Method for evaluating carbon footprint of industrial by-product hydrogen and application thereof

Abstract

The application provides a method and application for evaluating carbon footprint of industrial by-product hydrogen. The method and application for evaluating carbon footprint of industrial by-product hydrogen comprises the following steps: ① establishing a benchmark system of material chemical energy with combustion heat as the benchmark; ② calculating the relationship between reaction heat and combustion heat of a reaction system, and carbon emission generated by the reaction heat; and ③ calculating the carbon footprint of industrial by-product hydrogen. Under the benchmark system of material chemical energy with combustion heat as the benchmark, the transfer and conversion of chemical reaction heat and combustion heat of by-product hydrogen will comply with the conservation law, that is, combustion heat cannot be generated out of thin air or disappear, but can only be transferred from one substance to another substance, therefore, for the process of providing dehydrogenation reaction heat by fuel combustion, the combustion heat will be transferred to product hydrogen through the endothermic effect of dehydrogenation reaction, thereby establishing the balance relationship with combustion heat as the energy form, and calculating the carbon footprint of hydrogen.

Description

Technical Field

[0001] This invention relates to the field of evaluation and research on calculating the carbon footprint of hydrogen in the petrochemical and coal chemical industries, and particularly to a method and application for evaluating the carbon footprint of industrial by-product hydrogen. Background Technology

[0002] Hydrogen energy, as an increasingly important energy carrier, boasts high calorific value and pollution-free operation, making it a crucial direction for future low-carbon energy development. However, hydrogen production typically requires significant energy consumption and generates carbon emissions. Carbon footprint, a key indicator for evaluating carbon emissions during product acquisition, is widely used, and conducting product carbon footprint assessments is essential for achieving a low-carbon economic and social transformation. In situations where a single raw material is used to produce multiple products, it's necessary to allocate carbon emissions across these products. The accuracy of carbon footprint assessment hinges on the scientific and rational allocation of carbon emissions, forming a fundamental basis for the scientific validity of the assessment methods. Currently, commonly used methods include quality allocation and economic value allocation.

[0003] Industrial by-product hydrogen is a by-product of petrochemical production. Currently, the carbon footprint of hydrogen products is often calculated using the mass allocation method, which allocates carbon emissions from co-occurring processes according to the mass proportion of the product. This method can lead to significant biases. Firstly, hydrogen has a high energy content (calorific value per unit mass), as shown in Table 1. The heat of combustion of hydrogen is nearly three times that of gasoline. As a high-energy-content by-product, hydrogen production requires a significant energy input, primarily due to the strongly endothermic dehydrogenation reaction. Therefore, hydrogen production (or industrial by-product hydrogen) consumes a large amount of fuel (or other forms of energy) in heating furnaces and is accompanied by substantial carbon emissions. Processes involving dehydrogenation reactions and by-product hydrogen typically have high energy consumption and large carbon emissions. Secondly, due to the low density of hydrogen, its mass proportion in the reaction products is small, resulting in lower carbon emissions allocated by product mass. Consequently, the calculated hydrogen carbon footprint cannot reflect the energy consumption and transfer patterns of the production process.

[0004] Table 1

[0005]

[0006] Hydrogen produced as a byproduct in petrochemical production differs from that produced in coal-to-hydrogen processes, where hydrogen is the primary product. In coal-to-hydrogen, coal is used as a reactant; coal gasification provides the heat to decompose water, the primary reactant, to produce hydrogen. The carbon dioxide produced in this process both provides heat to the system and is a byproduct of the gasification reaction. In contrast, industrial hydrogen production processes often require fuel in heating furnaces to provide the heat for dehydrogenation reactions. This heat is supplied to the reaction system through utilities. Furthermore, the presence of multiple reaction products makes carbon emission allocation more challenging.

