Characterization method of coke reaction characteristics

Abstract

The invention relates to a characterization method of coke reaction characteristics. The characterization method comprises the steps of reaction of coke and carbon dioxide, carbon monoxide metering, carbon monoxide displacement calculation, coke reaction characteristic evaluation and the like. According to the characterization method of the coke reaction characteristics, reaction products are ingeniously utilized to speculate the pore structure of the coke, the defect that only two-dimensional pores can be detected through an image method is overcome, and the defect of direct destructive detection is overcome; the reaction processes of different cokes can be compared through the coke reaction surface area, and the method has important significance on coke quality evaluation.

Description

Technical Field

[0001] The invention relates to a method for characterizing coke reaction characteristics, and belongs to the technical field of coke quality evaluation. Background Art

[0002] The reactivity and post-reaction strength of coke are important indicators to characterize the thermal performance of coke. The existing coke reactivity index can only characterize the total amount of reaction, and the total amount of coke reaction is determined by the reaction rate of the coke matrix and the pore characteristics of the coke.

[0003] Current methods for detecting the pore characteristics of coke include vacuum water method, mercury injection method, nitrogen adsorption method and imaging method.

[0004] The test principle of vacuum water method (GB 4511.1-2008) is to extract the gas in the coke pores, fill the coke pores with water under the action of atmospheric pressure, measure the mass of water in the coke pores and the mass lost by the same sample when it is submerged in water, and then calculate the apparent porosity. This method only obtains the apparent porosity of coke, that is, the pore volume of coke, but not the pore area of ​​coke.

[0005] Mercury intrusion method and gas adsorption method (GB / T 21650.1-2008), the principle of mercury intrusion method is to fill mercury into the pores under pressure, which is suitable for materials with pore sizes ranging from about 0.003μm to 400μm. The gas adsorption method characterizes the pore structure by adsorbing a gas, such as nitrogen at liquid nitrogen temperature, and is suitable for measuring pores with pore sizes ranging from about 0.002μm to 0.1μm (2.0 nm to 100 nm). The mercury intrusion method may destroy the coke pores, and the obtained coke has a medium pore distribution; the nitrogen adsorption method obtains the coke micropores. Both detection methods characterize part of the pores of the coke, and neither can characterize the actual pore area of ​​the coke.

[0006] Image method "Zhang Dailin, Research on the determination of coke pore structure by image analysis method, Fuel and Chemical Industry, 2003, 34 (4), 175-178": Through image processing and analysis software, the pore structure image of coke is segmented and counted, and the determination of coke pore structure parameters by image analysis method is realized. More coke quality indicators are obtained than traditional methods, such as maximum (minimum) pore diameter, maximum (minimum) pore wall thickness, total number of pores, pore circumference, pore non-roundness, etc. Although this method obtains multiple parameters, the image method can only characterize the pore structure characteristics of the two-dimensional plane and cannot reflect the pore area of ​​coke.

[0007] Reference (Yu Zhen, Study on the correlation between coke reactivity and CO gas composition during the reaction, Chinese Inorganic Analytical Chemistry, 2011 (4), 77-80) studied the inevitable relationship between the carbon monoxide content in the coke reactivity test and the coke consumed in the reaction (coke reactivity). The weight loss was predicted by measuring the carbon monoxide gas content during the reactivity test. There is a strong correlation between the curves of the carbon monoxide gas content (y) and the coke reactivity result (x) in the reaction, and it is determined that y = xx + b (k, b are constants), so as to predict the coke reactivity in advance.

[0008] The reference literature inferred the reactivity relationship between CO gas and coke, but because the generation of CO gas is a result of the reaction between CO2 and coke, it cannot be determined whether the generation of CO gas is mostly due to the high reaction rate of CO2 and coke or the large reaction area. Summary of the invention

[0009] The technical problem to be solved by the present invention is: to overcome the disadvantages of the above-mentioned technology and provide a method for characterizing the coke reaction area by utilizing the gas composition after the coke reaction, so that the coke reaction area can be measured without destroying the coke structure.

[0010] In order to solve the above technical problems, the technical solution proposed by the present invention is: a method for characterizing the reaction characteristics of coke, comprising the following steps: (1) Coke reacts with carbon dioxide; using a coke reaction tube, a heating furnace, and an exhaust gas analysis system, coke is added into the reaction tube, the temperature is raised to a specified temperature T, carbon dioxide is introduced at this temperature, and the exhaust gas analysis system detects and records the carbon monoxide concentration in the exhaust gas until the carbon monoxide concentration reaches a stable state.

[0011] (2) Carbon monoxide measurement: Stop introducing carbon dioxide and introduce nitrogen instead. The carbon monoxide concentration in the tail gas gradually decreases to zero. Record the process of carbon monoxide concentration decreasing from a stable state to zero. (3) Calculation of carbon monoxide emissions: Based on the time it takes for the carbon monoxide concentration to decrease from a stable state to zero and the concentration change process, the carbon monoxide emissions after the carbon dioxide is stopped are obtained by integration; (4) Evaluation of coke reaction characteristics: The greater the carbon monoxide emission, the larger the pore reaction area of ​​the coke.

[0012] A further improvement of the above scheme is that the specified temperature T is 1000°C-1300°C.

