Method and system for evaluating mixed combustion characteristics of biomass and coal
By using evaluation methods and systems for the characteristics of biomass and coal co-combustion, the co-combustion ratio was determined, solving the problem of boiler output fluctuation in existing technologies and achieving accurate evaluation and stable boiler operation under actual working conditions.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHINA DATANG GRP TECH INNOVATION CO LTD
- Filing Date
- 2026-05-06
- Publication Date
- 2026-07-10
Smart Images
Figure CN122361699A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of clean utilization technology of biomass energy, and in particular to an evaluation method and system for the characteristics of co-combustion of biomass and coal. Background Technology
[0002] Biomass-coal co-combustion is one of the important technological pathways for achieving efficient utilization of renewable energy and low-carbon transformation of coal-fired power units. Biomass feedstocks are widely available, diverse in type, high in volatile matter, and easily combustible; however, this also leads to significant fluctuations in the calorific value, volatile matter content, and size of biomass feedstocks purchased by power plants. If biomass feedstocks are directly co-combusted according to predetermined blending ratios based on engineers' experience after entering the plant, it can easily cause problems such as fluctuations in boiler output.
[0003] To address this, a suitable blending ratio can be determined by studying the co-combustion characteristics of biomass and coal before co-combustion. However, the research methods for the co-combustion characteristics of biomass and coal in related technologies have the following problems: (1) Some methods use empirical formulas to make preliminary judgments on fuel quality and co-combustion feasibility based on the elemental analysis of biomass and coal; however, the fitting error of the empirical formulas used in this method is difficult to define, and it is difficult to accurately predict the co-combustion characteristics of biomass with different blending ratios. (2) Some methods are based on experimental collection of characteristic data of the co-combustion process, but they focus on the study of pyrolysis mechanism, combustion process simulation or transport process parameter detection. The focus is mainly on temperature control, residence time control or mixing flow measurement, and it is difficult to accurately obtain the evaluation results of the co-combustion ratio. At the same time, these methods are mostly based on small-scale laboratory test data and lack sufficient consideration of the actual operating conditions of industrial boilers. Summary of the Invention
[0004] This application aims to address at least one of the technical problems existing in the prior art. To this end, one objective of this application is to propose an evaluation method and system for the co-combustion characteristics of biomass and coal, aiming to solve the problem that existing evaluation methods are unable to accurately evaluate the co-combustion of mixed fuels under actual operating conditions.
[0005] Firstly, this application proposes an evaluation method for the co-combustion characteristics of biomass and coal. The evaluation method includes: determining the blending ratio of biomass and coal, and preparing a mixed sample according to the blending ratio; heating the mixed sample to induce a combustion reaction, and collecting the original mass data of the mixed sample during the combustion reaction; analyzing and calculating the original mass data to obtain the actual conversion rate data and combustion characteristic data of the mixed sample combustion reaction; acquiring the first conversion rate data of the biomass combustion reaction, the second conversion rate data of the coal combustion reaction, and the baseline characteristic data and baseline fluctuation range of the coal combustion reaction; analyzing and calculating the first conversion rate data and the second conversion rate data to obtain the theoretical conversion rate data of the mixed sample combustion reaction; generating a synergistic combustion index of the mixed sample based on the actual conversion rate data and the theoretical conversion rate data; generating a combustion deviation index of the mixed sample based on the combustion characteristic data, the baseline characteristic data, and the baseline fluctuation range; and determining the evaluation result of the blending ratio based on the synergistic combustion index and the combustion deviation index.
[0006] According to some embodiments of this application, the original mass data is analyzed and calculated to obtain the actual conversion rate data and combustion characteristic data of the mixed sample combustion reaction, including: heating an empty reaction vessel to collect the reference mass data of the reaction vessel; correcting the original mass data based on the reference mass data to obtain the corrected mass data of the mixed sample combustion reaction; and analyzing and calculating the corrected mass data to obtain the actual conversion rate data and combustion characteristic data.
