Quick determination method and system for hydrogen blending interchangeability in natural gas downstream terminals

Abstract

The present invention discloses a method and system for quickly determining the hydrogen blending interchangeability of natural gas in downstream terminals. The steps of the method include calculating the relative density of natural gas before hydrogen blending and the mixed gas after hydrogen blending; calculating the high calorific value and Wobbe number of natural gas before hydrogen blending; pre-determining natural gas before hydrogen blending; calculating the Wobbe number, CO generation index, and flashback index of the mixed gas after hydrogen blending; secondarily determining the mixed gas after hydrogen blending; calculating the flashback index of the mixed gas after hydrogen blending; finally determining the mixed gas after hydrogen blending; and thus determining whether the mixed gas after natural gas hydrogen blending meets the interchangeability requirements and can be safely used. It is possible to quickly pre-determine through the determination of natural gas before hydrogen blending. If it is known that the natural gas before hydrogen blending meets the characteristic indexes of 12T natural gas, only the flashback index of the mixed gas after hydrogen blending needs to be determined to obtain the interchangeability determination conclusion of the mixed gas after hydrogen blending, which helps to quickly determine the hydrogen blending interchangeability of in-service natural gas.

Description

Technical Field

[0001] The present invention belongs to the field of mixed gas, and particularly relates to a method and system for quickly determining the interchangeability of hydrogen-doped natural gas for downstream terminals of natural gas. Background Art

[0002] At present, the world's energy has formed a new pattern of "four powers sharing the world", namely coal, oil, natural gas, and new energy. The world's energy consumption has gradually shifted from past total volume growth to intensive and efficient development, and the main energy structure has transformed towards diversification, cleanliness, and low carbonization. New energy will gradually enter the golden development period. Among many new energy sources, electrical energy is generated using renewable energy such as wind energy and light energy, and then hydrogen energy is obtained through electrolysis. Hydrogen energy can be used for energy storage and utilization. At the same time, the combustion of hydrogen can achieve zero carbon emissions. Producing hydrogen energy through electrolysis of water can not only absorb large-scale abandoned electrical energy but also achieve energy conservation and environmental protection, so it has received great attention. In the process of global hydrogen energy application development, using natural gas blended with hydrogen is recognized as an important way to absorb hydrogen in the short term. During the use of hydrogen-doped natural gas, the adaptability of downstream users and terminal equipment to hydrogen-doped natural gas has received extensive attention.

[0003] The research on whether different gases can be used interchangeably at home and abroad is called the interchangeability problem. The interchangeability conditions can be summarized as follows: when the gas appliance is adjusted according to the regulated gas (i.e., the reference gas) supplied stably in the long term and then uses another component of gas, if there is a stable flame without further adjustment, a heat load (heat flow rate) that meets the requirements, heat flow rate and sanitary conditions, and no carbon deposition in the flame, etc., then the substitute gas and the regulated gas are considered interchangeable. Since the late 1920s, the world has successively proposed various interchangeability determination methods such as the Wobbe index and calorific value method, the Delbur index method, the Weaver index method, the AGA determination method, and the Dutton method, which can be used to determine the range of hydrogen-doped natural gas. However, since an important influencing factor for the interchangeability determination method is the form and specification of gas appliances, and the method-specifying party generally uses the gas appliances of its own country or region, and the differences in gas appliances between different countries or regions are sometimes very large, the applicability of the interchangeability determination methods used abroad to China remains to be discussed. Summary of the Invention

[0004] The present invention provides a method for quickly determining the interchangeability of hydrogen-doped natural gas for downstream terminals of natural gas. Given that the natural gas before hydrogen doping conforms to the 12T natural gas characteristic index, only the flashback index of the mixed gas after hydrogen doping needs to be determined to obtain the interchangeability determination conclusion of the mixed gas after hydrogen doping, which helps to quickly determine the interchangeability of in-service natural gas doped with hydrogen; to solve the problems raised in the above background art.

