312), and a power flow channel (311a) is formed between two adjacent turbine blades (311) and the cavity wall of the first air cavity (33a). The power flow channel (311a) is offset at a certain angle relative to the central axis of the turbine shaft (312), and one end of the power flow channel (311a) is connected to the first inlet (33a1), and the other end is connected to the first outlet (33a2).

6. The seawater desalination device according to claim 4, characterized in that: The second air cavity (33b) is connected to an air inlet channel (33b3) and an air outlet channel (33b4); the air inlet channel (33b3) and the air outlet channel (33b4) are arranged on both sides of the suction fan (32) along the radial direction of the fan shaft (322); The suction fan (32) further comprises fan blades (321), wherein the fan blades (321) are distributed circumferentially around the fan shaft (322), and two adjacent fan blades (321) and a partial area of ​​the second air cavity (33b) form an air supply space (321a), and the air supply space (321a) can be rotated to a position connected to the air inlet channel (33b3) and a position connected to the air outlet channel (33b4).

7. The seawater desalination device according to any one of claims 1 to 6, characterized in that: The collecting device (22) is provided with a liquid discharge port, and the liquid discharge port is used to communicate with the liquid replenishment port of the electrolysis module of the offshore hydrogen production system.

8. An offshore hydrogen production system, characterized in that: It comprises an electrolysis module and an oxygen-side gas-liquid separator (41) connected to the electrolysis module, wherein the oxygen-side gas-liquid separator (41) is provided with an oxygen outlet (41a); It also comprises the seawater desalination device according to any one of claims 1 to 7, wherein the oxygen outlet (41a) is adapted to the turbine structure (31) to drive the turbine structure (31) to rotate.

9. The offshore hydrogen production system according to claim 8, characterized in that: The oxygen-side gas-liquid separator (41) further comprises an alkali liquid outlet (43), and the alkali liquid outlet (43) is connected to the medium flow channel of the heat exchanger (5) of the seawater desalination device.

10. The offshore hydrogen production system according to claim 9, characterized in that: It also includes a heat exchanger (5) and a seawater supply module, the heat exchanger (5) having a heat exchange flow channel and a medium flow channel, the inlet of the heat exchange flow channel being in communication with the seawater supply module, the outlet of the heat exchange flow channel being in communication with the evaporation tank (21), and the inlet of the medium flow channel being in communication with the alkali liquid outlet (43) of the oxygen side gas-liquid separator (41) and the alkali liquid outlet (43) of the hydrogen side gas-liquid separator (42).

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