Method and device for quantitative evaluation of carbon footprint of sulfuric acid recycling symbiotic utilization system throughout its life cycle

Abstract

A method and apparatus for quantitatively evaluating the carbon footprint of a sulfuric acid recycling and symbiotic utilization system over its entire life cycle is described. The method comprises: 1) dividing the sulfuric acid recycling and symbiotic utilization system into subsystems within its entire life cycle and determining the system boundaries for carbon footprint quantitative evaluation; 2) identifying the carbon emission sources of sulfuric acid in each subsystem based on the production process and constructing a carbon emission inventory; 3) determining the carbon emission calculation method for each emission source and constructing a carbon footprint quantitative evaluation model; and 4) establishing activity data and carbon emission factors for each carbon emission source to calculate the carbon footprint of the sulfuric acid recycling and symbiotic utilization system. This method can determine the emission reduction objective function for the sulfuric acid recycling and symbiotic utilization system over its entire life cycle, and develop a carbon footprint optimization plan for different recycling and symbiotic utilization scenarios.

Description

Technical Field

[0001] The present invention relates to the field of carbon footprint quantitative evaluation, and specifically to a method and device for quantitatively evaluating the full life cycle carbon footprint of a sulfuric acid recycling industrial symbiotic system in a system consisting of nitration reaction, diazotization reaction, coupling reaction of aromatic compounds, and acidolysis reaction of aromatic amines. Background Art

[0002] Sulfuric acid, a key chemical raw material, is widely used in the production of dyes and organic chemical intermediates. In these processes, it typically serves as a reaction medium (e.g., in nitration, diazotization, and coupling reactions) and can also serve as a raw material (e.g., in the acidolysis of aromatic amines). After use, sulfuric acid concentration typically decreases, generating significant amounts of acidic wastewater. Reducing waste generation and saving sulfuric acid usage through sulfuric acid recycling and symbiotic utilization has become an industry consensus, achieving synergistic improvements in pollution and carbon reduction.

[0003] However, limited research exists on carbon emissions from sulfuric acid recycling systems used in dye and organic chemical intermediate reactions, and a systematic, quantitative approach to assessing their effectiveness in reducing pollution and carbon emissions is lacking. Furthermore, sulfuric acid concentrations often vary significantly across production systems, and the types and quantities of materials and energy used in the waste sulfuric acid and its treatment also vary. Therefore, a method for calculating carbon emissions from sulfuric acid recycling systems needs to be established based on the actual operating conditions of the systems.

[0004] Sulfuric acid production mostly uses the sulfur-based acid production process. The large amount of chemical reaction heat released during the reaction process can be co-produced into electricity and steam, replacing fossil energy consumption and achieving good carbon reduction benefits. When the used sulfuric acid is recycled and symbiotically utilized, it is coupled with the sulfur-based acid production process to increase the concentration of dilute sulfuric acid by adding sulfur trioxide, reducing the energy consumption and cost of the dilute sulfuric acid concentration and purification process. It can also improve the adaptability of the nitration reaction, diazotization reaction, coupling reaction and aromatic amine acidolysis reaction system with different concentration gradients of sulfuric acid and aromatic compounds. However, existing research still lacks a method for quantifying and comprehensively optimizing the pollution reduction and carbon reduction performance of the system under different coupling strategies of multiple systems including sulfuric acid regeneration, symbiotic utilization and sulfur-based acid production.

[0005] In order to solve the problems existing in the existing technology, it is necessary to clarify the material flow and energy flow of the sulfuric acid recycling symbiotic utilization system, and construct a carbon footprint quantitative evaluation method for the sulfuric acid recycling symbiotic utilization system from the perspective of system engineering and the entire life cycle. The material flow, energy flow and carbon emissions of each link in the process of sulfuric acid preparation during the reaction of dyes and organic intermediates, dilute sulfuric acid concentration treatment, purification, recycling, symbiotic utilization, resource disposal, etc., are characterized, and a multi-objective comprehensive optimization method for pollution reduction and carbon reduction in the sulfuric acid recycling symbiotic utilization system is established. Summary of the Invention

[0006] The present invention aims to overcome the above-mentioned shortcomings of the prior art and provides a method and device for quantitatively evaluating the carbon footprint of a sulfuric acid recycling symbiotic utilization system throughout its life cycle.

[0007] The present invention is directed to production systems involving the use of sulfuric acid, such as the nitration reaction, diazotization reaction, coupling reaction, and acidolysis reaction of aromatic compounds, to construct a sulfuric acid recycling and symbiotic utilization system, quantify the carbon footprint of sulfuric acid of different concentrations under recycling, cascade utilization, resource treatment and disposal, and compare the carbon footprint differences when producing the same product but taking conventional measures, thereby identifying the key links in the carbon emission of sulfuric acid throughout its life cycle, evaluating the carbon emission reduction benefits achieved by different concentrations of sulfuric acid through different recycling symbiotic utilization methods, and identifying the preferred recycling symbiotic utilization scheme. The present invention can provide decision support for sulfuric acid production and use enterprises, helping to achieve the goal of pollution reduction and carbon reduction.

[0008] The method for quantitatively evaluating the carbon footprint of a sulfuric acid recycling and symbiotic utilization system throughout its life cycle comprises the following steps:

[0009] 1) Divide the subsystems in the entire life cycle of the sulfuric acid cycle symbiotic utilization system and determine the system boundaries for carbon footprint quantitative evaluation;

[0010] 2) Determine the carbon emission sources of sulfuric acid in each subsystem according to the production process and construct a carbon emission inventory;

[0011] 3) Determine the carbon emission calculation method for each emission source and build a carbon footprint quantitative evaluation model;

[0012] 4) Establish activity data and carbon emission factors for each carbon emission source and calculate the carbon footprint of the sulfuric acid recycling symbiotic utilization system.

[0013] Through the above method, the emission reduction objective function of the sulfuric acid recycling symbiotic utilization system throughout its life cycle can be determined, and a carbon footprint optimization plan can be formed for different recycling symbiotic utilization scenarios.

[0014] Preferably, the boundary of the sulfuric acid circulation symbiotic utilization system described in step 1) is all processes from sulfuric acid production to acidic wastewater treatment and disposal, including four subsystems: ① sulfuric acid use subsystem, ② sulfuric acid concentration circulation subsystem, ③ sulfuric acid symbiotic utilization subsystem, and ④ acidic wastewater disposal subsystem.

[0015] The carbon footprint calculation formula of the sulfuric acid circulation symbiotic utilization system is:

[0016] (1)

[0017] Where:

[0018] is the carbon footprint of the sulfuric acid cycle symbiotic utilization system, in kg CO2 eq;

[0019] It is Carbon emissions of each sulfuric acid use subsystem, in kg CO2 eq;

[0020] It is Carbon emissions from each sulfuric acid concentration cycle subsystem, in kg CO2 eq;

[0021] It is Carbon emissions from each sulfuric acid symbiotic utilization subsystem, in kg CO2 eq;

[0022] It is Carbon emissions from each acid wastewater treatment subsystem, in kg CO2 eq.

[0023] ① Sulfuric acid usage subsystem

[0024] The sulfuric acid utilization subsystem is as follows: sulfuric acid participates in a round of reaction process after preparation, and the dilute sulfuric acid produced after the reaction enters the subsequent treatment and disposal process in the form of acid-containing wastewater.

[0025] The carbon emission sources of the sulfuric acid use subsystem include: carbon emissions generated by the sulfuric acid preparation process and carbon emissions generated by the treatment of acid-containing wastewater.

[0026] The calculation formula for the carbon emissions of the sulfuric acid use subsystem is:

[0027] (2)

[0028] Where:

[0029] It is Carbon emissions of each sulfuric acid use subsystem, in kg CO2 eq;

[0030] It is The mass of new sulfuric acid used in each sulfuric acid using subsystem, in kg;

[0031] is the cradle-to-gate carbon emission factor for sulfuric acid, expressed in kg CO2 eq / kg.

[0032] The calculation of carbon emissions from the treatment of acidic wastewater generated by the sulfuric acid use subsystem refers to ④ Acidic wastewater treatment subsystem.

[0033] ②Sulfuric acid concentration circulation subsystem

[0034] The sulfuric acid concentration circulation subsystem is as follows: sulfuric acid is prepared and then participates in a round of reaction process, and the sulfuric acid after the reaction is concentrated and then recycled to the previous round of reaction process.

[0035] The carbon emission sources of the sulfuric acid concentration circulation subsystem include: carbon emissions generated by the sulfuric acid preparation process, carbon emissions generated by the energy consumed in the sulfuric acid concentration process, carbon emissions generated by chemical reagents such as sulfur trioxide added in some concentration processes, carbon emissions generated by the disposal of some acid-containing wastewater after sulfuric acid recycling, and carbon performance brought about by replacing part of the new sulfuric acid after sulfuric acid recycling.

[0036] The calculation formula for the carbon emissions of the sulfuric acid concentration circulation subsystem is:

[0037] (3)

[0038] Where:

[0039] It is Carbon emissions from each sulfuric acid concentration cycle subsystem, in kg CO2 eq;

[0040] It is Carbon emissions from the preparation of sulfuric acid required in each sulfuric acid concentration circulation subsystem, in kgCO2 eq;

[0041] For the Carbon emissions from sulfuric acid concentration treatment in each sulfuric acid concentration circulation subsystem, in kg CO2 eq;

[0042] For the The carbon performance of the sulfuric acid cycle in the sulfuric acid concentration cycle subsystem, in kg CO2 eq.

[0043] The calculation formula for the carbon emissions of sulfuric acid required in the reaction process during the preparation process is:

[0044] (3a)

[0045] Where:

[0046] It is Carbon emissions from the preparation of sulfuric acid required for the reaction process in each sulfuric acid concentration circulation subsystem, in kg CO2 eq / kg;

[0047] It is The mass of new sulfuric acid required for the reaction process in each sulfuric acid concentration circulation subsystem, in kg;

[0048] is the cradle-to-gate carbon emission factor for sulfuric acid, expressed in kg CO2 eq / kg.