[0005] To achieve the above object, the technical solution adopted by the present invention is: a rapid determination method for hydrogen-doped interchangeability in the downstream terminal of natural gas, comprising the following steps:

[0006] Step 1, calculate the relative density of natural gas before hydrogen doping and the mixed gas after hydrogen doping;

[0007] Step 2, calculate the high calorific value and Wobbe number of natural gas before hydrogen doping;

[0008] Step 3, pre-determine the natural gas before hydrogen doping. If the high calorific value of the natural gas before hydrogen doping is H NG and the Wobbe number is W NG both are within the set range, then proceed to Step 6; if the high calorific value of the natural gas before hydrogen doping is H NG and the Wobbe number is W NG one of them exceeds the preset range, then proceed to Step 4,

[0009] Step 4, calculate the Wobbe number, CO generation index and flashback index of the mixed gas after hydrogen doping;

[0010] Step 5, conduct a secondary determination on the mixed gas after hydrogen doping. If the Wobbe number W s , flashback index J L and CO generation index of the mixed gas after hydrogen doping are all within the set range, then execute Step 6. If any one exceeds the set range, it is determined that the interchangeability of the mixed gas after hydrogen doping is unqualified, and then execute Step 8;

[0011] Step 6, calculate the flashback index of the mixed gas after hydrogen doping;

[0012] Step 7, conduct a final determination on the mixed gas after hydrogen doping according to the magnitude relationship between the flashback index of the mixed gas after hydrogen doping and the set value,

[0013] Step 8, comprehensively consider the results of the secondary determination and the final determination. If the secondary determination is unqualified or the final determination is unqualified, it is determined that the interchangeability of the mixed gas after hydrogen doping is unqualified; if the final determination is qualified, it is determined that the interchangeability of the mixed gas after hydrogen doping is qualified.

[0014] In Step 1, the specific content is as follows:

[0015] The initial parameters of each component of natural gas and hydrogen are: the volume fraction of hydrogen is f H , the density of hydrogen is ρ H , the volume fraction of each component gas of natural gas except hydrogen is f i , the density of each component gas is ρ i , then the density ρ NG of natural gas before hydrogen doping, the relative density s NG of natural gas before hydrogen doping, and the density ρs and the relative density s of the mixed gas after hydrogen doping s :

[0016] ρ NG = f i ρ i (1)

[0017]

[0018] ρ s = f i ρ i + f H ρ H (3)

[0019]

[0020] In step 2, the high calorific value H of natural gas before hydrogen doping is calculated using formulas (5) and (6) NG and the Wobbe index is W NG :

[0021] H NG = f i H i (5)

[0022]

[0023] where the high calorific value of each component gas of natural gas is H i , s NG is the relative density of natural gas before hydrogen doping

[0024] Step 3 is specifically as follows: The pre-judgment formula for natural gas before hydrogen doping is:

[0025] 31.97 MJ / m 3 < H NG < 43.57 MJ / m 3 (7)

[0026] 45.66 MJ / m 3 < W NG < 54.77 MJ / m 3 (8)

[0027] If both formula (7) and formula (8) hold, skip step 4 and step 5 and directly proceed to step 6; if either formula (7) or formula (8) does not hold, proceed to step 4

[0028] In step 4, it is specifically as follows:

[0029] It can be obtained from formula (9) - formula (16) that

[0030] Hs = f i H i + f H H H (9)

[0031]

[0032]

[0033]

[0034]

[0035]

[0036]

[0037]

[0038] where s s is the relative density of the hydrogen-doped mixed gas, V 0s is the theoretical air volume of the hydrogen-doped mixed gas, H H is the high calorific value of hydrogen, H s is the high calorific value of the mixed gas, W s is the Wobbe number of the mixed gas, J A is the entrainment index, S s is the flame speed index of the mixed gas, J L is the flashback index, R s is the ratio of the number of H atoms in the mixed gas to the number of C atoms in hydrocarbon compounds, J i is the CO generation index, and a, b, c, d, and e are constants.

[0039] The secondary determination formula for the hydrogen-doped mixed gas in Step 5 is:

[0040] 45.66 MJ / m 3 < W s < 54.77 MJ / m 3 (17)

[0041] J L > 0.90 (18)

[0042] J i < 0.10 (19)

[0043] If equations (17), (18), and (19) hold simultaneously, then proceed to Step 6; if any one of equations (17), (18), and (19) does not hold, then it is determined that the interchangeability of the hydrogen-doped mixed gas is unqualified and not applicable, and proceed to Step 8.

[0044] In step 6, the tempering index J of the hydrogen-doped mixed gas is calculated by formula (20). F ,

[0045]

[0046] S s is the flame speed index of the mixed gas, and J A is the entrainment index.

