A method and system for calculating control parameters of hydrogen and natural gas mixed transmission and separation process

Abstract

The present invention provides a method and system for calculating control parameters of a hydrogen and natural gas mixed transportation and separation process. The hydrogen and natural gas mixed transportation and separation process control process involves four types of equipment: an expander, a separation system, a methane compressor, and a hydrogen compressor. The control parameter calculation method specifically includes: step 1, calculating the total flow rate of raw materials based on the linear relationship between the production capacity load and the feed flow rate, and then obtaining the daily and hourly consumption of raw materials; step 2, respectively calculating the control parameters of the expander, separation system, methane compressor, and hydrogen compressor. The control parameters of each device include flow rate, pressure, temperature, and outlet gas composition; step 3, generating the control parameter calculation results. The present invention is only applicable to the specific process of hydrogen and natural gas mixed transportation and separation based on pressure energy recovery, and has universal applicability to various production capacity loads within the applicable range of production capacity load; the calculation results of large and complex theoretical knowledge are summarized into simple functional relationships to reduce dependence on theoretical knowledge.

Description

Technical Field

[0001] The present invention belongs to the technical field of process simulation calculation, and in particular relates to a method and system for calculating control parameters of a hydrogen and natural gas mixed transportation and separation process. Background Art

[0002] Before the current hydrogen and natural gas mixed transmission and separation process based on pressure energy recovery is put into operation, it is often necessary to calculate the process parameters under the corresponding capacity load according to different production capacities. In the corresponding technology, process simulation software is used to calculate and feedback to the operating conditions and customers, which has the following problems:

[0003] The mainstream process calculation tools are mainly process flow simulation software. This type of simulation software is based on a huge database and a collection of various interdisciplinary theoretical knowledge. It is more suitable for complex process control processes. However, for simple process control processes, the calculation of the entire process parameters still requires the modification of complex parameter data. Calculation errors are very likely to occur and difficult to adjust. It is a very complicated task for professional process simulation personnel, and it is extremely difficult for ordinary process personnel to operate this type of software, resulting in the inability to feedback correct results in a timely manner and delays in construction.

[0004] For example, the commonly used AspenPlus (product of Aspen Technology Co., Ltd.) software, because its principle involves a huge database and theoretical knowledge, its calculation process is briefly described as follows: input the substance → determine the physical property calculation method → ​​build a process flow model → input parameters → run the calculation → judge the result → adjust errors / adjust parameters → draw conclusions. It can be seen that Aspenplus is developed based on universal process calculations and scientific research purposes. Due to its universality requirements, its calculation process also has open parameter inputs, and calculations can be performed if the calculation requirements are met. Whether the results are correct or not requires judgment by professionals with rich theoretical knowledge and sufficient simulation calculation experience. The calculation of Aspenplus involves deeper theoretical knowledge and more complex software operations. This type of calculation software undoubtedly places dual requirements on software operation and personnel expertise, which invisibly sets up a larger obstacle for a simple process. Summary of the Invention

[0005] In response to the problems and defects of the existing technology, the present invention provides a method and system for calculating control parameters of the hydrogen and natural gas mixed transportation and separation process. The technical solution of the present invention is:

[0006] In the first aspect, the present invention provides a method for calculating control parameters of a hydrogen and natural gas mixed transportation and separation process. The control process of the hydrogen and natural gas mixed transportation and separation process involves four devices: an expander, a separation system, a methane compressor, and a hydrogen compressor. The control parameter calculation method specifically includes:

[0007] Step 1: Calculate the total raw material flow rate based on the linear relationship between production capacity load and feed flow rate, and then obtain the daily and hourly raw material consumption;

[0008] Step 2: Calculate the control parameters of the expander, separation system, methane compressor, and hydrogen compressor based on the total raw material flow rate obtained in step 1. The control parameters of each device include flow rate, pressure, temperature, and outlet gas composition.

[0009] Step 3: Generate control parameter calculation results based on the daily and hourly raw material consumption obtained in step 1 and the flow, pressure, temperature and outlet gas composition of the four devices obtained in step 2.