[0049] The calculation formula for the emission of sulfuric acid concentration process is:

[0050] (3b)

[0051] Where:

[0052] It is Carbon emissions from the sulfuric acid concentration process in the sulfuric acid concentration cycle subsystem, in kg CO2 eq / kg;

[0053] is the amount of steam consumed in the sulfuric acid concentration process, in MJ;

[0054] is the carbon emission factor for steam, in kg CO2 eq / MJ;

[0055] is the electricity consumed in the sulfuric acid concentration process, in kW·h;

[0056] is the carbon emission factor of electricity, with the unit of kg CO2 eq / kW·h; some sulfuric acid concentration processes use fossil energy such as coal or natural gas, This is the first The amount of fossil energy in kg or Nm 3 ;

[0057] For the Carbon emission factor of each fossil energy source, in kg CO2 eq / kg or kg CO2 eq / Nm 3 ;

[0058] The first The mass of the chemical in kg;

[0059] For the The cradle-to-gate carbon emission factor for each chemical is expressed in kg CO2 eq / kg.

[0060] The calculation formula for the carbon performance of sulfuric acid cycle is:

[0061] (3c)

[0062] Where:

[0063] It is The carbon performance of the sulfuric acid cycle in the sulfuric acid concentration cycle subsystem, in kg CO2 eq;

[0064] is the mass of recycled sulfuric acid, in kg;

[0065] is the cradle-to-gate carbon emission factor for sulfuric acid, expressed in kg CO2 eq / kg.

[0066] The calculation of carbon emissions from the treatment of acidic wastewater generated by the sulfuric acid concentration circulation subsystem refers to ④ Acidic wastewater treatment subsystem.

[0067] ③Sulfate symbiotic utilization subsystem

[0068] The sulfuric acid symbiotic utilization subsystem is as follows: sulfuric acid participates in a round of reaction process after preparation, and the sulfuric acid after the reaction participates in another reaction process after purification, forming a layer of symbiotic relationship between the two different reaction processes. After one or more layers of symbiosis, the used sulfuric acid enters the subsequent treatment and disposal process in the form of acid-containing wastewater.

[0069] The carbon emission sources of the sulfuric acid symbiotic utilization subsystem include: carbon emissions generated by the sulfuric acid preparation process, carbon emissions generated by the activated carbon, flocculants, oxidants and other chemical reagents consumed in the sulfuric acid purification process, carbon emissions generated by the subsequent treatment and disposal of acid-containing wastewater, and carbon performance brought by replacing part of the new sulfuric acid during sulfuric acid symbiosis.

[0070] The calculation formula for the carbon emissions of the sulfuric acid symbiotic utilization subsystem is:

[0071] (4)

[0072] Where:

[0073] It is Carbon emissions from each sulfuric acid symbiotic utilization subsystem, in kg CO2 eq;

[0074] It is Carbon emissions from the preparation of sulfuric acid required for the reaction process in each sulfuric acid symbiotic utilization subsystem, in kg CO2 eq;

[0075] It is Carbon emissions generated by the sulfuric acid symbiotic utilization subsystem during the purification process, in kg CO2 eq;

[0076] It is The carbon performance of sulfuric acid symbiotic utilization in each sulfuric acid symbiotic utilization subsystem, unit is kg CO2 eq.

[0077] The carbon emission calculation formula for the preparation of sulfuric acid required for the reaction process is:

[0078] (4a)

[0079] Where:

[0080] It is Carbon emissions from the preparation of sulfuric acid required in each sulfuric acid symbiotic utilization subsystem, in kgCO2 eq;

[0081] It is The mass of new sulfuric acid required for the first reaction process in the sulfuric acid symbiotic utilization subsystem, in kg;

[0082] It is The mass of new sulfuric acid required for the second reaction process in the sulfuric acid symbiotic utilization subsystem, in kg;

[0083] is the cradle-to-gate carbon emission factor for sulfuric acid, expressed in kg CO2 eq / kg.

[0084] The calculation formula for carbon emissions during the purification process of the sulfuric acid symbiotic utilization subsystem is:

[0085] (4b)

[0086] Where:

[0087] It is Carbon emissions generated by the sulfuric acid symbiotic utilization subsystem during the purification process, in kg CO2 eq;

[0088] is the amount of electricity consumed by the sulfuric acid purification process, in kW·h;

[0089] is the carbon emission factor of electricity, in kg CO2 eq / kW·h;

[0090] It is consumed The amount of fossil energy in kg or Nm 3 ;

[0091] For the Carbon emission factor of the fossil energy source, in kg CO2 eq / kg or kg CO2 eq / Nm 3 ;

[0092] It is The sulfuric acid symbiotic utilization subsystem consumes the first The mass of the chemical reagent, in kg;

[0093] It is The cradle-to-gate carbon emission factors for these chemical reagents are expressed in kg CO2 eq / kg.

[0094] The calculation formula for the carbon performance of sulfuric acid symbiosis is:

[0095] (4c)

[0096] Where:

[0097] It is The carbon performance of sulfuric acid symbiotic utilization in each sulfuric acid symbiotic utilization subsystem, in kg CO2 eq;

[0098] It is The amount of new sulfuric acid saved through symbiotic utilization in each sulfuric acid symbiotic utilization subsystem, in kg;

[0099] is the cradle-to-gate carbon emission factor for sulfuric acid, expressed in kg CO2 eq / kg.

[0100] In the sulfuric acid symbiotic utilization subsystem, the calculation formula for the saved new sulfuric acid usage is:

[0101] (4c-1)

[0102] Where:

[0103] It is The amount of new sulfuric acid saved through symbiotic utilization in each sulfuric acid symbiotic utilization subsystem, in kg;

[0104] It is The mass fraction of sulfuric acid that enters the next reaction process after purification in each sulfuric acid symbiotic utilization subsystem, unit is %

[0105] It is The mass fraction of new sulfuric acid used in each sulfuric acid symbiotic utilization subsystem, expressed in %, is usually 98%;

[0106] It is The mass of sulfuric acid that enters the next reaction process after purification in each sulfuric acid symbiotic utilization subsystem, in kg.

[0107] The calculation of carbon emissions from the treatment of acidic wastewater generated by the sulfuric acid symbiotic utilization subsystem refers to ④ Acidic wastewater treatment subsystem.

[0108] ④Acidic wastewater treatment subsystem

[0109] The acid wastewater treatment subsystem is as follows: the acid wastewater generated in each production link is combined, neutralized, purified, concentrated and crystallized, and then converted into sulfate to achieve harmlessness and resource utilization.

[0110] The carbon emission sources of the acid wastewater treatment subsystem include: a) carbon emissions generated by the neutralization process of acid wastewater, b) carbon emissions from the acid wastewater purification process, c) carbon emissions from the acid wastewater concentration and crystallization process, and d) carbon performance of recovering by-product sulfate.

[0111] The calculation formula for carbon emissions of the acid wastewater treatment subsystem is:

[0112] (5)

[0113] Where:

[0114] It is Carbon emissions from each acid wastewater treatment subsystem, in kg CO2 eq;

[0115] It is Carbon emissions from the neutralization process of acidic wastewater in each acidic wastewater treatment subsystem, in kgCO2 eq;

[0116] It is Carbon emissions from the purification process in each acid wastewater treatment subsystem, in kg CO2 eq;

[0117] It is Carbon emissions from the concentration and crystallization process of each acid wastewater treatment subsystem, in kg CO2eq;

[0118] It is The carbon performance of by-produced sulfate in each acid wastewater treatment subsystem, in kg CO2 eq.

[0119] a) Carbon emissions from the neutralization process of acidic wastewater

[0120] The carbon emissions from the neutralization process of acidic wastewater include the carbon emissions generated by the energy used and the carbon emissions generated by the addition of alkaline chemicals such as ammonia or lime during the preparation process. The calculation formula is:

[0121] (5a)

[0122] Where:

[0123] It is Carbon emissions from the neutralization process of acidic wastewater in each acidic wastewater treatment subsystem, in kgCO2 eq;

[0124] is the amount of steam consumed in the neutralization process of acidic wastewater, in MJ;

[0125] is the carbon emission factor for steam, in kg CO2 eq / MJ;

[0126] It is the amount of electricity consumed in the neutralization process of acidic wastewater, in kW·h;

[0127] is the carbon emission factor of electricity, in kg CO2 eq / kW·h;

[0128] It is the first The mass of the chemical reagent, in kg;

[0129] It is The cradle-to-gate carbon emission factors for these chemical reagents are expressed in kg CO2 eq / kg.

[0130] b) Carbon emissions from the acid wastewater purification process

[0131] The carbon emissions from the acid wastewater purification process include the carbon emissions from electricity, fossil energy, and chemical reagents used in the purification process. The calculation formula is:

[0132] (5b)

[0133] Where:

[0134] It is Carbon emissions from the purification process in each acid wastewater treatment subsystem, in kg CO2 eq;

[0135] is the amount of electricity consumed in the acid wastewater purification process, in kW·h;

[0136] is the carbon emission factor of electricity, in kg CO2 eq / kW·h;

[0137] It is the first The amount of fossil energy consumed. When the fossil energy consumed is coal, the unit is kg. When the fossil energy consumed is natural gas, the unit is Nm 3 ;

[0138] For the Carbon emission factor of each fossil energy source, in kg CO2 eq / kg or kg CO2 eq / Nm 3 ;

[0139] It is the first The mass of the chemical reagent, in kg;

[0140] It is The cradle-to-gate carbon emission factors for these chemical reagents are expressed in kg CO2 eq / kg.

[0141] c) Carbon emissions from the concentration and crystallization process of acidic wastewater

[0142] The carbon emissions from the acid wastewater concentration and crystallization process include the carbon emissions from electricity, steam, and fossil energy used in the concentration and crystallization process. The calculation formula is:

[0143] (5c)

[0144] Where:

[0145] It is Carbon emissions from the concentration and crystallization process of each acid wastewater treatment subsystem, in kg CO2eq;

[0146] It is the amount of steam consumed in the process of concentration and crystallization of acid wastewater, the unit is MJ;

[0147] is the carbon emission factor for steam, in kg CO2 eq / MJ;

[0148] It is the amount of electricity consumed in the process of concentration and crystallization of acid wastewater, in kW·h;

[0149] is the carbon emission factor of electricity, in kg CO2 eq / kW·h;

[0150] It is the first The amount of fossil energy consumed. When the fossil energy consumed is coal, the unit is kg. When the fossil energy consumed is natural gas, the unit is Nm 3 ;

[0151] For the Carbon emission factor of the fossil energy source, in kg CO2 eq / kg or kg CO2 eq / Nm 3 .

