Hydrogen plant, and control system and control method thereof

Abstract

A control system (30) for a hydrogen plant (100) is provided. The hydrogen plant includes: a first set of units (11,12…1n) comprising at least one hydrogen electrolyzer for producing hydrogen as a main product and heat as a byproduct; and a second set of units (21,22…2n) comprising at least one desalination unit partially operated with the heat from the at least one hydrogen electrolyzer for producing distilled water from raw water, and the at least one water desalination unit being configured to provide at least part of the distilled water to the at least one hydrogen electrolyzer. The control system is configured to control operation of the hydrogen plant including controlling electrical energy consumption of the at least one electrolyzer and the at least one desalination unit by adjusting at least one of: 1) electrical power supplied to the at least one hydrogen electrolyzer to produce the hydrogen and the heat; 2) flowrate of the at least part of the distilled water to the at least one hydrogen electrolyzer from the at least one desalination unit; and 3) heat transferred from the at least one hydrogen electrolyzer to the at least one desalination unit.

Description

HYDROGEN PLANT, AND CONTRO L SYSTEM AND CONTROLMETHOD THEREOFTECHNICAL FILED

[0001] The present disclosure relates to a hydrogen plant and a control system and a control method for the hydrogen plant.BACKGROUND

[0002] To reduce the global climate change, the fossil fuel-based generation will be reduced, and fossil-based production of plastic, fertilizer and fuel will instead be based on blue or green hydrogen production. The green hydrogen is hydrogen produced by electrolyzer stacks that get electricity from renewables. However, the electrolyzer stacks in a hydrogen plant usually have an efficiency varying between 50 and 70% and the remaining part represents losses as waste heat. Moreover, the efficiency is reduced when the power and hydrogen production are increased. For example, for a 1 GW electrolyzer plant the heat losses can become around 170 to 500 MW.

[0003] The climate change also influences weather systems that results in a larger need to utilize desalination plants to obtain fresh water to be used in food production and as drinking water. Today, a large part of desalination plants is using fossil fuel.

[0004] Membranes based desalination processes like Reverse Osmoses (RO) are energy intensive processes due to the massive electric motors that are used to provide the process required pressure. Even when this energy is generated by renewables, it could often be used primarily elsewhere. Thermal / distillation based desalination requires only around one third of the electric power required by RO. On the other hand, thermal desalination can be the solution when high organic loads are challenging for RO.

[0005] However, heat is needed for thermal / distillation based desalination. This desalination process is not economically competitive because the heat is generated by burningfossil fuels. Distillation processes include multi-stage flash (MSF), multiple-effect distillation (MED), and mechanical (MVC) or thermal vapor (TVC) compression. The distillation processes use generally small quantities of electricity, MED consumes 0.8-1.25kWhe / m3. However, for boiling the water the thermal desalination consumes a lot of thermal energy and causes an increase in the carbon footprint.SUMMARY

[0006] According to an embodiment of the disclosure, a control system for a hydrogen plant is provided. The hydrogen plant includes: a first set of units comprising at least one hydrogen electrolyzer for producing hydrogen as a main product and heat as a byproduct; and a second set of units comprising at least one desalination unit partially operated with the heat from the at least one hydrogen electrolyzer for producing distilled water from raw water, and the at least one water desalination unit being configured to provide at least part of the distilled water to the at least one hydrogen electrolyzer. The control system is configured to control operation of the hydrogen plant including controlling electrical energy consumption of the at least one electrolyzer and the at least one desalination unit by adjusting at least one of: 1) electrical power supplied to the at least one hydrogen electrolyzer to produce the hydrogen and the heat; 2) flowrate of the at least part of the distilled water to the at least one hydrogen electrolyzer from the at least one desalination unit; and 3) heat transferred from the at least one hydrogen electrolyzer to the at least one desalination unit.

[0007] According to another embodiment of the disclosure, a hydrogen plant is provided. The hydrogen plant includes: a first set of units comprising at least one hydrogen electrolyzer for producing hydrogen as a main product and heat as a byproduct; a second set of units comprising at least one desalination unit partially operated with the heat from the at least one hydrogen electrolyzer for producing distilled water from raw water, and the at least one water desalination unit being configured to provide at least part of the distilled water to the at least one hydrogen electrolyzer; and a control system configured to control operation of the hydrogen plant including controlling electrical energy consumption of the at least one electrolyzer and the at least one desalination unit by adjusting at least one of: 1) electrical power supplied to theat least one hydrogen electrolyzer to produce the hydrogen and the heat; 2) flowrate of the at least part of the distilled water to the at least one hydrogen electrolyzer from the at least one desalination unit; and 3) heat transferred from the at least one hydrogen electrolyzer to the at least one desalination unit.

[0008] According to yet another embodiment of the disclosure, a method for controlling operation of the above-mentioned hydrogen plant is provided. The method includes: controlling electrical energy consumption of the at least one electrolyzer and the at least one desalination unit by adjusting at least one of: 1) electrical power supplied to the at least one hydrogen electrolyzer to produce the hydrogen and the heat; 2) flowrate of the at least part of the distilled water to the at least one hydrogen electrolyzer from the at least one desalination unit; and 3) heat transferred from the at least one hydrogen electrolyzer to the at least one desalination unit.BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The disclosed aspects will hereinafter be described in connection with the appended drawings that are provided to illustrate but not to limit the scope of the disclosure.

