Oxygen and nitrogen gas supply and demand balance model for iron and steel enterprises

Abstract

The invention relates to an oxygen and nitrogen gas supply and demand balance model for iron and steel enterprises. The oxygen and nitrogen gas supply and demand balance model comprises oxygen and nitrogen gas supply and demand balance and optimization. The balance of oxygen and nitrogen is that a gas demand chain and a gas supply chain are linked by adopting oxygen and nitrogen gas balance factors, a gas balance chain and a gas balance weight, and the index parameters of the oxygen and nitrogen gas balance factors are adjusted, so that the index parameters of the balance factors of the oxygen and nitrogen gas production supply end and the demand end tend to be balanced and consistent; oxygen and nitrogen gas supply and demand balance is realized; the oxygen and nitrogen gas supply and demand balance optimization is to provide an oxygen and nitrogen gas supply and demand balance optimization strategy by excavating oxygen and nitrogen gas dynamic change characteristics and balance factor index parameter requirements; comprising developing oxygen and nitrogen with different pressure grades and purities, oxygen and nitrogen gas supply and demand balance optimization measures proposed by the model have remarkable effects on reducing the cost and improving the energy efficiency of an oxygen and nitrogen system, and the model has better popularization value.

Description

Technical Field

[0001] The present invention relates to the technical field of energy management, and particularly to an oxygen and nitrogen gas supply-demand balance model for iron and steel enterprises. Background Art

[0002] The supply-demand balance of oxygen and nitrogen gases is an important topic in the oxygen and nitrogen gas production systems of large integrated iron and steel enterprises, and is an important means to ensure the safe supply of oxygen and nitrogen gases and save energy and reduce consumption.

[0003] The most widely used oxygen and nitrogen gas production devices in industry are low-temperature air separation oxygen generators with air low-temperature separation technology as the core process. It can produce oxygen, nitrogen, liquid oxygen and liquid nitrogen. It consists of an air compression system, an air purification system, a cooling and heat exchange system, a refrigeration system, a low-temperature rectification system, an oxygen and nitrogen compression system, a liquid reserve storage system, etc. The process is long and complex. Due to the characteristics of the low-temperature air separation oxygen generator, its oxygen and nitrogen production rhythm is stable and balanced, and the output fluctuation range of gas products is generally between 85% and 105%, and will not change greatly with the large fluctuation of gas consumption. In addition, with the continuous development and improvement of process technology and equipment, oxygen and nitrogen gas production technologies different from the traditional air low-temperature separation route, such as molecular sieve oxygen generators and molecular sieve nitrogen generators, have been more and more widely used. The improvement of oxygen and nitrogen production technologies and equipment has brought new choices for the supply-demand balance of oxygen and nitrogen gases, and opened up space for optimizing the gas supply-demand balance and saving energy and reducing consumption.

[0004] For iron and steel enterprises, not only oxygen and nitrogen are used in steelmaking, but also a large amount of oxygen and nitrogen gases are required in processes such as ironmaking, rolling and coking. It is a non-single gas-using system. The gas-using methods and amounts of each process are different and variable, and the impacts on the supply-demand balance of oxygen and nitrogen gases are also different and coupled with each other. It is a complex and variable comprehensive gas-using system. To ensure the supply of oxygen and nitrogen gases, large iron and steel enterprises are generally equipped with multiple oxygen and nitrogen gas production devices with different specifications to meet the needs of different iron and steel production modes.

[0005] Scientifically planning the supply-demand balance of oxygen and nitrogen gases not only requires studying the average gas consumption of micro iron and steel rolling and coking users, but also studying the production rhythm, unevenness and volatility of user demands, studying the adjustable ranges of different oxygen and nitrogen production equipment, and the production and standby capabilities of liquids, and constructing the supply-demand balance relationship of oxygen and nitrogen gases to achieve the coordination and adaptation of the production, supply and demand of oxygen and nitrogen gases and liquids.

[0006] The oxygen and nitrogen production ratios produced by oxygen and nitrogen gas production devices of different specifications are different. If the oxygen and nitrogen production ratios at both ends of supply and demand cannot be kept consistent, the production, supply and demand of oxygen and nitrogen gases will be uncoordinated, resulting in waste of a single type of gas. Therefore, the coordination of production and use of oxygen and nitrogen gases is also an important part of the study of oxygen and nitrogen gas balance. Only when different types of oxygen and nitrogen gases are fully utilized can the gas energy consumption be more effectively reduced and the efficiency of oxygen and nitrogen gas production devices be improved.

[0007] In addition, from the perspective of gas variety structure, the oxygen and nitrogen gases that can be used in processes such as steel coking are not limited to a single type. For example, some require high pressure, some require low pressure; some require high gas purity, and some require low gas purity... Therefore, attention should also be paid to the equipment types and product structure of the oxygen and nitrogen gas production system, in order to seek balanced optimization methods to meet the needs of multiple types of oxygen and nitrogen gases, achieve the rationality and economy of the gas supply structure, and reduce the probability of high-quality and low-use oxygen and nitrogen gases.

[0008] The traditional oxygen and nitrogen gas supply and demand balance is mainly based on the maximum demand for oxygen and nitrogen gases. In essence, it meets user needs regardless of cost, sacrificing the energy efficiency of the oxygen and nitrogen systems to a certain extent. There is insufficient research on the personalized gas supply and demand characteristics as mentioned above, and there is no systematic and personalized oxygen and nitrogen gas supply and demand balance model formed, making it impossible to achieve accurate, low-consumption, efficient and dynamic oxygen and nitrogen gas supply and gas balance. Summary of the invention

[0009] The present invention provides a systematic and personalized oxygen and nitrogen gas supply and demand balance model for a steel enterprise, which enriches the gas supply and demand balance optimization strategy of metallurgical enterprises in theory and practice.