[0152] d) Carbon performance of recovering by-product sulfate

[0153] The calculation formula for the carbon performance of the by-product sulfate in the acid wastewater treatment subsystem is:

[0154] (5d)

[0155] Where:

[0156] It is Carbon performance of by-produced sulfate in each acid wastewater treatment subsystem, in kg CO2 eq;

[0157] It is The mass of by-product sulfate in each acid wastewater treatment subsystem, in kg;

[0158] is the cradle-to-gate carbon emission factor for this sulfate, expressed in kg CO2 eq / kg.

[0159] The target parameters in the life cycle emission reduction objective function of the sulfuric acid circulation symbiotic utilization system described in step 5) include: carbon emissions of the system throughout its life cycle, acid-containing wastewater disposal and discharge, and operating costs and benefits of the system throughout its life cycle.

[0160] The variables used in setting different recycling and symbiotic utilization scenarios include: the amount of sulfuric acid of different concentrations that is concentrated, recycled, symbiotically utilized, and directly treated as acidic wastewater.

[0161] The second aspect of the present invention relates to a device for quantitatively evaluating the carbon footprint of a sulfuric acid circulation symbiotic utilization system throughout its entire life cycle, comprising a memory and one or more processors, wherein the memory stores executable code. When the one or more processors execute the executable code, they are used to implement the method for quantitatively evaluating and optimizing the carbon footprint of a sulfuric acid circulation symbiotic utilization system throughout its entire life cycle of the present invention.

[0162] The advantages of the present invention are: a full life cycle carbon emission inventory and carbon footprint quantitative evaluation model for a sulfuric acid circulation and symbiotic utilization system with a more complete system, clearer modular unit processes, and wider applicability is constructed. A corresponding carbon emission calculation method is constructed for the entire life cycle of sulfuric acid from production to use to waste treatment and disposal, which improves the comprehensiveness and usability of the model, can provide decision makers with more complete and comprehensive carbon emission data, and promote the reduction of the overall carbon footprint of the sulfuric acid industry chain. The use process of sulfuric acid is divided into three categories: new sulfuric acid use, sulfuric acid concentration cycle, and sulfuric acid symbiotic utilization. Different processes can be flexibly combined according to the requirements of the product system and the reaction system for sulfuric acid concentration and quality, forming a widely applicable sulfuric acid use system carbon footprint accounting model, so that the carbon emission benefits of different sulfuric acid use modes can be scientifically quantified.

[0163] On this basis, an optimization method for the sulfuric acid recycling symbiotic utilization system is established, which can provide data support for decision makers to optimize the reaction process and use sulfuric acid efficiently and in a low-carbon manner. BRIEF DESCRIPTION OF THE DRAWINGS

[0164] Figure 1 Schematic diagram of the process of the present invention;

[0165] Figure 2 Schematic diagram of the boundaries of the sulfuric acid circulation symbiotic utilization system and subsystems in the present invention.

[0166] Figure 3 Schematic diagram of the sulfuric acid recycling and symbiotic utilization system in the dye and intermediate production system.

[0167] Figure 4 This is the carbon footprint distribution diagram of the sulfuric acid symbiotic utilization system in the dye intermediate production system.

[0168] Figure 5 Schematic diagram of the device for quantitatively evaluating the carbon footprint of the entire life cycle of the sulfuric acid recycling symbiotic utilization system in the present invention. DETAILED DESCRIPTION

[0169] To better understand the technical solutions and effects of the present invention, the following will be described in detail and clearly in conjunction with the embodiments of the present invention with reference to the accompanying drawings. However, it should be understood that these descriptions are merely exemplary and not exhaustive. They are intended only to facilitate a better understanding of the present invention by those skilled in the art, and are not intended to limit the scope of protection of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative effort fall within the scope of protection of the present invention.

[0170] In addition, in the following description, descriptions of common knowledge and technologies are omitted to avoid unnecessary confusion about the concepts of the present disclosure. All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein should be interpreted as having meanings consistent with the context of this specification and should not be interpreted in an idealized or overly rigid manner.

[0171] Example 1

[0172] like Figure 1 As shown, a method for quantitatively evaluating the carbon footprint of a sulfuric acid recycling symbiotic utilization system over its entire life cycle includes the following steps:

[0173] 1) Divide the subsystems in the entire life cycle of the sulfuric acid cycle symbiotic utilization system and determine the system boundaries for carbon footprint quantitative evaluation;

[0174] 2) Determine the carbon emission sources of sulfuric acid in each subsystem according to the production process and construct a carbon emission inventory;

[0175] 3) Determine the carbon emission calculation method for each emission source and build a carbon footprint quantitative evaluation model;

[0176] 4) Establish activity data and carbon emission factors for each carbon emission source and calculate the carbon footprint of the sulfuric acid cycle symbiotic utilization system;

[0177] 5) Determine the emission reduction objective function for the sulfuric acid recycling symbiotic utilization system throughout its life cycle, and formulate a carbon footprint optimization plan for different recycling symbiotic utilization scenarios.

[0178] like Figure 2 As shown, the boundary of the sulfuric acid circulation symbiotic utilization system is all processes of the entire life cycle of sulfuric acid from production to treatment and disposal of acidic wastewater, including four subsystems: ① sulfuric acid use subsystem, ② sulfuric acid concentration circulation subsystem, ③ sulfuric acid symbiotic utilization subsystem, and ④ acidic wastewater disposal subsystem.

[0179] In the present invention, by dividing the sulfuric acid circulation symbiotic utilization system into different subsystems, the carbon emissions of different sulfuric acid usage modes can be more clearly identified, calculated and managed. By separately calculating the carbon emissions of each subsystem, the carbon emission differences of sulfuric acid with the same concentration under different usage modes can be more intuitively compared, and then targeted emission reduction measures can be taken in the construction of the production process system and process optimization. Different types and different subsystems of the same type can be combined with each other to simulate the complex system of sulfuric acid circulation symbiotic utilization with multiple reaction processes, sulfuric acid of different concentrations, and integrated coupling of diversified subsystems in actual chemical scenarios, so that the applicability of the carbon footprint accounting method of the present invention is more extensive.

[0180] ① Sulfuric acid usage subsystem

[0181] The sulfuric acid utilization subsystem represents the basic model for sulfuric acid use in chemical reactions, spanning the entire process from sulfuric acid production to its conversion into acidic wastewater for disposal. Within this subsystem, sulfuric acid, after preparation, is fed into a specific reaction process. After reacting with other raw and auxiliary materials, it forms acidic wastewater and enters the subsequent recycling, symbiotic, and treatment and disposal stages. In this subsystem, sulfuric acid carbon emissions originate from both the sulfuric acid production process and the acidic wastewater disposal process. Calculating the carbon emissions from this subsystem allows for a quantitative assessment of emissions from chemical production systems without any sulfuric acid recycling or symbiotic utilization measures, providing a benchmark for evaluating the carbon reduction performance of these recycling or symbiotic utilization measures.

[0182] ②Sulfuric acid concentration circulation subsystem

[0183] The sulfuric acid concentration cycle subsystem includes sulfuric acid production, sulfuric acid use, sulfuric acid concentration treatment, and sulfuric acid recycling. In this subsystem, used sulfuric acid is concentrated through physical or chemical methods and then reused in the reaction process, replacing fresh sulfuric acid. The carbon footprint calculation for this subsystem includes the carbon emissions generated during the preparation of fresh sulfuric acid entering the subsystem, the carbon emissions generated during the concentration and disposal of the dilute sulfuric acid produced after the reaction, and the carbon performance of the sulfuric acid cycle. The carbon emissions from the dilute sulfuric acid concentration and disposal process vary depending on the sulfuric acid concentration required for different reaction processes. Higher concentrations of dilute sulfuric acid increase the energy and chemicals consumed during the concentration process, resulting in higher carbon emissions and lower overall carbon performance for the concentration cycle subsystem. By calculating the carbon footprint of this subsystem, we can quantitatively characterize the carbon emissions of the sulfuric acid concentration cycle at different concentrations and accurately assess whether the overall process is carbon-enhancing or carbon-reducing, thereby helping decision-makers design more scientifically-based, lower-carbon sulfuric acid circulation systems.

[0184] ③Sulfate symbiotic utilization subsystem

[0185] The sulfuric acid symbiotic utilization subsystem consists of at least two reaction processes in series. In this subsystem, sulfuric acid is prepared and fed into the reaction process. After the reaction, the concentration is reduced. This lower-concentration sulfuric acid is purified and used as a raw material to feed another reaction process with a lower sulfuric acid concentration requirement, replacing part of the new sulfuric acid. This forms a layer of sulfuric acid symbiotic relationship between the two different reaction processes. In engineering practice, one or more layers of sulfuric acid symbiotic relationships can be constructed based on the sulfuric acid concentration required by different reaction processes and the change in sulfuric acid concentration after the reaction, so that the sulfuric acid is fully utilized. Finally, the part that is difficult to utilize enters the subsequent treatment and disposal process in the form of acid-containing wastewater. Because the sulfuric acid concentration and corresponding purification process involved in each layer of sulfuric acid symbiotic relationship are different, carbon emissions need to be calculated separately. Therefore, the method constructed by the present invention divides each layer of sulfuric acid symbiotic relationship into a sulfuric acid symbiotic utilization subsystem. By calculating the carbon footprint of this subsystem, the carbon emissions caused by purification and the carbon performance caused by replacing new sulfuric acid in the sulfuric acid symbiotic utilization process can be fully quantified, and the carbon performance of sulfuric acid symbiotic utilization systems with different concentration gradients can be accurately evaluated. By calculating the carbon emissions of multiple sulfuric acid symbiotic utilization subsystems separately and then adding them up, the carbon emissions of multi-layer sulfuric acid symbiotic relationships can be quantitatively evaluated, achieving a quantitative characterization of the carbon emissions of complex sulfuric acid symbiotic utilization systems, and assisting in the low-carbon design and optimization of the overall system.