[0007] According to some embodiments of this application, the combustion characteristic data includes multiple combustion characteristic parameters, the reference characteristic data includes reference characteristic parameters corresponding one-to-one with the combustion characteristic parameters, and the reference fluctuation range includes the allowable fluctuation amount corresponding one-to-one with the combustion characteristic parameters; wherein, generating a combustion deviation index for a mixed sample based on the combustion characteristic data, the reference characteristic data, and the reference fluctuation range includes: calculating the deviation value corresponding to the combustion characteristic parameter based on the combustion characteristic parameter, the corresponding reference characteristic parameter, and the allowable fluctuation amount; determining the weight corresponding to each combustion characteristic parameter; and calculating the combustion deviation index based on the weight and deviation value corresponding to each combustion characteristic parameter.
[0008] According to some embodiments of this application, the evaluation result of the blending ratio is determined based on the synergistic combustion index and the combustion deviation index, including: obtaining the combustion deviation threshold and the synergistic combustion threshold of the mixed sample; calculating and analyzing the combustion deviation index and the combustion deviation threshold, and calculating and analyzing the synergistic combustion index and the synergistic combustion threshold to obtain the evaluation result of the blending ratio.
[0009] According to some embodiments of this application, the evaluation method further includes: determining the optimal blending ratio of the mixed sample based on the evaluation results of the blending ratio.
[0010] According to some embodiments of this application, the preparation of a mixed sample according to the blending ratio includes: processing biomass raw materials and coal raw materials separately while maintaining the original main particle size distribution unchanged, so as to obtain biomass samples and coal samples respectively; and blending the biomass samples and coal samples according to the blending ratio to obtain a mixed sample.
[0011] Secondly, this application proposes an evaluation system for the co-combustion characteristics of biomass and coal, used to implement the aforementioned evaluation method for the co-combustion characteristics of biomass and coal. The evaluation system includes a sample preparation unit, a reaction device, a data acquisition unit, and a data processing unit. The sample preparation unit is used to prepare a mixed sample; the reaction device is used to cause the mixed sample to undergo a combustion reaction; the data acquisition unit is connected to the reaction device to collect raw mass data of the combustion reaction of the mixed sample, and to obtain first conversion rate data of the biomass combustion reaction, second conversion rate data of the coal combustion reaction, and baseline characteristic data and baseline fluctuation range of the coal combustion reaction; the data processing unit is connected to the data acquisition unit; the data processing unit is used to calculate and analyze the raw mass data, first conversion rate data, second conversion rate data, baseline characteristic data, and baseline fluctuation range to obtain the evaluation results of the mixed sample.
[0012] According to some embodiments of this application, the reaction apparatus includes a test chamber, a reaction vessel, and a weighing component. The test chamber is equipped with a heating device; the reaction vessel is disposed within the test chamber; the weighing component is disposed below the reaction vessel and connected to the reaction vessel; wherein, the reaction vessel is used to hold the mixed sample, the heating device is used to heat the test chamber to cause the mixed sample to undergo a combustion reaction; and the weighing component is used to monitor the weight change of the mixed sample during the combustion reaction process to obtain raw mass data.
[0013] According to some embodiments of this application, the reaction vessel is constructed as a crucible, which includes a crucible body, a height limiting member, and a blocking member. The bottom plate and side wall of the crucible body are respectively provided with vent holes; the height limiting member is disposed inside the crucible body; and the blocking member is disposed at the top opening of the crucible body. The crucible body is used to hold the mixed sample, the height limiting member is used to limit the filling thickness of the mixed sample, and the blocking member is used to prevent the mixed sample from escaping.
[0014] According to some embodiments of this application, the reaction apparatus further includes an atmosphere control component connected to the test chamber; wherein the atmosphere control component is used to input reaction gas and simulated flue gas into the test chamber to control the atmosphere in the test chamber.