[0010] Furthermore, the expression of the relationship curve between the production capacity load m and the total raw material flow Q1 is:

[0011] Q1=a1m+b1, where m∈capacity load applicable interval, a1 and b1 are fitting coefficients.

[0012] Furthermore, in step 2, the hydrogen and natural gas mixed transmission and separation process control process is divided into equipment steady-state operation conditions, equipment startup phase conditions, and equipment shutdown phase conditions. The calculation process of the control parameters of the expander, separation system, methane compressor, and hydrogen compressor includes:

[0013] (1) Calculate the control parameters of each device under steady-state operation conditions:

[0014] (1-1) Establish the functional relationship between expander power and feed, the functional relationship between expander outlet flow and feed flow, and the functional relationship between expander outlet temperature and expander inlet and outlet pressure difference, which are:

[0015] P1=a2×Q1, Q2=a3×Q1, T1=a4×(p2-p1) 3 +a5×(p2-p1) 2 +a6×(p2-p1)+a7, where P1 is the expander shaft power, Q2 is the expander exhaust flow rate, T1 is the expander outlet temperature, p1 and p2 are the expander inlet and outlet pressures respectively, a2, a3, a4, a5, a6, and a7 are fitting coefficients. Based on the above relationship, the expander power, outlet temperature, and outlet flow rate can be calculated according to the feed flow rate and pressure difference. The outlet gas composition of the expander is the same as the raw material composition;

[0016] (1-2) Establish the functional relationship between the inlet and outlet flow of the separation system and the raw material flow, where the inlet flow of the separation system is Q3 = a8 × Q1, the outlet flow of the rich gas is Q4 = a9 × Q1, and the outlet flow of the lean gas is Q5 = a 10 ×Q1, in the above relationship: a8, a9, a 10is the fitting coefficient; the intake temperature of the separation system T2≈rich gas temperature≈lean gas temperature; the intake pressure of the separation system p3=p2, the lean gas pressure p4=a 11 ×p3, rich gas pressure p5=a 12 ×p3, where a 11 、a 12 is the fitting coefficient; the inlet gas composition of the separation system is the same as the raw material composition, and the outlet gas composition is: the methane percentage content F of the rich gas 1CH4 =F CH4 ×Q1×a 13 / Q4, hydrogen percentage of rich gas F 1H2 =F H2 ×Q1×a 14 / Q4, methane content of lean gas F 2CH4 =F CH4 ×Q1×a 15 / Q5, hydrogen percentage of rich gas F 2H2 =F H2 ×Q1×a 16 / Q5, in the above relationship: F CH4 is the percentage of raw material methane, F H2 is the percentage of hydrogen in the raw material, a 13 、a 14 、a 15 、a 16 is the fitting coefficient;

[0017] (1-3) The inlet flow rate of the methane compressor Q6 = Q5, and the outlet flow rate of the methane compressor Q7 = a 17 ×Q6, methane compressor outlet temperature T3=a 18 ×p1 2 +a 19 ×p1+a 20 , methane compressor outlet pressure p6=a 21 ×p1 2 +a 22 ×p1+a 23 , methane compressor shaft power P2 = a 24 ×Q1, in the above relationship, a 17 、a 18 、a 19 、a 20 、a 21 、a 22 、a 23 、a 24 is the fitting coefficient;

[0018] (1-4) Hydrogen compressor inlet flow rate Q8 = Q4, hydrogen compressor outlet flow rate Q9 = a 25×Q8, hydrogen compressor outlet pressure p7 = p6, hydrogen compressor outlet temperature (adiabatic compression) T4 = a 26 ×(p7-p5) 3 +a 27 ×(p7-p5) 2 +a 28 ×(p7-p5)+a 29 In the above relationship, a 25 、a 26 、a 27 、a 28 、a 29 is the fitting coefficient;

[0019] (2) Calculate the control parameters of the methane compressor and expander during the equipment startup phase:

[0020] (2-1) Methane compressor intake flow Q 10 =b1×Q5, methane compressor outlet flow Q 11 =b2×e (b 3 ×P 2 ) , methane compressor outlet temperature T3=b4×P2+b5, methane compressor outlet pressure p8=

[0021] b6×e (b 7 ×P 2 ) , where b1, b2, b3, b4, b5, b6, and b7 are fitting coefficients, and the gas composition of the methane compressor is the same as that of the feed gas;

[0022] (2-2) Establish the functional relationship between the expander inlet flow rate, outlet flow rate, outlet temperature and expander power, which are: Q 12 =b8×e (b 9 ×P 1 ) , Q 13 =b 10 ×P1 2 +b 11 ×P1+b 12 , T4=b 13 ×P1+b 14 , where Q 12 is the expander intake flow rate, Q 13 is the expander outlet gas flow rate, T4 is the expander outlet gas temperature, b8, b9, b 10 、b 11 、b 12 、b 13 、b 14 is the fitting coefficient;

[0023] (3) Calculate the control parameters of the equipment during shutdown: The calculation of the instantaneous control parameters of the expander, methane compressor, and hydrogen compressor is the same as that during steady-state operation. Subsequently, the methane compressor, expander, and hydrogen compressor stop running in sequence.

[0024] In a second aspect, the present invention provides a system for calculating control parameters of a hydrogen and natural gas mixed transmission and separation process, comprising:

[0025] The parameter input module is used to input the relevant calculation parameters of the hydrogen and natural gas mixed transmission and separation process, and provide calculation parameters for the calculation black box module;

[0026] Calculation black box module, used for automatic calculation of control parameters of hydrogen and natural gas mixed transmission and separation process;

[0027] The result display module displays the final calculation results.

[0028] Furthermore, the calculation parameters include: daily hydrogen production capacity, temperature, pressure, and component composition of the expander inlet gas, outlet pressure of the expander, temperature of the inlet and outlet gas of the separation system, and outlet pressure of the separation system.

[0029] The beneficial effects of the present invention are:

[0030] 1. The present invention is applicable only to the specific process of hydrogen and natural gas mixed transportation and separation based on pressure energy recovery, and is universally applicable to various production capacity loads within the applicable capacity load range; it summarizes the huge and complex theoretical knowledge calculation results into a simple functional relationship, reducing dependence on theoretical knowledge;

[0031] 2. The present invention performs correlation calculations through the functional relationship between the parameters of various equipment within the process, reducing the need for parameter input; and because the functional relationship has been summarized for the parameter correlation of a specific process, there will not be a large number of calculation errors that are difficult to adjust, so the calculation results are intuitive, accurate and fast. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 The present invention provides a flow chart of the method for calculating control parameters of the hydrogen and natural gas mixed transportation and separation process.

[0033] Figure 2 This is a structural framework diagram of the hydrogen and natural gas mixed transmission and separation process control parameter calculation system of the present invention. DETAILED DESCRIPTION

[0034] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, which are intended to explain the present invention rather than to limit it.

[0035] The process of hydrogen and natural gas mixed transportation and separation is as follows:

[0036] (1) The hydrogen-blended natural gas in the natural gas mixed transmission pipeline enters the expander through the buffer tank, and is depressurized by the expander to form low-pressure hydrogen-blended natural gas;

[0037] (2) The low-pressure hydrogen-blended natural gas is passed into a separation device, and the gas is separated into lean gas (low hydrogen content natural gas) and rich gas (high concentration hydrogen) through separation means such as membrane separation or pressure swing adsorption;

[0038] (3) The separated lean gas is compressed in a natural gas compressor to become high-pressure lean gas, while the rich gas is introduced into a hydrogen compressor to increase the pressure to obtain high-pressure rich gas.

[0039] The calculation process of the present invention first calculates the process parameters under different operating conditions based on the process capacity and the physical properties of the materials, such as the physical properties of the gas in each section under different capacity conditions. The key point is that each point corresponds to a working condition. These points are then matched, and each point corresponds to a working condition, which is an overall data connected by the process. Next, these data points are fitted, such as the volume flow rate of each section corresponding to different capacity. The difference in volume flow rate is due to the different operating conditions of the section, but its origin corresponds to the input capacity conditions. Then, the feed flow rate can be used as the horizontal coordinate and the volume flow rate of each section as the vertical coordinate to obtain the curve relationship between the volume flow rate of each section and the feed flow rate.