[0010] In order to achieve the above object, the present invention intends to adopt the following technical solutions:

[0011] A supply and demand balance model of oxygen and nitrogen gases in steel enterprises, including supply and demand balance and optimization of oxygen and nitrogen;

[0012] The oxygen and nitrogen gas supply and demand balance adopts three balance characteristics: oxygen and nitrogen gas balance factor, oxygen and nitrogen gas balance chain and oxygen and nitrogen gas balance weight. The gas demand chain and the gas supply chain are linked through the oxygen and nitrogen gas balance factor to form an oxygen and nitrogen gas supply and demand balance chain. Then, the oxygen and nitrogen gas balance factor index parameters are adjusted to make the balance factor index parameters of the oxygen and nitrogen gas production supply end and the demand end tend to be balanced and consistent, so as to achieve oxygen and nitrogen gas supply and demand balance.

[0013] The optimization of the oxygen and nitrogen gas supply-demand balance is to explore the dynamic change characteristics of oxygen and nitrogen gases and the balance factor index parameters, and propose an optimization strategy for the oxygen and nitrogen gas supply-demand balance, including dynamically adjusting the oxygen and nitrogen gas balance with the production changes in the steelmaking, ironmaking, and rolling processes, including developing the use of low-index oxygen and nitrogen gases and the interchangeable use of nitrogen with compressed air and steam, including the following:

[0014] 1) Optimization of the oxygen and nitrogen gas supply-demand balance: including oxygen enrichment before the blast furnace blower and oxygen optimization in the steelmaking system;

[0015] 2) Optimization of the oxygen and nitrogen gas supply-demand balance: including developing the oxygen discharged from the air separation tower of the oxygen generator with an external compression process, developing oxygen at 0.6 - 0.8 Mpa, developing oxygen with a purity of 75 - 85%, and developing nitrogen at the grade of 0.8 - 1 Mpa;

[0016] 3) Adjustment of the operation mode of the oxygen generation system;

[0017] 4) Using liquid oxygen and liquid nitrogen.

[0018] Furthermore, the oxygen and nitrogen gas balance factors are respectively the physical and chemical properties of the gases targeted by the balanced oxygen and nitrogen gases, including gas pressure, purity, volume, and temperature characteristics; the characteristic indicators with common requirements for the physical and chemical properties of oxygen and nitrogen gases in the demand chain and supply chain are summarized and integrated respectively as the oxygen balance factor and the nitrogen balance factor.

[0019] Furthermore, the oxygen and nitrogen gas supply-demand balance chains respectively include an oxygen demand chain and a nitrogen demand chain; the oxygen and nitrogen demand chains respectively include oxygen and nitrogen demand users and user processes, which are the sets of oxygen and nitrogen users and user processes; the oxygen and nitrogen supply chains respectively include various oxygen and nitrogen production devices, which are the sets of oxygen and nitrogen production devices.

[0020] Furthermore, the oxygen and nitrogen gas balance weights are the proportions of the oxygen and nitrogen consumption of each user and process respectively in the total oxygen consumption and nitrogen consumption.

[0021] Furthermore, for the development of the oxygen discharged from the air separation tower of the oxygen generator with an external compression process, it means that the oxygen discharged from the air separation oxygen generator of the external compression type is directly sent to the pipeline in front of the blast furnace blower through the oxygen pipeline without compression.

[0022] Furthermore, for the development of oxygen at 0.6 - 0.8 Mpa, it means that the oxygen discharged from the air separation tower is pressurized to 0.6 - 0.8 Mpa and sent to the users of this grade of oxygen through the pipeline.

[0023] Furthermore, the developed oxygen with a purity of 75-85% is produced by a pressure swing adsorption oxygen generator specifically designed through oxygen balance analysis to explore the optimization space for oxygen quality surplus based on the analysis of the required oxygen quality grade and the demand for oxygen of different quality grades.

[0024] Furthermore, the developed nitrogen with a pressure of 0.8-1 Mpa is produced by a nitrogen compressor with a pressure of 0.8-1 Mpa specifically designed through nitrogen balance analysis to explore the optimization space for nitrogen pressure surplus based on the analysis of the required nitrogen pressure grade and the demand for nitrogen of different pressure grades for users of this nitrogen grade.

[0025] Furthermore, the interchange of nitrogen and compressed air is carried out under the premise of the best selection in terms of safety, energy conservation, and economic benefits when there are no special requirements for nitrogen pressure and gas purity, low-pressure nitrogen or compressed air can meet the requirements, and nitrogen and compressed air can be interchanged.

[0026] Furthermore, the interchange of nitrogen and steam is carried out when both nitrogen and steam are applicable to the user process, and the interchange is selected for this process on the premise of energy conservation and safety.

[0027] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0028] Through the three balance characteristics of the oxygen and nitrogen gas balance factors, the oxygen and nitrogen gas balance chain, and the oxygen and nitrogen gas balance weights of the present invention, an oxygen and nitrogen gas supply-demand balance model is constructed, which enriches and expands the oxygen and nitrogen gas balance optimization strategies of metallurgical enterprises theoretically and practically. Through the application of the model, a in-depth analysis and evaluation of the oxygen and nitrogen gas supply-demand balance can be carried out, and optimization measures for the oxygen and nitrogen gas supply-demand balance can be proposed, which have a significant effect on reducing energy and resource waste, reducing costs, and improving the energy efficiency of the oxygen and nitrogen systems, and have good promotion value. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is a diagram showing the relationship of oxygen balance factors according to an embodiment of the present invention.