[0015] The evaluation method and system for the co-combustion characteristics of biomass and coal according to this application have the following technical effects: Combustion testing can accurately, quickly, and stably reflect the reaction characteristics of mixed fuels; an evaluation system directly serving raw material acceptance and boiler blending is constructed, and the compatibility of biomass and coal co-combustion in the field is rapidly evaluated through joint judgment using pure coal benchmarks and synergistic combustion indicators; a testing and evaluation technology for the co-combustion characteristics of biomass-coal particles with industrial application value is formed, which can be directly used for raw material acceptance, blending optimization, and boiler stable combustion decisions; and the problem that existing evaluation methods are difficult to accurately evaluate the co-combustion of mixed fuels under actual working conditions is solved. Compared with existing technologies, this invention emphasizes the representativeness of field samples, is more applicable to coarse particle or fibrous samples, is closer to actual production conditions, and can be practically deployed and applied; this application is of great significance for improving the level of biomass raw material control at the plant, optimizing co-combustion schemes, and ensuring the safe and stable operation of boilers.
[0016] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description
[0017] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This is a flowchart of a method for evaluating the characteristics of biomass and coal co-combustion according to some embodiments of this application; Figure 2 This is a schematic diagram of the composition of an evaluation system for the characteristics of biomass and coal co-combustion according to some embodiments of this application; Figure 3 This is a schematic diagram of the structure of a reaction apparatus according to some embodiments of this application; Figure 4 This is a schematic diagram of the structure of a reaction vessel according to some embodiments of this application.
[0018] Figure label: Reaction apparatus 100; Sample preparation unit 200; Data acquisition unit; Data processing unit; Test chamber 10; reaction vessel 20; heating device 30; weighing assembly 40; atmosphere control assembly 50; Crucible body 21; bottom plate 211; side wall 212; height limiting component 22; barrier component 23. Detailed Implementation
[0019] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.
[0020] The following is for reference. Figure 1 This application describes a method for evaluating the characteristics of biomass and coal co-combustion according to embodiments of the present application.
[0021] Firstly, this application proposes an evaluation method for the characteristics of biomass and coal co-combustion, the evaluation method including: S1. Determine the blending ratio of biomass and coal, and prepare a mixed sample according to the blending ratio.
[0022] The blending ratio of biomass and coal can be determined based on their mass fractions, such as 5% biomass blended with 95% coal; or the blending ratio can be determined based on the actual operating conditions of the power plant.
[0023] According to some embodiments of this application, the preparation of a mixed sample according to the blending ratio includes: processing biomass raw materials and coal raw materials separately while maintaining the original main particle size distribution unchanged, so as to obtain biomass samples and coal samples respectively; and blending the biomass samples and coal samples according to the blending ratio to obtain a mixed sample.
[0024] In this embodiment, biomass feedstock is taken from the raw materials to be fed into the plant or the raw materials to be blended, while coal feedstock is taken from the actual coal fed into the boiler or the coal blending system. When processing biomass and coal feedstock separately, only particle size classification and necessary impurity removal are performed, maintaining the original main particle size distribution to obtain biomass and coal samples. The biomass and coal samples are then thoroughly mixed according to the determined blending ratio to obtain a mixed sample. Necessary impurity removal refers to removing individual particles with excessively large or small particle sizes that are clearly outside the actual feed size range. This embodiment maintains the main particle size distribution of the biomass and coal samples the same as the power plant feedstock, without subjecting the feedstock to pulverization or refining processes that would significantly alter its original morphology, fiber structure, size characteristics, and packing characteristics. This allows for a true reflection of the actual particle size conditions during power plant blending and combustion, thus helping to accurately reflect the actual heating and combustion reaction behavior of coarse-grained or fibrous biomass mixed with coal at the power plant site during testing, resulting in more accurate and meaningful evaluation results.
[0025] Furthermore, the moisture content of biomass and coal samples was determined separately. The moisture content was measured using an air-dried basis or a uniform moisture standard, and the initial mass, moisture content, and sample mass were recorded to ensure comparability between different batches of samples.