[0040] Based on the above calculation process, it's important to note the underlying knowledge, which provides a theoretical basis for this approach. For hydrogen and natural gas mixed transmission, since it's a mixture, the first step is to calculate the mixture's virtual characteristic parameters, such as the virtual critical parameter and the second virial coefficient Bm, based on the p-V relationship for real gases in chemical thermodynamics. These parameters are then substituted into the equation of state for the virtual pure substance. Alternatively, the generalized compressibility factor method can be used. The compression process involved in the process is actually polytropic compression, but the compression time is relatively short, making it an adiabatic compression process. Using the formulas for polytropic and adiabatic compression processes, the compressor power consumption under different operating conditions can be calculated, providing a reference for compressor selection. Fitting the obtained power consumption to the feed flow rate yields a relationship curve.

[0041] The expansion process of gas is an adiabatic expansion. When the gas expands and does work externally, the temperature of the expanded gas always drops. According to the integral isentropic expansion effect formula and the Ts diagram, the parameters such as the gas temperature after expansion can be obtained, which can be used as the basis for selecting the expander.

[0042] The above calculation process (excluding the data fitting process) also involves querying some parameters, such as graphs of data such as compression factor. Since the calculation process of these process parameters is a universal calculation process based on professional theoretical knowledge such as chemical thermodynamics, it is a universal calculation method and essential theoretical knowledge for engineers in this field. It is the same for all similar chemical processes and does not constitute the core requirements of this invention. Therefore, a detailed calculation description is not provided.

[0043] According to the control process of hydrogen and natural gas mixed transportation and separation process involving four equipments: expander, separation system, methane compressor and hydrogen compressor, the method for calculating the control parameters of hydrogen and natural gas mixed transportation and separation process of the present invention specifically includes:

[0044] Step 1: Calculate the total raw material flow rate based on the linear relationship between the capacity load and the feed flow rate, and then obtain the daily and hourly raw material consumption; the expression of the relationship curve between the capacity load m and the total raw material flow rate Q1 is: Q1=a1m+b1, where m∈capacity load applicable interval, a1 and b1 are fitting coefficients.

[0045] Step 2: Based on the total raw material flow obtained in step 1, the control parameters of the expander, separation system, methane compressor, and hydrogen compressor are calculated respectively. The control parameters of each device include flow, pressure, temperature, and outlet gas composition. Specifically, the hydrogen and natural gas mixed transmission and separation process control process is divided into equipment steady-state operation conditions, equipment startup phase conditions, and equipment shutdown phase conditions. The calculation process of the control parameters of the expander, separation system, methane compressor, and hydrogen compressor includes:

[0046] (1) Calculate the control parameters of each device under steady-state operation conditions:

[0047] (1-1) During steady-state operation, the raw material first enters the expander for pressure relief. The functional relationships between the expander power and the feed, the expander outlet flow rate and the feed flow rate, and the expander outlet temperature and the expander inlet and outlet pressure difference are established, which are: P1 = a2 × Q1, Q2 = a3 × Q1, T1 = a4 × (p2 - p1) 3 +a5×(p2-p1) 2 +a6×(p2-p1)+a7, where P1 is the expander shaft power, Q2 is the expander exhaust flow rate, T1 is the expander outlet temperature, p1 and p2 are the expander inlet and outlet pressures respectively, a2, a3, a4, a5, a6, and a7 are fitting coefficients. According to the above relationship, the expander power, outlet temperature, and outlet flow rate can be calculated according to the feed flow rate and pressure difference. The outlet composition of the expander is the same as the raw material composition, that is, the expander does not change the material composition.