[0010] Figure 1 is a block diagram of a hydrogen plant according to an embodiment of the present disclosure.

[0011] Figures 2A-2B show examples of a converter of the hydrogen plant shown in Figure 1.

[0012] Figures 3A-3C show examples of an integrated unit of the hydrogen plant shown in Figure 1.

[0013] Figure 4~8 show exemplary methods for controlling operation of the hydrogen plant shown in Figure 1.DETAILED DESCRIPTIONOverview

[0014] Examples of the disclosure provide a smart and controlled integration of an industrial process that generates massive waste heat and another industrial process that consumes it.

[0015] In an example of the disclosure, an electrolysis process and a desalination process with common boundary conditions (e.g., pressure or temperature boundary conditions) are fully integrated to each other. For example, in a hydrogen plant, an electrolyzer station is combined with a desalination plant. The electrolyzer station utilizes at least some of the water that the desalination plant produces. Moreover, the heat losses that the electrolyzer station generate will be used in the desalination plant, i.e., the heat produced in the electrolyzer station is to be fed to desalination plant.

[0016] In an example of the disclosure, heat pumps or heat exchangers can be used to regulate temperature levels in the boundary conditions, so as to increase the efficiency of the hydrogen plant. There might be a case where the heat produced by the electrolyzer station satisfies the demand for the desalination process but can be slightly fluctuating. In this case, the heat exchangers or heat pumps can be used to stabilize the input temperature input to the desalination process.

[0017] In an example of the disclosure, the levels of output temperature of the electrolysis process is almost what is needed as the input temperature for the desalination process, and the temperature of distilled water released from the desalination process is almost at the temperature level required by the input to the electrolyzer station. This situation is ideal to minimize the heat pumps and / or heat exchangers operation cost.

[0018] In addition, the produced hydrogen can be used in a different way (e.g., for storage or as an input to a fuel cell) and the produced distilled water can also be shared differently depending on the geographic situation and many other parameters (e.g., a part of the produced distilled water is provided to another industrial process than the electrolysis process).Hydrogen plant

[0019] Examples of one aspect of the disclosure provide a hydrogen plant includingintegrated electrolyzers and desalination units. The hydrogen plant gets its electricity from a transmission / distribution system. A large part of the electricity can come from renewable power sources to produce green hydrogen. Converters (e.g., rectifiers) are mounted between electrolyzers and the distribution grid. The hydrogen plant can handle the hydrogen production to obtain hydrogen with required purity, pressure, and production volume. The electrolyzers consume water when producing hydrogen. Moreover, cooling of the electrolyzers need water. Therefore, a continuous flow of distilled water is produced out from raw water that the desalination units produce. A cooling water loop may be provide to remove the heat from the electrolyzers, which may circulate through a heat pump through which the heat is absorbed from electrolyzer and transferred. The cooled water after transfer of heat is fed back to the electrolyzers where it may be heated again in the electrolyzer. To prevent degradation of the electrolyzers, the cooling water needs to be free of metal particles and other substances that clog the membrane of the electrolyzers, and a separate water treatment unit can be used for this purpose. The heat from the electrolyzers and heat pump is fed to the desalination plant in which it contributes to heat up raw water (e.g., sea water) to produce steam to remove salts. Then, the steam can be cooled down by a cooling device and then fed back to the electrolyzers again. The steam can also be cooled down by an additional heat pump and the heat taken from the steam can be fed into the desalination process where it can be reused to further improve the efficiency of the desalination units.

[0020] In an example, if the heat that are produced by the electrolyzers is not high enough for the desalination process, a heater element must be used. The heater element obtains its power / energy from an electrical power source, for example, the electric transmission / distribution grid.

[0021] Examples of the hydrogen plant will be described with reference to Figures 1~3.

[0022] Figure 1 is a hydrogen plant 100 according an embodiment of the disclosure. The hydrogen plant 100 includes a first set of units 1 l~ln, a second set of units 21~2n and a control system 30.

[0023] Each of the first set of units 1 l~ln can be implemented as a hydrogen electrolyzer (hereafter referred to as electrolyzer) which produces hydrogen as a main product and heatas a byproduct.

[0024] Each electrolyzer can include one electrolysis stack or include multiple electrolysis stacks connected in series or in parallel. Each electrolyzer can include or is coupled to various sensors (not shown) for measuring an electric current, a voltage, a temperature in the electrolyzer, purity of hydrogen produced by the electrolyzer and other parameters required for operation of the electrolyzer.

[0025] Each electrolyzer is coupled with a converter (e.g., power converter) and the converter can provide the electrolyzer with an adjustable DC voltage. For example, the electrolyzer 11 is coupled with the converter CON I, the electrolyzer 12 is coupled with the converter CON_2... the electrolyzer In is coupled with the converter CON_n.

