An oxygen carrier evaluation and screening method for industrial applications

Abstract

The application relates to an oxygen carrier evaluation and screening method for industrial application, and belongs to the field of oxygen carrier preparation in chemical looping combustion technology. The method adopts a standardized test procedure combining strength test-oxygen carrying rate test-dynamics test-cycle stability test-post-cycle strength test to screen and obtain oxygen carriers meeting the requirements of industrial application. The application establishes a systematic oxygen carrier evaluation and screening method, can provide scientific evaluation and screening basis for different types of oxygen carrier materials, and provides an important reference for future scientific research and engineering design.

Description

Technical Field

[0001] This invention relates to a method for evaluating and screening oxygen carriers for industrial applications, belonging to the field of oxygen carrier preparation in chemical looping combustion technology. Background Technology

[0002] Chemical looping combustion (CLC) is a novel carbon capture technology that utilizes two fluidized bed reactors and fluidized bed circulation of oxygen-carrying particles, dividing the traditional direct combustion process into two steps. In the fuel reactor (FR), the oxygen-carrying particles provide lattice oxygen to the fuel, oxidizing it to CO2 and H2O, while simultaneously losing lattice oxygen and being reduced. In the air reactor (AR), the reduced oxygen-carrying particles react with air to replenish lattice oxygen, then return to the FR to continue the cycle. This technology avoids direct contact between air and fuel, exhibiting internal CO2 separation characteristics, and has garnered significant attention from major research institutions worldwide. After years of development, in March 2024, the team led by Zhenshan Li at Tsinghua University achieved, for the first time internationally, over 60 hours of continuous self-heating operation of a megawatt-level chemical looping combustion device, marking a significant milestone as CLC technology has reached the megawatt level and holds promise for industrial application in the coming years.

[0003] Oxygen carriers are the core functional materials in chemical looping combustion technology, and their performance directly determines the economic efficiency and safety of the system during industrial scale-up. Common types of oxygen carriers include iron-based, copper-based, nickel-based, manganese-based, cobalt-based, perovskite-type composite oxides, spinel-type composite oxides, and natural mineral oxygen carriers. Different types of oxygen carriers exhibit significant differences in oxygen loading capacity, mechanical strength, cost, environmental friendliness, and long-term cycle stability. Because chemical looping combustion technology is still in the critical stage of transitioning from laboratory research to industrial application, a unified, standardized, and systematic testing method and evaluation standard for the industrial evaluation and screening of oxygen carriers has not yet been established. In existing research, different institutions and research teams often select different test conditions and evaluation indicators based on their own experimental conditions, target fuel types, and device characteristics. While these evaluation methods can reflect the performance of oxygen carriers under specific experimental conditions to some extent, they are insufficient to meet the needs of comprehensive evaluation and rapid screening of oxygen carriers under industrial application conditions.

[0004] Therefore, establishing a method for evaluating and screening oxygen carriers for industrial applications, and conducting comparability evaluation and screening of different oxygen carriers by standardizing testing procedures, unifying testing conditions, and constructing an evaluation index system, is of great significance for promoting the engineering application of chemical looping combustion technology. Summary of the Invention

[0005] The following is an overview of the subject matter described in detail herein. This overview is not intended to limit the scope of the claims.

[0006] CN121354729A discloses a machine learning method for screening oxygen carriers in chemical looping reactors. This method, based on a gradient boosting regression model, is an intelligent screening method for multi-metal oxide oxygen carriers, suitable for efficiently screening multi-metal oxide oxygen carrier materials with excellent gasification performance. This method only requires the mass percentage of each metal in the oxygen carrier to be tested to predict the syngas composition and gas yield. However, while this method focuses on the correlation between oxygen carrier composition and gasification performance, the industrial application performance of oxygen carriers depends not only on the metal composition but also on various factors such as specific surface area, particle size, mechanical strength, and preparation method. Therefore, relying solely on the metal mass percentage is insufficient to accurately evaluate the overall performance of oxygen carriers in industrial chemical looping reactors, especially to determine their long-term cycle stability and wear resistance. Furthermore, the accuracy of machine learning screening methods is highly dependent on the quality, quantity, and consistency of the training data. If the training data comes from different literature, experimental platforms, or testing conditions, there may be differences in temperature, atmosphere, flow rate, reactor type, and number of cycles, leading to uncertainty in the model's prediction results. Although this method can achieve rapid prediction using the model, it does not fundamentally solve the problems of inconsistent testing conditions, inconsistent evaluation criteria, and difficulty in cross-referencing experimental data for chemically chained oxygen carriers. In other words, this method is more of a data-driven initial screening tool than a standardized evaluation method for industrial applications, which further highlights the importance of this application.

[0007] CN106185807B discloses a pilot-scale device and method for single-tower fixed-bed chemical looping hydrogen production. This device includes a feeding system, a reaction system, a tail gas treatment and analysis system, and auxiliary systems. It can evaluate oxygen carriers and identify technical bottlenecks on a large scale, and obtain high-purity hydrogen without complex gas purification devices, resulting in a simple hydrogen production process. The core of this patent lies in the system composition of the single-tower fixed-bed chemical looping hydrogen production pilot-scale device and the hydrogen production method. It mainly addresses the issues of device construction, gas switching, reaction operation, and high-purity hydrogen production in the chemical looping hydrogen production process. However, it does not disclose standardized testing procedures, evaluation index systems, and screening rules for different oxygen carriers, and therefore cannot solve the problems of unified testing, quantitative evaluation, and graded screening in oxygen carrier evaluation.

[0008] To address the shortcomings of existing technologies, this invention aims to establish a systematic method for evaluating and screening oxygen carriers, providing a scientific basis for evaluating and screening different types of oxygen carrier materials, and offering important references for future scientific research and engineering design.