[0048] (1-2) Establish the functional relationship between the inlet and outlet flow of the separation system and the raw material flow, where the inlet flow of the separation system is Q3 = a8 × Q1, the outlet flow of the rich gas is Q4 = a9 × Q1, and the outlet flow of the lean gas is Q5 = a 10 ×Q1, in the above relationship: a8, a9, a 10 is the fitting coefficient; the intake temperature of the separation system T2≈rich gas temperature≈lean gas temperature; the intake pressure of the separation system p3=p2, the lean gas pressure p4=a 11 ×p3, rich gas pressure p5=a 12 ×p3, where a 11 、a 12 is the fitting coefficient; the inlet gas composition of the separation system is the same as the raw material composition, and the outlet gas composition is: the methane percentage content F of the rich gas 1CH4 =F CH4 ×Q1×a 13 / Q4, hydrogen percentage of rich gas F 1H2 =F H2 ×Q1×a 14 / Q4, methane content of lean gas F 2CH4 =F CH4 ×Q1×a 15 / Q5, hydrogen percentage of rich gas F 2H2 =F H2 ×Q1×a 16 / Q5, in the above relationship: F CH4 is the percentage of raw material methane, F H2 is the percentage of hydrogen in the raw material, a 13 、a 14 、a 15 、a 16 is the fitting coefficient.

[0049] (1-3) The inlet flow rate of the methane compressor Q6 = Q5, and the outlet flow rate of the methane compressor Q7 = a 17 ×Q6, methane compressor outlet temperature T3=a 18 ×p1 2 +a 19 ×p1+a 20 , methane compressor outlet pressure p6=a 21 ×p1 2 +a 22 ×p1+a 23 , methane compressor shaft power P2 = a 24 ×Q1, in the above relationship, a 17 、a 18 、a 19 、a 20 、a 21 、a 22 、a 23、a 24 is the fitting coefficient.

[0050] (1-4) Hydrogen compressor inlet flow rate Q8 = Q4, hydrogen compressor outlet flow rate Q9 = a 25 ×Q8, hydrogen compressor outlet pressure p7 = p6, hydrogen compressor outlet temperature (adiabatic compression) T4 = a 26 ×(p7-p5) 3 +a 27 ×(p7-p5) 2 +a 28 ×(p7-p5)+a 29 In the above relationship, a 25 、a 26 、a 27 、a 28 、a 29 is the fitting coefficient. Both the hydrogen compressor and the methane compressor do not change the composition of the inlet and outlet gases (no phase change).

[0051] (2) Calculate the control parameters of the methane compressor and expander during the equipment startup phase:

[0052] (2-1) The raw materials first enter the methane compressor. At this time, the methane compressor is driven by a motor. The methane compressor intake flow rate Q 10 =b1×Q5, methane compressor outlet flow Q 11 =b2×e (b 3 ×P 2 ) , methane compressor outlet temperature T3=b4×P2+b5, methane compressor outlet pressure p8=b6×e (b 7 ×P 2 ) , where P2 is the power of the methane compressor, b1, b2, b3, b4, b5, b6, and b7 are fitting coefficients, and the gas composition of the methane compressor is the same as that of the feed gas.

[0053] (2-2) The second step is to start the expander and establish the functional relationship between the expander inlet flow rate, outlet flow rate, outlet temperature and expander power, which are: Q 12 =b8×e (b 9 ×P 1 ) , Q 13 =b 10 ×P1 2 +b 11 ×P1+b 12 , T4=b 13 ×P4+b 14 , where Q 12 is the expander intake flow rate, Q 13is the expander outlet gas flow rate, T4 is the expander outlet gas temperature, P1 is the expander shaft power, b8, b9, b 10 、b 11 、b 12 、b 13 、b 14 is the fitting coefficient; after that, the separation system is turned on and enters the steady-state operation condition.

[0054] (3) During shutdown / emergency shutdown (the shutdown phase also covers emergency shutdown situations), the separation system is first shut down. The state parameter calculation at this time is the same as that during steady-state operation. The control parameters of the expander and methane compressor under the shutdown phase of the equipment are calculated: the instantaneous control parameter calculation of the expander and methane compressor is the same as that during steady-state operation. Then the methane compressor stops running. The separation system relies on the above three devices to operate. When the above three devices stop, the separation system stops working without a gas source.