[0026] Each converter can be implemented in a similar way. The converter will be introduced with reference to Figures 2A and 2B in which the converter CON_1 is shown as an example.

[0027] Figure 2A shows an example of the converter CON I. As show in Figure 2A, the converter CON_1 is implemented as a single stage AC-DC converter. The AC-DC converter can also be implemented as a thyristor (i.e., a half-controlled device) to output an adjustable DC voltage.

[0028] Figure 2B shows another example of the converter CON I . As shown in Figure 2B, the converter CON_1 is implemented by means of a two-stage conversion, for example, an AC- DC converter and a DC-DC converter connected in series, to output an adjustable DC voltage. In the case of two-stage conversion, the control flexibility can be improved.

[0029] It is noted that Figures 2A and 2B show examples where the converter CON I is coupled to an AC power source. The converter CON I can also be coupled to a DC power source and implemented as a DC-DC converter which is coupled with the DC power source.

[0030] It is noted that each converter can include one or more converters and at least one of the one or more converters includes a controlled device (e.g., IGBT or MOSFET) or a semicontrolled device (e.g., thyristor), so that the converter can be operated to control powering of the electrolyzer. The converter can include a converter controller (not shown) to control thecontrolled device or the semi-controlled device to control DC power supplied to the electrlyzer.

[0031] Each of the second set of units 21~2n can be implemented as a desalination unit for producing distilled water from raw water. Some of the thermal desalination units can be a thermal desalination unit which is partially operated with the heat from at least one hydrogen electrolyzer. Each thermal desalination unit for example includes a multi-effect distillation (MED) system or a multi-stage flash (MSF) system.

[0032] With reference to Figure 1, the hydrogen plant 100 also can be said to include a plurality of integrated units 1A-1N. Each integrated unit includes a desalination unit and an electrolyzer integrated with said one desalination unit. For example, the integrated unit 1A includes the desalination unit 21 and the electrolyzer 11 integrated with the desalination unit 21, the integrated unit IB includes the desalination unit 22 and the electrolyzer 12 integrated with the desalination unit 22... the integrated unit IN includes the desalination unit 2n and the electrolyzer In integrated with the desalination unit 2n. The integrated unit can also have the respective converters (CON I, CON 2... CONji) integrated along with auxilary devices (e.g., pump, heat pump, heat exchanger, etc.) and a local controller to manage operation of the integrated unit. In each integrated unit, the heat produced during the eletrolysis process is fed to the desalination unit to heat up raw water to remove the salt and to produce distilled water. The distilled water is fed to the electrolyzer for producing hydrogen and also for cooling the electrolyzer. The control system 30 can be a plant level controller controlling operation of the integrated units. The control system 30 includes local controllers made available in the integrated units.

[0033] In an example of an integrated unit, for example referring to the integrated unit 1A, a temperature difference between an output temperature (see “Water_Tl”) of coolant water (the coolant water refers to the distilled water that is input into the electrolyzer and circulated in the electrolyzer for cooling) heated by the heat produced as the byproduct in the electrolyzer 11 and an input temperature required for thermal desalination in the desalination unit 21 is within a predetermined temperature range, such that the levels of the output temperature of the electrolyzer 11 is almost what is needed for effectively transferring heat to the thermal desalination in the desalination unit. Moreover, in this example, the flowrate of the distilledwater output by the desalination unit 21 can meet the needs of the electrolyzer 11 for water for electrolysis and cooling. That is to say, the distilled water from the desalination unit 21 is almost what is required by the input to the electrolyzer 11.

[0034] It is noted that, in this example, the electrolyzer 11 has an input port for receiving the distilled water from the desalination unit 21 and the received distilled water will be used for the electrolysis and the cooling in the electrolyzer 11.

[0035] In another example of an integrated unit, for example referring to the integrated unit IN, a heat controlling device 3n is provided between an output of the electrolyzer In and an input of the desalination unit 2n for regulating a temperature of water to be input into desalination unit 2n. The heat controlling device 3n can be a heat pump (HP) or a heat exchanger (HX). For example, the HP 3n can increase the temperature of coolant water output from the electrolyzer In from a first temperature (see “Water _T1”) to a second temperature (see “Water _T2”) by consuming electrical energy (see “Electrical energy_l”). Then, the coolant water with the second temperature (i.e., Water _T2) is input into the desalination unit 2n and transfers thermal energy, thereby contributing to heat up the raw water. In addition, if the amount of thermal energy transferred to the desalination unit 2n is not high enough for the thermal desalination in the desalination unit 2n, the desalination unit 2n can obtain external electrical energy (see “Electrical energy_0”) to further heat up the raw water.

