Dynamic control method for synthesis of marine floating green hydrogen derived fuel

Abstract

The invention discloses an offshore floating type green hydrogen derived fuel synthesis dynamic control method. The method comprises the following steps: calculating a green hydrogen fluctuation amplitude range of delta nH2, min-delta nH2 and max according to time-varying data of green electricity or meteorological prediction data in combination with a wind field fan output and wind speed curve, and adjusting the opening degree of a hydrogen storage tank to enable the green hydrogen fluctuation real-time amplitude to be delta nH2 and delta nH2, min < delta nH2 < delta nH2, max; when the green hydrogen fluctuation real-time amplitude delta nH2 meets a judgment condition (formula 1), a control method of a fixed feed gas ratio is adopted, and if the green hydrogen fluctuation real-time amplitude delta nH2 does not meet the judgment condition, a control method of an average feed gas ratio is adopted:-delta nCM, lim + delta nCM, act < delta nH2 < delta nCM, lim + delta nCM and act (1) (in the formula 1), the value range of delta nCM and lim is 0%-100%, and delta nCM and act represent the feeding fluctuation amplitude of other components except green hydrogen. By adopting the control method provided by the invention, the hydrogen conversion rate is obviously improved.

Description

Technical Field

[0001] The present invention relates to the field of offshore energy development, and in particular to a dynamic control method for offshore floating green hydrogen derivative fuel synthesis. Background Art

[0002] The hydrogen for offshore green hydrogen-derived fuel synthesis systems is derived from the electrolysis of offshore green electricity. Therefore, fluctuations in the gas supply are influenced by the characteristics of offshore green electricity output, as well as weather and climate. In the short term, daily gas supply troughs are deep, and hourly gas supply fluctuations can reach half. In the long term, gas supply is seasonal, with average monthly output fluctuating dramatically from year to year. Unstable offshore gas supply can lead to uncontrolled reactor operating temperatures, uncontrolled circulating gas flow rates, reduced yields and hydrogen conversion rates, and even, in severe cases, compressor failure, necessitating system shutdown.

[0003] A literature search of prior art revealed an invention patent, CN113135815A, titled "Control Method and Device for Methanol Synthesis." This patent, which detects components at the reactor inlet and outlet, controls the internal composition of the reactor, improving methanol detection rates. This method primarily targets reactor control and excludes modules such as condensation, purification, and circulating compression. Dynamic fluctuations in a methanol synthesis system occur simultaneously across all modules, each of which influences the other. Therefore, this method is not suitable for dynamic control and performance adjustment of the entire process flow.

[0004] A literature search of prior art revealed an invention patent application with patent number CN117666500A, entitled "Methanol Synthesis System Method, Apparatus, Computer Equipment, and Storage Medium." This patent effectively controls a methanol synthesis system by constructing a DCS process model. This method is designed based on an onshore methanol synthesis system. From a control system perspective, the patent's control system primarily includes early warning and alarm control, equipment liquid level and flow control, and reactor pressure and temperature control. Equipment liquid level and flow control, a conventional onshore methanol control solution, is not suitable for offshore methanol synthesis systems that do not utilize distillation equipment. Reactor pressure and temperature control primarily considers parameter variations in the distillation and reactor equipment, not the operating conditions of the compressor. Furthermore, conventional onshore methanol synthesis control systems employ a one-to-one strategy for equipment control, while the compressor is located in the compression recovery unit, requiring the interaction of multiple units and monitored parameters to maintain stability. Furthermore, due to the significant fluctuations in the offshore hydrogen source, the compressor cannot maintain stability, making the traditional strategy of setting the compressor flow rate as a monitored variable unsuitable for control.

[0005] A literature search of the prior art revealed an invention patent application with patent number CN116451408A, titled “Multi-period Dispatchable Domain Analysis Method for Wind-Solar Hydrogen Production and Methanol Synthesis System”. The application proposed an analysis method that can intuitively quantify the load regulation potential of the P2M system under the uncertainty conditions of wind and solar power generation, providing a quantitative reference for the safe and economic operation of the wind and solar hydrogen production and methanol synthesis system as a flexible load when participating in the absorption of wind and solar power generation and grid balance regulation. The method mainly evaluates the fluctuation of green hydrogen under unstable load conditions to determine whether the current operating conditions meet the operating conditions of the methanol synthesis system, thereby reducing the start-up and shutdown frequency of the chemical plant. However, the method cannot guarantee the production capacity and yield of the system, nor does it fundamentally improve the methanol synthesis system's ability to resist fluctuations.