[0007] The majority of carbon emissions from industrial by-product hydrogen production are caused by energy consumption. Therefore, assessing the carbon footprint of industrial by-product hydrogen requires understanding the energy conversion patterns of the process and the energy evolution path of the products during production. This is essential to objectively reflect the energy consumption and carbon emissions during product acquisition. Distributing the heat supplied to the chemical reaction among the products is a crucial step in establishing the logical chain for using the energy balance method to assess the carbon footprint of by-product hydrogen. Currently, there is no relevant research in this field. This application proposes a reaction heat distribution method based on the heat of combustion for carbon footprint assessment. Summary of the Invention

[0008] The purpose of this invention is to provide a method and application for evaluating the carbon footprint of industrial by-product hydrogen. A method is established using the heat of combustion as the benchmark of chemical energy. The transfer and conversion of the heat of combustion follows the law of conservation, meaning that the heat of combustion cannot be created or destroyed; it can only be transferred from one substance to another. For processes where fuel combustion provides the heat of dehydrogenation, the heat of combustion is transferred to the products through the endothermic effect of the dehydrogenation reaction. This allows for the establishment of a balance relationship using the heat of combustion as the energy form, and the calculation of the carbon footprint of the products. The carbon footprint of by-product hydrogen calculated from the energy balance reflects the fundamental source of carbon emissions from the by-product hydrogen production process. Any energy-saving or carbon-reduction effects in this process will be accurately reflected in changes in the product carbon footprint results, ensuring the scientific rigor of the carbon footprint evaluation process.

[0009] In the by-product hydrogen production process in the petrochemical industry, the heating furnace consumes fuel and releases heat from the combustion reaction. This heat is transferred to the reaction products through the endothermic effect of the dehydrogenation reaction, thus increasing the chemical energy of the reaction products compared to the reactants. When evaluating the carbon footprint of hydrogen production, it is necessary to calculate the increase in the chemical energy of the substances during the reaction process and allocate the carbon emissions calculated from the input energy to the relevant products. The selection of the chemical energy benchmark (the corresponding reaction process) is crucial to the scientific validity of the carbon footprint assessment.

[0010] Chemical energy is a form of energy that uses the heat effect of a chemical reaction as its energy source. It represents the energy changes that occur during the breaking and formation of chemical bonds in a chemical reaction. When a chemical reaction is endothermic, the chemical energy of the products will be higher than that of the reactants due to the external energy supply, and vice versa. Furthermore, chemical energy exists not only in the reactants and products but also corresponds to the specific reaction process that occurs. Evaluating the magnitude of a substance's chemical energy must be based on the chemical reaction it undergoes. Currently, the method of calculating the heat of chemical reaction using standard molar enthalpy of formation and standard molar enthalpy of combustion also uses a certain benchmark chemical reaction as a characterization of chemical energy.

[0011] Taking the dehydrogenation of propane to produce propylene with hydrogen as a byproduct as an example, the relevant data of reactants and products are shown in Table 2.

[0012] Table 2

[0013]

[0014] The standard molar enthalpy of formation is the enthalpy change of a chemical process in which the most stable elemental substance under the reference state forms a substance (reactant or product). The heat of reaction can be calculated by using the standard molar enthalpy of formation data and combining it with the stoichiometric relationship between reactants and products before and after the chemical reaction. The heat of reaction for propane dehydrogenation is 20.41 - (-103.85) = 124.26 kJ / mol.

[0015] The standard molar enthalpy of combustion is the enthalpy change of a substance (reactant or product) during complete oxidation to CO2 and H2O at the same temperature. Using standard molar enthalpy of combustion data and combining it with the stoichiometric relationship between reactants and products before and after a chemical reaction, the heat of reaction can be calculated. For example, the heat of reaction for propane dehydrogenation is 2058.52 + 285.83 - 2219.9 = 124.45 kJ / mol.