[0036] In yet another example of an integrated unit, for example referring to the integrated unit IB, a flowrate controlling device 24 is provided between an output of the desalination unit 22 and an input of the electrolyzer 12 for regulating the flowrate of the distilled water to be input into the electrolyzer 12. The flowrate controlling device 24 can be a pump. The pump 24 can be controlled to regulate the flowrate of the distilled water to be input into the electrolyzer 12. The faster the flowrate is, the less heat the coolant water absorbs when circulating in the electrolyzer 12, so the temperature of the coolant water when flowing out of the electrolyzer 12 is lower, that is, the temperature of water Tl is lower. On the other hand, the slower the flow rate is, the more heat the coolant water absorbs when circulating in the electrolyzer 12, so the temperature of the coolant water when flowing out of the electrolyzer 12 is higher, that is, the temperature of water_Tl is higher. Thus, the thermal energy (heat)transferred to the desalination unit 22 can be controlled by operating the pump 24 to adjust the flowrate.

[0037] Figure 3A shows an example of the integrated unit IB. As shown in Figure 3A, a rational valve 25 is provided at an output of the desalination unit 22 for controlling a ration between of an amount of a part of the distilled water (Distilled water l) to be input into the electrolyzer 21 and an amount of the other part of the distilled water (Distilled water_2) for another industrial process. The inclusion of the rational valve 25 is particularly suitable for the situation where the amount of the distilled water (see “Distilled water”) produced by desalination unit 22 is greater than the amount of water required for the electrolysis and cooling in the electrolyzer 21.

[0038] Moreover, in this example, a cooling device 26 is provided between an output of the desalination unit 22 and an input of the electrolyzer 21. The cooling device 26 cools distilled water from the desalination unit 22 to reduce the temperature of the distilled water. Then, the cooled water with the reduced temperature (see “Water_T0) is fed to the electrolyzer 21 where it is heated again.

[0039] It is noted that, in this example, the electrolyzer 12 has two different input ports. One input port (the input port coupled with the pump 24) is to receive distilled water for electrolysis and another input port (the input port coupled with the cooling device 26) is to receive distilled water for cooling. That is to say, the pipeline for water for the electrolysis is different than that for water for cooling.

[0040] With continuing reference to Figure 3A, the raw water can flow through a filter 27, another flowrate or pressure controlling device 28 (e.g., another pump 28), and another heat controlling device 29 (e.g., another heat pump 29) in sequence, and then flow into the desalination unit 22. In this way, the purity, flowrate and temperature of the raw water can be adjusted before flowing into the desalination unit 22 for thermal desalination.

[0041] According to an example of the disclosure, an additional heat controlling device is provided in the at least one desalination unit or at an output of the at least one desalination unit to transfer heat from the distilled water or steam produced in the at least one desalination unit to a thermal desalination process in the at least one desalination unit. The additional heatcontrolling device can be implemented as a heat pump. Such an example will be introduce with reference to Figure 3B.

[0042] Figure 3B shows an example of the integrated unit IN. As shown in Figure 3B, a ham pump 2nl (i.e., the above-mentioned additional heat controlling device) is provided in the desalination unit 2n. Another heat pump (or a heat exchanger) 2n2 is also provided in the desalination unit 2n to regulate the temperature of the coolant water from the electrolyzer In for the thermal desalination process in the desalination unit 2n. The heat fed to the desalination unit 2n in which it contributes to heat up the raw water (e.g., sea water) to steam or hot water to remove the salt. Then, the steam or hot water is cooled down by the ham pump 2nl and the heat taken from the steam or hot water during the cooling process is fed back to the thermal desalination process in the desalination unit 2n. That is to say, the heat produced during the cooling of the steam or hot water can also be fed into the thermal desalination process where it can be reused to further improve the efficiency of the desalination unit.

[0043] In an example, although not shown in Figure 3B, the ham pump 2nl can also be provided at an output of desalination unit 2n and outside the desalination unit 2n.

[0044] In an example, the heat from the electrolyzer In can be used to heat the raw water before the desalination process in the desalination unit 2n.

[0045] It is noted that, in some specific applications, the heat pump 3n shown in Figure 3B can be removed to reduce the plant cost.

[0046] The control system 30 controls operation of the hydrogen plant 100 to operate the hydrogen plant 100 with at least one of a predetermined hydrogen production, a predetermined distilled water production, and predetermined energy consumption. For example, controlling the operation of the hydrogen plant 100 includes one or more of l) controlling the heat pump or heat exchanger 23 to adjust the temperature of coolant water to be input into the desalination unit 22; 2) controlling the converter CON_2 to control electrical power to be supplied to the electrolyzer 12; 3) controlling the pump 24 to adjust the flowrate of distilled water to be input into the electrolyzer 21; 4) controlling the rational valve 25 to control a ration between of an amount of a part of distilled water to be input into the electrolyzer 21 and an amount of the other part of distilled water for another industrial process; and 5) controlling the cooling device26 to adjust the temperature of water to be input into the electrolyzer 21 for cooling the electrolyzer.

[0047] In an example of the disclosure, an integrated unit includes one or more local controllers for controlling operation of the integrated unit.

[0048] Although it is described that one desalination unit is coupled with one electrolyzer to form an integrated unit in the above-described examples, in an example of the disclosure, it can also be implemented as an integrated unit including one desalination unit and a plurality of electrolyzers.

[0049] In another example of the disclosure, it can be also implemented as an integrated unit including one desalination unit and a plurality of electrolyzers wherein the desalination unit is optionally coupled to any one or more of the plurality of electrolyzers. Such an example will be introduced with reference to Figure 3C.