[0009] This invention proposes a method for evaluating and screening oxygen carriers for industrial applications. Based on a fluidized bed thermogravimetric analyzer, a digital force gauge, and a micrometer, it employs a standardized testing procedure that combines strength testing, oxygen carrying capacity testing, kinetic testing, cycle stability testing, and post-cycle strength testing to screen for oxygen carriers that meet the requirements of industrial applications.

[0010] This application provides a method for evaluating and screening oxygen carriers for industrial applications, characterized by the following steps: (1) Screen the oxygen carrier particles to be tested, and the particles that meet the particle size requirements are further evaluated. (2) Test the median compressive strength of the oxygen carrier particles to be tested. P and crushing force F If compressive strength P <30MPa or particle crushing force F If the value is <10N, the oxygen carrier being tested is considered to be unsuitable for industrial applications; otherwise, the next step of evaluation is carried out. (3) Test the oxygen carrying capacity of the oxygen carrier to be tested. R If oxygen carrying capacity R If the oxygen carrier concentration is less than 2%, it is considered that the oxygen carrier does not meet the requirements for industrial application; otherwise, the next step of evaluation is carried out. (4) Test the redox reaction kinetics of the oxygen carrier to be tested, and determine the time required for the oxygen carrier to achieve complete conversion in the reduction reaction. t re >200s or the time required for complete conversion in an oxidation reaction. t ox If the test time is greater than 15 seconds, the oxygen carrier being tested is considered to be unsuitable for industrial applications; otherwise, the next step of evaluation is carried out. (5) Conduct long-term cycle stability tests on the oxygen carrier. If the oxygen carrier wear rate during long-term cycle testing is... A >0.10 wt.% / h or oxygen carrying capacity R` If the oxygen carrier concentration is less than 2%, the tested oxygen carrier is considered unsuitable for industrial applications; otherwise, further evaluation is conducted. (6) Test the median compressive strength of oxygen carrier particles after long-term cycling. P` and crushing force F` If compressive strength P ` <15MPa or particle crushing force F` If the value is less than 5N, the oxygen carrier to be tested is considered to be unsuitable for industrial applications; otherwise, the oxygen carrier to be tested is considered to be a qualified oxygen carrier that meets industrial requirements.

[0011] In some exemplary embodiments, the oxygen carrier evaluation and screening method includes the following steps: (1) Screen the oxygen carrier particles to be tested, and the particles that meet the particle size requirements are further evaluated. (2) Use a micrometer to measure the diameter of a single particle and record it as . d 1. Rotate the same particle 90° and measure the particle size again, recording it as . d 2. Obtain the average particle size d 平均 The particles were then transferred to a digital force gauge to obtain their crushing force, and the value was recorded. F； Repeat the above steps to obtain the particle size and corresponding crushing force of several particles. Then, using the compressive strength calculation formula, obtain the median compressive strength of the oxygen carrier to be tested. P， If compressive strength P <30MPa or particle crushing force F If the value is <10N, the oxygen carrier being tested is considered to be unsuitable for industrial applications; otherwise, the next step of evaluation is carried out. (3) The oxygen carrying capacity of the oxygen carrier to be tested was tested using a fluidized bed thermogravimetric analyzer: Quartz sand and the oxygen carrier particles to be tested were added to the reactor of the fluidized bed thermogravimetric analyzer, and the bed height was set to a certain height. The reactor was heated to a certain temperature at a certain heating rate to activate the oxygen carrier first, and then the oxygen carrying capacity was tested. If the oxygen carrying capacity was... R If the oxygen carrier concentration is less than 2%, it is considered that the oxygen carrier does not meet the requirements for industrial application; otherwise, the next step of evaluation is carried out. (4) The oxidation-reduction reaction kinetics of the oxygen carrier to be tested were tested using a fluidized bed thermogravimetric analyzer: the time required for the oxygen carrier to achieve complete conversion in the reduction reaction. t re >200s or the time required for complete conversion in an oxidation reaction. t ox If the time exceeds 15 seconds, the oxygen carrier being tested is considered unsuitable for industrial applications; otherwise, the next step of evaluation is conducted. (5) Long-term cycle stability test of oxygen carrier was conducted using a fluidized bed thermogravimetric analyzer: If the oxygen carrier wear rate during long-term cycle is... A >0.10 wt.% / h or oxygen carrying capacity R` If the oxygen carrier concentration is less than 2%, it is considered that the oxygen carrier does not meet the requirements for industrial application; otherwise, the next step of evaluation is carried out. (6) Using a micrometer, measure the particle size of the oxygen carrier particles after a single long-cycle test, and record it as _____. d` 1; Rotate the same particle 90° and measure the particle size again, recording it as . d` 2. Obtain the average particle size d` 平均 The particles were then transferred to a digital force gauge to obtain their crushing force, and the value was recorded.F` Repeat the above steps to obtain the particle size and corresponding crushing force of several particles. Based on the compressive strength calculation formula, obtain the median compressive strength of the oxygen carrier after long-term cycling. P` If compressive strength P` <15MPa or particle crushing force F` If the value is less than 5N, the oxygen carrier to be tested is considered to be unsuitable for industrial applications; otherwise, the oxygen carrier to be tested is considered to be a qualified oxygen carrier that meets industrial requirements.

[0012] In some exemplary embodiments, the oxygen carrier to be tested is one or more of the following: a natural ore containing at least one of Fe, Cu, Ni, Mn and Co, optionally hematite, ilmenite, lean iron ore, magnetite or manganese ore; an industrial waste containing at least one of Fe, Cu, Ni, Mn and Co, optionally steel slag, red mud or fly ash; and artificially prepared oxide particles containing at least one of Fe, Cu, Ni, Mn and Co.

[0013] In some exemplary embodiments, the oxygen carrier includes, but is not limited to, perovskite oxygen carriers or spinel oxygen carriers.