[0186] ④Acidic wastewater treatment subsystem

[0187] The acid wastewater treatment subsystem is the final stage of the sulfuric acid lifecycle. After passing through various use stages, sulfuric acid enters this subsystem as acid wastewater. Within this subsystem, sulfuric acid is first converted to sulfate through a neutralization reaction with alkaline substances containing ammonia, magnesium, and calcium. Purification then removes the sulfate and impurities in the solution. The sulfate is then separated through efficient concentration and crystallization processes such as steam mechanical recompression (MVR) and multiple-effect evaporation, ultimately achieving efficient sulfuric acid utilization. Carbon emissions from this subsystem primarily come from the chemicals and energy used in the neutralization and purification processes. Sulfate recovery contributes to a certain carbon footprint. Currently, ammonia neutralization is primarily used to produce ammonium sulfate as a byproduct. Other processes also produce magnesium sulfate or calcium sulfate, which are then further disposed of as hazardous waste. By calculating the carbon footprint of this subsystem, we can quantify the carbon emissions of different treatment processes for sulfuric acid of varying concentrations, helping decision-makers select lower-carbon treatment options based on the synergistic benefits of pollution and carbon reduction.

[0188] In the sulfuric acid circulation and symbiotic utilization system, the sulfuric acid use process produces carbon emissions, while the sulfuric acid concentration circulation process, sulfuric acid symbiotic utilization process and acidic wastewater disposal process all involve carbon emissions and carbon performance at the same time, and vary with the differences in sulfuric acid concentration and actual operating conditions of each chemical process. This requires a more systematic and comprehensive approach to evaluate the carbon footprint of the entire life cycle.

[0189] In the full life cycle carbon footprint accounting of the sulfuric acid recycling symbiotic utilization system, the use process of sulfuric acid is divided into four subsystems based on production practice. The flexible combination of different subsystems can construct a diversified sulfuric acid recycling symbiotic utilization system, thereby depicting the carbon footprint of the sulfuric acid recycling symbiotic utilization system in different product systems and supporting decision makers in selecting appropriate solutions.

[0190] Specifically, the carbon emissions calculation method of the sulfuric acid circulation symbiotic utilization system is as follows:

[0191] It should be noted that the calculation of carbon emissions from the acidic wastewater treatment and disposal processes involved in ① sulfuric acid utilization subsystem, ② sulfuric acid concentration circulation subsystem, and ③ sulfuric acid symbiotic utilization subsystem is the same as the carbon emissions calculation method in ④ acidic wastewater disposal subsystem, and will not be repeated here.

[0192] ① Sulfuric acid usage subsystem

[0193] The calculation formula for the carbon emissions of the sulfuric acid use subsystem is:

[0194] (2)

[0195] Where:

[0196] It is Carbon emissions of each sulfuric acid use subsystem, in kg CO2 eq;

[0197] It is The mass of new sulfuric acid used in each sulfuric acid using subsystem, in kg;

[0198] is the cradle-to-gate carbon emission factor for sulfuric acid, expressed in kg CO2 eq / kg.

[0199] ②Sulfuric acid concentration circulation subsystem

[0200] The calculation formula for the carbon emissions of the sulfuric acid concentration circulation subsystem is:

[0201] (3)

[0202] Where:

[0203] It is Carbon emissions from each sulfuric acid concentration cycle subsystem, in kg CO2 eq;

[0204] It is Carbon emissions from the preparation of sulfuric acid required in each sulfuric acid concentration circulation subsystem, in kgCO2 eq;

[0205] For the Carbon emissions from sulfuric acid concentration treatment in each sulfuric acid concentration circulation subsystem, in kg CO2 eq;

[0206] For the The carbon performance of the sulfuric acid cycle in the sulfuric acid concentration cycle subsystem, in kg CO2 eq.

[0207] In the sulfuric acid concentration circulation subsystem, sulfuric acid enters the reaction process as a reaction raw material. This part of sulfuric acid will produce indirect carbon emissions during the preparation process. The carbon emissions of sulfuric acid required for the reaction process during the preparation process are calculated as follows:

[0208] (3a)

[0209] Where:

[0210] It is Carbon emissions from the preparation of sulfuric acid required for the reaction process in each sulfuric acid concentration circulation subsystem, in kg CO2 eq / kg;

[0211] It is The mass of new sulfuric acid required for the reaction process in each sulfuric acid concentration circulation subsystem, in kg;

[0212] is the cradle-to-gate carbon emission factor for sulfuric acid, expressed in kg CO2 eq / kg.

[0213] The concentration of sulfuric acid decreases during the reaction process. If it is recycled, it needs to be concentrated and purified. For example, physical concentration processes such as vacuum concentration and kettle concentration can be used to heat and concentrate to remove water to increase the concentration of sulfuric acid. It can also be concentrated by adding sulfur trioxide. The carbon emissions of this process come from the energy consumed and the addition of chemical reagents such as sulfur trioxide. The formula for calculating the emissions from the sulfuric acid concentration process is:

[0214] (3b)

[0215] Where:

[0216] It is Carbon emissions from the sulfuric acid concentration process in the sulfuric acid concentration cycle subsystem, in kg CO2 eq / kg;

[0217] is the amount of steam consumed in the sulfuric acid concentration process, in MJ;

[0218] is the carbon emission factor for steam, in kg CO2 eq / MJ;

[0219] is the electricity consumed in the sulfuric acid concentration process, in kW·h;

[0220] is the carbon emission factor of electricity, with the unit of kg CO2 eq / kW·h; some sulfuric acid concentration processes use fossil energy such as coal or natural gas, This is the first The amount of fossil energy in kg or Nm 3 ;

[0221] For the Carbon emission factor of the fossil energy source, in kg CO2 eq / kg or kg CO2 eq / Nm 3 ;

[0222] The first The mass of the chemical in kg;

[0223] For the The cradle-to-gate carbon emission factor for each chemical is expressed in kg CO2 eq / kg.

[0224] The concentrated sulfuric acid can be recycled back into the reaction process, saving the amount of new sulfuric acid. The carbon performance calculation formula for sulfuric acid recycling is:

[0225] (3c)

[0226] Where:

[0227] It is The carbon performance of the sulfuric acid cycle in the sulfuric acid concentration cycle subsystem, in kg CO2 eq;

[0228] is the mass of recycled sulfuric acid, in kg;

[0229] is the cradle-to-gate carbon emission factor for sulfuric acid, expressed in kg CO2 eq / kg.

[0230] ③Sulfate symbiotic utilization subsystem

[0231] The calculation formula for the carbon emissions of the sulfuric acid symbiotic utilization subsystem is:

[0232] (4)

[0233] Where:

[0234] It is Carbon emissions from each sulfuric acid symbiotic utilization subsystem, in kg CO2 eq;

[0235] It is Carbon emissions from the preparation of sulfuric acid required for the reaction process in each sulfuric acid symbiotic utilization subsystem, in kg CO2 eq;

[0236] It is Carbon emissions generated by the sulfuric acid symbiotic utilization subsystem during the purification process, in kg CO2 eq;

[0237] It is The carbon performance of sulfuric acid symbiotic utilization in each sulfuric acid symbiotic utilization subsystem, unit is kg CO2 eq.

[0238] The sulfuric acid symbiotic utilization subsystem involves two different reaction processes. Each reaction process requires a certain amount of sulfuric acid, which will generate carbon emissions during the preparation process. The calculation formula is:

[0239] (4a)

[0240] Where:

[0241] It is Carbon emissions from the preparation of sulfuric acid required in each sulfuric acid symbiotic utilization subsystem, in kgCO2 eq;

[0242] It is The mass of new sulfuric acid required for the first reaction process in the sulfuric acid symbiotic utilization subsystem, in kg;

[0243] It is The mass of new sulfuric acid required for the second reaction process in the sulfuric acid symbiotic utilization subsystem, in kg;

[0244] is the cradle-to-gate carbon emission factor for sulfuric acid, expressed in kg CO2 eq / kg.

[0245] In the sulfuric acid symbiotic utilization subsystem, the sulfuric acid produced after the first reaction process needs to be purified to remove impurities to prevent these impurities from interfering with the second reaction process and the quality of the product. The calculation formula for the carbon emissions from the purification process of the sulfuric acid symbiotic utilization subsystem is:

[0246] (4b)

[0247] Where:

[0248] It is Carbon emissions generated by the sulfuric acid symbiotic utilization subsystem during the purification process, in kg CO2 eq;

[0249] is the amount of electricity consumed by the sulfuric acid purification process, in kW·h;

[0250] is the carbon emission factor of electricity, in kg CO2 eq / kW·h;

[0251] It is consumed The amount of fossil energy in kg or Nm 3 ;

[0252] For the Carbon emission factor of the fossil energy source, in kg CO2 eq / kg or kg CO2 eq / Nm 3 ;

[0253] It is The sulfuric acid symbiotic utilization subsystem consumes the first The mass of the chemical reagent, in kg;

[0254] It is The cradle-to-gate carbon emission factors for these chemical reagents are expressed in kg CO2 eq / kg.

[0255] The sulfuric acid produced in the first reaction process is purified and can enter the second reaction process to replace part of the new sulfuric acid in the second reaction process, thereby reducing the use of new sulfuric acid and the carbon emissions generated by its preparation process, thereby generating carbon emission reduction performance. The calculation formula for the carbon performance of symbiotic utilization of sulfuric acid is:

[0256] (4c)

[0257] Where:

[0258] It is The carbon performance of sulfuric acid symbiotic utilization in each sulfuric acid symbiotic utilization subsystem, in kg CO2 eq;

[0259] It is The amount of new sulfuric acid saved through symbiotic utilization in each sulfuric acid symbiotic utilization subsystem, in kg;

[0260] is the cradle-to-gate carbon emission factor for sulfuric acid, expressed in kg CO2 eq / kg.

[0261] The calculation formula for the amount of new sulfuric acid saved through symbiotic utilization is:

[0262] (4c-1)

[0263] Where:

[0264] It is The amount of new sulfuric acid saved through symbiotic utilization in each sulfuric acid symbiotic utilization subsystem, in kg;

[0265] It is The mass fraction of sulfuric acid that enters the next reaction process after purification in each sulfuric acid symbiotic utilization subsystem, unit is %

[0266] It is The mass fraction of new sulfuric acid used in each sulfuric acid symbiotic utilization subsystem, expressed in %, is usually 98%;

[0267] It is The mass of sulfuric acid that enters the next reaction process after purification in each sulfuric acid symbiotic utilization subsystem, in kg.