[0050] Figure 3C shows an embodiment of an integrated unit, for example, an integrated unit 1 A’. As shown in Figure 3C, the desalination unit 21 is coupled to electrolyzers 111~113 through switches SW1-SW3 that can manipulate the piping arrangement with valves to control thermal inclusion of an electrolyzer unit to transfer heat to the desalination plant and / or inclusion of a heat pump to control heat transfer to the desalination plant. Such control may be required to improve energy efficiency of the operation of the hydrogen plant where the electrolyzers that are producing significant heat as a byproduct that is sufficient to transfer heat for the input water (electrolyte) to the electrolyzer and transfer heat for the desalination unit 21 are coupled for transferring heat to the desalination unit. The integrated unit 1A’ further includes a local controller 31 for controlling each of the switches SW1-SW3. For example, the local controller 31 outputs a first control signal CS1 to the switch SW1 coupled between the desalination unit 21 and the electrolyzer 111 to control an ON or OFF state of the switch SW1. This allows the local controller 31 to control whether the desalination unit 21 is coupled to the electrolyzer 111. Similarly, the local controller 31 outputs a second control signal CS2 to the switch SW2 coupled between the desalination unit 21 and the electrolyzer 112 to control an ON or OFF state of the switch SW2. This allows the local controller 31 to control whether the desalination unit 21 is coupled to the electrolyzer 112. The local controller 31 outputs a thirdcontrol signal CS3 to the switch SW3 coupled between the desalination unit 21 and the electrolyzer 113 to control an ON or OFF state of the switch SW3. This allows the local controller 31 to control whether the desalination unit 21 is coupled to the electrolyzer 113.

[0051] The local controller 31 determines the number of hydrogen electrolyzers to be coupled to the desalination unit 21 based on the amount of heat required for thermal desalination process in the desalination unit 21, and generate control signals based on the determination.

[0052] In addition, the thermal desalination process can be integrated with multiple other heat-producing processes that produce heat as a byproduct. For example, the hydrogen plant can be combined with data centers, industrial furnaces, and / or steel production plants. Therefore, multiple sources can contribute to the heat input to the thermal desalination process.

[0053] Examples of another aspect of the disclosure provide a control system (e.g., the control system 30 described above) for controlling operation of the hydrogen plant 100. The control system can perform control methods for controlling operation of the hydrogen plant 100, and such methods will be described in the below.Example methods

[0054] Further to examples of the hydrogen described above, example methods are now described. Such methods can be performed by the control system 30 described above. It should be understood that the operations involved in the following methods need not be performed in the precise order described. Rather, various operations may be performed in a different order or simultaneously, and operations may be added or omitted.

[0055] Figure 4 is a flowchart of a method 400 for controlling operation of the hydrogen plant 100 according to an embodiment of the present disclosure. The above descriptions for the hydrogen plant 100 are also applicable here.

[0056] Referring to Figure 4, at block 410, the control system 30 controls operation of the hydrogen plant 100 to control electrical energy consumption of at least one electrolyzer and at least one desalination unit comprised in the hydrogen plant 100. For clarity, an example of block 410 is described with reference to the integrated unit IB shown in Figure 1.

[0057] In an example, controlling the operation of the hydrogen plant 100 includesadjusting at least one of: 1) electrical power (see “DC power”) supplied to the electrolyzer 12 to produce hydrogen and heat (block 411); 2) flowrate of the distilled water (see “Distilled water”) to be fed to the electrolyzer 12 from the desalination unit 22 (block 412); and 3) heat transferred to the desalination unit 22 from the electrolyzer 12 (block 413).

[0058] In this example, if the control system 30 controls the converter CON 2 to increase the electrical power supplied to the electrolyzer 12, the current of the electrolyzer 12 will increase and the hydrogen production rate of the electrolyzer 12 will also increase. In the case that the flowrate of the distilled water (see “Distilled water”) to be fed to the electrolyzer 12 remains unchanged, more heat will be produced during the electrolysis process in the electrolyzer 12, and the output temperature (see “Water Tl”) of the coolant water output from the electrolyzer 12 will increase. If the control system 30 controls the converter CON_2 to decrees the electrical power supplied to the electrolyzer 12, the current of the electrolyzer 12 will decrease and the hydrogen production rate of the electrolyzer 12 will also decrease. In the case that the flowrate of the distilled water (see “Distilled water”) to be fed to the electrolyzer 12 remains unchanged, less heat will be produced during the electrolysis process in the electrolyzer 12, and the output temperature (see “Water Tl”) of the coolant water output from the electrolyzer 12 will decrease.