[0013] The method for characterizing the reaction characteristics of coke provided by the present invention ingeniously utilizes the reaction products to infer the pore structure of coke, overcomes the defect that the imaging method can only detect two-dimensional pores, and overcomes the deficiency of direct destructive detection; the reaction surface area of ​​coke can compare the reaction process of different cokes, which is of great significance for the evaluation of coke quality. Implementation

[0014] Embodiment: A method for characterizing the reaction characteristics of coke in this embodiment comprises the following steps: (1) Coke reacts with carbon dioxide; using a coke reaction tube, a heating furnace, and an exhaust gas analysis system, coke is added into the reaction tube, the temperature is raised to 1000°C-1300°C, carbon dioxide is introduced at this temperature, and the exhaust gas analysis system detects and records the carbon monoxide concentration in the exhaust gas until the carbon monoxide concentration reaches a stable state.

[0015] (2) Carbon monoxide measurement: Stop introducing carbon dioxide and introduce nitrogen instead. The carbon monoxide concentration in the tail gas gradually decreases to zero. Record the process of carbon monoxide concentration decreasing from a stable state to zero. (3) Calculation of carbon monoxide emissions: Based on the time it takes for the carbon monoxide concentration to decrease from a stable state to zero and the concentration change process, the carbon monoxide emissions after the carbon dioxide is stopped are obtained by integration; (4) Evaluation of coke reaction characteristics: The greater the carbon monoxide emission, the larger the pore reaction area of ​​the coke.

[0016] The residual carbon monoxide emission is proportional to the coke pore reaction area. The greater the carbon monoxide emission, the larger the pore reaction area. For cokes with the same reactivity, there are cases where the coke reaction area is large and the reaction rate is low; there are also cases where the coke reaction area is small and the reaction rate is high. If the coke reaction area is greater than the reference value, that is, greater than the residual carbon monoxide emission reference value L, the coke pore structure needs to be improved.

[0017] The important improvement of this embodiment is that the residual carbon monoxide after the coke reaction stops is collected instead of the carbon monoxide during the reaction. The main reason is that the amount of carbon monoxide during the reaction is linearly related to the weight loss of the coke reaction, which is a comprehensive reflection of the reaction rate and the reaction area, while the amount of residual carbon monoxide after the reaction stops has nothing to do with the carbon reaction rate, but only with the reaction area. Only by collecting the residual carbon monoxide after the residual coke reaction stops can the reaction area be reflected.

[0018] The reaction area of ​​coke pores is inferred based on the reaction products, which is mainly due to the in-depth study of coke reaction and coke pore structure. In the process of studying coke porosity and coke micropores, it was found that microscopic pores have no good correlation with coke macropores and coke reactions. The reaction mechanism of coke is that the reaction of carbon dioxide and carbon takes place on the surface of coke pores. In order to describe the reaction characteristics of coke, the coke reaction surface area was proposed.

[0019] The total reactivity of coke is determined by the reactivity of the carbon matrix and the reaction area of ​​the coke pores. For cokes with the same reactivity as existing coke reactivity indicators, if the coke pore reaction area is greater than the benchmark value, the pore structure of the coke needs to be improved. Therefore, studying the coke pore reaction area is of great value for coke quality evaluation and improvement.

[0020] Coke A and Coke B were taken as test samples, and the following results were obtained through the above steps:

[0021] Table 1 According to the coke used by the enterprise, the residual CO emission baseline value L is determined to be 9L. As shown in Table 1, for coke A and coke B with the same reactivity, the amount of residual CO in coke A is 10.2L, which is greater than the residual CO emission baseline value L, indicating that the pore reaction area of ​​coke A is large and the pore structure of coke needs to be improved; the amount of residual CO in coke B is 8.8L, which is less than the residual CO emission baseline value L, indicating that the pore reaction area of ​​coke B is small and can meet production needs.

[0022] The present invention is not limited to the above embodiments. Any technical solution formed by equivalent replacement falls within the protection scope required by the present invention.

Claims

1. A method for characterizing coke reaction characteristics, characterized in that: The steps include: (1) Coke reacts with carbon dioxide; using a coke reaction tube, a heating furnace, and an exhaust gas analysis system, coke is added into the reaction tube, the temperature is raised to a specified temperature T, carbon dioxide is introduced at this temperature, and the exhaust gas analysis system detects and records the carbon monoxide concentration in the exhaust gas until the carbon monoxide concentration reaches a stable state; (2) Carbon monoxide measurement: Stop introducing carbon dioxide and introduce nitrogen instead. The carbon monoxide concentration in the tail gas gradually decreases to zero. Record the process of carbon monoxide concentration decreasing from a stable state to zero. (3) Calculation of carbon monoxide emissions: Based on the time it takes for the carbon monoxide concentration to decrease from a stable state to zero and the concentration change process, the carbon monoxide emissions after the carbon dioxide is stopped are obtained by integration; (4) Evaluation of coke reaction characteristics: The greater the carbon monoxide emission, the larger the pore reaction area of ​​the coke.

2. The method for characterizing the coke reaction characteristics according to claim 1, characterized in that: The specified temperature T is 1000°C-1300°C.

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