[0268] ④Acidic wastewater treatment subsystem

[0269] The calculation formula for the carbon emissions of the acid wastewater treatment subsystem is:

[0270] (5)

[0271] Where:

[0272] It is Carbon emissions from each acid wastewater treatment subsystem, in kg CO2 eq;

[0273] It is Carbon emissions from the neutralization process of acidic wastewater in each acidic wastewater treatment subsystem, in kgCO2 eq;

[0274] It is Carbon emissions from the purification process in each acid wastewater treatment subsystem, in kg CO2 eq;

[0275] It is Carbon emissions from the concentration and crystallization process of each acid wastewater treatment subsystem, in kg CO2eq;

[0276] It is The carbon performance of by-produced sulfate in each acid wastewater treatment subsystem, in kg CO2 eq.

[0277] The calculation formula for carbon emissions from the neutralization process of acidic wastewater is:

[0278] (5a)

[0279] Where:

[0280] It is Carbon emissions from the neutralization process of acidic wastewater in each acidic wastewater treatment subsystem, in kgCO2 eq;

[0281] is the amount of steam consumed in the neutralization process of acidic wastewater, in MJ;

[0282] is the carbon emission factor for steam, in kg CO2 eq / MJ;

[0283] It is the amount of electricity consumed in the neutralization process of acidic wastewater, in kW·h;

[0284] is the carbon emission factor of electricity, in kg CO2 eq / kW·h;

[0285] It is the first The mass of the chemical reagent, in kg;

[0286] It is The cradle-to-gate carbon emission factors for these chemical reagents are expressed in kg CO2 eq / kg.

[0287] After neutralization, the wastewater needs to be purified, for example, by using activated carbon adsorption, membrane filtration, etc., to remove impurities in the wastewater and improve the purity of sulfate, thus laying the foundation for sulfate recovery. The carbon emissions of this process include the carbon emissions generated by the electricity, fossil energy, and chemical reagents used in the purification process, and the calculation formula is:

[0288] (5b)

[0289] Where:

[0290] It is Carbon emissions from the purification process in each acid wastewater treatment subsystem, in kg CO2 eq;

[0291] is the amount of electricity consumed in the acid wastewater purification process, in kW·h;

[0292] is the carbon emission factor of electricity, in kg CO2 eq / kW·h;

[0293] It is the first The amount of fossil energy consumed. When the fossil energy consumed is coal, the unit is kg. When the fossil energy consumed is natural gas, the unit is Nm 3 ;

[0294] For the Carbon emission factor of the fossil energy source, in kg CO2 eq / kg or kg CO2 eq / Nm 3 ;

[0295] It is the first The mass of the chemical reagent, in kg;

[0296] It is The cradle-to-gate carbon emission factors for these chemical reagents are expressed in kg CO2 eq / kg.

[0297] After purification, the purity of sulfate in the wastewater is already high. At this time, it is necessary to extract the sulfate in the wastewater in solid form through concentration and crystallization, so as to ultimately achieve efficient resource symbiosis of sulfuric acid as a by-product. This process can be carried out through processes such as steam mechanical recompression (MVR) and multi-effect evaporation. These processes all require the consumption of energy such as electricity and steam, and some processes also require the consumption of fossil energy such as coal or natural gas. The carbon emissions from the acid wastewater concentration and crystallization process come from the consumption of steam, electricity and fossil energy. The carbon emissions calculation formula is:

[0298] (5c)

[0299] Where:

[0300] It is Carbon emissions from the concentration and crystallization process of each acid wastewater treatment subsystem, in kg CO2eq;

[0301] It is the amount of steam consumed in the process of concentration and crystallization of acid wastewater, the unit is MJ;

[0302] is the carbon emission factor for steam, in kg CO2 eq / MJ;

[0303] It is the amount of electricity consumed in the process of concentration and crystallization of acid wastewater, in kW·h;

[0304] is the carbon emission factor of electricity, in kg CO2 eq / kW·h;

[0305] It is the first The amount of fossil energy consumed. When the fossil energy consumed is coal, the unit is kg. When the fossil energy consumed is natural gas, the unit is Nm 3 ;

[0306] For the Carbon emission factor of the fossil energy source, in kg CO2 eq / kg or kg CO2 eq / Nm 3 .

[0307] After concentration and crystallization, the acid wastewater treatment subsystem can recover by-product sulfate. These sulfates can be put into production as raw materials for other chemical reaction processes, replacing sulfate produced by other processes, thereby generating a certain amount of carbon emission reduction performance. The calculation formula is:

[0308] (5d)

[0309] Where:

[0310] It is Carbon performance of by-produced sulfate in each acid wastewater treatment subsystem, in kg CO2 eq;

[0311] It is The mass of by-product sulfate in each acid wastewater treatment subsystem, in kg;

[0312] is the cradle-to-gate carbon emission factor for this sulfate, expressed in kg CO2 eq / kg.

[0313] In actual production systems, a sulfuric acid recycling and symbiotic utilization system may simultaneously include multiple different sulfuric acid use subsystems, sulfuric acid concentration and circulation subsystems, sulfuric acid symbiotic utilization subsystems, and acid wastewater disposal subsystems. Therefore, after calculating the carbon footprint of each subsystem separately, it is necessary to combine the subsystems according to the actual production process system. When combining, the product types and quantities of each subsystem must be consistent with the actual operating conditions. The corresponding carbon footprints of each subsystem are then converted and finally added together to obtain the carbon footprint of the entire sulfuric acid recycling and symbiotic system.

[0314] The carbon footprint calculation formula of the sulfuric acid circulation symbiotic utilization system is:

[0315] (1)

[0316] Where:

[0317] is the carbon footprint of the sulfuric acid cycle symbiotic utilization system, in kg CO2 eq;

[0318] It is Carbon emissions of each sulfuric acid use subsystem, in kg CO2 eq;

[0319] It is Carbon emissions from each sulfuric acid concentration cycle subsystem, in kg CO2 eq;

[0320] It is Carbon emissions from each sulfuric acid symbiotic utilization subsystem, in kg CO2 eq;

[0321] It is Carbon emissions from each acid wastewater treatment subsystem, in kg CO2 eq.

[0322] Example 2

[0323] This example takes the cyclic symbiotic utilization of sulfuric acid in dyes and intermediate products as an example, and combines actual statistical experimental data to fully illustrate the full life cycle carbon footprint quantitative evaluation method of a sulfuric acid cyclic symbiotic utilization system provided by the present invention. Figure 3 shown.

[0324] The boundary of the system is the entire life cycle from sulfuric acid production to sulfuric acid use and then to final treatment and disposal, including three reaction processes: benzene nitration, reduced product nitration and diamine hydrolysis.

[0325] In a basic production system—that is, one without any sulfuric acid recycling or symbiotic utilization measures—the system can be divided into three sulfuric acid-using subsystems and three corresponding acidic wastewater treatment subsystems based on the reaction process. After sulfuric acid production is completed, it enters the reaction processes of benzene nitration, dye diazo coupling, reduced product nitration, and m-phenylenediamine hydrolysis, generating acidic wastewater of varying concentrations. This wastewater is then treated and utilized as a resource through neutralization, purification, concentration, and crystallization. By collecting sulfuric acid consumption in each sulfuric acid-using subsystem and energy and chemical reagent consumption in the acidic wastewater treatment subsystem, the carbon footprint of this system can be calculated.

[0326] like Figure 3 , in the basic production system:

[0327] I. Sulfuric acid use subsystem

[0328] The sulfuric acid usage data is shown in Table 1.

[0329] Table 1 List of emission activity data for the sulfuric acid use subsystem

[0330]

[0331] The carbon emissions of the sulfuric acid use subsystem are derived from the carbon emissions generated during the sulfuric acid preparation process. The calculation formula is:

[0332] (2a)

[0333] Where:

[0334] is the carbon emission of the sulfuric acid use subsystem, in kg CO2 eq;

[0335] It is The mass of new sulfuric acid used in each sulfuric acid using subsystem, in kg;

[0336] It is The mass concentration of new sulfuric acid used in each sulfuric acid-using subsystem;

[0337] is the cradle-to-gate carbon emission factor for sulfuric acid, expressed in kg CO2 eq / kg.

[0338] The calculation process is as follows:

[0339]

[0340] The carbon footprint of the sulfuric acid use subsystem is calculated using the data in Table 1 to be 3293.63 kg CO2 eq.

[0341] II. Acidic wastewater treatment subsystem

[0342] The emission source activity data of the acid wastewater treatment subsystem are shown in Table 2.

[0343] Table 2 Emission source activity data of acid wastewater treatment subsystem

[0344]

[0345] The calculation formula for carbon emissions from the neutralization process of acidic wastewater is:

[0346] (5a-1)

[0347] Where:

[0348] It is Carbon emissions from the neutralization process of acidic wastewater in each acidic wastewater treatment subsystem, in kgCO2 eq;

[0349] It is the amount of electricity consumed in the neutralization process of acidic wastewater, in kW·h;

[0350] is the carbon emission factor of electricity, in kg CO2 eq / kW·h;

[0351] It is the first The mass of the chemical reagent, in kg;

[0352] It is The cradle-to-gate carbon emission factors for these chemical reagents are expressed in kg CO2 eq / kg.

[0353] The calculation process is as follows:

[0354]

[0355] The carbon emission calculation formula for the wastewater purification process is:

[0356] (5b)

[0357] Where:

[0358] It is Carbon emissions from the purification process in each acid wastewater treatment subsystem, in kg CO2 eq;

[0359] is the amount of electricity consumed in the acid wastewater purification process, in kW·h;

[0360] is the carbon emission factor of electricity, in kg CO2 eq / kW·h;

[0361] It is the first The amount of fossil energy consumed. When the fossil energy consumed is coal, the unit is kg. When the fossil energy consumed is natural gas, the unit is Nm 3 ;

[0362] For the Carbon emission factor of the fossil energy source, in kg CO2 eq / kg or kg CO2 eq / Nm 3 ;

[0363] It is the first The mass of the chemical reagent, in kg;

[0364] It is The cradle-to-gate carbon emission factors for these chemical reagents are expressed in kg CO2 eq / kg.

[0365] The calculation process is as follows:

[0366]

[0367] After purification, sulfate in the wastewater is extracted in solid form through concentrated crystallization. The carbon emission calculation formula for this process is:

[0368] (5c-1)

[0369] Where:

[0370] It is Carbon emissions from the concentration and crystallization process of each acid wastewater treatment subsystem, in kg CO2eq;

[0371] It is the amount of steam consumed in the process of concentration and crystallization of acidic wastewater, in kg;

[0372] is the carbon emission factor of steam, in kg CO2 eq / kg;

[0373] It is the amount of electricity consumed in the process of concentration and crystallization of acid wastewater, in kW·h;

[0374] is the carbon emission factor of electricity, with the unit being kg CO2 eq / kW·h.