[0059] In this example, if the control system 30 controls the pump 24 to increase the flowrate of the distilled water (see “Distilled water”) to be fed to the electrolyzer 12, the coolant water will absorb less heat when circulating in the electrolyzer. In the case that the electrical power (see “DC power”) supplied to the electrolyzer 12 remains unchanged, less heat will be produced during the electrolysis process in the electrolyzer 12, and the output temperature (see “Water Tl”) of the coolant water output from the electrolyzer 12 will decrease. If the control system 30 controls the pump 24 to decrease the flowrate of the distilled water (see “Distilled water”) to be fed to the electrolyzer 12, the coolant water will absorb more heat when circulating in the electrolyzer. In the case that the electrical power (see “DC power”) supplied to the electrolyzer 12 remains unchanged, more heat will be produced during the electrolysis process in the electrolyzer 12, and the output temperature (see “Water Tl”) of the coolant water output from the electrolyzer 12 will increase.

[0060] In this example, as described above, the control system 30 can control the heat transferred to the desalination unit 22 by adjusting the 1) electrical power and / or the 2) flowrate. The control system 30 can also control the heat transferred to the desalination unit 22 by controlling the heat pump 23. For example, the control system 30 controls the heat pump 23 to increase the temperature of the coolant water. In this case, the heat pump 23 consumes external electrical energy (see “Electrical energy_l”).

[0061] The above adjustments and possible additional adjustments will have an impact on power consumption of the hydrogen plant 100. According to examples of the disclosure, the control system 30 can determine corresponding adjustment strategies based on a predetermined control target.

[0062] Figure 5 is a flowchart of a method 500 for controlling operation of the hydrogen plant 100 according to another embodiment of the disclosure. According to the method 500, control system 30 control the operation of the hydrogen plant 100 to produce hydrogen at a predetermined hydrogen production rate. The control system 30 can be a part of a Distributed Control System (DCS) deployed in the hydrogen plant 100 or can be a part of an industrial plant that comprises the hydrogen plant 100. Further, the one or more controllers includes local controllers deployed in integrated units of at least one electrolyzer unit and at least one desalination unit.

[0063] For clarity, the method 500 is described with reference to the integrated unit IB shown in Figure 1.

[0064] Referring to Figure 5, at block 510, the control system 30 receives a predetermined hydrogen production rate (i.e., a target hydrogen production rate) as a control target.

[0065] At block 520, the control system 30 calculates a power set point and a water setpoint of the electrolyzer 12 based on the target hydrogen production rate by using an electrolyzer model included in the control system 30.

[0066] At block 530, the control system 30 sends the power set point to a converter controller (not shown) of the converter CON_2 such that the converter controller controls the converter CON_2 to provide DC power to the electrolyzer 12 according to the power setpoint.

[0067] At block 540, the control system 30 sends the water setpoint to a desalination controller (not shown) of the desalination unit 22 such that the desalination controller controls the desalination unit 22 to produce distilled water according to the water setpoint.

[0068] At block 550, the control system 30 receives an actual hydrogen production rate of the electrolyzer 12. The actual hydrogen production rate of the electrolyzer 12 can be measured by a gas flow meter coupled with the electrolyzer 12 or calculated based on an actual current of the electrolyzer 12.

[0069] At block 560, the control system 30 calculates a difference between the actual hydrogen production rate and the target hydrogen production rate.

[0070] At block 570, the control system 30 dynamically regulates the power setpoint and the water setpoint such the difference is reduced or minimized.

[0071] Figure 6 is a flowchart of a method 600 for controlling operation of the hydrogen plant 100 according to yet another embodiment of the disclosure. According to the method 600, the control system 30 controls the operation of the hydrogen plant 100 to produce distilled water at a predetermined water production rate. For clarity, the method 600 is described with reference to the integrated unit IB shown in Figure 1.

[0072] Referring to Figure 6, at block 610, the control system 30 receives a predetermined water production rate (i.e., a target water production rate) as a control target.

[0073] At block 620, the control system 30 calculates a raw water setpoint and a heat setpoint based on the target water production rate by using a desalination device model included in the control system 30.

[0074] At block 630, the control system 30 determined if the heat from the electrolyzer 12 is high enough for the thermal desalination in the desalination unit 22.

[0075] If the determination result is yes (i.e., the heat from the electrolyzer 12 is high enough for the thermal desalination in the desalination unit 22), the method 600 proceeds to block 640. At block 640, the thermal desalination is performed by reusing the heat from the electrolyzer 12.

[0076] If the determination result is no (i.e., the heat from the electrolyzer 12 is not highenough for the thermal desalination in the desalination unit 22), the method 600 proceeds to block 650. At block 650, the thermal desalination is performed by reusing the heat from the electrolyzer 12 and by consuming external electrical energy.

[0077] At block 660, the control system 30 receives an actual water production rate of the desalination unit 22. The actual water production rate of the unit 22 can be measured by a water flow sensor coupled with the desalination unit 22.

[0078] At block 670, the control system 30 calculates a difference between the actual water production rate and the target water production rate.

[0079] At block 680, the control system 30 dynamically regulates the raw water setpoint and the heat setpoint such the difference is reduced or minimized.

[0080] Figure 7 is a flowchart of a method 700 for controlling operation of the hydrogen plant 100 according to yet another embodiment of the disclosure. For clarity, the method 500 is described with reference to the integrated unit IB shown in Figure 3A.