[0030] Figure 2 is a diagram showing the relationship of nitrogen balance factors according to the present invention.

[0031] Figure 3 is a schematic diagram of the oxygen supply-demand balance chain according to the present invention.

[0032] Figure 4 is a schematic diagram of the nitrogen supply-demand balance chain according to the present invention.

[0033] Figure 5 is a schematic diagram of the oxygen supply-demand balance chain according to an embodiment of the present invention.

[0034] Figure 6 It is a schematic diagram of the oxygen supply and demand balance chain described in the embodiments of the present invention.

[0035] Figure 7 It is a bar chart of the balance weights of oxygen users described in the embodiments of the present invention.

[0036] Figure 8 It is a bar chart of the balance weights of nitrogen-consuming users described in the embodiments of the present invention. Specific Embodiments

[0037] The following further describes the specific embodiments of the present invention with reference to the accompanying drawings:

[0038] A model for the supply and demand balance of oxygen and nitrogen gases in an iron and steel enterprise according to the present invention includes the supply and demand balance and optimization of oxygen and nitrogen gases.

[0039] I. Proposing an oxygen and nitrogen gas balance model and a strategy for using the model to balance oxygen and nitrogen gases

[0040] The physical and chemical properties of oxygen and nitrogen gases are different, which determines their different functions and usage methods in iron and steel enterprises. Therefore, although they are both gases, the optimization strategies for oxygen and nitrogen balance are not the same. The balance takes the gas balance factor as a link, analyzes the demand conditions of each process at the demand side and the production capacity formed by the composition and different operating modes of the oxygen and nitrogen production devices at the supply side, links the production, supply and demand of oxygen and nitrogen gases, and basically establishes the gas production supply mode and gas usage mode through the gas supply and demand balance model to complete the supply and demand balance of oxygen and nitrogen gases.

[0041] 1. Oxygen and nitrogen gas supply and demand balance model

[0042] An oxygen and nitrogen gas supply and demand balance model is constructed based on three balance characteristics: the oxygen and nitrogen gas balance factor, the oxygen and nitrogen gas balance chain, and the oxygen and nitrogen gas balance weight. The supply and demand balance model consists of three parts: the oxygen and nitrogen gas balance factor relationship, the oxygen and nitrogen gas supply and demand balance chain, and the gas balance weight.

[0043] 1) Oxygen and nitrogen gas balance factor relationship

[0044] The oxygen and nitrogen gas balance relationship takes the oxygen and nitrogen gas balance factor as a link, respectively links the production, supply and demand of oxygen and nitrogen gases, and is the basis of the oxygen and nitrogen gas supply and demand balance relationship. See Figure 1 the oxygen balance factor relationship diagram, Figure 2 the nitrogen balance factor relationship diagram:

[0045] Gas balance factor: It is a set of characteristic indicators formed by summarizing and integrating the characteristic indicators with common requirements for the physical and chemical properties of gases in the demand chain and the supply chain, and is called the gas balance factor; for oxygen and nitrogen, they are respectively called the oxygen balance factor and the nitrogen balance factor; the physical and chemical properties of gases include pressure, temperature, volume, density, mass, entropy, enthalpy, melting point, thermal conductivity, electrical conductivity, boiling point, acidity and alkalinity, heat of chemical reaction, chemical bond, etc. When doing the supply-demand balance of oxygen and nitrogen gases, mainly several limited physical or chemical properties are targeted, including gas pressure, purity, volume (consumption), temperature, etc. Other properties can be not considered if there are no special requirements.

[0046] For Figure 1 Interpretation is as follows. The production and demand of oxygen are two independent systems. First, there is the demand of users for oxygen. The demand of users for oxygen is mainly reflected in the demand for certain indicators of oxygen, such as oxygen pressure, oxygen purity, oxygen temperature, enthalpy of oxygen, boiling point of oxygen, quantity of oxygen, etc. For iron and steel enterprises, the main demands are oxygen pressure, purity, and flow rate at normal temperature. Summarize the types of characteristics proposed by the above users into a set. In this way, there is a basic basis for the oxygen supply-demand balance model. Transmit various characteristic parameters in this set to the oxygen production end, put forward requirements to the production end, compare with the oxygen characteristics at the production end and reach an agreement. The production end then takes the agreed requirements as basic technical indicators to produce oxygen products and send them to the oxygen demand end through physical pipelines and other facilities to complete a balance closed-loop. Through the relationship of the oxygen balance factor, the oxygen supply-demand balance relationship is clearly shown;

[0047] Figure 2 It is the relationship diagram of the nitrogen balance factor. The interpretation of the relationship of the nitrogen balance factor is similar to that of oxygen.

[0048] 2) Oxygen and nitrogen gas supply-demand balance chain

[0049] Construct the gas demand chain by analyzing the users and process requirements of oxygen and nitrogen gases; construct the oxygen and nitrogen gas supply chain by analyzing the composition of oxygen and nitrogen gas production devices and the oxygen and nitrogen gas production capacity formed by different equipment operation modes. Link the gas demand chain and the gas supply chain through the oxygen and nitrogen gas balance factors to form the oxygen and nitrogen gas supply-demand balance chains respectively. The oxygen and nitrogen gas supply-demand balance chains are the application of the oxygen and nitrogen balance factor relationships. See Figure 3 Schematic diagram of the oxygen supply-demand balance chain, Figure 4 Schematic diagram of the nitrogen supply-demand balance chain.