[0375] The calculation process is as follows:

[0376]

[0377] After concentration and crystallization, the acid wastewater treatment subsystem can recover by-product sulfate. These sulfates can be put into production as raw materials for other chemical reaction processes, replacing sulfate produced by other processes, thereby generating a certain amount of carbon emission reduction performance. The calculation formula is:

[0378] (5d)

[0379] Where:

[0380] It is Carbon performance of by-produced sulfate in each acid wastewater treatment subsystem, in kg CO2 eq;

[0381] It is The mass of by-product sulfate in each acid wastewater treatment subsystem, in kg;

[0382] is the cradle-to-gate carbon emission factor for this sulfate, expressed in kg CO2 eq / kg.

[0383] The calculation process is as follows:

[0384]

[0385] The calculation formula for carbon emissions from the acid wastewater treatment subsystem is:

[0386] (5)

[0387] Where:

[0388] It is Carbon emissions from each acid wastewater treatment subsystem, in kg CO2 eq;

[0389] It is Carbon emissions from the neutralization process of acidic wastewater in each acidic wastewater treatment subsystem, in kgCO2 eq;

[0390] It is Carbon emissions from the purification process in each acid wastewater treatment subsystem, in kg CO2 eq;

[0391] It is Carbon emissions from the concentration and crystallization process of each acid wastewater treatment subsystem, in kg CO2eq;

[0392] It is The carbon performance of by-produced sulfate in each acid wastewater treatment subsystem, in kg CO2 eq.

[0393] The calculation process is as follows:

[0394]

[0395] III. Summary of the carbon footprint of sulfuric acid throughout the entire life cycle of the basic production system

[0396] The calculation formula for the carbon footprint of sulfuric acid throughout its life cycle in the basic production system is:

[0397] (1a)

[0398] Where:

[0399] is the carbon footprint of sulfuric acid over its entire life cycle in the basic production system, in kg CO2 eq;

[0400] It is Carbon emissions of each sulfuric acid use subsystem, in kg CO2 eq;

[0401] It is Carbon emissions from each acid wastewater treatment subsystem, in kg CO2 eq.

[0402] The calculation process is as follows:

[0403]

[0404] After the production process, the product data of the basic production system is shown in Table 3.

[0405] Table 3 Basic production system product data

[0406]

[0407] Calculations show that when producing the product mix shown in Table 3, the sulfuric acid carbon footprint of the basic production system is 37,259.66 kg CO₂ eq. The carbon footprints of the three sulfuric acid use subsystems, corresponding to benzene nitration, reduced product nitration, and diamine hydrolysis, account for 2.73%, 2.60%, and 3.51% of the total system carbon footprint, respectively. Carbon emissions from the acid wastewater disposal subsystem are 33,966.02 kg CO₂ eq, of which 24,240.18 kg CO₂ eq is contributed by recovering the by-product ammonium sulfate. Acid wastewater disposal is a significant source of carbon emissions; its carbon emissions can be effectively reduced through its resource utilization and the subsequent production of ammonium sulfate.

[0408] Building upon the basic production system, a sulfuric acid recycling and symbiotic utilization system was implemented. In this system, sulfuric acid production enters the benzene nitration process. The resulting acidic wastewater, with a sulfuric acid concentration of 69%, is concentrated and disposed of. A portion is concentrated to 98% sulfuric acid and recycled back to the benzene nitration process, forming a sulfuric acid concentration subsystem within the system. Another portion, concentrated to 93%, then serves as a feedstock in the reductant nitration process for the production of the reductant. After the reaction, this acidic wastewater has a sulfuric acid concentration of 28%. A third portion enters the dye diazo coupling process, where it becomes wastewater with a sulfuric acid concentration of 5%, forming the first sulfuric acid symbiotic utilization subsystem within the system. After sulfuric acid purification, the 28% acidic wastewater is again used as a feedstock in the diamine hydrolysis process for the production of hydroquinone. After the reaction, this acidic wastewater has a sulfuric acid concentration of 6%, forming the second sulfuric acid symbiotic utilization subsystem within the system. Ultimately, acidic wastewater with sulfuric acid concentrations of 5% and 6% is treated and recycled through neutralization, purification, concentration, and crystallization, producing ammonium sulfate as a by-product. The sulfuric acid recycling and symbiotic utilization system comprises a sulfuric acid concentration circulation subsystem, two sulfuric acid symbiotic utilization subsystems, and an acidic wastewater treatment subsystem. Material and energy consumption at each link in each subsystem is collected and their carbon footprints calculated. After establishing a full lifecycle carbon emission model for the sulfuric acid recycling and symbiotic utilization system, different recycling and symbiotic utilization scenarios are set, a carbon footprint optimization plan is developed, and the mass of sulfuric acid of different concentrations allocated to different utilization pathways is determined. This allows the carbon footprint of the entire system to be calculated under a comprehensive optimization scenario for carbon reduction and pollution reduction.

[0409] In the calculation, the production data of the sulfuric acid circulating symbiotic utilization system when it outputs the same product combination as shown in Table 3 are used to first calculate the change in the carbon footprint of the sulfuric acid circulating symbiotic utilization system relative to the basic production system (including carbon performance and carbon footprint increase) and the carbon footprint of the acid-containing wastewater treatment process of the sulfuric acid circulating symbiotic utilization system. The results are then integrated with the calculated carbon footprint of the basic production system to obtain the calculated carbon footprint of the sulfuric acid circulating symbiotic utilization system.

[0410] like Figure 3 , in the sulfuric acid circulation symbiotic utilization system:

[0411] I. Sulfuric acid use subsystem

[0412] The data on the use of recycled symbiotic sulfuric acid by the sulfuric acid use subsystem are shown in Table 4.

[0413] Table 4 Data on the use of circulating symbiotic sulfuric acid in the sulfuric acid use subsystem

[0414]

[0415] The carbon performance calculation formula for the sulfuric acid use subsystem using recycled symbiotic sulfuric acid is:

[0416] (3c-1)

[0417] Where:

[0418] is the carbon performance of the sulfuric acid cycle symbiotic process, in kg CO2 eq;

[0419] It is The mass of circulating symbiotic sulfuric acid used by each sulfuric acid-using subsystem, in kg;

[0420] is the cradle-to-gate carbon emission factor for sulfuric acid, expressed in kg CO2 eq / kg.

[0421] The calculation process is as follows:

[0422]

[0423] Based on the data in Table 4, the carbon emission reduction performance of the sulfuric acid cycle symbiotic process is calculated to be 2364.61 kg CO2 eq.

[0424] II. Sulfuric acid concentration subsystem

[0425] The emission source data of the sulfuric acid concentration process are shown in Table 5.

[0426] Table 5 Emission source data of sulfuric acid concentration process

[0427]

[0428] The calculation formula for the emission of sulfuric acid concentration process is:

[0429] (3b-1)

[0430] Where:

[0431] It is Carbon emissions from the sulfuric acid concentration process in each sulfuric acid concentration circulation subsystem, in kg CO2eq;

[0432] is the amount of steam consumed in the sulfuric acid concentration process, in kg;

[0433] is the carbon emission factor of steam, in kg CO2 eq / kg;

[0434] is the amount of electricity consumed in the sulfuric acid concentration process, in kW·h;

[0435] is the carbon emission factor of electricity, in kg CO2 eq / kW·h;

[0436] The first The mass of the chemical in kg;

[0437] For the The cradle-to-gate carbon emission factor for each chemical is expressed in kg CO2 eq / kg.

[0438] The calculation process is as follows:

[0439]

[0440] III. Sulfuric acid purification subsystem

[0441] The data of sulfuric acid purification process are shown in Table 6.

[0442] Table 6 Sulfuric acid purification process data

[0443]

[0444] The calculation formula for carbon emissions during the purification process of the sulfuric acid symbiotic utilization subsystem is:

[0445] (4b)

[0446] Where:

[0447] It is Carbon emissions generated by the sulfuric acid symbiotic utilization subsystem during the purification process, in kg CO2 eq;

[0448] is the amount of electricity consumed by the sulfuric acid purification process, in kW·h;

[0449] is the carbon emission factor of electricity, in kg CO2 eq / kW·h;

[0450] It is consumed The amount of fossil energy in kg or Nm 3 ;

[0451] For the Carbon emission factor of each fossil energy source, in kg CO2 eq / kg or kg CO2 eq / Nm 3 ;

[0452] It is The sulfuric acid symbiotic utilization subsystem consumes the first The mass of the chemical reagent, in kg;

[0453] It is The cradle-to-gate carbon emission factors for these chemical reagents are expressed in kg CO2 eq / kg.

[0454] The calculation process is as follows:

[0455]

[0456] IV. Acidic wastewater treatment subsystem

[0457] The process emission source activity data of the acid wastewater treatment subsystem are shown in Table 7.

[0458] Table 7 Emission source activity data of the acid wastewater treatment subsystem process

[0459]

[0460] The calculation formula for carbon emissions from the neutralization process of acidic wastewater is:

[0461] (5a-1)

[0462] Where:

[0463] It is Carbon emissions from the neutralization process of acidic wastewater in each acidic wastewater treatment subsystem, in kgCO2 eq;

[0464] It is the amount of electricity consumed in the neutralization process of acidic wastewater, in kW·h;

[0465] is the carbon emission factor of electricity, in kg CO2 eq / kW·h;

[0466] It is the first The mass of the chemical reagent, in kg;

[0467] It is The cradle-to-gate carbon emission factors for these chemical reagents are expressed in kg CO2 eq / kg.

[0468] The calculation process is as follows:

[0469]

[0470] The carbon emission calculation formula for the wastewater purification process is:

[0471] (5b)

[0472] Where:

[0473] It is Carbon emissions from the purification process in each acid wastewater treatment subsystem, in kg CO2 eq;

[0474] is the amount of electricity consumed in the acid wastewater purification process, in kW·h;

[0475] is the carbon emission factor of electricity, in kg CO2 eq / kW·h;

[0476] It is the first The amount of fossil energy consumed. When the fossil energy consumed is coal, the unit is kg. When the fossil energy consumed is natural gas, the unit is Nm 3 ;

[0477] For the Carbon emission factor of the fossil energy source, in kg CO2 eq / kg or kg CO2 eq / Nm 3 ;

[0478] It is the first The mass of the chemical reagent, in kg;

[0479] It is The cradle-to-gate carbon emission factors for these chemical reagents are expressed in kg CO2 eq / kg.