[0081] Referring to Figure 7, at block 710, the control system 30 controls the operation of the hydrogen plant 100 to reduce external electrical energy (see “Electrical energy_0”) supplied to the desalination unit 22 by increasing thermal energy supplied to the desalination unit 22.

[0082] In an example, increasing thermal energy supplied to the desalination unit 22 includes at least one of: 1) increasing electrical power supplied to the electrolyzer 12 (block 711); 2) decreasing the flowrate of distilled water to be fed to the electrolyzer 12 (block 712); 3) increasing the temperature of the coolant water to be input into the desalination unit 22 by operating the heat pump 23 (block 713); and 4) increasing the temperature of the raw water to be input into the desalination unit 22 by operating the heat pump 28 and / or heating the raw water to be input into the desalination unit 22 by the heat extracted from the electrolyzer 12 and / or heating the water in the desalination unit 22 by the heat extracted from the electrolyzer 12 and / or heating the water in the desalination unit 22 with the heat from the output steam or distilled water produced in the desalination unit 22 before providing the distilled water as an output (block 714).

[0083] Figure 8 is a flowchart of a method 800 for controlling the operation of the hydrogenplant 100 according to yet another embodiment of the disclosure. For clarity, the method 800 is described with reference to the integrated unit 1A’ shown in Figure 3C.

[0084] Referring to Figure 8, at block 810, the control system 30 predicts the amount of heat to be produced by each of the electrolyzers 111-113 when operating at full load, and the amount of heat to be consumed by desalination unit 21 for the thermal desalination process.

[0085] At block 820, the control system 30 determines one or more of the electrolyzers 111-113 to be operated to produce hydrogen such that the total heat to be produced by the determined one or more electrolyzers meets the heat required by the desalination process in the desalination unit 21. For example, in the case that the total heat to be produced by the electrolyzers 111 and 112 can meet the heat required by the thermal desalination process in the desalination unit 21, the control system 30 determines the electrolyzers 111 and 112 from the electrolyzers 111-113 to be operated to produce hydrogen.

[0086] At block 830, the control system 30 generates a control instruction based on the above determination and sends the control instruction to the local controller 31, so that the local controller 31 generates corresponding control signals based on the control instruction for controlling an on or off operation of each of the switches SW1-SW3.

[0087] In addition, in a case where renewable energy is available, electrolyzers can be operated to produce green hydrogen by making the most use of the available renewable energy. When the produced green hydrogen is more than demand hydrogen, the excess hydrogen can be stored in a hydrogen storage (see “H2 storage”) or provided to a fuel cell.

[0088] The previous description is provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects. Thus, the claims are not intended to be limited to the aspects shown herein. All structural and functional equivalent transformations to the elements of the various aspects of the present disclosure, which are known or to be apparent to those skilled in the art, are intended to be covered by the claims.

Claims

WHAT IS CLAIMED IS:

1. A control system for a hydrogen plant, the hydrogen plant comprising: a first set of units comprising at least one hydrogen electrolyzer for producing hydrogen as a main product and heat as a byproduct; and a second set of units comprising at least one desalination unit partially operated with the heat from the at least one hydrogen electrolyzer for producing distilled water from raw water, and the at least one water desalination unit being configured to provide at least part of the distilled water to the at least one hydrogen electrolyzer; wherein the control system is configured to control operation of the hydrogen plant including controlling electrical energy consumption of the at least one electrolyzer and the at least one desalination unit by adjusting at least one of: electrical power supplied to the at least one hydrogen electrolyzer to produce the hydrogen and the heat; flowrate of the at least part of the distilled water to the at least one hydrogen electrolyzer from the at least one desalination unit; and- heat transferred from the at least one hydrogen electrolyzer to the at least one desalination unit.

2. The control system of claim 1, wherein the hydrogen plant is configured to reuse the heat from the at least one electrolyzer for a thermal desalination process in the at least one desalination unit, and wherein the control system is configured to reduce external electrical energy supplied to the at least one desalination unit by at least partly transferring an amount of thermal energy from the heat from the at least one electrolyzer for the thermal desalination process carried out in the at least one desalination unit.

3. The control system of claim 2, wherein controlling the heat produced by the at least one hydrogen electrolyzer comprises at least one of:- adjusting the electrical power supplied to the at least one hydrogen electrolyzer to increase or decrease the heat produced by the at least one hydrogen electrolyzer;- adjusting the flowrate of the at least part of the distilled water distilled water supplied as an input to the at least one hydrogen electrolyzer; and- adjusting the flowrate of the raw water into the at least one desalination unit.

4. The control system of claim 1, wherein the control system is configured to control the at least one hydrogen electrolyzer to produce hydrogen at a predetermined hydrogen production rate by:- adjusting the electrical power to be supplied to the at least one hydrogen electrolyzer; and / or- adjusting the flowrate of the at least part of the distilled water to be input to the at least one hydrogen electrolyzer from the at least one desalination unit.

5. The control system of claim 1, wherein the control system is configured to control the at least one desalination unit to produce distilled water at a predetermined water production rate by:- adjusting flowrate of the raw water to be input into the at least one desalination unit to produce the distilled water; and / or- adjusting a temperature of coolant water heated by the heat produced in the at least one electrolyzer and fed as a part of input to the at least one desalination unit.