[0055] Step 3: Generate control parameter calculation results based on the daily and hourly raw material consumption obtained in step 1 and the flow, pressure, temperature and outlet gas composition of the four devices obtained in step 2.

[0056] The second aspect of the present invention discloses a process parameter calculation system for a hydrogen and natural gas mixed transmission and separation system based on pressure energy recovery, comprising: a parameter input module for providing calculation parameters for a calculation black box module; a built-in calculation black box module; and a result display module for displaying the final calculation results.

[0057] The following is a detailed example of the calculation method of the control parameters of the hydrogen and natural gas mixed transportation and separation process.

[0058] Example 1

[0059] In this example, for a hydrogen production capacity of 2000 kg / d, the calculation results of the control parameters for the equipment under steady-state operating conditions, startup phase conditions, and shutdown phase conditions during the hydrogen and natural gas mixed transmission and separation process control process are as follows:

[0060] Steady-state operation phase:

[0061] According to P1=a2×Q1、Q2=a3×Q1、T1=a4×(p2-p1) 3 +a5×(p2-p1) 2 +a6×(p2-p1)+a7, a2, a3, a4, a5, a6, a7 are taken as 2.2072, 1.8803, -0.0721, 1.7461, -18.215, 25.294, and the control parameters of the expander are shown in Table 1:

[0062] Table 1 Expander control parameters

[0063]

[0064] According to Q3 = a8 × Q1, Q4 = a9 × Q1, Q5 = a 10 ×Q1, the intake temperature of the separation system ≈ rich gas temperature ≈ lean gas temperature = T2; p3 = p2, p4 = a 11 ×p3, p5=a 12 ×p3,F 1CH4 =F CH4 ×Q1×a 13 / Q4,F 1H2 =F H2 ×Q1×a 14 / Q4,F 2CH4 =F CH4 ×Q1×a 15 / Q5,F 2H2 =F H2 ×Q1×a 16 / Q5,a8~a 16 The control parameters of the separation system are shown in Table 2 by taking the values ​​as 2.7488, 2.5305, 1.5554, 0.975, 0.15, 1.6781, 0.4511, 0.5382, and 20.4617.

[0065] Table 2 Separation system control parameters

[0066]

[0067] According to Q7=a 17 ×Q6, T3=a 18 ×p1 2 +a 19 ×p1+a 20 , p6=a 21 ×p1 2 +a 22 ×p1+a 23 , P2=a 24 ×Q1,a 17 ~a 24 The values ​​are 0.5865, -0.007, 1.8887, -25.296, -0.0039, 1.2332, -3.8505, and 2.2072, and the control parameters of the methane compressor are shown in Table 3:

[0068] Table 3 Methane compressor control parameters

[0069]

[0070]

[0071] According to Q8=Q4, Q9=a 25 ×Q8, p7=p6, T4=a 26 ×(p7-p5) 3 +a 27 ×(p7-p5) 2 ×p5+a 28 ×(p7-p5)+a 29 , a 25 ~a 29 The values ​​are 0.195, 0.0007, -0.1254, 10.505, and 52.711, and the control parameters of the hydrogen compressor are shown in Table 4:

[0072] Table 4 Hydrogen compressor control parameters

[0073]

[0074] Boot-up phase:

[0075] The first step is to 10 =b1×Q5, outlet flow rate Q 11 =b2×e (b3×P2) , T3=b4×P3+b5, p8=b6×e (b7 ×P3) , b1~b7 are taken as 1.0863, 387.2, -0.0001, 0.1561, 35.76, 41.604, 0.0015, and the control parameters of the methane compressor are shown in Table 5:

[0076] Table 5 Methane compressor control parameters

[0077]

[0078] The second step is to 12 =b8×e (b9×P1) , Q 13 =b 10 ×P4 2 +b 11 ×P4+b 12 , T4=b 13 ×P4+b 14 , b8~b 14 The values ​​are 384.99, -0.002, 0.00002, -0.1468, 390.09, -0.086, and 34.08, and the control parameters of the expander are shown in Table 6:

[0079] Table 6 Expander control parameters

[0080]

[0081] Shutdown / Emergency Shutdown Phase:

[0082] Control parameters of the expander and methane compressor during the equipment shutdown phase: The calculation of the instantaneous control parameters of the expander and methane compressor is the same as that during steady-state operation, and then the methane compressor stops running.