[0480] The calculation process is as follows:

[0481]

[0482] After purification, sulfate in the wastewater is extracted in solid form through concentrated crystallization. The carbon emission calculation formula for this process is:

[0483] (5c-1)

[0484] Where:

[0485] It is Carbon emissions from the concentration and crystallization process of each acid wastewater treatment subsystem, in kg CO2eq;

[0486] It is the amount of steam consumed in the process of concentration and crystallization of acidic wastewater, in kg;

[0487] is the carbon emission factor of steam, in kg CO2 eq / kg;

[0488] It is the amount of electricity consumed in the process of concentration and crystallization of acid wastewater, in kW·h;

[0489] is the carbon emission factor of electricity, with the unit being kg CO2 eq / kW·h.

[0490] The calculation process is as follows:

[0491]

[0492] After concentration and crystallization, the acid wastewater treatment subsystem can recover by-product sulfate. These sulfates can be put into production as raw materials for other chemical reaction processes, replacing sulfate produced by other processes, thereby generating a certain amount of carbon emission reduction performance. The calculation formula is:

[0493] (5d)

[0494] Where:

[0495] It is Carbon performance of by-produced sulfate in each acid wastewater treatment subsystem, in kg CO2 eq;

[0496] It is The mass of by-product sulfate in each acid wastewater treatment subsystem, in kg;

[0497] is the cradle-to-gate carbon emission factor for this sulfate, expressed in kg CO2 eq / kg.

[0498] The calculation process is as follows:

[0499]

[0500] The calculation formula for carbon emissions from the acid wastewater treatment subsystem is:

[0501] (5)

[0502] Where:

[0503] It is Carbon emissions from each acid wastewater treatment subsystem, in kg CO2 eq;

[0504] It is Carbon emissions from the neutralization process of acidic wastewater in each acidic wastewater treatment subsystem, in kgCO2 eq;

[0505] It is Carbon emissions from the purification process in each acid wastewater treatment subsystem, in kg CO2 eq;

[0506] It is Carbon emissions from the concentration and crystallization process of each acid wastewater treatment subsystem, in kg CO2eq;

[0507] It is The carbon performance of by-produced sulfate in each acid wastewater treatment subsystem, in kg CO2 eq.

[0508] The calculation process is as follows:

[0509]

[0510] The formula for calculating the carbon footprint of the sulfuric acid cycle symbiotic utilization system throughout its life cycle is:

[0511] (1b)

[0512] Where:

[0513] is the life cycle carbon footprint of the sulfuric acid cycle symbiotic utilization system, in kg CO2 eq;

[0514] It is the basic production system Carbon emissions of each sulfuric acid use subsystem, in kg CO2 eq;

[0515] is the carbon performance of the sulfuric acid using subsystem using recycled symbiotic sulfuric acid, in kg CO2 eq;

[0516] It is Carbon emissions from each sulfuric acid concentration treatment subsystem, in kg CO2 eq;

[0517] It is Carbon emissions from each sulfuric acid purification subsystem, in kg CO2 eq;

[0518] It is Carbon emissions from each acid wastewater treatment subsystem, in kg CO2 eq.

[0519] The calculation process is as follows:

[0520]

[0521] The calculation results of the carbon footprint of the sulfuric acid cycle symbiotic utilization system throughout its life cycle are as follows: Figure 4 When producing the product mix shown in Table 3, the lifecycle carbon footprint of the sulfuric acid recycling and symbiotic utilization system is reduced by 19,459.24 kg CO2 eq compared to the basic production system. Specifically, the sulfuric acid concentration subsystem generates an additional 3,230.48 kg CO2 eq of carbon emissions during the sulfuric acid concentration and disposal process, and the sulfuric acid purification process generates an additional 1,674.82 kg CO2 eq of carbon emissions. However, through the recycling and symbiotic use of sulfuric acid, a carbon performance of 2,364.61 kg CO2 eq is achieved. Due to the reduction in the amount of acidic wastewater generated and treated, the carbon emissions of the acidic wastewater disposal subsystem are reduced by 21,999.94 kg CO2 eq compared to the basic production system.

[0522] The results show that, in order to address the carbon emissions generated during the preparation of sulfuric acid required for the reaction, the sulfuric acid utilization system can be transformed for circular symbiotic utilization. By replacing new sulfuric acid with recycled and symbiotically utilized sulfuric acid, the utilization efficiency of sulfuric acid can be effectively improved, and the amount of acid-containing wastewater generated can be greatly reduced, thereby more effectively reducing the carbon footprint of sulfuric acid throughout its life cycle.

[0523] Example 3

[0524] This embodiment is a device for quantitatively evaluating the carbon footprint of a sulfuric acid recycling and symbiotic utilization system throughout its life cycle. Figure 5 The device includes a memory and one or more processors. The memory stores executable code, which can input the full life cycle operation data of the sulfuric acid circulation symbiotic utilization system. When the one or more processors execute the executable code, they are used to implement the sulfuric acid circulation symbiotic utilization system full life cycle carbon footprint quantitative evaluation and optimization method of Example 1 or Example 2, and output the sulfuric acid circulation symbiotic utilization system full life cycle carbon footprint quantitative evaluation and optimization results.

[0525] The contents described in the embodiments of this specification are merely an enumeration of the implementation forms of the inventive concept. The scope of protection of the present invention should not be regarded as limited to the specific forms described in the embodiments. The scope of protection of the present invention also extends to equivalent technical means that can be conceived by those skilled in the art based on the inventive concept.

Claims

1. A method for quantitatively evaluating the carbon footprint of a sulfuric acid recycling symbiotic utilization system throughout its life cycle, characterized in that: The following steps are involved: 1) Divide the subsystems in the entire life cycle of the sulfuric acid cycle symbiotic utilization system and determine the system boundaries for carbon footprint quantitative evaluation; 2) Determine the carbon emission sources of sulfuric acid in each subsystem according to the production process and construct a carbon emission inventory; 3) Determine the carbon emission calculation method for each emission source and build a carbon footprint quantitative evaluation model; 4) Establish activity data and carbon emission factors for each carbon emission source and calculate the carbon footprint of the sulfuric acid cycle symbiotic utilization system; The boundary of the sulfuric acid circulation symbiotic utilization system described in step 1) is all processes from sulfuric acid production to acid wastewater treatment and disposal, including four subsystems: ① sulfuric acid use subsystem, ② sulfuric acid concentration circulation subsystem, ③ sulfuric acid symbiotic utilization subsystem, and ④ acid wastewater disposal subsystem; The carbon footprint calculation formula of the sulfuric acid circulation symbiotic utilization system is: （1） Where: CF is the carbon footprint of the sulfuric acid cycle symbiotic utilization system, in kg CO2 eq; It is Carbon emissions of each sulfuric acid use subsystem, in kg CO2 eq; It is Carbon emissions from each sulfuric acid concentration cycle subsystem, in kg CO2 eq; It is Carbon emissions from each sulfuric acid symbiotic utilization subsystem, in kg CO2 eq; It is Carbon emissions from each acid wastewater treatment subsystem, in kg CO2 eq; The acid wastewater treatment subsystem includes: acid wastewater generated in various production links is combined and then converted into sulfate after neutralization, purification, concentration and crystallization, so as to achieve harmlessness and resource utilization; The carbon emission sources of the acid wastewater treatment subsystem include: carbon emissions generated by the neutralization process of acid wastewater, carbon emissions from the purification process of acid wastewater, carbon emissions from the concentration and crystallization process of acid wastewater, and carbon performance of recovering by-product sulfate; The calculation formula for carbon emissions of the acid wastewater treatment subsystem is: （5） Where: It is Carbon emissions from each acid wastewater treatment subsystem, in kg CO2 eq; It is Carbon emissions from the neutralization process of acidic wastewater in each acidic wastewater treatment subsystem, in kg CO2 eq; It is Carbon emissions from the purification process in each acid wastewater treatment subsystem, in kg CO2 eq; It is Carbon emissions from the concentration and crystallization process in the acid wastewater treatment subsystem, in kg CO2 eq; It is Carbon performance of by-produced sulfate in each acid wastewater treatment subsystem, in kg CO2 eq; The carbon emissions generated by the neutralization process of the acidic wastewater include: The carbon emissions from the neutralization process of acidic wastewater include the carbon emissions generated by the energy used and the carbon emissions generated by the added alkaline chemical reagents during the preparation process. The calculation formula is: （5a） Where: It is Carbon emissions from the neutralization process of acidic wastewater in each acidic wastewater treatment subsystem, in kg CO2 eq; is the amount of steam consumed in the neutralization process of acidic wastewater, in MJ; is the carbon emission factor for steam, in kg CO2 eq / MJ; It is the amount of electricity consumed in the neutralization process of acidic wastewater, in kW·h; is the carbon emission factor of electricity, in kg CO2 eq / kW·h; It is the first The mass of the chemical reagent, in kg; It is The cradle-to-gate carbon emission factor for each chemical agent is expressed in kg CO2 eq / kg; The carbon emissions from the acid wastewater purification process include the carbon emissions from electricity, fossil energy, and chemical reagents used in the purification process, and are calculated as follows: （5b） Where: It is Carbon emissions from the purification process in each acid wastewater treatment subsystem, in kg CO2 eq; is the amount of electricity consumed in the acid wastewater purification process, in kW·h; is the carbon emission factor of electricity, in kg CO2 eq / kW·h; It is the first The amount of fossil energy consumed. When the fossil energy consumed is coal, the unit is kg. When the fossil energy consumed is natural gas, the unit is Nm 3 ; For the Carbon emission factor of each fossil energy source, in kg CO2 eq / kg or kg CO2 eq / Nm 3 ; It is the first The mass of the chemical reagent, in kg; It is The cradle-to-gate carbon emission factor for each chemical agent is expressed in kg CO2 eq / kg; The carbon emissions from the acid wastewater concentration and crystallization process include the carbon emissions from electricity, steam, and fossil energy used in the concentration and crystallization process, and are calculated as follows: （5c） Where: It is Carbon emissions from the concentration and crystallization process in the acid wastewater treatment subsystem, in kg CO2 eq; It is the amount of steam consumed in the process of concentration and crystallization of acid wastewater, the unit is MJ; is the carbon emission factor for steam, in kg CO2 eq / MJ; It is the amount of electricity consumed in the process of concentration and crystallization of acid wastewater, in kW·h; is the carbon emission factor of electricity, in kg CO2 eq / kW·h; It is the first The amount of fossil energy consumed. When the fossil energy consumed is coal, the unit is kg. When the fossil energy consumed is natural gas, the unit is Nm 3 ; For the Carbon emission factor of each fossil energy source, in kg CO2 eq / kg or kg CO2 eq / Nm 3 ; The calculation formula for the carbon performance of the by-product sulfate in the acid wastewater treatment subsystem is: （5d） Where: It is Carbon performance of by-produced sulfate in each acid wastewater treatment subsystem, in kg CO2 eq; It is The mass of by-product sulfate in each acid wastewater treatment subsystem, in kg; is the cradle-to-gate carbon emission factor for this sulfate, expressed in kg CO2 eq / kg.