[0016] The methods for calculating the heat of chemical reaction using standard molar enthalpy of formation and standard molar enthalpy of combustion are both based on artificially selected reference states. They correlate the heat of reaction, a process quantity related to the state change of the system, with state quantities related to the state of matter (standard molar enthalpy of formation and standard molar enthalpy of combustion), and calculate the heat of reaction from the changes in these state quantities.

[0017] Because different baseline chemical reactions are selected, the chemical energies of substances characterized by the standard molar enthalpy of formation and the standard molar enthalpy of combustion, which are state quantities, are different. However, for a certain reaction, regardless of the form of chemical energy used as the baseline, the change in chemical energy is constant, which is the heat of reaction. Figure 1 A comparison of chemical energy processes characterized by different baseline states is presented. Figure 1In the diagram, the order of substances in the vertical arrangement indicates the magnitude of their chemical potentials. CO2 and H2O have the lowest chemical potentials, followed by elemental C and H2, then C3H8, and C3H6 and H2 have the highest chemical potentials. The chemical potentials of the reference state substances for heat of formation and heat of combustion are different.

[0018] Currently, fossil fuels, through combustion (limited to the point where their chemical potential is reduced to the level most stable with the surrounding environment, CO2 and H2O), release heat of oxidation (heat of combustion), which is the main source of energy acquisition and carbon dioxide emission for humans. For dehydrogenation reactions with endothermic effects, the chemical energy of the reaction products is higher than that of the reactants. This increase in chemical energy usually comes from the heat released by fuel combustion, the final products of which are CO2 and H2O.

[0019] In summary, the energy supplied by the heat of reaction in the dehydrogenation process is provided by the combustion of fuel into CO2 and H2O, and its baseline state is the same as that of the heat of combustion. Therefore, this invention establishes a baseline system based on the heat of combustion as the chemical energy of the substance. Compared to carbon emissions calculated based on changes in enthalpy of formation (heat of reaction), this system can more accurately reflect the source of the increase in chemical energy and the root cause of carbon emissions in the process of industrial by-product hydrogen production. Its calculation benchmark is unified, reflecting the consistency of the process pathways of heat acquisition, heat transfer, heat of reaction conversion, and increase in chemical energy in the hydrogen production process.

[0020] In this invention, for the dehydrogenation of propane to propylene, the heat of combustion of hydrogen in propane can be calculated from the partial oxidation of propane to propylene, or from the bond energies of the CH and HO bonds. The oxidative dehydrogenation reaction of propane is as follows:

[0021] 2C3H8 + O2 → 2C3H6 + 2H2

[0022] The heat of reaction is 235 kJ / mol per mol of stoichiometric volume. The heat of reaction calculated by verifying chemical bonds is shown in Tables 3 and 4 below:

[0023] Table 3

[0024]

[0025] Table 4

[0026]

[0027] That is, the bond energy increase per 1 mol of this reaction is 8716 - 8482 = 234 kJ / mol. The product water is in the gas phase. Considering the heat of vaporization of water vapor at 25℃ is 44.0 kJ / mol, the heat of reaction for the partial oxidation of propane (i.e., the heat of combustion of hydrogen) is 235 kJ / mol + 44.0 kJ / mol × 2 = 323 kJ / mol. One mol of this reaction corresponds to 2 mol of H2, meaning the heat of combustion of hydrogen is 162 kJ / mol.

[0028] For a system consisting of propane dehydrogenation, propane partial oxidation, and a combustion enthalpy-based reaction, it is possible to construct a system such as... Figure 2 The reaction paths shown are summarized and calculated.

[0029] exist Figure 2 In the reaction pathway, the sum of the heat of reaction for the complete combustion of propane (heat of reaction 2220 kJ / mol) and the heat of reaction for the partial oxidation of propane to propylene (heat of reaction 162 kJ / mol) and the complete oxidation of propylene (heat of reaction 2058 kJ / mol) is equal, which conforms to Hess's Law. Therefore, the heat of combustion of hydrogen in propane can be calculated from the difference between the heats of combustion of propane and propylene.