[0026] S2. Heat the mixed sample to induce a combustion reaction, and collect the raw mass data of the mixed sample during the combustion reaction.
[0027] In this study, the mass of the biomass and coal mixture sample decreases during the combustion reaction. Continuous monitoring of the mass change of the mixture sample yields the original mass data, which represents the change in mass of the mixture sample over time, and can be recorded as the original mass-time curve. .
[0028] S3. Analyze and calculate the original mass data to obtain the actual conversion rate data and combustion characteristic data of the mixed sample combustion reaction.
[0029] It should be noted that during the actual combustion of the mixed sample, the accuracy of the quality monitoring results is insufficient due to factors such as thermal buoyancy, airflow disturbance, and reaction device drift.
[0030] In this regard, according to some embodiments of this application, the original mass data is analyzed and calculated to obtain the actual conversion rate data and combustion characteristic data of the mixed sample combustion reaction, including: heating an empty reaction vessel to collect the reference mass data of the reaction vessel; correcting the original mass data based on the reference mass data to obtain the corrected mass data of the mixed sample combustion reaction; and analyzing and calculating the corrected mass data to obtain the actual conversion rate data and combustion characteristic data.
[0031] In step S2, the empty reaction vessel is heated under the same test conditions as the combustion reaction of the mixed sample. The mass change of the reaction vessel during the heating time is continuously monitored, and the obtained baseline mass data, i.e., the mass change of the reaction vessel over time, can be recorded as the mass drift curve. The test conditions include heating temperature, heating time, and environmental conditions, including the atmosphere, which must be kept consistent when heating the mixed sample and the reaction vessel.
[0032] Correcting the original mass data based on baseline mass data can eliminate the influence of factors such as thermal buoyancy, airflow disturbance, and instrument drift on subsequent calculations and analyses. The corrected mass data is then obtained. : (1) Among them, the calibration quality data is the calibration quality-time curve.
[0033] Furthermore, based on the calibrated mass-time curve, the weight loss curve of the mixed sample can be calculated, and the actual conversion rate data can be further calculated: (2) In the formula, The initial mass of the mixed sample. This refers to the final mass of the mixed sample after the combustion reaction is complete or when the reaction is stable. Indicates the time of the mixed sample t The normalized conversion rate, i.e., the actual conversion rate-time curve.
[0034] right After smoothing and differentiating, the actual reaction rate data is obtained: (3) Among them, the actual reaction rate data, namely the actual reaction rate-time curve, can be used to characterize the reaction intensity and stage change characteristics of the mixed sample during rapid heating.
[0035] Furthermore, based on actual conversion rate data and actual reaction rate data, combustion characteristic data can be extracted, including the following combustion characteristic parameters: (1) Characteristic parameters for volatile analysis, used to characterize the ability of mixed samples to volatilize after rapid heating, such as preset time. conversion rate , or the average reaction rate in the early stage [0, t1]; (2) Stage weight loss parameters, used to characterize the mass loss characteristics of the mixed sample at different stages, such as the conversion increment. : ; (3) Reaction rate parameters, used to characterize the degree of fluctuation in the reaction of mixed samples, such as peak reaction rate. R max and peak occurrence time t p ; (4) Fixed time period conversion parameters are used to evaluate the degree of reaction completion of the mixed sample within a limited residence time. For example, the time corresponding to achieving n% conversion rate is determined according to the requirements. t n Where n is typically 50.
[0036] S4. Obtain the first conversion rate data of biomass combustion reaction, the second conversion rate data of coal combustion reaction, and the baseline characteristic data and baseline fluctuation range of coal combustion reaction.
[0037] The first conversion rate data of biomass combustion reaction, the second conversion rate data of coal combustion reaction, and the baseline characteristic data and baseline fluctuation range of coal combustion reaction can be obtained through combustion tests or directly based on the test data of raw materials.