[0014] In some exemplary embodiments, the particle size requirement in step (1) is 200μm-500μm.

[0015] In some exemplary embodiments, in step (2), the number of test particles is 20 or more, and the crushing force of the fresh test particles is... F ≥10N and compressive strength P ≥30MPa. Only particles that meet both of the above requirements are considered to be compliant. If either the crushing force or the compressive strength does not meet the requirements, the particle will be eliminated.

[0016] compressive strength P The formula is calculated according to GB / T 43091-2023 and is as follows: in, F Crushing force, in N. d 平均 The average particle size is expressed in meters (m).

[0017] In some exemplary embodiments, in step (3), the bed height is 1.50cm-2.50cm; optionally, the quartz sand particle size ranges from 300μm to 500μm, and the mass is 15g-18g; the mass of the oxygen carrier to be tested is 0.8g-1.2g; optionally, the heating rate is 10-20℃ / min, and the temperature is 850℃-950℃. The oxygen carrier activation procedure is as follows: using 99.99 vol.% N2 as the purge gas, 10 vol.% H2 as the reducing gas, and 10.5 vol.% O2 as the oxidizing gas, with the flow rate set to three times the minimum fluidization velocity of the particles, and performing 20 consecutive redox cycles. Cycles 1-10: Nitrogen purging for 10s → 10 vol.% H2 reduction for 120s → Nitrogen purging for 10s → 10.5 vol.% O2 oxidation for 120s; 11-20 cycles: nitrogen purging for 10s → 10 vol.% H2 reduction for 90s → nitrogen purging for 10s → 10.5 vol.% O2 oxidation for 120s; The oxygen carrying capacity test procedure is as follows: nitrogen purging for 40s → 10 vol.% H2 reduction for 60s → nitrogen purging for 40s → 20 vol.% O2 oxidation for 120s, and the redox cycle reaction is carried out continuously for 10 times. The average oxygen carrying capacity of the 10 cycles is calculated as the oxygen carrying capacity of the oxygen carrier to be tested.

[0018] The formula for calculating oxygen carrying capacity is: in, m ox The mass of the particles in the oxidized state. m re The mass of the particles in their reduced state. m 0 represents the total mass of particles fed into the reactor.

[0019] In some exemplary embodiments, in step (4), the time required for the oxygen carrier to achieve complete conversion in the reduction reaction is... t re ≤200s and the time required for complete conversion in the oxidation reaction. t ox ≤15s; only particles that simultaneously meet both of the above requirements are considered to be compliant. t re and t ox If any requirement is not met, the application will be eliminated. The kinetic test procedure is as follows: 0.80g-1.0g of particles are randomly weighed from the oxygen carrier after the reaction in step (3), and 16.00g of quartz sand with a diameter of 300μm-500μm is weighed and placed together in the reactor. The reactor is heated to 850℃-950℃ at a heating rate of 5-40℃ / min. 99.99vol.% N2 is used as the purging gas, 5vol.% H2 is used as the reducing gas, and 10.5vol.% O2 is used as the oxidizing gas. The flow rate is set to 3 times the minimum fluidization rate of the particles. The following redox cycle is performed: nitrogen purging for 10s → 5vol.% H2 reduction for 200s → nitrogen purging for 10s → 10.5vol.% O2 oxidation for 200s.

[0020] The complete conversion of oxygen carrier is defined as follows: when the oxygen carrier loses 3% of its own mass, it is considered that the oxygen carrier has been completely converted.

[0021] In some exemplary embodiments, in step (5), the wear rate of the oxygen carrier under test during long-cycle cycling is... A ≤0.10 wt.% / h and oxygen carrying capacity R` ≥2%, only particles that meet both of the above requirements are considered to be compliant, wear rate. A and oxygen carrying capacity R` If any requirement is not met, the system will be disqualified. Optionally, the stability test may include a long-term cycle count of ≥100.

[0022] The cycle stability test procedure is as follows: Weigh 5g-15g of the oxygen carrier obtained in step (1) and place it in the reactor. Heat the reactor to 850℃-950℃ at a heating rate of 5-40℃ / min. Use 99.99 vol.% N2 as the purge gas, 10 vol.% H2 as the reducing gas, and 10.5 vol.% O2 as the oxidizing gas. Set the flow rate to 3 times the minimum fluidization rate of the particles. Perform 100 redox cycles continuously: nitrogen purge for 10s → 10 vol.% H2 reduction for 100s → nitrogen purge for 10s → 10.5 vol.% O2 oxidation for 100s.

[0023] Wear rate A The calculation formula is: in, m 稳定性循环后 It is the total mass of the oxygen carrier after stability cycling. m 稳定性循环前 It is the total mass of oxygen carrier before stable cycling. t It is the cycle time.

[0024] In some exemplary embodiments, in step (6), the number of test particles is more than 20, and the crushing force of the test particles after long-term cycling is... F` ≥5N and compressive strength P` ≥15MPa; only particles that simultaneously meet both of the above requirements are considered to meet the requirements for crushing force. F` and compressive strength P` If any requirement is not met, the application will be eliminated.