6. The control system of claim 1, wherein the control system is further configured to control operation of the hydrogen plant with increased energy efficiency by operating the at least oneelectrolyzer unit such that a temperature of coolant water heated by the heat produced as the byproduct in the at least one electrolyzer is within a temperature range required for thermal desalination process in the at least one desalination unit.

7. A hydrogen plant, comprising: a first set of units comprising at least one hydrogen electrolyzer for producing hydrogen as a main product and heat as a byproduct; and a second set of units comprising at least one desalination unit partially operated with the heat from the at least one hydrogen electrolyzer for producing distilled water from raw water, and the at least one water desalination unit being configured to provide at least part of the distilled water to the at least one hydrogen electrolyzer; and a control system configured to control operation of the hydrogen plant including controlling electrical energy consumption of the at least one electrolyzer and the at least one desalination unit by adjusting at least one of:- electrical power supplied to the at least one hydrogen electrolyzer to produce the hydrogen and the heat;- flowrate of the at least part of the distilled water to the at least one hydrogen electrolyzer from the at least one desalination unit; and- heat transferred from the at least one hydrogen electrolyzer to the at least one desalination unit.

8. The hydrogen plant of claim 7, further comprising a heat controlling device coupled between an output of the at least one hydrogen electrolyzer and an input of the at least one desalination unit for regulating a temperature of coolant water heated by the heat produced in the at least one electrolyzer and fed as a part of input to the at least one desalination unit, and optionally the heat controlling device comprises a heat pump and / or a heat exchanger.

9. The hydrogen plant of claim 8, further comprising a flowrate controlling device coupled between an output of the at least one desalination unit and an input of the at least one hydrogen electrolyzer for regulating flowrate of the at least part of the distilled water to be input to the at least one desalination unit, and optionally the flowrate controlling device comprises a pump.

10. The hydrogen plant of claim 9, further comprising a rational valve coupled at an output of the at least one desalination unit for controlling a ration between of an amount of the at least part of the distilled water to be input into the at least one hydrogen electrolyzer and an amount of the other part of the distilled water for another industrial process.

11. The hydrogen plant of claim 10, wherein the control system is configured to control the heat controlling device and / or the flowrate controlling device to adjust the heat transferred from the at least one hydrogen electrolyzer to the at least one desalination unit.

12. The hydrogen plant of claim 7, further comprising an additional heat controlling device arranged in the at least one desalination unit or at an output of the at least one desalination unit to transfer heat from the distilled water or steam produced in the at least one desalination unit to a thermal desalination process in the at least one desalination unit.

13. The hydrogen plant of any of claims 7-12, wherein the first set of units comprise a plurality of hydrogen electrolyzers, and the second set of units comprise a plurality of desalination units, and each of the plurality of desalination units is configurable to be coupled with one or more of the plurality of hydrogen electrolyzers.

14. The hydrogen plant of claim 7, wherein the first set of units comprise a plurality of hydrogen electrolyzers, and the second set of units comprise a plurality of desalination units, and each ofthe plurality of desalination units is configured to be coupled with a corresponding one of the plurality of hydrogen electrolyzers.

15. The hydrogen plant of claim 14, wherein a temperature difference between a temperature of coolant water heated by the heat produced as the byproduct in the at least one electrolyzer and a temperature required for thermal desalination in the corresponding desalination unit is within a predetermined temperature range.

16. The hydrogen plant of any one of claims 14-15, wherein the amount of the distilled water produced by each of the plurality of desalination units is greater than the amount of water required for an electrolysis process in the corresponding hydrogen electrolyzer.

17. A method for controlling operation of the hydrogen plant according to any of claims 7-16, comprising: controlling electrical energy consumption of the at least one electrolyzer and the at least one desalination unit by adjusting at least one of:- electrical power supplied to the at least one hydrogen electrolyzer to produce the hydrogen and the heat;- flowrate of the at least part of the distilled water to the at least one hydrogen electrolyzer from the at least one desalination unit; and- heat transferred from the at least one hydrogen electrolyzer to the at least one desalination unit.

18. The method of claim 17, further comprising: controlling the thermal energy transferred to the at least one desalination unit.

19. The method of claim 18, wherein controlling the thermal energy transferred to the at least one desalination unit comprises at least one of:- controlling the heat produced by at least one hydrogen electrolyzer;- controlling the heat provided to the at least one desalination unit by controlling a temperature of the coolant water fed into the at least one desalination unit to transfer heat for the thermal desalination process with a heat pump or a heat exchanger connected to the coolant water from the at least one electrolyzer unit; and- controlling a temperature of coolant water heated by the heat produced in the at least one electrolyzer and fed as a part of input to the at least one desalination unit.

20. The method of claim 17, further comprising: predicting electrical energy consumption of the hydrogen plant for providing a predetermined hydrogen production or a predetermined distilled water production; and minimizing the predicted electrical energy consumption by the adjusting of at least one of the electrical power, the flowrate and the heat.

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