[0038] Specifically, referring to steps S2 and S3, the biomass sample and coal sample obtained in step S1 are heated under the same test conditions to cause combustion reaction, so as to obtain the first mass data of the biomass sample (pure biomass) and the second mass data of the coal sample (pure coal), namely the first mass-time curve and the second mass-time curve; then, referring to formula (2), the first conversion rate data of biomass and the second conversion rate data of coal are calculated, namely the first conversion rate-time curve and the second conversion rate-time curve.
[0039] Furthermore, referring to equation (3), the second conversion rate data of the coal sample is calculated and analyzed to obtain the second reaction rate data, i.e., the second reaction rate-time curve; further, based on the second reaction rate data and the second conversion rate data, the baseline characteristic data is extracted. Among them, the baseline characteristic data can be obtained by averaging the baseline characteristic data from multiple tests.
[0040] Furthermore, the baseline fluctuation range of a coal sample refers to the allowable fluctuation in the combustion reaction of pure coal, which can be determined based on the standard deviation obtained from repeated tests of pure coal, engineering experience thresholds, or the allowable fluctuation range of the boiler.
[0041] The baseline characteristic data includes baseline characteristic parameters that correspond one-to-one with the combustion characteristic parameters, specifically including baseline characteristic parameters for volatile analysis, stage weight loss, reaction rate, and fixed-time conversion. Each baseline characteristic parameter corresponds to an allowable fluctuation amount; therefore, the baseline fluctuation range includes fluctuations in volatile analysis characteristics, stage weight loss fluctuations, reaction rate fluctuations, and fixed-time conversion fluctuations.
[0042] S5. Analyze and calculate the first conversion rate data and the second conversion rate data to obtain the theoretical conversion rate data of the combustion reaction of the mixed sample; and generate the synergistic combustion index of the mixed sample based on the actual conversion rate data and the theoretical conversion rate data.
[0043] Wherein, the proportion of biomass sample in the mixed sample is set as follows: In the absence of synergistic effects, the theoretical conversion rate of the mixed sample should be approximately a linear weighted sum of the first and second conversion rate data according to the doping ratio, specifically: (4) In the formula, This is the first conversion rate data. This is the second conversion rate data. This refers to the theoretical conversion rate data, i.e., the theoretical conversion rate-time curve.
[0044] Furthermore, based on theoretical and actual conversion rate data, the synergistic combustion index S is defined as follows: (5) In the formula, This is the actual conversion rate data for the mixed sample. t total For evaluation duration.
[0045] When the theoretical conversion rate data and the actual conversion rate data are discrete sampling results, the synergistic combustion index S is: (6) In the formula, k This represents the number of sampling points.
[0046] Wherein, S>0 indicates that the overall conversion rate of the mixed sample is higher than that of the theoretical case without synergy, indicating that there is a positive synergistic effect when biomass and coal samples are mixed and burned; S<0 indicates that there is an inhibitory effect when biomass and coal samples are mixed and burned; S=0 or S close to 0 indicates that the reaction of biomass and coal samples mixed and burned is basically a simple superposition of the biomass combustion reaction and the coal combustion reaction.
[0047] Furthermore, when more detailed evaluation results are required, a phased synergistic combustion index can be further defined: (7) In the formula, For [t] j-1 ,t j The phased synergistic combustion index over a specific time period.
[0048] The phased synergistic combustion index can be used to evaluate the synergistic effect of the rapid volatilization analysis stage, the main combustion stage, and the subsequent slow conversion stage.
[0049] S6. Based on combustion characteristic data, baseline characteristic data, and baseline fluctuation range, generate the combustion deviation index of the mixed sample.
[0050] The combustion deviation index is used to determine whether the combustion behavior of the mixed sample is within the acceptable fluctuation range of the power plant boiler. Specifically, the combustion deviation index is calculated and evaluated based on the combustion reaction of the coal sample. The coal sample used is the one obtained in step S1, and its raw material is qualified coal fed into the boiler on-site or coal of a stable operating type in the boiler.