[0083] Example 2

[0084] For comparison, the following table is a comparison of the calculation results of the same parameters in the hydrogen and natural gas mixed transmission and separation process calculated using the calculation method of the present invention and using a certain software. Specifically, the parameters of the expander, compressor and separation system in the process during steady-state operation are calculated under different production capacity conditions. It can be seen that there is almost no difference between the calculation results of the method of the present invention and the results calculated using professional software. For example, under the production capacity of 1500 kg / d (the underlined data in the table are illustrative), the expander outlet temperature calculated using the patented method is -38.0°C, while the expander outlet flow rate calculated using a certain software is -38.9°C. The calculated results differ by 0.9°C, with a deviation of 2.4%.

[0085]

[0086]

[0087] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A method for calculating control parameters of a hydrogen and natural gas mixed transportation and separation process, characterized by: The process control of hydrogen and natural gas mixed transmission and separation involves four types of equipment: expander, separation system, methane compressor, and hydrogen compressor. The control parameter calculation method specifically includes: Step 1: Calculate the total raw material flow rate based on the linear relationship between production capacity load and feed flow rate, and then obtain the daily and hourly raw material consumption; Step 2: Calculate the control parameters of the expander, separation system, methane compressor, and hydrogen compressor based on the total raw material flow rate obtained in step 1. The control parameters of each device include flow rate, pressure, temperature, and outlet gas composition. Step 3: Generate control parameter calculation results based on the daily and hourly raw material consumption obtained in step 1 and the flow, pressure, temperature and outlet gas composition of the four devices obtained in step 2.

2. The method for calculating control parameters of a hydrogen and natural gas mixed transportation and separation process according to claim 1, characterized in that: The expression of the relationship curve between the production capacity load m and the total raw material flow Q1 is: Q1=a1m+b1, where m∈capacity load applicable interval, a1 and b1 are fitting coefficients.