[0030] It can be seen that the heat of combustion of hydrogen produced by the dehydrogenation reaction consists of two parts: one part is provided by the externally supplied reaction heat of 124 kJ / mol, and the other part is provided by the difference in the heat of combustion of propane and propylene (162 kJ / mol).

[0031] In this invention, the carbon footprint of hydrogen is calculated using the following formula I:

[0032]

[0033] In formula I,

[0034] ΔCF h The carbon footprint of hydrogen;

[0035] Δ c H represents the heat of combustion of hydrogen;

[0036] E represents the carbon emission factor for consuming externally supplied energy;

[0037] m h This represents the production of hydrogen.

[0038] In this invention, the formula for calculating the heat of combustion of hydrogen in Formula I is shown in Formula II below:

[0039] Δ c H=(H cr -∑H cp,i )+Δ r H type II

[0040] In formula II,

[0041] Δ c H represents the heat of combustion of hydrogen;

[0042] H cr Represents the heat of combustion of the reactants;

[0043] H cp,i The heat of combustion of the main product i represents the heat of combustion of the reaction.

[0044] Δ r H represents the heat of reaction in the dehydrogenation reaction.

[0045] Therefore, in the process of industrial by-product hydrogen production, the heat of combustion of hydrogen, i.e., its calorific value, is derived from the calorific value of external fuel. In other words, the chemical energy (calorific value) of the fuel combustion reaction is converted into the calorific value of hydrogen.

[0046] In this invention, the method further includes the calculation of the carbon footprint of the reaction main product.

[0047] Since the changes in the heat of combustion of reactants and main products are transferred to the by-product hydrogen, a portion of the process carbon emissions can be offset. The offset carbon emissions should be calculated based on the carbon emission factor of the heat provided by the external environment for the process.

[0048] In this invention, the carbon footprint of the main reaction product i is calculated using the following formula (III):

[0049]

[0050] In Formula III,

[0051] ΔCF i The carbon footprint of the main product i in the reaction;

[0052] H cp,i The heat of combustion of the main product i represents the heat of combustion of the reaction.

[0053] H cr Represents the heat of combustion of the reactants;

[0054] m p,i This represents the yield of the main product i in the reaction;

[0055] E represents the carbon emission factor for consuming externally supplied energy.

[0056] Secondly, the present invention provides a method and application for evaluating the carbon footprint of industrial by-product hydrogen as described above. Applicable processes include propane dehydrogenation to propylene, ethylbenzene dehydrogenation to styrene, hydrogen production by-products in catalytic reforming, hydrogen production by-products in chlor-alkali production, or steam cracking. Attached Figure Description

[0057] To more clearly illustrate the technical solutions in the specific embodiments of the present invention or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0058] Figure 1 A comparison of the chemical energies of propane dehydrogenation to propylene under different baseline states.

[0059] Figure 2 A schematic diagram of the propane dehydrogenation to propylene reaction pathway provided by the present invention. Figure 3 This is a schematic diagram of the hydrogen production process as a byproduct of the reforming reaction provided by the present invention. Detailed Implementation

[0060] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0061] Example 1

[0062] This embodiment provides an example of using the present invention to evaluate the carbon footprint of hydrogen produced as a byproduct in the propane dehydrogenation to propylene process.

[0063] A 600,000-ton / year propane dehydrogenation unit consists of four process units: pretreatment, reaction, catalyst regeneration, and separation, as well as supporting utilities. Its material balance is shown in Table 5.

[0064] Table 5

[0065]

[0066] In Table 5, the PSA hydrogen in the feedstock is mainly used for hydrogenation in the feedstock pretreatment process and for hydrogenation of alkynes in the products. The C4 hydrocarbons in the products... + The components were separated at the bottom of the propane tower in the pretreatment unit and did not participate in the dehydrogenation reaction process. The composition of each raw material and product is shown in Tables 6 and 7.