[0051] Furthermore, the baseline characteristic data and baseline fluctuation range can be obtained by repeatedly testing multiple batches of coal samples under the same conditions to obtain the mean value of each baseline characteristic parameter and the mean value of each baseline fluctuation range.
[0052] According to some embodiments of this application, the combustion characteristic data includes multiple combustion characteristic parameters, the reference characteristic data includes reference characteristic parameters corresponding one-to-one with the combustion characteristic parameters, and the reference fluctuation range includes the allowable fluctuation amount corresponding one-to-one with the combustion characteristic parameters; wherein, generating a combustion deviation index for a mixed sample based on the combustion characteristic data, the reference characteristic data, and the reference fluctuation range includes: calculating the deviation value corresponding to the combustion characteristic parameter based on the characteristic parameter, the corresponding reference characteristic parameter, and the allowable fluctuation amount; determining the weight corresponding to each combustion characteristic parameter; and calculating the combustion deviation index based on the weight and deviation value corresponding to each combustion characteristic parameter.
[0053] In calculating the combustion deviation index, the deviation value is calculated sequentially for each combustion characteristic parameter. Let the reference characteristic parameter corresponding to the i-th combustion characteristic parameter be... The corresponding allowable fluctuation is The combustion deviation index D of the mixed sample combustion reaction relative to the coal sample combustion reaction benchmark can be defined as: (8) in, Let i be the combustion characteristic parameter corresponding to the mixed sample. This refers to the weight of the combustion characteristic parameter. The specific value of the weight can be determined according to the engineering focus, and it must satisfy... Σ = 1; m This represents the total number of selected combustion characteristic parameters. This represents the deviation value corresponding to the i-th combustion characteristic parameter.
[0054] Among them, the allowable fluctuation amount It can be determined by the standard deviation of repeated tests on pure coal, engineering experience thresholds, or the allowable fluctuation range of the boiler.
[0055] The smaller the value of D, the closer the combustion reaction behavior of the mixed sample is to the combustion reaction behavior of pure coal in the field, the closer it is to the benchmark, and the less likely it is to cause significant disturbance to the existing combustion organization of the boiler.
[0056] S7. Determine the evaluation results of the blending ratio based on the synergistic combustion index and the combustion deviation index.
[0057] Among them, the synergistic combustion index is used to determine whether there is a positive synergistic effect in the mixed sample, and the combustion deviation index is used to determine whether the mixed sample causes excessive disturbance to the boiler. By comprehensively considering the synergistic combustion index and the combustion deviation index, it can be determined whether the blending ratio is appropriate.
[0058] According to some embodiments of the present application, the evaluation result of the co-firing ratio is determined based on the co-combustion index and the combustion deviation index, including: obtaining the combustion deviation threshold and the co-combustion threshold of the mixed sample; calculating and analyzing the combustion deviation index and the combustion deviation threshold, and calculating and analyzing the co-combustion index and the co-combustion threshold to obtain the evaluation result of the co-firing ratio.
[0059] Among them, the co-combustion threshold S0 is a co-determination threshold set based on the theoretical no-cooperation benchmark, and S0 is not less than 0. The combustion deviation threshold D0 is a preset threshold determined based on the reference characteristic parameters and the reference fluctuation range obtained from repeated tests of the coal sample under the same test conditions, and in combination with the upper limit of the combustion disturbance allowed by the target boiler. For different boilers and different coal types, the corresponding D0 and S0 can be calibrated respectively. In a specific embodiment, the specific values or value ranges of D0 and S0 under the corresponding test conditions are given, and based on this, it is determined whether the co-firing ratio of the test is appropriate.
[0060] Furthermore, when D ≤ D0 and S ≥ S0, it is determined that the corresponding co-firing ratio of the mixed sample is suitable for co-firing; when D > D0 or S < S0, it indicates that the mixed sample deviates too much from the pure coal combustion behavior on-site or does not show effective cooperation at the corresponding co-firing ratio, and it should be determined that the corresponding co-firing ratio of the mixed sample is not suitable for co-firing.