3. The method for calculating control parameters of a hydrogen and natural gas mixed transportation and separation process according to claim 1, characterized in that: In step 2, the hydrogen and natural gas mixed transmission and separation process control process is divided into equipment steady-state operation conditions, equipment startup phase conditions, and equipment shutdown phase conditions. The calculation process of the control parameters of the expander, separation system, methane compressor, and hydrogen compressor includes: (1) Calculate the control parameters of each device under steady-state operation conditions: (1-1) Establish the functional relationship between expander power and feed, the functional relationship between expander outlet flow and feed flow, and the functional relationship between expander outlet temperature and expander inlet and outlet pressure difference, which are: P1=a2×Q1, Q2=a3×Q1, T1=a4×(p2-p1) 3 +a5×(p2-p1) 2 +a6×(p2-p1)+a7, where P1 is the expander shaft power, Q2 is the expander exhaust flow rate, T1 is the expander outlet temperature, p1 and p2 are the expander inlet and outlet pressures respectively, a2, a3, a4, a5, a6, and a7 are fitting coefficients. Based on the above relationship, the expander power, outlet temperature, and outlet flow rate can be calculated according to the feed flow rate and pressure difference. The outlet gas composition of the expander is the same as the raw material composition; (1-2) Establish the functional relationship between the inlet and outlet flow of the separation system and the raw material flow, where the inlet flow of the separation system is Q3 = a8 × Q1, the outlet flow of the rich gas is Q4 = a9 × Q1, and the outlet flow of the lean gas is Q5 = a 10 ×Q1, in the above relationship: a8, a9, a 10 is the fitting coefficient; the intake temperature of the separation system T2≈rich gas temperature≈lean gas temperature; the intake pressure of the separation system p3=p2, the lean gas pressure p4=a 11 ×p3, rich gas pressure p5=a 12 ×p3, where a 11 、a 12 is the fitting coefficient; the inlet gas composition of the separation system is the same as the raw material composition, and the outlet gas composition is: the methane percentage content F of the rich gas 1CH4 =F CH4 ×Q1×a 13 / Q4, hydrogen percentage of rich gas F 1H2 =F H2 ×Q1×a 14 / Q4, methane content of lean gas F 2CH4 =F CH4 ×Q1×a 15 / Q5, hydrogen percentage of rich gas F 2H2 =F H2 ×Q1×a 16 / Q5, in the above relationship: F CH4 is the percentage of raw material methane, F H2 is the percentage of hydrogen in the raw material, a 13 、a 14 、a 15 、a 16 is the fitting coefficient; (1-3) The inlet flow rate of the methane compressor Q6 = Q5, and the outlet flow rate of the methane compressor Q7 = a 17 ×Q6, methane compressor outlet temperature T3=a 18 ×p1 2 +a 19 ×p1+a 20 , methane compressor outlet pressure p6=a 21 ×p1 2 +a 22 ×p1+a 23 , methane compressor shaft power P2 = a 24 ×Q1, in the above relationship, a 17 、a 18 、a 19 、a 20 、a 21 、a 22 、a 23 、a 24 is the fitting coefficient; (1-4) Hydrogen compressor inlet flow rate Q8 = Q4, hydrogen compressor outlet flow rate Q9 = a 25 ×Q8, hydrogen compressor outlet pressure p7 = p6, hydrogen compressor outlet temperature (adiabatic compression) T4 = a 26 ×(p7-p5) 3 +a 27 ×(p7-p5) 2 +a 28 ×(p7-p5)+a 29 In the above relationship, a 25 、a 26 、a 27 、a 28 、a 29 is the fitting coefficient; (2) Calculate the control parameters of the methane compressor and expander during the equipment startup phase: (2-1) Methane compressor intake flow Q 10 =b1×Q5, methane compressor outlet flow Q 11 =b2×e (b 3 ×P 2 ) , methane compressor outlet temperature T 30 =b4×P2+b5, methane compressor outlet pressure p8=b6×e (b 7 ×P 2 ) , where b1, b2, b3, b4, b5, b6, and b7 are fitting coefficients, and the gas composition of the methane compressor is the same as that of the feed gas; (2-2) Establish the functional relationship between the expander inlet flow rate, outlet flow rate, outlet temperature and expander power, which are: Q 12 =b8×e (b 9 ×P 1 ) , Q 13 =b 10 ×P1 2 +b 11 ×P1+b 12 , T4=b 13 ×P1+b 14 , where Q 12 is the expander intake flow rate, Q 13 is the expander outlet gas flow rate, T4 is the expander outlet gas temperature, b8, b9, b 10 、b 11 、b 12 、b 13 、b 14 is the fitting coefficient; (3) Calculate the control parameters of the equipment during shutdown: The calculation of the instantaneous control parameters of the expander, methane compressor, and hydrogen compressor is the same as that during steady-state operation. Subsequently, the methane compressor, expander, and hydrogen compressor stop running in sequence.

4. A hydrogen and natural gas mixed transmission and separation process control parameter calculation system, characterized by: The system is applied to a method for calculating control parameters of a hydrogen and natural gas mixed transportation and separation process as described in any one of claims 1 to 3; the system comprises: The parameter input module is used to input the relevant calculation parameters of the hydrogen and natural gas mixed transmission and separation process, and provide calculation parameters for the calculation black box module; Calculation black box module, used for automatic calculation of control parameters of hydrogen and natural gas mixed transmission and separation process; The result display module displays the final calculation results.

5. The hydrogen and natural gas mixed transportation and separation process control parameter calculation system according to claim 4 is characterized by: The calculation parameters include: daily hydrogen production capacity, temperature, pressure, and component composition of the expander inlet gas, outlet pressure of the expander, temperature of the inlet and outlet gas of the separation system, and outlet pressure of the separation system.

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