[0047] The final judgment formula for the hydrogen-doped mixed gas in step 7 is as follows:

[0048] J F <0.64(21)

[0049] If formula (21) holds, it is determined that the interchangeability of the hydrogen-doped mixed gas is qualified and applicable; if formula (21) does not hold, it is determined that the interchangeability of the hydrogen-doped mixed gas is unqualified and not applicable.

[0050] Based on the concept of the above method, the present invention provides a rapid determination system for hydrogen-doped interchangeability for natural gas downstream terminals, including a first calculation module, a first judgment module, a second calculation module, a second judgment module, a third judgment module, and a fourth judgment module;

[0051] The first calculation module is used to calculate the relative density of natural gas before hydrogen doping and the hydrogen-doped mixed gas, the high calorific value and the Wobbe number of natural gas before hydrogen doping; the second calculation module is used to calculate the Wobbe number, CO generation index and flashback index of the hydrogen-doped mixed gas, and the third calculation module is used for the flashback index of the hydrogen-doped mixed gas;

[0052] The first judgment module is used to pre-judge the natural gas before hydrogen doping. If the high calorific value H NG and the Wobbe number W NG of the natural gas before hydrogen doping are both within the set range, the third calculation module is started; if either the high calorific value H NG or the Wobbe number W NG of the natural gas before hydrogen doping exceeds the preset range, the second calculation module is started;

[0053] The second judgment module is used to perform a secondary judgment on the hydrogen-doped mixed gas. If the Wobbe number W s , flashback index J L and CO generation index of the hydrogen-doped mixed gas are all within the set range, the third calculation module is started. If any one exceeds the set range, it is determined that the interchangeability of the hydrogen-doped mixed gas is unqualified, and the third judgment module is started;

[0054] The third judgment module is used to judge the hydrogen-doped mixed gas according to the magnitude of the flashback index of the hydrogen-doped mixed gas and the set value to obtain the final judgment result;

[0055] The fourth determination module is used to comprehensively consider the results of the secondary determination and the final determination. If the secondary determination is unqualified or the final determination is unqualified, it is determined that the interchangeability of the hydrogen-blended mixed gas is unqualified; if the final determination is qualified, it is determined that the interchangeability of the hydrogen-blended mixed gas is qualified.

[0056] In addition, a computer device is provided, including a processor and a memory. The memory is used to store computer-executable programs. The processor reads the computer-executable programs from the memory and executes them. When the processor executes the computer-executable programs, it can implement the rapid determination method for hydrogen blending interchangeability for natural gas downstream terminals of the present invention.

[0057] Compared with the prior art, the present invention has at least the following beneficial effects:

[0058] The present invention can quickly pre-determine by determining the natural gas before hydrogen blending. If it is known that the natural gas before hydrogen blending meets the characteristic indexes of 12T natural gas, only the tempering index of the hydrogen-blended mixed gas needs to be determined to obtain the determination conclusion of the interchangeability of the hydrogen-blended mixed gas, which helps the rapid determination of the hydrogen blending interchangeability of in-service natural gas;

[0059] At present, the application of natural gas is becoming more and more mature. Blending hydrogen into natural gas helps to achieve large-scale consumption of hydrogen energy. The present invention proposes a method for determining the interchangeability of hydrogen blending for natural gas for gas terminal users, filling the domestic gap in this technical field;

[0060] The present invention can obtain a mixed gas that can be used normally without adjusting gas terminal equipment by adding hydrogen to natural gas, which can reduce carbon emissions and contribute to the energy revolution and green development. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] Figure 1 It is a schematic flow chart of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0062] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0063] Please refer to Figure 1 , the present invention provides a technical solution: a rapid determination method for hydrogen blending interchangeability for natural gas downstream terminals, including the following steps:

[0064] Step 1: Calculate the relative densities of the natural gas before hydrogen blending and the hydrogen-blended mixed gas; Initial parameters of each component of natural gas and hydrogen: The volume fraction of hydrogen is fH , the density of hydrogen is ρ H , let the volume fraction of each component gas in natural gas except hydrogen be f i , the density of each component gas is ρ i , the density of natural gas before hydrogen addition is ρ NG , the relative density is s NG , the density of the mixed gas after hydrogen addition is ρ s , the relative density is s s , then from equations (1), (2), (3), and (4), it can be obtained that

[0065] ρ NG = f i ρ i (1)

[0066]

[0067] ρ s = f i ρ i + f H ρ H (3)

[0068]