[0050] For iron and steel enterprises, the oxygen demand users and user processes mainly include the blast furnace ironmaking system (including the blast furnace oxygen enrichment system and other systems other than the blast furnace oxygen enrichment), the steelmaking system, the rolling system, the scrap steel treatment system, the wastewater treatment system, the power generation system, and other oxygen-using systems (such as some hot stove systems using oxygen for combustion). Although the oxygen demand of each user includes characteristic parameters such as pressure, purity, and flow rate, the specific requirements for each characteristic parameter are different, and these characteristics need to be classified and summarized; for oxygen and nitrogen gas production devices, the characteristics of the oxygen, nitrogen, liquid oxygen, liquid nitrogen and other products produced and supplied by different production devices are different, and the product characteristics of these production devices also need to be statistically summarized, as shown in Table 1 Technical Parameter Summary Table of Oxygen Balance Factor at Both Supply and Demand Ends and Table 2 Technical Parameter Summary Table of Nitrogen Balance Factor at Both Supply and Demand Ends:

[0051] Table 1 Technical Condition Summary Table of Oxygen Balance Factor at the User End

[0052]

[0053] Among them, Nm 3 is the oxygen demand; or Nm 3 / h is the hourly oxygen demand; Nm 3 / t is the oxygen demand per ton of steel rolling or coke and other products;

[0054] Table 2 Technical Condition Summary Table of Nitrogen Balance Factor at Both Supply and Demand Ends

[0055]

[0056] Among them, Nm 3 is the nitrogen demand; or Nm 3 / h is the hourly nitrogen demand; Nm 3 / t is the nitrogen demand per ton of steel rolling or coke and other products.

[0057] Table 1 and Table 2 are the specific applications of the oxygen and nitrogen supply and demand balance chains respectively. By unifying the characteristic parameters of the oxygen and nitrogen gas balance factors at both supply and demand ends in these Table 1 and Table 2, the intersection of the gas characteristic indicators at both supply and demand ends can be found, and based on this, the operation modes of the oxygen and nitrogen gas production devices can be arranged and combined to find the optimal device operation mode.

[0058] 3) Gas Balance Weight

[0059] The gas balance weight is the proportion of the consumption of gases such as oxygen and nitrogen by each user and process in the total consumption of oxygen and nitrogen in the steel production system. For oxygen and nitrogen, they are the oxygen balance weight and the nitrogen balance weight respectively. Through the gas balance weight, the main gas users and secondary gas users are distinguished, and the main direction of the oxygen and nitrogen gas supply-demand balance is clarified. The gas supply-demand balance is mainly compiled for these key demands.

[0060] 2. Optimization of Oxygen and Nitrogen Gas Supply-Demand Balance

[0061] The optimization strategy for the oxygen and nitrogen gas supply-demand balance is based on the oxygen and nitrogen gas supply-demand balance model. It is proposed according to the dynamic change characteristics of the oxygen and nitrogen gas demand side, the change rules and adjustable ranges of the balance factor index parameters on the oxygen and nitrogen gas demand side. The oxygen and nitrogen gas optimization strategy is proposed to dynamically adjust the oxygen and nitrogen gas supply-demand balance according to the steel rolling production rhythm and the adjustable range of index parameters, and based on the principles of gas supply security and economy, so as to achieve the dynamic balance of oxygen and nitrogen gas supply and demand, including:

[0062] 1) Optimization of oxygen and nitrogen gas supply-demand balance: including developing the oxygen enrichment process before the blast furnace blower and optimizing the oxygen in the steelmaking system;

[0063] 2) Optimization of oxygen and nitrogen gas supply-demand balance: including developing the oxygen out of the air separation tower of the external compression process oxygen generator, developing 0.6 - 0.8 Mpa oxygen, developing 80% purity oxygen, and developing 0.8 - 1 Mpa grade low-pressure nitrogen;

[0064] 3) Optimization of oxygen and nitrogen gas supply-demand balance: including interchanging nitrogen with compressed air and interchanging nitrogen with steam;

[0065] 4) Optimization of oxygen and nitrogen gas supply-demand balance: including adjusting the operation mode of the oxygen and nitrogen gas production devices;

[0066] 5) Optimization of oxygen and nitrogen gas supply-demand balance: including using liquid oxygen and liquid nitrogen.

[0067] The optimization of oxygen in the steelmaking system mainly has two directions: one is to increase the oxygen production supply during the concentrated blowing stage and reduce the oxygen production supply during the non-blowing stage; the other is to moderately increase the blowing times of the low-oxygen-consumption converters and reduce the blowing times of the high-oxygen-consumption converters.

[0068] Developing the oxygen from the air separation column of an externally compressed process oxygen generator and oxygen at 0.6 - 0.8 Mpa is based on analyzing the oxygen demand pressure grades and the demand quantities of oxygen at different pressure grades, exploring the optimization space for excessive oxygen pressure, and developing the oxygen from the air separation column of the externally compressed process oxygen generator and oxygen at the 0.6 - 0.8 Mpa grade through the following means: First, the oxygen from the air separation column of the externally compressed process oxygen generator is directly sent to the front of the blast furnace blower for oxygen enrichment through the oxygen pipeline without compression; Second, for user processes with relatively low oxygen demand pressure, such as oxygen enrichment after the blower, oxygen use in steel rolling and scrap steel cutting, etc., if the demand quantity is large, through oxygen balance analysis, a low-pressure oxygen compressor at 0.6 - 0.8 Mpa is additionally set up specifically for users of this grade of oxygen.