[0067] Table 1

[0068]

[0069]

[0070] Table 7

[0071]

[0072] Side reactions in the propane dehydrogenation process include propane cracking and ethylene hydrogenation, as shown in the following equation:

[0073] C3H8→CH4+C2H4 Δ r H 298K =81kJ / mol

[0074] C2H4 + H2 → C3H8 Δ r H 298K = -137kJ / mol

[0075] If the reaction of components with C4 or higher is ignored, the material balance of the reaction process can be calculated from the quantities and composition of feed and products, as shown in Table 8:

[0076] Table 8

[0077]

[0078] The reactions that occur in this system mainly include the following three reactions:

[0079] C3H8→CH4+C2H4 (1)

[0080] C2H4 + H2 → C3H8 (2)

[0081] C3H8→C3H6+H2 (3)

[0082] In this reaction system, methane is relatively stable. Therefore, given the methane production of 20,900 tons, it can be concluded that reaction (1) requires the consumption of 57,500 tons of propane and the production of 36,600 tons of ethylene. The reaction stoichiometry is 1306Mmol.

[0083] Ethane production is 30,400 tons, requiring 28,400 tons of ethylene and 1,900 tons of hydrogen, with a reaction stoichiometry of 1013 Mmol.

[0084] Propylene production is 597,800 tons, requiring 616,900 tons of propane, with 28,500 tons of hydrogen produced as a byproduct, and a reaction stoichiometry of 14,020 mmol.

[0085] The heat of reaction can be calculated from the above reaction stoichiometry, as shown in Table 9:

[0086] Table 9

[0087]

[0088]

[0089] As shown in Table 9, the total heat of reaction of this system is 1,705,485 GJ / a, equivalent to approximately 59.22 MW. The four reaction heating furnaces of this unit produce 36.7 t / h of 4.2 MPa superheated steam for recovering high-temperature waste heat, equivalent to approximately 30.58 MW, so the total effective heat load is 89.8 MW.

[0090] The design heat loads of the four heating furnaces in this unit are 24.16MW, 29.72MW, 21.79MW, and 16.27MW, respectively, totaling 91.94MJ. The heating furnaces consume a total of 9.58t / hr of fuel gas and emit 209,100 tons / year of carbon. Therefore, the carbon emissions generated by the heat of reaction are 592,200 ÷ 898,000 × 209,100 = 138,000 tons.

[0091] The carbon footprint of this reaction process can be calculated using the carbon footprint calculation formulas I to III above:

[0092] The carbon footprint of by-product hydrogen is 13.8 × (1738480 ÷ 1705485) ÷ 1738480 × (286 × 14020) ÷ 2.85 = 11.384 tCO2 / t; where 13.8 × (1738480 ÷ 1705485) ÷ 1738480 = 0.0809 tCO2 / GJ is the carbon emission factor per unit heat of reaction.

[0093] Therefore, the carbon footprint of propylene = 13.8wtCO2 × (1738480 ÷ 1705485) ÷ 1738480 GJ × [(2058 kJ / mol - 2220 kJ / mol) × 14020 Mmol] ÷ 59.78wt = -0.307tCO2 / t.

[0094] Example 2

[0095] This embodiment provides a method for evaluating the carbon footprint of hydrogen produced as a byproduct of a catalytic reforming process using the present invention.

[0096] A 1 million tons / year catalytic reforming unit uses atmospheric and vacuum straight-run heavy naphtha hydrocracking heavy naphtha and ethylene cracked gasoline (C6-C8 fractions) as feedstock to produce benzene, toluene, mixed xylenes, and high-octane gasoline blending component C9. + Distillate oils, byproducts include reformed hydrogen, C5 distillate oil, raffinate oil, liquefied petroleum gas, and fuel gas. The extraction unit extracts aromatics from the reformed C6 / C7 distillate oil and the ethylene C6 / C7 distillate oil, respectively. The reformed raffinate oil is sent to the ethylene unit as ethylene cracking feedstock, while the ethylene raffinate oil is pretreated before entering the reforming reaction system. Figure 3 This is a schematic diagram of the hydrogen production process as a byproduct of the reforming reaction.