[0069] Step 2: Calculate the high calorific value and Wobbe number of natural gas before hydrogen addition; the high calorific value of each component gas in natural gas is H i , the high calorific value of natural gas before hydrogen addition is H NG , the Wobbe number is W NG , then from equations (5) and (6), it can be obtained that

[0070] H NG = f i H i (5)

[0071]

[0072] Step 3: Pre - judge natural gas before hydrogen addition; the pre - judgment formula for natural gas before hydrogen addition is:

[0073] 31.97 MJ / m 3 < H NG < 43.57 MJ / m 3 (7)

[0074] 45.66 MJ / m 3 < W NG < 54.77 MJ / m 3 (8)

[0075] If both Equation (7) and Equation (8) hold, skip Step 4 and Step 5 and directly proceed to Step 6; if either Equation (7) or Equation (8) does not hold, proceed to Step 4.

[0076] Step 4: Calculate the Wobbe number, CO generation index, and flashback index of the hydrogen-doped mixed gas; assume the relative density of the hydrogen-doped mixed gas is s s , the theoretical air volume of the hydrogen-doped mixed gas is V 0s , the high calorific value of hydrogen is H H , the high calorific value of the mixed gas is H s , the Wobbe number of the mixed gas is W s , the entrainment index is J A , the flame speed index of the mixed gas is S s , the flashback index is J L , the ratio of the number of H atoms in the mixed gas to the number of C atoms in the hydrocarbon compound is R s , the CO generation index is J i , assume constants a, b, c, d, e, then from Equation (9) - Equation (16), we can obtain

[0077] H s = f i H i + f H H H (9)

[0078]

[0079]

[0080]

[0081]

[0082]

[0083]

[0084]

[0085] Step 5: Conduct a secondary determination on the hydrogen-doped mixed gas; the secondary determination formula for the hydrogen-doped mixed gas is:

[0086] 45.66 MJ / m 3 < W s < 54.77 MJ / m 3 (17)

[0087] J L > 0.90 (18)

[0088] Ji <0.10(19)

[0089] If equations (17), (18) and (19) hold simultaneously, then proceed to step 6; if any one of equations (17), (18) and (19) does not hold, it is determined that the interchangeability of the hydrogen-doped mixed gas is unqualified and not applicable, and proceed to step 8.

[0090] Step 6: Calculate the flashback index of the hydrogen-doped mixed gas; let the flashback index of the hydrogen-doped mixed gas be J F , then from equation (20), it can be obtained that

[0091]

[0092] The specific content of step 7 is as follows:

[0093] The final judgment formula for the hydrogen-doped mixed gas is:

[0094] J F <0.64(21)

[0095] If equation (21) holds, it is determined that the interchangeability of the hydrogen-doped mixed gas is qualified and applicable; if equation (21) does not hold, it is determined that the interchangeability of the hydrogen-doped mixed gas is unqualified and not applicable.

[0096] Step 7: Make a final judgment on the hydrogen-doped mixed gas;

[0097] Step 8: Output the judgment result: Based on the comprehensive secondary judgment and the final judgment result, if the secondary judgment is unqualified or the final judgment is unqualified, it is determined that the interchangeability of the hydrogen-doped mixed gas is unqualified and not applicable; if the final judgment is qualified, it is determined that the interchangeability of the hydrogen-doped mixed gas is qualified and applicable.

[0098] The constants of the present invention are: a = 148, b = 301, c = 398, d = 513, e = 339.

[0099] Specific embodiment 1: The composition of the natural gas in Shaanxi-Gansu-Ningxia region: methane 94.7%, ethane: 0.55%, propane: 0.08%, butane: 1.01%, nitrogen: 4.64%.

[0100] Since the natural gas in Shaanxi-Gansu-Ningxia region is the in-service natural gas, equations (7) and (8) in step 3 hold simultaneously, and directly proceed to step 6.

[0101] Calculate the flashback index J of the hydrogen-doped mixed gas according to formula (20) F , and the results are shown in Table 1:

[0102] Table 1

[0103] Hydrogen blending ratio <![CDATA[The tempering index J F > 0％ 0.070 20％ 0.614 21％ 0.645

[0104] When the hydrogen doping ratio is 20%, Equation (21) holds, and it is determined that the interchangeability of the hydrogen-doped mixed gas is qualified and applicable.

[0105] When the hydrogen doping ratio is 21%, Equation (21) does not hold, and J F > 0.64. It is determined that the interchangeability of the hydrogen-doped mixed gas is unqualified and not applicable.