[0006] In summary, onshore synthesis control schemes cannot be directly applied to offshore green hydrogen derivative fuel synthesis systems. Furthermore, the control schemes are complex in logic and difficult to install and deploy offshore. Therefore, the control methods for offshore floating green hydrogen derivative fuel synthesis systems need to be improved. This invention introduces a dynamic control strategy that selects different feed control methods based on different forecast conditions. This allows the offshore floating green hydrogen derivative fuel synthesis system to withstand unstable fluctuations in wind power output, improving the system's adaptability to operating conditions and hydrogen conversion efficiency. Summary of the Invention

[0007] Considering the unstable supply of offshore green electricity and the sharp fluctuations in hydrogen gas sources, conventional onshore green hydrogen-derived fuel synthesis control methods cannot be applied to offshore conditions, and special control of the raw gas ratio is required.

[0008] The present invention provides a dynamic control method for offshore floating green hydrogen derivative fuel synthesis, which comprises:

[0009] According to the green electricity change data or meteorological forecast data, combined with the wind farm wind turbine output and wind speed curve, the green hydrogen fluctuation range is calculated as: Δn H2，min ~Δn H2，max By adjusting the opening of the hydrogen storage tank, the real-time amplitude of green hydrogen fluctuation is Δn H2 , and Δn H2，min <Δn H2 <Δn H2，max ;

[0010] When the green hydrogen fluctuates in real time by an amplitude Δn H2 When the judgment condition (Formula 1) is met, the fixed raw gas ratio control method is adopted; if it is not met, the average raw gas ratio control method is adopted:

[0011] -Δn CM,lim +Δn CM,act <Δn H2 <Δn CM,lim+Δn CM,act (1)

[0012] In (Equation 1), Δn CM，lim The value range is 0%-100%, Δn CM，act Indicates the fluctuation range of feed of other components except green hydrogen.

[0013] Where Δn CM，lim Select a value based on actual equipment and system characteristics, for example, 20%.

[0014] In the present invention, based on the green electricity change data or meteorological forecast data, combined with the wind farm wind turbine output and wind speed curve, the green hydrogen fluctuation range is calculated as: Δn H2，min ~Δn H2，max , the calculation method is conventional in this field.

[0015] In the present invention, preferably, when a control method with a fixed raw gas ratio is adopted, the fluctuation range of the supply of other components except green hydrogen and green hydrogen is 1:1.

[0016] In the present invention, preferably, when the average raw gas ratio control method is adopted, the fluctuation range of the feed of other components except green hydrogen within a certain period of time is controlled, and Δn CM，act Based on the original value, a correction is added to the calculation method such as (Formula 2).

[0017]

[0018] In a preferred embodiment of the present invention, the green hydrogen supply fluctuation range is Δn H2，min ~Δn H2，max -6% to -4%, take Δn H2 The tolerance of the methanol synthesis system to the change rate of carbon dioxide feed is -5%, Δn CM，lim Less than 20%, Δn CM，act The initial correction is 0, that is, the real-time amplitude of green hydrogen fluctuation Δn H2 When the judgment condition (Formula 1) is met and a control method with a fixed raw gas ratio is adopted, the fluctuation range of carbon dioxide and hydrogen is 1:1.

[0019] In another preferred embodiment of the present invention, the green hydrogen supply fluctuation range starts at Δn H2，min ~Δn H2，max -60% to -40%, after which the green hydrogen fluctuation range is Δn H2，min ~Δn H2，max =-10%~10%, start taking Δn H2 The tolerance of the methanol synthesis system to the change rate of carbon dioxide feed is -50%, Δn CM，lim is 20%, ΔnCM，act The initial correction is 0, that is, the real-time amplitude of green hydrogen fluctuation Δn H2 When the judgment condition (Formula 1) is not met, the average raw gas ratio control method is adopted, that is, the average carbon dioxide and hydrogen fluctuation range is 1:1.