[0069] Developing oxygen with a purity of 80% is based on analyzing the oxygen demand quality grades and the demand quantities of oxygen at different quality grades, exploring the optimization space for excessive oxygen quality, and through oxygen balance analysis, an oxygen production device with a purity of 80% is additionally set up, such as a pressure swing adsorption oxygen generator, to specifically produce low-quality oxygen for low-quality oxygen users, such as oxygen enrichment in front of the blast furnace blower, etc.

[0070] Developing nitrogen at the 0.8 - 1 Mpa grade is based on analyzing the nitrogen demand pressure grades and the demand quantities of nitrogen at different pressure grades, exploring the optimization space for excessive nitrogen pressure, and through nitrogen balance analysis, a low-pressure nitrogen compressor at the 0.8 - 1 Mpa grade is additionally set up specifically for users of nitrogen at the 0.8 - 1 Mpa grade.

[0071] Interchanging nitrogen and compressed air is to select the gas with lower production cost for replacement on the premise that the user process has no special requirements for nitrogen pressure and gas purity, both low-pressure nitrogen and compressed air can meet the requirements, and nitrogen and compressed air can be interchanged.

[0072] Interchanging nitrogen and steam is to select the gas with lower production cost for replacement when nitrogen or steam is applicable to certain user processes.

[0073] Adjusting the operation mode of oxygen and nitrogen gas production devices is based on the balance between oxygen and nitrogen gas supply and demand. Through the reasonable combination of different oxygen and nitrogen gas production devices, the produced oxygen, nitrogen, and other product gases and liquids can all be used to the maximum extent, achieving the lowest cost, maximizing benefits, and ensuring production safety at the same time.

[0074] The use of liquid oxygen and liquid nitrogen mainly targets emergency standby in production. On the premise that the reserve of liquid oxygen and liquid nitrogen for standby is guaranteed, liquid oxygen and liquid nitrogen can also be vaporized and respectively transported to oxygen and nitrogen gas pipelines as a means of regulating unbalanced oxygen and nitrogen gas use, with emergency standby taking priority.

[0075] The oxygen and nitrogen gas supply and demand balance model was established, and the optimization strategy of the oxygen and nitrogen gas supply and demand balance was proposed. The following example illustrates the application of the oxygen and nitrogen gas supply and demand balance model;

[0076] 2. Specific application cases of oxygen and nitrogen gas supply and demand balance model

[0077] The oxygen and nitrogen gas supply and demand balance model is highly practical. The following example illustrates the use of the oxygen and nitrogen gas supply and demand balance model.

[0078] (I) Balance of supply and demand of oxygen and nitrogen gases

[0079] See Figure 5 , Figure 6 , respectively, are schematic diagrams of a company's oxygen and nitrogen supply and demand balance chain. Figure 5 The left chain in the middle is the oxygen user demand chain, which is composed of various oxygen user process nodes, including 7 nodes such as No. 1 Steel, No. 2 Steel, resource recycling, large blast furnace, small blast furnace, steel rolling, and coking wastewater treatment; the right chain is the oxygen production and supply chain, including 7 oxygen production and supply nodes such as 3, 4, 5, 6, 7, 8 oxygen generators and liquid oxygen backup system. 3, 4, 5, 6, 7, 8 oxygen generators are all traditional low-temperature air separation oxygen generators, among which No. 3, 4, 5, and 6 oxygen generators are external compression processes, and No. 7 and 8 oxygen generators are internal compression processes. For details, see Table 3: Oxygen generator technical indicators and equipment level list. The left chain and the right chain together form a complete oxygen balance chain.

[0080] Table 3 Technical indicators and equipment level of oxygen production system

[0081]

[0082] Figure 6 Schematic diagram of a company's nitrogen supply and demand balance chain; the left chain is the nitrogen user demand chain, including iron and steel mills, rolling mills, three cold rolling mills, energy general plant and other units, and the right chain is the nitrogen production and supply chain, which is similar to the oxygen balance chain. For this company, both oxygen and nitrogen come from oxygen production units 3 to 8. Therefore, the oxygen and nitrogen production supply chains are similar. However, for companies with other oxygen and nitrogen gas production supporting equipment (such as pressure swing adsorption, etc.), the oxygen and nitrogen production supply chains are not the same. Through the oxygen and nitrogen gas supply and demand balance chain, the gas supply and use end users and user processes are clarified, and an oxygen and nitrogen gas supply and demand system is established.

[0083] For the supply and demand balance of oxygen and nitrogen gases, the balancing weights of each user and user process can reveal the main focus of gas balance and put the balance focus on these main points.

[0084] Figure 7 , Figure 8They are respectively the bar charts of the oxygen and nitrogen user balance weights formed by collecting the data of oxygen and nitrogen consumption from January to June 2024; Figure 7 , Figure 8 They respectively and clearly and intuitively reflect the oxygen and nitrogen balance weights of each user. For oxygen, the key is to do a good job in the oxygen balance of the large blast furnace, small blast furnace, No. 1 Steel, and No. 2 Steel, and the other user processes can be taken into account; the main users of nitrogen are the large blast furnace, No. 2 Steel, New No. 1 Steel, coking, No. 3 cold rolling, small blast furnace, sintering pellets, and the power generation, gas, and water supply processes of the General Energy Factory. The nitrogen consumption of rolling and raw materials is very small. When doing the nitrogen balance, it is necessary to focus on studying the nitrogen consumption characteristics of these main users.