[0097] Its material balance is shown in Table 10:

[0098] Table 2

[0099]

[0100] The C6 / C7 fraction obtained from the ethylene cracking gasoline is used as feedstock for the aromatics extraction unit, while the C8 and higher fractions enter the aromatics distillation unit. Therefore, most of the C8 and C9 aromatics end up in the product. The ethylene cracking residue, accounting for 21.2%, will be used as feedstock for the reforming reaction. The group composition data of each feedstock are shown in Tables 11-13.

[0101] The composition of straight-run heavy naphtha is shown in Table 11 below:

[0102] Table 3

[0103]

[0104]

[0105] The composition of the compound oil from the fractured heavy mineral is shown in Table 12 below:

[0106] Table 4

[0107]

[0108] The composition of the compound oil in the fractured heavy mineral naphtha is shown in Table 13 below:

[0109] Table 5

[0110]

[0111]

[0112] The reaction starter families for the reforming reaction can be calculated from the above, as shown in Table 14 below:

[0113] Table 6

[0114]

[0115] The group composition of ethylene cracked gasoline is shown in Table 15:

[0116] Table 15

[0117]

[0118] Catalytic reforming reactions mainly consider the dehydrogenation and cyclization dehydrogenation of alkanes and cycloalkanes, which are conducive to the formation of aromatics and high-octane gasoline components. At the same time, it also includes the side reactions of hydrogenolysis of saturated hydrocarbons and hydrocracking to produce light hydrocarbon products. Therefore, it is necessary to approximate the reaction stoichiometry of the above reactions.

[0119] Since the composition of ethylene cracked gasoline can be approximated by subtracting the aromatic portion, the composition of the reforming reaction products can be obtained from Tables 10 and 15. The calculated results of the reforming reaction products are shown in Table 16.

[0120] Table 16

[0121]

[0122] Comparing Tables 14 and 16, we can see the reaction stoichiometry: C6 cycloalkanes produce 87,400 tons of benzene; C7 alkanes and C7 cycloalkanes produce 47,300 tons and 71,900 tons of toluene, respectively; C8 alkanes and cycloalkanes produce 120,400 tons and 77,900 tons of mixed xylene, respectively; and C9 alkanes and cycloalkanes produce 138,400 tons and 58,300 tons of trimethylbenzene, respectively. The amounts of products generated from each reactant are shown in Table 17.

[0123] Table 17

[0124]

[0125] The calorific values ​​of each product are shown in Table 18:

[0126] Table 18

[0127]

[0128] The molar heat of combustion of hydrogen is 285 kJ / mol. Therefore, the heat of reaction for the production of benzene from C6 cycloalkanes can be calculated as 3267.62 + 3 × 285 - 3919.6 = 203.02 kJ / mol. This corresponds to the heat of reaction for 1 kg of benzene being 203.02 × (1000 ÷ 78) = 2602.56 kJ / kg. The above heat of reaction is for the dehydrogenation of cyclohexane under standard conditions, but in practice, reforming reactions occur between 400 and 550 °C. Therefore, the heat of reaction should be calculated based on the average reforming temperature.

[0129] The thermal data for aromatization are shown in Table 19:

[0130] Table 19

[0131]

[0132] The heat of reaction for cyclohexane dehydrogenation is 2822 kJ / kg × 87,400 tons / year = 246,642,800 MJ / a = 8.56 MW. Similarly, the heat of reaction for other reactions can be calculated.