[0020] To complement the feed control method, hydrogen storage tanks are needed to improve the predictability of green hydrogen supply. By implementing control over the hydrogen tanks, the pressure and the regulating valve opening of the hydrogen tanks are increased when the power supply is sufficient, and the pressure and the regulating valve opening are reduced when the power supply is insufficient. This reduces fluctuations in the green hydrogen supply and makes the green hydrogen supply more predictable.

[0021] In the present invention, the method for dynamic control of offshore floating green hydrogen derivative fuel synthesis further includes:

[0022] When the green hydrogen supply fluctuation range Δn cannot be predicted H2，min ~Δn H2，max When the real-time amplitude of the green hydrogen fluctuation is greater than the minimum load of the synthesis system, the shutdown process is entered; when the real-time amplitude of the green hydrogen fluctuation is less than the minimum load of the synthesis system, a feed control method with a fixed raw gas ratio is adopted.

[0023] In another preferred embodiment of the present invention, due to data transmission problems, it is impossible to obtain meteorological data forecasts, that is, it is impossible to obtain the green hydrogen supply fluctuation range Δn H2，min ~Δn H2，max According to real-time feed monitoring, the green hydrogen fluctuation real-time amplitude Δn H2 =60%, due to the real-time amplitude of green hydrogen fluctuation Δn H2 If the load is greater than 50% of the minimum load of the methanol synthesis system, the system will enter the shutdown process.

[0024] In the present invention, under the condition of unstable hydrogen source, in order to meet the demand for high hydrogen conversion rate, the raw gas ratio should be controlled to an optimal value.

[0025] In the present invention, under the condition of unstable hydrogen source, in order to meet the demand for high hydrogen conversion rate, the average raw material gas ratio within a period of time should be controlled to be the optimal value for the synthesis system.

[0026] In the present invention, preferably, when the real-time amplitude of green hydrogen fluctuation is different from the green hydrogen supply fluctuation amplitude range, feedback correction is performed on the existing control scheme based on existing data.

[0027] In order to cooperate with the feed control method, it is necessary to improve the operational flexibility of the offshore floating green hydrogen derivative fuel synthesis process through an overall dynamic control system for green hydrogen derivative fuel synthesis. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a flow chart of a dynamic control method for offshore floating green hydrogen derivative fuel synthesis in one embodiment of the present invention; DETAILED DESCRIPTION

[0029] The following describes several preferred embodiments of the present invention with reference to the accompanying drawings to make its technical content clearer and easier to understand. The present invention can be embodied in many different forms of embodiments, and the scope of protection of the present invention is not limited to the embodiments mentioned herein.

[0030] Example 1

[0031] Offshore floating methanol is a typical example of an offshore green hydrogen-derived fuel synthesis process flow, with the synthesis unit being able to withstand a load range of 50%-100%.

[0032] according to Figure 1 Dynamic control method to implement control

[0033] In this embodiment, the tolerance of the methanol synthesis system to the change rate of carbon dioxide feed is Δn CM，lim Less than 20%.

[0034] In this embodiment, the methanol synthesis system has a stable hydrogen supply in the past few hours, and the green hydrogen supply fluctuation is small. Therefore, there is no preset control change in the carbon dioxide feed in the next 8 hours, that is, Δn CM，act The initial correction is 0. Therefore, when the hydrogen change rate per hour is less than Δn CM，lim =20%, a fixed raw gas ratio control method will be used to keep the other components in the raw gas consistent with the fluctuation range of green hydrogen supply, that is, the fluctuation range of carbon dioxide and hydrogen is 1:1.

[0035] In this embodiment, hydrogen is produced entirely by electricity provided by offshore wind power. According to meteorological data forecasts, the wind speed will gradually drop to 8.15-8.90 m / s in the next 10 hours, which is 10 m / s lower than the rated wind speed. Therefore, the hydrogen production will gradually decrease in the next 10 hours. It is necessary to control the system according to the hydrogen production situation to ensure stable operation of the system.