[0085] Through the oxygen and nitrogen supply and demand balance chains, the users and user processes of oxygen and nitrogen are clarified. Through the weight charts of oxygen and nitrogen consumption, the main processes and secondary processes of gas consumption are revealed. It is also necessary to analyze the technical conditions of the oxygen and nitrogen balance factors at both the supply and demand ends to clarify the supply and demand link conditions; Tables 4 and 5 are respectively the summaries of the technical conditions of the oxygen and nitrogen balance factors of the company at both the supply and demand ends:

[0086] Table 4: Summary Table of Technical Conditions of Oxygen Balance Factors at the User End

[0087]

[0088] Table 5: Summary Table of Technical Conditions of Nitrogen Balance Factors at Both the Supply and Demand Ends

[0089]

[0090]

[0091] It can be seen from Table 4 that although there are certain differences in the oxygen pressure and quality required by each user process, as long as the pressure reaches 1.2 - 1.3 Mpa and the quality reaches 99.5% (O2), it can be downward compatible to meet the needs of all users for pressure, quality, etc. Therefore, 1.2 - 1.3 Mpa, 99.5% (O2) are the common characteristics of the oxygen balance factors of each user process.

[0092] Similar to oxygen, it can be seen from Table 5 that the nitrogen balance factors of each user process also show certain differences, but as long as the nitrogen pressure reaches 1.2 - 1.3 Mpa and the quality reaches 99.99% (N2), it can be downward compatible to meet the needs of all users for pressure, quality, etc. Therefore, 1.2 - 1.3 Mpa, 99.99% (N2) are the common characteristics of the nitrogen balance factors of each user process.

[0093] The technical conditions of the oxygen and nitrogen balance factors are clarified, and the oxygen and nitrogen balance characteristics of each user process are systematically analyzed respectively. Based on the systematic analysis, oxygen and nitrogen balance strategies are proposed, as shown in Table 6 and Table 7:

[0094] Table 6: Oxygen Demand Table under Different BF Production Modes

[0095]

[0096]

[0097] Table 7: Nitrogen Demand Balance Table under Different BF Production Modes

[0098]

[0099]

[0100] For iron and steel enterprises, the demand for oxygen mainly utilizes its strong oxidizing property, which has a strong correlation with the output of steel rolling, etc. The certainty of balance is relatively higher than that of nitrogen. The difficulty of nitrogen balance lies in that it has both stable and continuous usage scenarios and unstable and irregular usage scenarios. In addition, nitrogen is used as a security gas and a sealing gas in some application scenarios, and has a weak correlation with the output of steel rolling and coking, etc., and does not all increase or decrease with the increase or decrease of these products. These variable application scenarios increase the difficulty of nitrogen balance. The above-mentioned variable application scenarios increase the difficulty of nitrogen balance. Therefore, nitrogen balance needs to be combined with the actual situation on site, that is, it is necessary to take into account the relative stability of the production process and also take into account the changes in production and equipment status. Since the use of nitrogen is mostly related to the safety of the production process of iron and steel enterprises, therefore, sufficient emergency, adjustment, and standby space must be reserved for nitrogen balance to meet the emergency needs of safe production.

[0101] (2) Explore the dynamic change characteristics of oxygen and nitrogen gases and the technical conditions of balance factors, and propose optimization strategies for oxygen and nitrogen gases

[0102] Since the production of steel rolling is a dynamic change process, the oxygen and nitrogen consumption must be a dynamic change process. Therefore, the oxygen and nitrogen gas balance also needs to be dynamically adjusted with the production changes of steel rolling, which is one of the purposes of optimizing the oxygen and nitrogen gas balance; in addition, through the analysis of balance factors, on the basis of the dynamic balance of oxygen and nitrogen production and use, find the improvement points of high-quality and low-utilization of oxygen and nitrogen, and find the weak links affecting gas balance, so as to achieve the purpose of ensuring supply and reducing consumption, which is another purpose of optimizing the oxygen and nitrogen gas balance.

[0103] 1. Optimization of the oxygen system balance;

[0104] (1)Oxygen enrichment before the blast furnace blower; Through the study of the oxygen balance factor, it can be found that the demand conditions for balance factors such as pressure and oxygen purity of oxygen in different processes such as steelmaking, ironmaking, and rolling are different. For example, the oxygen demand pressure in the ironmaking process can be either 0.7 Mpa (oxygen enrichment after the blower) or 5 - 10 kpa (oxygen enrichment before the blower, which requires transformation), and the oxygen purity reaches 80%. While in the steelmaking process, it is 1.2 - 1.3 Mpa, and the oxygen purity requirement is > 99.5%. The oxygen supply pressure of the oxygen production system of many steel enterprises is 1.5 Mpa and the oxygen purity is above 99.6%. For the blast furnace system, there is a phenomenon of high-quality and low-utilization between the oxygen supply pressure and the gas consumption pressure, and between the supply quality and the gas consumption quality. The balance factor conditions at the supply end are much higher than those at the demand end, and there is a certain surplus space. This space also means the space for optimizing and reducing oxygen consumption. For many steel enterprises, through oxygen balance analysis, this space can be exploited. In addition, the domestic blast furnace oxygen enrichment rate is gradually increasing, and the oxygen demand needs to increase synchronously. The increased oxygen volume is similar to the optimizable space mentioned above, and it can be achieved by directly using the low-pressure oxygen out of the air separation tower of the low-temperature air separation oxygen generator or by introducing pressure swing adsorption oxygen production technology combined with oxygen enrichment before the blower.