[0061] According to some embodiments of the present application, the evaluation method further includes: determining the optimal co-firing ratio of the mixed sample according to the evaluation result of the co-firing ratio.
[0062] Among them, in step S1, multiple co-firing ratios can be determined, the corresponding mixed samples are configured respectively, and steps S1 - S7 are executed to determine the corresponding evaluation results. According to the evaluation results corresponding to multiple co-firing ratios, when multiple co-firing ratios of the same biomass all meet the conditions (D ≤ D0 and S ≥ S0), the maximum biomass blending ratio that meets the conditions is used as the recommended co-firing ratio, and the recommended co-firing ratio can be used as the optimal co-firing ratio.
[0063] Furthermore, according to the co-combustion index and the combustion deviation index corresponding to multiple co-firing ratios, the corresponding relationship between the co-combustion index, the combustion deviation index and the co-firing ratio can be analyzed, and the optimal co-firing ratio can be determined by methods such as fitting or supplementary testing.
[0064] According to the evaluation method for biomass and coal co-combustion characteristics proposed in this application, coal and biomass samples with actual particle sizes used in power plants are used as test objects. Under conditions where their original particle size, fiber morphology, and packing state are not altered or are altered as little as possible, combustion tests are conducted on coal samples, biomass samples, and mixed samples with different blending ratios. Standard combustion behavior tests are performed using pure coal as fuel. A theoretical non-synergistic curve is formed by linearly superimposing pure coal and pure biomass according to their blending ratios. By comparing the parameters corresponding to the non-synergistic curve and the standard combustion behavior, the combustion deviation index and synergistic combustion index of the mixed samples are extracted and calculated. Based on this, it is determined whether the biomass is suitable for blending with the coal type used in the field, and the appropriate maximum blending ratio, thus providing optimal blending ratio recommendations for biomass and coal co-combustion. This application can realistically reproduce the actual operating conditions of biomass and coal co-combustion, accurately calculate the synergistic combustion index and combustion deviation index based on real-time collected parameters, comprehensively evaluate the co-combustion characteristics of biomass and coal under different blending ratios, and accurately assess the blending ratio. This is of great significance for optimizing co-combustion schemes and ensuring the safe and stable operation of boilers.
[0065] like Figure 2 As shown, in a second aspect, this application proposes an evaluation system for the co-combustion characteristics of biomass and coal, used to implement the aforementioned evaluation method for the co-combustion characteristics of biomass and coal. The evaluation system includes a sample preparation unit 200, a reaction device 100, a data acquisition unit 300, and a data processing unit 400. The sample preparation unit 200 is used to prepare a mixed sample; the reaction device is used to cause the mixed sample to undergo a combustion reaction; the data acquisition unit 300 is connected to the reaction device 100 to collect the raw mass data of the combustion reaction of the mixed sample, and to obtain the first conversion rate data of the biomass combustion reaction, the second conversion rate data of the coal combustion reaction, and the baseline characteristic data and baseline fluctuation range of the coal combustion reaction; the data processing unit 400 is connected to the data acquisition unit 300; the data processing unit 400 is used to calculate and analyze the raw mass data, the first conversion rate data, the second conversion rate data, the baseline characteristic data, and the baseline fluctuation range to obtain the evaluation results of the mixed sample.
[0066] Among them, such as Figure 3 As shown, the sample preparation unit 200 selects biomass feedstock A and coal feedstock B, processes them to obtain biomass samples and coal samples, and prepares mixed sample C according to the determined blending ratio. The sample preparation unit 200 can be implemented through automated equipment or a combination of equipment and manual operation.