[0106] Specific Example 2: A certain natural gas A, components: methane: 80%, ethane: 10%, propane: 10%

[0107] Through the calculations in Steps 1 and 2, the high calorific value and Wobbe number of the natural gas before hydrogen doping can be obtained, and the results are shown in Table 2:

[0108] Table 2

[0109] Higher heating value Wobbe index <![CDATA[46.453MJ / m 3 > <![CDATA[55.385MJ / m 3 >

[0110] Then both Equation (7) and Equation (8) in Step 3 do not hold, and Step 4 is carried out.

[0111] Through the calculations in Step 4, the Wobbe number, flashback index J L and CO generation index J i of the hydrogen-doped mixed gas can be obtained, and the results are shown in Table 3:

[0112] Table 3

[0113] Hydrogen blending ratio Wobbe index <![CDATA[Flashback index J L > <![CDATA[CO generation index J i > 0 <![CDATA[55.385MJ / m 3 > 1.152 0.125 10％ <![CDATA[53.768MJ / m 3 > 1.295 0.072 20％ <![CDATA[52.122MJ / m 3 > 1.454 0.013 30％ <![CDATA[50.451MJ / m 3 > 1.632 -0.052

[0114] When the hydrogen doping ratio is 0, the Wobbe number and CO generation index J i do not satisfy Equation (17) and Equation (19), and it is determined that the interchangeability of the hydrogen-doped mixed gas is unqualified and not applicable;

[0115] When the hydrogen doping ratio is 10%, Equation (17), Equation (18), and Equation (19) hold simultaneously, and Step 6 is carried out;

[0116] When the hydrogen doping ratio is 20%, Equation (17), Equation (18), and Equation (19) hold simultaneously, and Step 6 is carried out;

[0117] When the hydrogen doping ratio is 30%, Equation (17), Equation (18), and Equation (19) hold simultaneously, and Step 6 is carried out;

[0118] Through the calculations in Step 6, the flashback index J F of the hydrogen-doped mixed gas can be obtained, and the results are shown in Table 4:

[0119] Table 4

[0120] Hydrogen blending ratio <![CDATA[The tempering index J F > 10％ 0.167 20％ 0.427 30％ 0.728

[0121] When the hydrogen doping ratio is 10%, Equation (21) holds, and it is determined that the interchangeability of the mixed gas after hydrogen doping is qualified and applicable;

[0122] When the hydrogen doping ratio is 20%, Equation (21) holds, and it is determined that the interchangeability of the mixed gas after hydrogen doping is qualified and applicable;

[0123] When the hydrogen doping ratio is 30%, Equation (21) does not hold, J F > 0.64, and it is determined that the interchangeability of the mixed gas after hydrogen doping is unqualified and not applicable;

[0124] In summary, when the hydrogen doping ratio is 0% and 30%, it is determined that the interchangeability of the mixed gas after hydrogen doping is unqualified and not applicable; when the hydrogen doping ratio is 10% and 20%, it is determined that the interchangeability of the mixed gas after hydrogen doping is qualified and applicable.

[0125] Based on the concept of the above method, the present invention also provides a rapid determination system for hydrogen doping interchangeability for natural gas downstream terminals, including a first calculation module, a first determination module, a second calculation module, a second determination module, a third determination module, and a fourth determination module;

[0126] The first calculation module is used to calculate the relative density of natural gas before hydrogen doping and the mixed gas after hydrogen doping, the high calorific value and the Wobbe number of natural gas before hydrogen doping; the second calculation module is used to calculate the Wobbe number, CO generation index and flashback index of the mixed gas after hydrogen doping, and the third calculation module is used for the flashback index of the mixed gas after hydrogen doping;

[0127] The first determination module is used to pre-determine the natural gas before hydrogen doping. If the high calorific value H NG and the Wobbe number W NG of the natural gas before hydrogen doping are both within the set range, the third calculation module is started; if either the high calorific value H NG or the Wobbe number W NG of the natural gas before hydrogen doping exceeds the preset range, the second calculation module is started;

[0128] The second determination module is used to perform a secondary determination on the mixed gas after hydrogen doping. If the Wobbe number W s , flashback index J L and CO generation index of the mixed gas after hydrogen doping are all within the set range, the third calculation module is started. If any one exceeds the set range, it is determined that the interchangeability of the mixed gas after hydrogen doping is unqualified, and the third determination module is started;

[0129] The third determination module is used to determine the mixed gas after hydrogen doping according to the magnitude of the flashback index of the mixed gas after hydrogen doping and the set value, and obtain the final determination result;

[0130] The fourth determination module is used to synthesize the results of the secondary determination and the final determination. If the secondary determination is unqualified or the final determination is unqualified, it is determined that the interchangeability of the hydrogen-doped mixed gas is unqualified; if the final determination is qualified, it is determined that the interchangeability of the hydrogen-doped mixed gas is qualified.