[0133] The heat of reaction in the reforming process is shown in Table 20:

[0134] Table 20

[0135]

[0136] The total load of the four-in-one reforming reactor in this unit is 15 + 23.9 + 14.43 + 11.1 = 64.43 MW. It simultaneously produces 30 t / hr of 3.5 MPa medium-pressure steam. The enthalpy of 3.5 MPa saturated steam is 2.80 GJ / t, and the enthalpy of saturated water is 1.05 GJ / t. Therefore, the estimated heat absorption of the generated steam is 30 × (2.80 - 1.0) × 1000 ÷ 3600 = 14.58 MW. The total effective heat is 46.52 + 14.58 = 61.10 MW. The heating furnace consumes 8578 Nm³ of fuel gas. 3 / hr, carbon emissions 16.51tCO2.

[0137] The carbon footprint of this reaction process can be calculated using the carbon footprint calculation formulas I to III above:

[0138] The carbon footprint of by-product hydrogen is calculated as follows: (16.51tCO2 ÷ 61.10MW) × (143.0GJ / t × 4.116t / hr × 1000MJ / GJ ÷ 3600s) ÷ 4.116t / hr = 10.74tCO2 / t. In this formula, (16.51tCO2 ÷ 61.10MW) represents the carbon emissions per unit furnace load, and (143.0GJ / t × 4.116t / hr × 1000MJ / GJ ÷ 3600s) represents the heat of combustion of by-product hydrogen converted to MW.

[0139] The carbon footprint of the product benzene = -8.57MW ÷ 61.10MW × 16.51tCO2 ÷ 8.74t = -0.265tCO2 / t.

[0140] The carbon footprint of the product toluene = -10.35 ÷ 61.10 MW × 16.51 tCO2 ÷ (4.73 t / hr + 7.19 t / hr) = -0.235 tCO2 / t.

[0141] The carbon footprint of the product C8 aromatics = -14.95 ÷ 61.10 MW × 16.51 tCO2 ÷ (12.04 t / hr + 7.79 t / hr) = -0.204 tCO2 / t.

[0142] The carbon footprint of the product C9 aromatics = -12.64 ÷ 61.10 MW × 16.51 tCO2 ÷ (13.84 t / hr + 5.83 t / hr) = -0.174 tCO2 / t.

Claims

1. A method for evaluating the carbon footprint of industrial by-product hydrogen, characterized in that, The method includes the following steps: Establish a benchmark system based on the heat of combustion as the chemical energy of a substance; The carbon footprint of by-product hydrogen is calculated by analyzing the composition and source of the heat of combustion of hydrogen in the reaction system. The carbon footprint of the hydrogen is calculated as shown in Equation I below: Formula I In formula I, The carbon footprint of hydrogen; The heat of combustion of hydrogen; E represents the carbon emission factor for consuming externally supplied energy; Represents the production of hydrogen; The heat of combustion of hydrogen described in Equation I is calculated as shown in Equation II below: Formula II In formula II, The heat of combustion of hydrogen; Represents the heat of combustion of the reactants; The heat of combustion of the main product i represents the heat of combustion. The heat of reaction represents the dehydrogenation reaction process.

2. The method for evaluating the carbon footprint of industrial by-product hydrogen according to claim 1, characterized in that, The method also includes the calculation of the carbon footprint of the reaction main product i.

3. The method for evaluating the carbon footprint of industrial by-product hydrogen according to claim 2, characterized in that, The carbon footprint of the main product i is calculated as shown in Equation III below: Formula III In Formula III, The carbon footprint of the main product i in the reaction; The heat of combustion of the main product i represents the heat of combustion. Represents the heat of combustion of the reactants; This represents the yield of the main product i in the reaction; E represents the carbon emission factor for consuming externally supplied energy.

4. The application of the method according to any one of claims 1-3 in evaluating the carbon footprint of industrial by-product hydrogen and / or industrial hydrogen production processes.

5. The application according to claim 4, characterized in that, The process includes propane dehydrogenation to propylene, ethylbenzene dehydrogenation to styrene, ethane dehydrogenation to ethylene, hydrogen production as a byproduct of catalytic reforming, hydrogen production as a byproduct of chlor-alkali production, or steam cracking.

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