[0025] The reasons for selecting strength, oxygen carrying capacity, kinetics, and wear rate as performance evaluation indicators in this application are as follows: Currently, most research on oxygen carriers aims to improve their oxygen carrying capacity; however, the 5MW oxygen carrier established at Tsinghua University... th During the operation of the chemical looping combustion pilot plant, it was found that a high circulation ratio was a key factor in maintaining the plant's self-heating stability. This operation resulted in a short residence time of the oxygen carrier in the fuel reactor, leading to an actual oxygen-carrying capacity of only about 2%. Furthermore, the oxygen carrier experienced severe pulverization, wear, and escape during operation. The particles, subjected to the combined effects of mechanical, thermal, and chemical stresses, continuously weakened in strength, and their particle size gradually decreased after wear. They were eventually separated from the plant by the cyclone separator, resulting in significant oxygen carrier loss. These experiences indicate that in actual pilot operation, the oxygen-carrying capacity (activity) of the oxygen carrier is relatively abundant; for example, a typical oxygen carrier can achieve an oxygen-carrying capacity of 3-8%, but only 2% is actually used. However, the mechanical properties (strength) of the oxygen carrier are far from sufficient. Therefore, in the selection of oxygen carriers for industrial applications, the mechanical properties of the oxygen carrier must be fully considered, a point that most current research has not yet recognized. Crushing force and compressive strength are intuitive data reflecting the strength of the oxygen carrier. Furthermore, the pilot plant must employ a high circulation rate operation strategy, resulting in a relatively short actual residence time of the oxygen carrier in both reactors. Therefore, the kinetic requirements of this application are essentially requirements regarding the residence time of the oxygen carrier. Actual calculations show that the residence time of the oxygen carrier in the fuel reactor is 150-200 s, and in the air reactor, it is 10-15 s. Accordingly, this invention proposes that the complete conversion time for the reduction reaction should not exceed 200 s, and the complete conversion time for the oxidation reaction should not exceed 15 s. Complete conversion is defined as the oxygen carrier releasing / replenishing lattice oxygen to reach 3% (oxygen carrying capacity reaching 3%).

[0026] In summary, the requirements for compressive strength / crushing force in this application are to ensure that the particles have sufficient mechanical strength and will not wear during operation; oxygen carrying capacity is to ensure that the particles have sufficient lattice oxygen carrying capacity to meet the requirements of the pilot plant; kinetics is to ensure that the oxygen carrier completes the transfer of lattice oxygen within a specified time; and wear rate is the most intuitive data for evaluating the wear of the oxygen carrier.

[0027] This application requires the crushing force of the test particles in their fresh state.F ≥10N is chosen because particles with a strength of 5N or higher will not experience severe wear, while the strength of the particles after the reaction will generally decrease by half. Therefore, 10N is selected as the crushing force that the oxygen carrier in its fresh state should have.

[0028] This application requires compressive strength. P The requirement of ≥30MPa is because the oxygen carrier particle size range proposed in this application is 200μm-500μm. Considering the most extreme working condition, that is, an oxygen carrier particle size of 500μm, the required crushing force is... F The compressive strength calculated using the formula is given as 10N. P =31.58MPa, therefore the required compressive strength is... P ≥30MPa.

[0029] This application requires oxygen carrying capacity. R Oxygen load in ≥2% and long-cycle stability tests R ≥2% is based on 5MW th The actual oxygen-carrying capacity of the oxygen carrier was calculated using a chemical looping combustion pilot plant.

[0030] This application requires the time necessary for complete conversion in a reduction reaction. t re ≤200s and the time required for complete conversion in the oxidation reaction. t ox ≤15s is based on 5MW th The actual residence time of the oxygen carrier was calculated by a pilot-scale chemical looping combustion apparatus.

[0031] This application requires a wear rate. A ≤0.10 wt.% / h is based on the current consensus in the field of chemical chaining that the lifetime of an oxygen carrier should not be less than 1000h, and lifetime is defined as 100 wt.% / h. A Therefore, it can be deduced that the wear rate should be ≤0.1 wt.% / h.

[0032] This application requires the crushing force of oxygen carrier particles after long-cycle cycling. F The reason why oxygen carriers with a crushing force of ≥5N have good wear resistance is that oxygen carriers should have at least this level of strength after long-term cycling.

[0033] This application requires the compressive strength of the oxygen carrier particles after long-cycle cycling. P The pressure requirement of ≥15MPa is based on the most extreme operating conditions, requiring a crushing force when the oxygen carrier particle size is 500μm. F The compressive strength calculated according to the formula is 5N. P =15.79MPa, therefore the required compressive strength is...P` ≥15MPa.

[0034] This application also includes calculating the cost of the oxygen carrier before the screening in step (1). If the cost of the oxygen carrier is ≥30,000 yuan / ton, it can be directly excluded without further testing, because the cost is too high to be industrially applicable. The calculation of the preparation cost of the oxygen carrier includes the following aspects: cost of oxygen carrier raw materials. C 材料 The unit is 10,000 yuan / ton; oxygen carrier logistics cost C 物流 This refers to the cost of transporting raw materials to the pellet manufacturing plant, expressed in tens of thousands of yuan per ton; and the cost of water, electricity, and gas consumed during the preparation process, including grinding, drying, molding, and sieving of the oxygen carrier. C 消耗 The unit is 10,000 yuan / ton; the cost of high-temperature calcination of oxygen carrier. C 煅烧 This refers to the cost of high-temperature calcination of the oxygen carrier, expressed in tens of thousands of yuan per ton. Total cost. C = C 材料 +C 物流 + C 消耗 + C 煅烧 ,like C If the price is ≥30,000 yuan / ton, the oxygen carrier can be directly excluded.

[0035] The beneficial effects of this invention are as follows: By establishing a systematic method for evaluating oxygen carriers, this invention ensures that oxygen carriers that meet industrial requirements are selected, thereby improving the selectivity and applicability of oxygen carriers, effectively reducing overall operating costs, and providing a reliable technical foundation for subsequent industrial applications.

[0036] Other features and advantages of this application will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the application. Other advantages of this application can be realized and obtained by means of the embodiments described in the description and the accompanying drawings. Attached Figure Description

[0037] The accompanying drawings are used to provide an understanding of the technical solutions of this application and constitute a part of the specification. They are used together with the embodiments of this application to explain the technical solutions of this application and do not constitute a limitation on the technical solutions of this application.