[0131] Meanwhile, a computer device is provided, including a processor and a memory. The memory is used to store computer-executable programs. The processor reads the computer-executable programs from the memory and executes them. When the processor executes the computer-executable programs, it can implement the rapid determination method for hydrogen-doped interchangeability in the downstream terminals of natural gas according to the present invention.

[0132] The advantages of the present invention are as follows: The present invention fills the domestic blank in the field of determination of the interchangeability of hydrogen-doped natural gas; it can achieve rapid determination of the interchangeability of in-service hydrogen-doped natural gas; and it realizes carbon emission reduction and energy revolution.

[0133] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A rapid determination method for the hydrogen blending interchangeability of natural gas downstream terminals, characterized in that, It includes the following steps: Step 1: Calculate the relative density of natural gas before hydrogen addition and the mixed gas after hydrogen addition; Step 2: Calculate the higher calorific value and Wobbe number of natural gas before hydrogen addition; Step 3, pre-determine the natural gas before hydrogen addition. The high calorific value of the natural gas before hydrogen addition is H NG and the Wobbe index is W NG both within the set range, then proceed to Step 6; if the high calorific value of the natural gas before hydrogen addition is H NG and the Wobbe index is W NG one of them exceeds the preset range, then proceed to Step 4 Step 4: Calculate the Wobbe number, CO generation index and flashback index of the mixed gas after hydrogen addition; Step 5, perform a secondary determination on the hydrogen-doped mixed gas. The Wobbe number W s of the hydrogen-doped mixed gas, the flashback index J L and the CO generation index are all within the set range, then execute Step 6. If any one exceeds the set range, it is determined that the interchangeability of the hydrogen-doped mixed gas is unqualified, and then execute Step 8; Step 6: Calculate the flashback index of the mixed gas after hydrogen addition; Step 7: Make a final determination of the mixed gas after hydrogen addition according to the magnitude relationship between the flashback index of the mixed gas after hydrogen addition and the set value; Step 8: Synthesize the results of the secondary determination and the final determination. If the secondary determination is unqualified or the final determination is unqualified, it is determined that the interchangeability of the mixed gas after hydrogen addition is unqualified; if the final determination is qualified, it is determined that the interchangeability of the mixed gas after hydrogen addition is qualified.

2. The rapid determination method for the hydrogen blending interchangeability of natural gas downstream terminals according to claim 1, characterized in that, In the said Step 1, the specific content is as follows: The initial parameters of each component of natural gas and hydrogen are as follows: the volume fraction of hydrogen is f H , the density of hydrogen is ρ H , the volume fraction of each component gas in natural gas except hydrogen is f i , the density of each component gas is ρ i , then the density ρ NG of natural gas before hydrogen addition, the relative density s NG of natural gas before hydrogen addition, the density ρ s of the mixed gas after hydrogen addition, and the relative density s s of the mixed gas after hydrogen addition are calculated by formulas (1), (2), (3) and (4) respectively: ρ NG = f i ρ i (1) ρ s = f i ρ i + f H ρ H (3) 3. The rapid determination method for the hydrogen blending interchangeability of natural gas downstream terminals according to claim 2, characterized in that, In step 2, the high calorific value of natural gas before hydrogen addition is calculated as H using formulas (5) and (6) NG and the Wobbe index is W NG : H NG = f i H i (5) Among them, the high calorific value of each component gas of natural gas is H i , s NG is the relative density of natural gas before hydrogen blending.

4. The rapid determination method for the hydrogen blending interchangeability of natural gas downstream terminals according to claim 1, characterized in that, The said Step 3 is specifically as follows: The pre-determination formula for natural gas before hydrogen addition is: 31.97MJ / m 3 <H NG <43.57MJ / m 3 (7) 45.66MJ / m 3 <W NG <54.77MJ / m 3 (8) If both Formula (7) and Formula (8) hold, skip Step 4 and Step 5 and directly go to Step 6; if either Formula (7) or Formula (8) does not hold, go to Step 4.