[0105] (2)Oxygen optimization in the steelmaking system; Although the oxygen supply and demand pressure and quality factors in the steelmaking system are compatible, there is an imbalance in the rhythm of steelmaking: the oxygen consumption is relatively large during the concentrated blowing stage, and the oxygen supply needs to be increased; the oxygen consumption is small during the non-blowing stage, and the oxygen supply needs to be reduced. There needs to be a buffer adjustment between the increase and decrease. The effective methods are, first, to improve the buffer capacity of the oxygen storage sphere, second, to tap the liquid potential and use the liquid for making up deficiencies; third, to increase the number of operating oxygen generators. To improve the buffer capacity of the oxygen storage sphere, it is necessary to balance the oxygen outlet pressure between the oxygen generators and optimize the process, improve the throughput capacity and set pressure of the oxygen storage sphere, and avoid the gas flow transportation blockage and dispersion caused by limitations such as the oxygen pipe diameter and valve.

[0106] 2. Balance optimization of the nitrogen system;

[0107] Similar to the oxygen system, the balance optimization of the nitrogen system also starts from analyzing the technical conditions of the nitrogen balance factor in each process. As shown in Table 2, the optimization path is found by analyzing the nitrogen balance factor.

[0108] (1)Development of low-pressure nitrogen; First, it is necessary to analyze the nitrogen demand pressure grade, then analyze the nitrogen demand volume at different pressure grades, and also analyze the nitrogen purity requirements of each nitrogen-using process. The optimizable space with functional surplus is found from these three balance factors;

[0109] The nitrogen in this iron and steel enterprise is divided into two pressure grades: medium-pressure nitrogen at about 1.5 Mpa and low-pressure nitrogen at about 0.8 Mpa. From the technical condition summary table of the nitrogen balance factor at the user end, it can be seen that except for the coal injection of two large blast furnaces, the slag splashing and hearth protection of steelmaking, and the bottom blowing using medium-pressure nitrogen, low-pressure nitrogen can be used in other processes. In this way, the optimization entry point for nitrogen supply in the high-low pressure sub-systems is found, and the optimization purpose can be achieved by adding low-pressure nitrogen compressors and other means.

[0110] (2) Interchangeability of nitrogen and compressed air; in some application scenarios, such as pneumatic conveying, dust removal, pneumatic regulation and other links, there are no special requirements for nitrogen pressure and gas purity. Both low-pressure nitrogen and compressed air can meet the requirements. In such scenarios, nitrogen and compressed air can be interchanged, which is also a strategy for nitrogen balance optimization and can bring comprehensive benefits to the enterprise.

[0111] The mutual replacement of nitrogen and compressed air needs to follow three principles: First, the safety principle. Due to the asphyxiation of nitrogen, there are relatively large potential safety risks in some scenarios. Therefore, sufficient safety measures need to be taken for the replacement of nitrogen in such scenarios; second, the feasibility principle of the application scenario. For example, the choice of nitrogen or compressed air will be restricted by the ambient temperature. In summer and autumn, since the temperature is higher than 0 °C, compressed air can be used to replace nitrogen for operation; while in winter in the north, compressed air is prone to saturation and icing, causing blockages in pipelines, valves, etc., and nitrogen should be preferred; third, the principle of priority for nitrogen surplus. Because the nitrogen supply pressure is stable and it does not contain moisture, many processes prefer to use nitrogen. Since the manufacturing cost of nitrogen is higher than that of compressed air, it is very easy to increase the energy cost of the entire system. Therefore, compressed air is still the first choice. However, if there is nitrogen surplus in the system, this part of the surplus gas needs to be utilized to avoid waste of resources. At this time, the surplus nitrogen should be given priority and the compressed air should be reduced to maintain the high energy efficiency state of the system.

[0112] (3) Interchange of nitrogen and steam; in processes such as iron and steel rolling and coking, nitrogen and steam can be interchanged in some parts, such as coal injection in blast furnaces, and partial sealing gas in converters, etc. These parts can use either nitrogen or steam. Which gas to use needs to be comprehensively measured in terms of energy-saving benefits and economic benefits, and the principles of safety, feasibility of the application scenario, and priority for gas surplus also need to be followed.

[0113] 3. Adjustment of the operation mode of the oxygen generator

[0114] According to different iron and steel production plans and blast furnace operation modes, calculate the oxygen and nitrogen gas supply-demand balance, and then combine the technical characteristic indicators of each oxygen generator to determine the operation mode of the oxygen generator. For this iron and steel company, the main operation is mainly carried out by the 6th, 7th, and 8th oxygen generators with higher energy efficiency. Since the production capacity of the 3rd and 4th oxygen generators is small, they are mainly used for adjusting the changes in oxygen and nitrogen gas demand. The 5th oxygen generator is a high-energy-consuming oxygen generator and should not be put into production operation as much as possible.

[0115] 4. Use of liquids;

[0116] The production and use of liquid oxygen and liquid nitrogen are important links in optimizing the oxygen-nitrogen balance. The prerequisite for tapping the potential of liquids is that the oxygen generator has sufficient liquid production and storage capabilities, which enhances the adjustment space for liquid oxygen to supplement the pipeline network through vaporization. The vaporization and supplementation of liquids need to be carried out on the premise of sufficient liquid emergency reserves and taking into account liquid sales. There are many limiting factors. If the liquid emergency reserves are insufficient and the cost of creating efficiency from liquids is lower than the operating cost of the oxygen generator, it is necessary to consider adjusting the operating mode of the oxygen generator to increase gas production.

[0117] Optimizing the balance between the supply and demand of oxygen and nitrogen is a highly practical technology that needs to develop with the development of oxygen production and nitrogen production technologies, as well as the development of oxygen and nitrogen utilization technologies such as steel rolling and coking. At the same time, the gas balance technology itself also needs to be gradually improved and continuously improved with the development of equipment and digital technologies to achieve the refinement and intelligentization of gas balance.