2. The method according to claim 1, wherein The sulfuric acid utilization subsystem includes: sulfuric acid is prepared and participates in a round of reaction process, and the dilute sulfuric acid produced after the reaction enters the subsequent treatment and disposal process in the form of acid-containing wastewater; The carbon emission sources of the sulfuric acid use subsystem include: carbon emissions generated by the sulfuric acid preparation process and carbon emissions generated by the treatment of acid-containing wastewater; The calculation formula for the carbon emissions of the sulfuric acid use subsystem is: （2） Where: It is Carbon emissions of each sulfuric acid use subsystem, in kg CO2 eq; It is The mass of new sulfuric acid used in each sulfuric acid using subsystem, in kg; is the cradle-to-gate carbon emission factor for sulfuric acid, expressed in kg CO2 eq / kg; The carbon emissions generated by the treatment of acidic wastewater are calculated with reference to ④ Acidic wastewater treatment subsystem.

3. The method according to claim 1, wherein The sulfuric acid concentration circulation subsystem is as follows: sulfuric acid is prepared and then participates in a round of reaction process, and the sulfuric acid after the reaction is concentrated and then recycled to the previous round of reaction process; The carbon emission sources of the sulfuric acid concentration circulation subsystem include: carbon emissions generated by the sulfuric acid preparation process, carbon emissions generated by the energy consumed in the sulfuric acid concentration process, carbon emissions generated by the sulfur trioxide chemical reagent added in some concentration processes, carbon emissions generated by the disposal of some acid-containing wastewater after sulfuric acid recycling, and carbon performance brought about by the replacement of some new sulfuric acid after sulfuric acid recycling; The calculation formula for the carbon emissions of the sulfuric acid concentration circulation subsystem is: （3） Where: It is Carbon emissions from each sulfuric acid concentration cycle subsystem, in kg CO2 eq; It is Carbon emissions from the preparation of sulfuric acid required in each sulfuric acid concentration circulation subsystem, in kg CO2eq; For the Carbon emissions from sulfuric acid concentration treatment in each sulfuric acid concentration circulation subsystem, in kg CO2 eq; For the The carbon performance of the sulfuric acid cycle in the sulfuric acid concentration cycle subsystem, in kg CO2 eq; The calculation formula for the carbon emissions of sulfuric acid required in the reaction process during the preparation process is: （3a） Where: It is Carbon emissions from the preparation of sulfuric acid required for the reaction process in each sulfuric acid concentration circulation subsystem, in kg CO2 eq / kg; It is The mass of new sulfuric acid required for the reaction process in each sulfuric acid concentration circulation subsystem, in kg; is the cradle-to-gate carbon emission factor for sulfuric acid, expressed in kg CO2 eq / kg; The calculation formula for the emission of sulfuric acid concentration process is: （3b） Where: It is Carbon emissions from the sulfuric acid concentration process in the sulfuric acid concentration cycle subsystem, in kg CO2 eq / kg; is the amount of steam consumed in the sulfuric acid concentration process, in MJ; is the carbon emission factor for steam, in kg CO2 eq / MJ; is the electricity consumed in the sulfuric acid concentration process, in kW·h; is the carbon emission factor of electricity, with the unit of kg CO2 eq / kW·h; some sulfuric acid concentration processes use coal or natural gas fossil energy, This is the first The amount of fossil energy in kg or Nm 3 ; For the Carbon emission factor of the fossil energy source, in kg CO2 eq / kg or kg CO2 eq / Nm 3 ; The first The mass of the chemical in kg; For the The cradle-to-gate carbon emission factor for each chemical, in kg CO2 eq / kg; The calculation formula for the carbon performance of sulfuric acid cycle is: （3c） Where: It is The carbon performance of the sulfuric acid cycle in the sulfuric acid concentration cycle subsystem, in kg CO2 eq; is the mass of recycled sulfuric acid, in kg; is the cradle-to-gate carbon emission factor for sulfuric acid, expressed in kg CO2 eq / kg; The calculation of carbon emissions from the treatment of acidic wastewater generated by the sulfuric acid concentration circulation subsystem refers to ④ Acidic wastewater treatment subsystem.

4. The method according to claim 1, wherein The sulfuric acid symbiotic utilization subsystem includes: sulfuric acid is prepared and then participates in a round of reaction process, and the sulfuric acid after the reaction is purified and then participates in another reaction process, forming a layer of symbiotic relationship between the two different reaction processes. After one or more layers of symbiosis, the used sulfuric acid enters the subsequent treatment and disposal process in the form of acid-containing wastewater; The carbon emission sources of the sulfuric acid symbiotic utilization subsystem include: carbon emissions generated during the sulfuric acid preparation process, carbon emissions generated during the preparation process of activated carbon, flocculants, and oxidant chemicals consumed during the sulfuric acid purification process, carbon emissions generated during the subsequent treatment and disposal of acidic wastewater, and carbon performance brought about by replacing part of the new sulfuric acid during sulfuric acid symbiosis; The calculation formula for the carbon emissions of the sulfuric acid symbiotic utilization subsystem is: （4） Where: It is Carbon emissions from each sulfuric acid symbiotic utilization subsystem, in kg CO2 eq; It is Carbon emissions from the preparation of sulfuric acid required for the reaction process in each sulfuric acid symbiotic utilization subsystem, in kg CO2 eq; It is Carbon emissions generated by the sulfuric acid symbiotic utilization subsystem during the purification process, in kg CO2 eq; It is The carbon performance of sulfuric acid symbiotic utilization in each sulfuric acid symbiotic utilization subsystem, in kg CO2 eq; The calculation formula for the carbon emissions from the preparation of sulfuric acid required for the reaction process of the sulfuric acid symbiotic utilization subsystem is: （4a） Where: It is Carbon emissions from the preparation of sulfuric acid required in each sulfuric acid symbiotic utilization subsystem, in kg CO2 eq; It is The mass of new sulfuric acid required for the first reaction process in the sulfuric acid symbiotic utilization subsystem, in kg; It is The mass of new sulfuric acid required for the second reaction process in the sulfuric acid symbiotic utilization subsystem, in kg; is the cradle-to-gate carbon emission factor for sulfuric acid, expressed in kg CO2 eq / kg; The calculation formula for carbon emissions during the purification process of the sulfuric acid symbiotic utilization subsystem is: （4b） Where: It is Carbon emissions generated by the sulfuric acid symbiotic utilization subsystem during the purification process, in kg CO2 eq; is the amount of electricity consumed by the sulfuric acid purification process, in kW·h; is the carbon emission factor of electricity, in kg CO2 eq / kW·h; It is consumed The amount of fossil energy in kg or Nm 3 ; For the Carbon emission factor of each fossil energy source, in kg CO2 eq / kg or kg CO2 eq / Nm 3 ; It is The sulfuric acid symbiotic utilization subsystem consumes the first The mass of the chemical reagent, in kg; It is The cradle-to-gate carbon emission factor for each chemical agent is expressed in kg CO2 eq / kg; The calculation formula for the sulfuric acid symbiotic utilization carbon performance of the sulfuric acid symbiotic utilization subsystem is: （4c） Where: It is The carbon performance of sulfuric acid symbiotic utilization in each sulfuric acid symbiotic utilization subsystem, in kg CO2 eq; It is The amount of new sulfuric acid saved through symbiotic utilization in each sulfuric acid symbiotic utilization subsystem, in kg; is the cradle-to-gate carbon emission factor for sulfuric acid, expressed in kg CO2 eq / kg; In the aforementioned carbon performance of sulfuric acid symbiotic utilization, the calculation formula for the saved amount of new sulfuric acid usage is: （4c-1） Where: It is The amount of new sulfuric acid saved through symbiotic utilization in each sulfuric acid symbiotic utilization subsystem, in kg; It is The mass fraction of sulfuric acid that enters the next reaction process after purification in each sulfuric acid symbiotic utilization subsystem, unit is % It is The mass fraction of new sulfuric acid used in each sulfuric acid symbiotic utilization subsystem, expressed in %, is usually 98%; It is The mass of sulfuric acid that enters the next reaction process after purification in each sulfuric acid symbiotic utilization subsystem, in kg; The calculation of carbon emissions from the treatment of acidic wastewater generated by the sulfuric acid symbiotic utilization subsystem refers to ④ Acidic wastewater treatment subsystem.

5. The method according to claim 1, wherein The target parameters of the full life cycle emission reduction objective function of the sulfuric acid circulation symbiotic utilization system include: the carbon emissions of the system throughout its life cycle, the disposal and discharge of acidic wastewater, and the operating costs and benefits of the system throughout its life cycle; The variables used in setting different recycling and symbiotic utilization scenarios include: the amount of sulfuric acid of different concentrations that is concentrated, recycled, symbiotically utilized, and directly treated as acidic wastewater.

6. A device for quantitatively evaluating the carbon footprint of a sulfuric acid recycling and symbiotic utilization system throughout its life cycle, characterized in that: The invention comprises a memory and one or more processors, wherein the memory stores executable code, and when the one or more processors execute the executable code, they are used to implement the method for quantitatively evaluating the carbon footprint of the whole life cycle of the sulfuric acid circulation symbiotic utilization system according to any one of claims 1 to 5.

Images