[0038] Figure 1 This is a flowchart of the technology of the present invention; Figure 2 CaMn from Example 1 0.5 Ti 0.375 Fe 0.125 O 3-δResults of perovskite particle activation and oxygen carrying capacity tests; Figure 3 CaMn from Example 1 0.5 Ti 0.375 Fe 0.125 O 3-δ Results of perovskite particle kinetics tests; Figure 4 CaMn from Example 1 0.5 Ti 0.375 Fe 0.125 O 3-δ Results of perovskite particle cycle stability tests; and Figure 5 The results show the activation and oxygen carrying capacity of the oxygen carrier particles in Comparative Example 2. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of this application clearer, the embodiments of this application will be described in detail below. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be arbitrarily combined with each other.

[0040] The present invention will be further described in detail below with reference to specific embodiments, but these embodiments should not be construed as limiting the present invention.

[0041] Those skilled in the art will readily understand that the following description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

[0042] Example 1 With CaMn 0.5 Ti 0.375 Fe 0.125 O 3-δ The perovskite particles were used as the oxygen carriers to be tested, and were tested according to the evaluation and screening methods proposed in this application.

[0043] The total cost of the oxygen carrier is 8432.08 yuan / ton. C 材料 +1000 yuan / ton C 物流 +2000 yuan / ton C 消耗 ) + 4000 yuan / ton C 煅烧 =15432.08 yuan / ton, which meets the requirements.

[0044] (1) Screening ① Place a certain mass of oxygen carrier particles to be tested in a vibrating sieve and run it continuously for 10 minutes to obtain no less than 50g of particles with a diameter of 200μm-500μm; ② After running the particles obtained in step ① in a vibrating sieve for 10 minutes, randomly weigh 20g of particles with a diameter of 200-500μm for the next test. The purpose of the second sieving is to remove fine powder adhering to the particle surface and to prevent particles of other size ranges from being mixed in.

[0045] (2) Strength test Randomly select one particle from the particles obtained in step (1), and first use a micrometer to obtain its particle size. d 1. Then rotate the particle 90° and measure its particle size again. d 2. Obtain the average particle size d 平均 The crushing force of a single particle was measured by placing it on a digital force gauge. F And according to the formula Calculate compressive strength P Repeat the above steps 20 times and record the obtained data, as shown in Table 1. Based on the results, the crushing force of the oxygen carrier can be determined. F It has a strength of 29N and a compressive strength of P The pressure was 114.83 MPa, which meets the screening requirements, so we will proceed to the next step of testing.

[0046] Table 1 CaMn 0.5 Ti 0.375 Fe 0.125 O 3-δ Strength test results of perovskite oxygen carrier (3) Oxygen carrying capacity test ① Before testing the oxygen carrying capacity of the oxygen carrier, the oxygen carrier must first be activated.

[0047] The CaMn obtained from step (1) 0.5 Ti 0.375 Fe 0.125 O 3-δ One g of perovskite particles was weighed and placed in a reactor, which was then heated to 900°C at a heating rate of 20°C / min. 99.99 vol.% N2 was used as the purge gas, 10 vol.% H2 as the reducing gas, and 10.5 vol.% O2 as the oxidizing gas. The flow rate was set to three times the minimum fluidization rate of the particles, and 20 redox cycles were performed continuously. Cycles 1-10: Nitrogen purging for 10s → 10 vol.% H2 reduction for 120s → Nitrogen purging for 10s → 10.5 vol.% O2 oxidation for 120s; 11-20 cycles: nitrogen purging for 10s → 10 vol.% H2 reduction for 90s → nitrogen purging for 10s → 10.5 vol.% O2 oxidation for 120s; ② Oxygen loading rate test: After 20 activation cycles, the oxygen loading rate was tested: nitrogen purging for 40s → 10 vol.% H2 reduction for 60s → nitrogen purging for 40s → 20 vol.% O2 oxidation for 120s, and the redox cycle was repeated 10 times. The average oxygen loading rate of the 10 cycles was calculated according to the following formula as the oxygen loading rate of the oxygen carrier to be tested. in, m ox The mass of the particles in the oxidized state. m re The mass of the particles in their reduced state. m 0 represents the total mass of particles fed into the reactor.

[0048] CaMn 0.5 Ti 0.375 Fe 0.125 O 3-δ The activation process and oxygen carrying capacity results of perovskite particles are as follows: Figure 2 As shown, the oxygen carrying capacity was obtained from the test. R The result was 3.35%, which meets the screening requirements, so we will proceed to the next step of testing.

[0049] (4) Dynamic testing 0.8 g of particles were randomly weighed from the oxygen carrier after step (3), and 16 g of quartz sand with a diameter of 300 μm-500 μm was weighed. Both were placed in the reactor, and the reactor was heated to 900 °C at a heating rate of 20 °C / min. 99.99 vol.% N2 was used as the purge gas, 5 vol.% H2 as the reducing gas, and 10.5 vol.% O2 as the oxidizing gas. The flow rate was set to 3 times the minimum fluidization velocity of the particles. The following redox cycle was performed: nitrogen purging for 10 s → 5 vol.% H2 reduction for 200 s → nitrogen purging for 10 s → 10.5 vol.% O2 oxidation for 200 s.

[0050] Complete conversion of the oxygen carrier is defined as a weight loss of 3% of its own mass, i.e., a mass decrease of 24 mg, at which point the oxygen carrier is considered completely converted. (CaMn) 0.5 Ti 0.375 Fe 0.125 O 3-δ Perovskite particle kinetic test results are as follows Figure 3 As shown, the complete conversion time of the reduction reaction t re The complete conversion time of the oxidation reaction is 21.6 s.t ox The result was 4 seconds, which meets the screening requirements, so we will proceed to the next step of testing.