[0118] The above embodiments are implemented on the premise of the technical solution of the present invention, and the detailed implementation manners and specific operation processes are given. However, the protection scope of the present invention is not limited to the above embodiments. The methods used in the above embodiments are all conventional methods unless otherwise specified.

Claims

1. A supply and demand balance model of oxygen and nitrogen gas in a steel enterprise, characterized in that: Including the balance and optimization of supply and demand of oxygen and nitrogen; The oxygen and nitrogen gas supply and demand balance adopts three balance characteristics: oxygen and nitrogen gas balance factor, oxygen and nitrogen gas balance chain and oxygen and nitrogen gas balance weight. The gas demand chain and the gas supply chain are linked through the oxygen and nitrogen gas balance factor to form an oxygen and nitrogen gas supply and demand balance chain. Then, the oxygen and nitrogen gas balance factor index parameters are adjusted to make the balance factor index parameters of the oxygen and nitrogen gas production supply end and the demand end tend to be balanced and consistent, so as to achieve oxygen and nitrogen gas supply and demand balance. The optimization of oxygen and nitrogen gas supply and demand balance is to explore the dynamic change characteristics of oxygen and nitrogen gases and the balance factor index parameters, and propose an optimization strategy for oxygen and nitrogen gas supply and demand balance, including dynamic adjustment of oxygen and nitrogen gas balance with production changes in steelmaking, ironmaking, and steel rolling processes, including the development of the use of low-index oxygen and nitrogen gases and the interchangeable use of nitrogen with compressed air and steam, including the following contents: 1) Optimization of oxygen and nitrogen gas supply and demand balance: including oxygen enrichment before blast furnace blowers and oxygen optimization of steelmaking systems; 2) Optimization of oxygen and nitrogen supply and demand balance: including the development of oxygen outlet from the air separation tower of the external compression process oxygen generator, the development of 0.6-0.8Mpa oxygen, the development of 75-85% purity oxygen, and the development of 0.8-1Mpa grade nitrogen; 3) Adjustment of the operation mode of the oxygen production system; 4) Use liquid oxygen and liquid nitrogen.

2. The oxygen and nitrogen gas supply and demand balance model for a steel enterprise according to claim 1, characterized in that: The oxygen and nitrogen gas balance factors are the physical and chemical properties of the gases for balancing oxygen and nitrogen gases, respectively, including gas pressure, purity, volume, and temperature characteristics; the characteristic indicators with common requirements for the physical and chemical properties of oxygen and nitrogen gases in the demand chain and the supply chain are summarized and integrated as the oxygen balance factor and the nitrogen balance factor, respectively.

3. The oxygen and nitrogen supply and demand gas balance model for a steel enterprise according to claim 1, characterized in that: The oxygen and nitrogen gas supply and demand balance chains include an oxygen demand chain and a nitrogen demand chain respectively; the oxygen and nitrogen demand chains include oxygen and nitrogen demand users and user processes respectively, which are a collection of oxygen and nitrogen users and user processes; the oxygen and nitrogen supply chains include various types of oxygen and nitrogen production equipment respectively, which are a collection of oxygen and nitrogen production equipment.

4. The oxygen and nitrogen supply and demand balance model for a steel enterprise according to claim 1, characterized in that: The oxygen and nitrogen gas balance weights are the proportions of oxygen and nitrogen consumption of each user and process to the total oxygen consumption and nitrogen consumption, respectively.

5. The oxygen and nitrogen gas supply and demand balance model for a steel enterprise according to claim 1, characterized in that: The oxygen outlet from the air separation tower of the external compression process oxygen concentrator developed is to directly send the oxygen outlet from the external compression type air separation oxygen concentrator to the front pipe of the blast furnace blower through the oxygen pipeline without being compressed.

6. The oxygen and nitrogen gas supply and demand balance model for a steel enterprise according to claim 1, characterized in that: The development of 0.6-0.8Mpa oxygen is to pressurize the oxygen discharged from the air separation tower to 0.6-0.8Mpa and send it to the oxygen users of this level through pipelines.

7. The oxygen and nitrogen gas supply and demand balance model for a steel enterprise according to claim 1, characterized in that: The development of oxygen with a purity of 75-85% is to explore the optimization space of excess oxygen quality based on the analysis of the oxygen demand quality level and the demand for oxygen of different quality levels. Through oxygen balance analysis, a pressure swing adsorption oxygen generator is set up to specially produce this oxygen.

8. The oxygen and nitrogen gas supply and demand balance model for a steel enterprise according to claim 1, characterized in that: The development of 0.8-1Mpa grade nitrogen is to explore the optimization space of nitrogen pressure surplus based on the analysis of nitrogen demand pressure level and the demand for nitrogen of different pressure levels. Through nitrogen balance analysis, a 0.8-1Mpa grade nitrogen compressor is set up specifically for this grade of nitrogen users.

9. The oxygen and nitrogen gas supply and demand balance model for a steel enterprise according to claim 1, characterized in that: The interchange of nitrogen and compressed air is that there is no special requirement for nitrogen pressure and gas purity, low-pressure nitrogen or compressed air can meet the requirements, nitrogen and compressed air can be interchanged, and the interchange is carried out under the premise of best choice in terms of safety, energy saving and economic benefits.

10. The oxygen and nitrogen gas supply and demand balance model for a steel enterprise according to claim 1, characterized in that: The interchange of nitrogen and steam is that when both nitrogen and steam are suitable for the user's process, they are selected to be used interchangeably in the process on the premise of energy saving and safety.

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