5. The rapid determination method for the hydrogen blending interchangeability of natural gas downstream terminals according to claim 3, characterized in that, In the said Step 4, the specific content is as follows: It is assumed that from Formula (9) - Formula (16), it can be obtained that H s = f i H i + f H H H (9) Among them, s s is the relative density of the hydrogen-doped mixed gas, V 0s is the theoretical air volume of the hydrogen-doped mixed gas, H H is the high calorific value of hydrogen, H s is the high calorific value of the mixed gas, W s is the Wobbe number of the mixed gas, J A is the entrainment index, S s is the flame speed index of the mixed gas, J L is the flashback index, R s is the ratio of the number of H atoms in the mixed gas to the number of C atoms in hydrocarbon compounds, J i is the CO generation index, where a, b, c, d, and e are constants.

6. The rapid determination method for the hydrogen blending interchangeability of natural gas downstream terminals according to claim 5, characterized in that, The secondary determination formula for the mixed gas after hydrogen addition in Step 5 is: 45.66 MJ / m 3 <W s <54.77 MJ / m 3 (17) J L >0.90(18) J i <0.10(19) If Formula (17), Formula (18) and Formula (19) hold simultaneously, go to Step 6; if any one of Formula (17), Formula (18) and Formula (19) does not hold, it is determined that the interchangeability of the mixed gas after hydrogen addition is unqualified and not applicable, and go to Step 8.

7. The rapid determination method for hydrogen blending interchangeability in natural gas downstream terminals according to claim 1, characterized in that, In step 6, the tempering index J of the hydrogen-doped mixed gas is calculated by formula (20). F , S s is the flame speed index of the mixed gas, J A is the entrainment index.

8. The rapid determination method for hydrogen blending interchangeability in natural gas downstream terminals according to claim 7, characterized in that, The final determination formula for the mixed gas after hydrogen addition in the said Step 7 is: J F <0.64 (21) If Formula (21) holds, it is determined that the interchangeability of the mixed gas after hydrogen addition is qualified and applicable; if Formula (21) does not hold, it is determined that the interchangeability of the mixed gas after hydrogen addition is unqualified and not applicable.

9. A rapid determination system for hydrogen blending interchangeability in natural gas downstream terminals, characterized in that, It includes a first calculation module, a first determination module, a second calculation module, a second determination module, a third determination module and a fourth determination module; The first calculation module is used to calculate the relative density of natural gas before hydrogen addition and the mixed gas after hydrogen addition, the higher calorific value and Wobbe number of natural gas before hydrogen addition; the second calculation module is used to calculate the Wobbe number, CO generation index and flashback index of the mixed gas after hydrogen addition, and the third calculation module is used for the flashback index of the mixed gas after hydrogen addition; The first determination module is used to pre-determine the natural gas before hydrogen addition. The high calorific value of the natural gas before hydrogen addition is H NG and the Wobbe index is W NG both are within the set range, then the third calculation module is started; if the high calorific value of the natural gas before hydrogen addition is H NG and the Wobbe index is W NG one of them exceeds the preset range, then the second calculation module is started; The second determination module is used to perform a secondary determination on the hydrogen-doped mixed gas. The Wobbe number W of the hydrogen-doped mixed gas s , the flashback index J L and the CO generation index are all within the set range, then the third calculation module is started. If any one exceeds the set range, it is determined that the interchangeability of the hydrogen-doped mixed gas is unqualified, and then the third determination module is started; The third determination module is used to make a determination of the mixed gas after hydrogen addition according to the magnitude relationship between the flashback index of the mixed gas after hydrogen addition and the set value, and obtain the final determination result; The fourth determination module is used to synthesize the results of the secondary determination and the final determination. If the secondary determination is unqualified or the final determination is unqualified, it is determined that the interchangeability of the mixed gas after hydrogen addition is unqualified; if the final determination is qualified, it is determined that the interchangeability of the mixed gas after hydrogen addition is qualified.

10. A computer device, characterized in that, It includes a processor and a memory. The memory is used to store computer-executable programs. The processor reads the computer-executable programs from the memory and executes them. When the processor executes the computer-executable programs, it can implement the rapid determination method for hydrogen addition interchangeability for natural gas downstream terminals described in any one of claims 1 to 8.

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