[0051] (5) Cyclic stability test The CaMn obtained from step (1) 0.5 Ti 0.375 Fe 0.125 O 3-δ 10g of perovskite particles were weighed and placed in a reactor, which was then heated to 900℃ at a heating rate of 20℃ / min. 99.99 vol.% N2 was used as the purge gas, 10 vol.% H2 as the reducing gas, and 10.5 vol.% O2 as the oxidizing gas. The flow rate was set to three times the minimum fluidization velocity of the particles. One hundred redox cycles were performed continuously: nitrogen purge for 10 s → 10 vol.% H2 reduction for 100 s → nitrogen purge for 10 s → 10.5 vol.% O2 oxidation for 100 s.

[0052] CaMn 0.5 Ti 0.375 Fe 0.125 O 3-δ The results of the perovskite particle cycle stability test are as follows: Figure 4 As shown, the oxygen carrier wear rate is calculated according to the following formula. A It is 0.0008 wt.% / h. R` The result was 2.95%, which meets the screening requirements, so we will proceed to the next step of testing. in, m 稳定性循环后 It is the total mass of the oxygen carrier after stability cycling. m 稳定性循环前 It is the total mass of oxygen carrier before stable cycling. t It is the cycle time.

[0053] (6) Post-cycle strength test Twenty particles were randomly selected from the particle sample after step (5) test. The particle size of each individual particle was first obtained using a micrometer. d` 1. Then rotate the particle 90° and measure its particle size again. d` 2. Obtain the average particle size d` 平均 The crushing force of a single particle was measured by placing it on a digital force gauge. F` And calculate the compressive strength. P` Repeat the above steps 20 times and record the obtained data as shown in Table 2. Based on the results, CaMn... 0.5 Ti 0.375 Fe 0.125 O3-δ Collapse stress of perovskite oxygen carriers after long-term cycling F` It is 15.89N, and the compressive strength is P` The pressure is 54.44 MPa, which meets the screening requirements.

[0054] Table 2 CaMn 0.5 Ti 0.375 Fe 0.125 O 3-δ Strength test results of perovskite oxygen carrier after long-term cycling After the above 6 steps of evaluation and screening, CaMn 0.5 Ti 0.375 Fe 0.125 O 3-δ Perovskite meets all the requirements and is therefore a suitable oxygen carrier for industrial applications.

[0055] Comparative Example 1 Using ilmenite from a certain location in Vietnam as the oxygen carrier to be tested, the tests were conducted according to the evaluation and screening methods proposed in this application.

[0056] Total cost of oxygen carrier = Cost of oxygen carrier raw materials C 材料 +Logistics costs C 物流 +Water, electricity, and gas consumption costs during the preparation process of oxygen carrier grinding, drying, molding, and sieving. C 消耗 + High-temperature calcination cost C 煅烧 =7800 yuan / ton, meets the requirements.

[0057] (1) Screening ① Place a certain mass of the particles to be tested in a vibrating sieve and run it continuously for 10 minutes to obtain no less than 50g of particles with a diameter of 200μm-500μm; ② After running the particles obtained in step ① in the vibrating screen for 10 minutes, randomly weigh 20g of the particles for the next test.

[0058] (2) Strength test Randomly select one particle from the particles obtained in step (1), and first use a micrometer to obtain its particle size. d 1. Then rotate the particle 90° and measure its particle size again. d 2. Obtain the average particle size d 平均 The crushing force of a single particle was measured by placing it on a digital force gauge. F And calculate the compressive strength. PRepeat the above steps 20 times and record the obtained data, as shown in Table 3. Based on the results, the crushing force of the oxygen carrier can be determined. F The value is 6.51N, which does not meet the screening requirements.

[0059] Table 3. Test results of oxygen carrier strength in a certain ilmenite mine in Vietnam Comparative Example 2 Particles made from a mixture of red mud and ilmenite were used as the oxygen carriers to be tested, and the tests were conducted according to the evaluation and screening methods proposed in this application.

[0060] Total cost of oxygen carrier = Cost of oxygen carrier raw materials C 材料 +Logistics costs C 物流 +Water, electricity, and gas consumption costs during the oxygen carrier grinding, drying, molding, and sieving processes. C 消耗 + High-temperature calcination cost C 煅烧 =6650 yuan / ton, meets the requirements.

[0061] (1) Screening ① Place a certain mass of the particles to be tested in a vibrating sieve and run it continuously for 10 minutes to obtain no less than 50g of particles with a diameter of 200μm-500μm; ② After running the particles obtained in step ① in the vibrating screen for 10 minutes, randomly weigh 20g of the particles for the next test.

[0062] (2) Strength test Randomly select one particle from the particles obtained in step (1), and first use a micrometer to obtain its particle size. d 1. Then rotate the particle 90° and measure its particle size again. d 2. Obtain the average particle size d 平均 The crushing force of a single particle was measured by placing it on a digital force gauge. F And calculate the compressive strength. P Repeat the above steps 20 times and record the obtained data, as shown in Table 4. Based on the results, the crushing force of the oxygen carrier can be determined. F The compressive strength is 25.85 N. P The pressure was 89.45 MPa, which met the screening requirements, so we proceeded to the next step of testing.

[0063] Table 4. Strength test results of an oxygen carrier made from a mixture of red mud and ilmenite. (3) Oxygen carrying capacity test ① Before testing the oxygen carrying capacity of the oxygen carrier, the oxygen carrier must first be activated.