[0036] According to the data of green electricity changing over time, the fluctuation range of green hydrogen production per hour in the future is calculated as Δn according to the conventional method in this field. H2，min ~Δn H2，max The hydrogen feed rate is -6% to -4%, so the hydrogen tank regulating valve is adjusted to change the hydrogen feed rate by Δn per hour in the next 10 hours. H2 The hydrogen feed rate is -5%, and after 10 hours the hydrogen feed rate is reduced to 50%, thereby avoiding the problem of excessively rapid changes in the feed rate due to insufficient hydrogen production.

[0037] In this embodiment, the hydrogen gas change rate per hour is less than ΔnCM，lim = 20%, the control strategy automatically selects the feed control strategy with fixed raw gas ratio, so that the carbon dioxide is Δn in 10 hours. CM，act Adding a -5% correction can increase the hydrogen conversion rate by 55.73%.

[0038] Example 2:

[0039] according to Figure 1 Dynamic control methods implement control.

[0040] Different from Example 1, according to meteorological data, the wind speed is predicted to drop from the rated wind speed to 8.15-8.90 m / s in the next hour and remain in this range for the next 10 hours. According to the predicted green electricity change data over time, the green hydrogen fluctuation range in the next hour is calculated as Δn according to the conventional calculation method in this field. H2，min ~Δn H2，max =-60%~-40%, after which the green hydrogen fluctuation range is Δn H2，min ~Δn H2，max =-10%~10%.

[0041] Different from Example 1, the remaining reserve of the hydrogen storage tank only supports methanol production at rated load for 1 hour.

[0042] Different from Example 1, the problem of insufficient hydrogen production cannot be addressed by slightly fluctuating the hydrogen feed, so the hydrogen feed amount needs to be significantly reduced.

[0043] The difference from Example 1 is that the hydrogen feed load is adjusted to Δn in the next hour by adjusting the regulating valve of the hydrogen storage tank. H2 is -50%.

[0044] The difference from Example 1 is that the hydrogen feed load fluctuation exceeds the limit value Δn CM，lim =20%, so the average raw gas control method is selected, that is, the average carbon dioxide and hydrogen fluctuation range is 1:1.

[0045] The difference from Example 1 is that the carbon dioxide Δn CM，act The added correction was reduced at a constant rate from 0 to -85%, and then changed at a constant rate to -50% after 1.8 hours, which increased the carbon dioxide conversion rate by 50.85%.

[0046] Example 3:

[0047] according to Figure 1 Dynamic control methods implement control.

[0048] Different from Example 1, due to data transmission problems, it is impossible to obtain meteorological data forecasts.

[0049] Different from Example 1, according to real-time feed monitoring, the real-time amplitude of green hydrogen supply fluctuation per hour is Δn H2 =60%.

[0050] The difference from Example 1 is that the real-time amplitude Δn of green hydrogen supply fluctuation per hour is H2 It is greater than 50% of the minimum load of the methanol synthesis system, so it is necessary to enter the shutdown process to avoid irreversible damage to the equipment and catalyst due to drastic changes in feed load.

[0051] The preferred embodiments of the present invention have been described in detail above. It should be understood that numerous modifications and variations based on the concepts of the present invention are possible without inventive effort by those skilled in the art. Therefore, any technical solution that can be derived by one skilled in the art through logical analysis, reasoning, or limited experimentation based on the concepts of the present invention and the prior art should be within the scope of protection defined by the claims.

Claims

1. A dynamic control method for offshore floating green hydrogen derivative fuel synthesis, characterized in that: It includes: According to the green electricity change data or meteorological forecast data, combined with the wind farm wind turbine output and wind speed curve, the green hydrogen fluctuation range is calculated as: Δn H2，min ~Δn H2，max By adjusting the opening of the hydrogen storage tank, the real-time amplitude of green hydrogen fluctuation is Δn H2 , and Δn H2，min <Δn H2 <Δn H2，max ; When the green hydrogen fluctuates in real time by an amplitude Δn H2 When the judgment condition (Formula 1) is met, the fixed raw gas ratio control method is adopted; if it is not met, the average raw gas ratio control method is adopted: -Δn CM，lim +Δn CM，act <Δn H2 <Δn CM，lim +Δn CM，act (1) In (Equation 1), Δn CM，lim The value range is 0%-100%, Δn CM，act Indicates the fluctuation range of feed of other components except green hydrogen.