[0064] Weigh 1 g of particles from the oxygen carrier obtained in step (1) and place them in the reactor. Heat the reactor to 900 °C at a heating rate of 20 °C / min. Use 99.99 vol.% N2 as the purge gas, 10 vol.% H2 as the reducing gas, and 10.5 vol.% O2 as the oxidizing gas. Set the flow rate to 3 times the minimum fluidization rate of the particles and perform 20 redox cycles continuously. Cycles 1-10: Nitrogen purging for 10s → 10 vol.% H2 reduction for 120s → Nitrogen purging for 10s → 10.5 vol.% O2 oxidation for 120s; 11-20 cycles: nitrogen purging for 10s → 10 vol.% H2 reduction for 90s → nitrogen purging for 10s → 10.5 vol.% O2 oxidation for 120s; ② Oxygen Loading Rate Test: After 20 activation cycles, the oxygen loading rate was tested: nitrogen purging for 40s → 10 vol.% H2 reduction for 60s → nitrogen purging for 40s → 20 vol.% O2 oxidation for 120s, and this redox cycle was repeated 10 times. The average oxygen loading rate of the 10 cycles was calculated as the oxygen loading rate of the oxygen carrier under test. The activation process and oxygen loading rate results of the oxygen carrier under test are as follows: Figure 5 As shown, the oxygen carrying capacity was obtained from the test. R The percentage was 1.81%, which did not meet the screening requirements.

[0065] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A method for evaluating and screening oxygen carriers for industrial applications, characterized in that, Includes the following steps: (1) Screen the oxygen carrier particles to be tested, and the particles that meet the particle size requirements are further evaluated. (2) Test the median compressive strength of the oxygen carrier particles to be tested. P and crushing force F If compressive strength P <30MPa or particle crushing force F If the value is <10N, the oxygen carrier being tested is considered to be unsuitable for industrial applications; otherwise, the next step of evaluation is carried out. (3) Test the oxygen carrying capacity of the oxygen carrier to be tested. R If oxygen carrying capacity R If the oxygen carrier concentration is less than 2%, it is considered that the oxygen carrier does not meet the requirements for industrial application; otherwise, the next step of evaluation is carried out. (4) Test the redox reaction kinetics of the oxygen carrier to be tested. If the time required for the oxygen carrier to achieve complete conversion in the reduction reaction is... t re >200s or the time required for complete conversion in an oxidation reaction. t ox If the time exceeds 15 seconds, the oxygen carrier being tested is considered unsuitable for industrial applications; otherwise, the next step of evaluation is conducted. (5) Conduct long-term cycle stability tests on the oxygen carrier. If the oxygen carrier wear rate during long-term cycle testing is... A >0.10 wt.% / h or oxygen carrying capacity R` If the oxygen carrier concentration is less than 2%, it is considered that the oxygen carrier does not meet the requirements for industrial application; otherwise, the next step of evaluation is carried out. (6) Test the median compressive strength of oxygen carrier particles after long-term cycling. P` and crushing force F` If compressive strength P` <15MPa or particle crushing force F` If the value is less than 5N, the oxygen carrier to be tested is considered to be unsuitable for industrial applications; otherwise, the oxygen carrier to be tested is considered to be a qualified oxygen carrier that meets industrial requirements.

2. The oxygen carrier evaluation and screening method according to claim 1, characterized in that, Includes the following steps: (1) Screen the oxygen carrier particles to be tested, and the particles that meet the particle size requirements are further evaluated. (2) Use a micrometer to measure the diameter of a single particle and record it as . d 1. Rotate the same particle 90° and measure the particle size again, recording it as _____. d 2. Obtain the average particle size d 平均 The particles were then transferred to a digital force gauge to obtain their crushing force, and the value was recorded. F； Repeat the above steps to obtain the particle size and corresponding crushing force of several particles. Then, using the compressive strength calculation formula, obtain the median compressive strength of the oxygen carrier to be tested. P， If compressive strength P <30MPa or particle crushing force F If the value is <10N, the oxygen carrier being tested is considered to be unsuitable for industrial applications; otherwise, the next step of evaluation is carried out. (3) The oxygen carrying capacity of the oxygen carrier to be tested was tested using a fluidized bed thermogravimetric analyzer: Quartz sand and the oxygen carrier particles to be tested were added to the reactor of the fluidized bed thermogravimetric analyzer, and the bed height was set to a certain height. The reactor was heated to a certain temperature at a certain heating rate to activate the oxygen carrier first, and then the oxygen carrying capacity was tested. If the oxygen carrying capacity was... R If the oxygen carrier concentration is less than 2%, it is considered that the oxygen carrier does not meet the requirements for industrial application; otherwise, the next step of evaluation is carried out. (4) The oxidation-reduction reaction kinetics of the oxygen carrier to be tested were tested using a fluidized bed thermogravimetric analyzer: the time required for the oxygen carrier to achieve complete conversion in the reduction reaction. t re >200s or the time required for complete conversion in an oxidation reaction. t ox If the time exceeds 15 seconds, the oxygen carrier being tested is considered unsuitable for industrial applications; otherwise, the next step of evaluation is conducted. (5) Long-term cycle stability test of oxygen carrier was conducted using a fluidized bed thermogravimetric analyzer: If the oxygen carrier wear rate during long-term cycle is... A >0.10 wt.% / h or oxygen carrying capacity R` If the oxygen carrier concentration is less than 2%, it is considered that the oxygen carrier does not meet the requirements for industrial application; otherwise, the next step of evaluation is carried out. (6) Using a micrometer, measure the particle size of the oxygen carrier particles after a single long-cycle test, and record it as _____. d` 1; Rotate the same particle 90° and measure the particle size again, recording it as . d` 2. Obtain the average particle size d` 平均 The particles were then transferred to a digital force gauge to obtain their crushing force, and the value was recorded. F` Repeat the above steps to obtain the particle size and corresponding crushing force of several particles. Based on the compressive strength calculation formula, obtain the median compressive strength of the oxygen carrier after long-term cycling. P` If compressive strength P` <15MPa or particle crushing force F` If the value is less than 5N, the oxygen carrier to be tested is considered to be unsuitable for industrial applications; otherwise, the oxygen carrier to be tested is considered to be a qualified oxygen carrier that meets industrial requirements.

3. The oxygen carrier evaluation and screening method according to claim 2, characterized in that, The oxygen carrier to be tested is one or more of the following: natural ore containing at least one of Fe, Cu, Ni, Mn and Co, optionally hematite, ilmenite, lean iron ore, magnetite or manganese ore; industrial waste containing at least one of Fe, Cu, Ni, Mn and Co, optionally steel slag, red mud or fly ash; and artificially prepared oxide particles containing at least one of Fe, Cu, Ni, Mn and Co. Optionally, the oxygen carrier includes, but is not limited to, perovskite oxygen carriers or spinel oxygen carriers.

4. The method for evaluating and screening oxygen carriers according to any one of claims 1-3, characterized in that, The particle size requirement in step (1) is 200μm-500μm.

5. The method for evaluating and screening oxygen carriers according to claim 2, characterized in that, In step (2), the number of test particles is more than 20, and the crushing force of the fresh test particles is measured. F ≥10N and compressive strength P ≥30MPa. Only particles that meet both of the above requirements are considered compliant. Particles that fail to meet either the crushing force or compressive strength requirement are disqualified. The compressive strength P The formula is calculated according to GB / T 43091-2023 and is as follows: in, F Crushing force, in N. d 平均 The average particle size is expressed in meters (m).

6. The method for evaluating and screening oxygen carriers according to claim 2, characterized in that, In step (3), the bed height is 1.50cm-2.50cm, optionally, the quartz sand particle size range is 300μm-500μm, the mass is 15g-18g, the mass of the oxygen carrier to be tested is 0.8g-1.2g, optionally, the heating rate is 10-20℃ / min, and the temperature is 850℃-950℃. The oxygen carrier activation procedure is as follows: using 99.99 vol.% N2 as the purge gas, 10 vol.% H2 as the reducing gas, and 10.5 vol.% O2 as the oxidizing gas, with the flow rate set to three times the minimum fluidization velocity of the particles, and performing 20 consecutive redox cycles. Cycles 1-10: Nitrogen purging for 10s → 10 vol.% H2 reduction for 120s → Nitrogen purging for 10s → 10.5 vol.% O2 oxidation for 120s; 11-20 cycles: nitrogen purging for 10s → 10 vol.% H2 reduction for 90s → nitrogen purging for 10s → 10.5 vol.% O2 oxidation for 120s; The oxygen carrying capacity test procedure is as follows: nitrogen purging for 40 s → 10 vol.% H2 reduction for 60 s → nitrogen purging for 40 s → 20 vol.% O2 oxidation for 120 s, and perform 10 consecutive redox cycles. Calculate the average oxygen carrying capacity of the 10 cycles as the oxygen carrying capacity of the oxygen carrier under test. The formula for calculating the oxygen carrying capacity is as follows: in, m ox The mass of the particles in the oxidized state. m re The mass of the particles in their reduced state. m 0 represents the total mass of particles fed into the reactor.

7. The method for evaluating and screening oxygen carriers according to any one of claims 1-3, characterized in that, In step (4), the time required for the oxygen carrier to achieve complete conversion in the reduction reaction. t re ≤200s and the time required for complete conversion in the oxidation reaction. t ox ≤15s; only particles that simultaneously meet both of the above requirements are considered to be compliant. t re and t ox If any requirement is not met, the application will be eliminated. The kinetic test procedure is as follows: 0.80g-1.0g of particles are randomly weighed from the oxygen carrier after the reaction in step (3), and 16.00g of 300μm-500μm quartz sand is weighed and placed together in the reactor. The reactor is heated to 850℃-950℃ at a heating rate of 5-40℃ / min. 99.99 vol.% N2 is used as the purging gas, 5 vol.% H2 as the reducing gas, and 10.5 vol.% O2 as the oxidizing gas. The flow rate is set to 3 times the minimum fluidization velocity of the particles. The following redox cycle is performed: nitrogen purging for 10s → 5 vol.% H2 reduction for 200s → nitrogen purging for 10s → 10.5 vol.% O2 oxidation for 200s. The complete conversion of oxygen carrier is defined as follows: when the oxygen carrier loses 3% of its own mass, it is considered that the oxygen carrier has been completely converted.

8. The method for evaluating and screening oxygen carriers according to any one of claims 1-3, characterized in that, In step (5), the wear rate of the oxygen carrier under test during long-term cycling is measured. A ≤0.10 wt.% / h and oxygen carrying capacity R` ≥2%, only particles that meet both of the above requirements are considered to be compliant, wear rate. A and oxygen carrying capacity R` If any requirement is not met, the system will be disqualified; optionally, the stability test may include a long-cycle cycle of ≥100 times. The cycle stability test procedure is as follows: Weigh 5g-15g of particles from the oxygen carrier obtained in step (1) and place them in the reactor. Heat the reactor to 850℃-950℃ at a heating rate of 5-40℃ / min. Use 99.99 vol.% N2 as the purge gas, 10 vol.% H2 as the reducing gas, and 10.5 vol.% O2 as the oxidizing gas. Set the flow rate to 3 times the minimum fluidization rate of the particles. Perform 100 redox cycles continuously: nitrogen purge for 10s → 10 vol.% H2 reduction for 100s → nitrogen purge for 10s → 10.5 vol.% O2 oxidation for 100s. Among them, wear rate A The calculation formula is: in, m 稳定性循环后 It is the total mass of the oxygen carrier after stability cycling. m 稳定性循环前 It is the total mass of oxygen carrier before stable cycling. t It is the cycle time.

9. The method for evaluating and screening oxygen carriers according to any one of claims 1-3, characterized in that, In step (6), the number of test particles is more than 20, and the crushing force of the test particles after long-term cycling is measured. F` ≥5N and compressive strength P` ≥15MPa; only particles that simultaneously meet both of the above requirements are considered to meet the requirements for crushing force. F` and compressive strength P` If any requirement is not met, the application will be eliminated.

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