2. The method for dynamic control of offshore floating green hydrogen derivative fuel synthesis according to claim 1, characterized in that: When a control method with a fixed raw gas ratio is adopted, the real-time fluctuation amplitude of the other components except green hydrogen and the green hydrogen is 1:

1.

3. The dynamic control method for offshore floating green hydrogen derivative fuel synthesis according to claim 1, characterized in that: When the average raw gas ratio control method is adopted, the fluctuation range of the feed of other components except green hydrogen within a certain period of time is controlled, and Δn CM，act Add the calculation method as shown in (Formula 2) based on the original value:

4. The method for dynamic control of offshore floating green hydrogen derivative fuel synthesis according to claim 1, characterized in that: The green hydrogen supply fluctuation range is Δn H2，min ~Δn H2，max -6% to -4%, take Δn H2 The tolerance of the methanol synthesis system to the change rate of carbon dioxide feed is -5%, Δn CM，lim Less than 20%, Δn CM，act The initial correction is 0, that is, the real-time amplitude of green hydrogen fluctuation Δn H2 When the judgment condition (Formula 1) is met and a control method with a fixed raw gas ratio is adopted, the fluctuation range of carbon dioxide and hydrogen is 1:

1.

5. The method for dynamic control of offshore floating green hydrogen derivative fuel synthesis according to claim 1, characterized in that: The green hydrogen supply fluctuation range starts at Δn H2，min ~Δn H2，max -60% to -40%, after which the green hydrogen fluctuation range is Δn H2，min ~Δn H2，max =-10%~10%, start taking Δn H2 The tolerance of the methanol synthesis system to the change rate of carbon dioxide feed is -50%, Δn CM，lim is 20%, Δn CM，act The initial correction is 0, that is, the real-time amplitude of green hydrogen fluctuation Δn H2 When the judgment condition (Formula 1) is not met, the average raw gas ratio control method is adopted, that is, the average carbon dioxide and hydrogen fluctuation range is 1:

1.

6. The method for dynamic control of offshore floating green hydrogen derivative fuel synthesis according to claim 1, characterized in that: Also includes: When the green hydrogen supply fluctuation range Δn cannot be predicted H2，min ~Δn H2，max When the real-time amplitude of the green hydrogen fluctuation is greater than the minimum load of the synthesis system, the shutdown process is entered; when the real-time amplitude of the green hydrogen fluctuation is less than the minimum load of the synthesis system, a feed control method with a fixed raw gas ratio is adopted.

7. The method for dynamic control of offshore floating green hydrogen derivative fuel synthesis according to claim 1, characterized in that: Due to data transmission problems, it is impossible to obtain meteorological data forecasts, that is, it is impossible to obtain the green hydrogen supply fluctuation range Δn H2，min ~Δn H2，max According to real-time feed monitoring, the green hydrogen fluctuation real-time amplitude Δn H2 =60%, due to the real-time amplitude of green hydrogen fluctuation Δn H2 If the load is greater than 50% of the minimum load of the methanol synthesis system, the system will enter the shutdown process.

8. The method for dynamic control of offshore floating green hydrogen derivative fuel synthesis according to claim 4, 5 or 7, characterized in that: Δn CM，lim The value is 20%.

9. The method for dynamic control of offshore floating green hydrogen derivative fuel synthesis according to claim 4, 5 or 7, characterized in that: Δn CM，act The initial correction is 0.

10. The method for dynamic control of offshore floating green hydrogen derivative fuel synthesis according to claim 5, characterized in that: Δn CM，act The initial correction is 0, and the CO2 Δn in the next 4.27 hours CM，act The added correction decreases at a constant rate from 0 to -85%, and then changes to a constant rate of -50% after 1.8 hours.

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