[0067] The reaction apparatus 100 provides a site for heating the mixed sample (or biomass sample, coal sample) and for the combustion reaction to occur. The reaction apparatus 100 can be a drop-tube furnace, a settling furnace, a vertical tube furnace with a rapid feed mechanism, a micro-suspension reactor, or a small fluidized bed, etc. Furthermore, the reaction apparatus 100 is also used to provide the environmental conditions necessary for the combustion reaction.
[0068] The data acquisition unit 300 is connected to the reaction device 100 to collect raw mass data of the mixed sample combustion reaction in real time during the combustion reaction. Furthermore, the data acquisition unit 300 is used to acquire first conversion rate data of the biomass combustion reaction, second conversion rate data of the coal combustion reaction, and baseline characteristic data and baseline fluctuation range of the coal combustion reaction; this data acquisition process can be achieved through testing or based on production test data of biomass and coal raw materials.
[0069] The data processing unit 400 performs calculations and analysis on the raw data, and determines the evaluation results of the mixed sample under the corresponding blending ratio based on the testing requirements, so as to evaluate whether the blending ratio is suitable for co-firing. The raw data includes raw quality data, first conversion rate data, second conversion rate data, baseline characteristic data, and baseline fluctuation range.
[0070] The evaluation system for biomass and coal co-combustion characteristics proposed in this application integrates sample preparation, combustion testing, data acquisition, and processing analysis, which can significantly improve the evaluation efficiency of biomass and coal co-combustion behavior, enhance experimental repeatability, and promote the research and application of biomass and coal co-combustion technology. By testing and analyzing, the most suitable co-combustion ratio for the target boiler can be determined, ensuring the safe and stable operation of the boiler.
[0071] like Figure 3 As shown, according to some embodiments of this application, the reaction apparatus 100 includes a test chamber 10, a reaction container 20, and a weighing component 40. The test chamber 10 is equipped with a heating device 30; the reaction container 20 is disposed inside the test chamber 10; the weighing component 40 is disposed below the reaction container 20 and connected to the reaction container 20; wherein, the reaction container 20 is used to hold the mixed sample, the heating device 30 is used to heat the test chamber 10 so that the mixed sample undergoes a combustion reaction; the weighing component 40 is used to monitor the weight change of the mixed sample during the combustion reaction process to obtain the original mass data.
[0072] In this embodiment, the test chamber 10 provides a space for heating and combustion of the mixed sample (or biomass sample, coal sample), offering a high-temperature, rapid heating, and short-residence-time reaction environment. The reaction vessel 20 holds the mixed sample (or biomass sample, coal sample) and is placed inside the test chamber 10. A heating device 30 is located in the test chamber 10 to heat the test chamber 10 and the mixed sample (or biomass sample, coal sample) inside, causing the mixed sample to undergo a combustion reaction. A weighing component 40 is located below the reaction vessel 20 to monitor the mass change of the mixed sample in real time.
[0073] Specifically, the testing chamber 10 can be a drop-tube furnace, settling furnace, vertical tube furnace with a rapid feeding mechanism, micro-suspension reactor, or small fluidized bed. The reaction vessel 20 can be a perforated plate, metal mesh basket, porous ceramic tray, or special crucible, which can hold the sample while maintaining good air permeability and heating uniformity. The weighing component 40 can be an electronic balance, tension / compression sensor, magnetic levitation weighing component, or micro-weighing sensor; in some embodiments, the sampling frequency of the weighing component 40 is preferably 1Hz to 50Hz, more preferably 5Hz to 20Hz, to meet the data recording requirements of the rapid weight loss process of the mixed sample. The heating device 30 can be an electric heating device with a heating range of 600~1100℃ and a maximum heating rate of 40K / min.
[0074] In some embodiments, the reaction vessel 20 can be connected to a weighing sensor located below the test chamber 10 via a high-temperature resistant boom. A heat insulation component and a water-cooled sealing component are provided between the weighing sensor and the test chamber to reduce the influence of high-temperature radiation and thermal drift on the weighing signal.
[0075] like Figure 4 As shown, according to some embodiments of this application, the reaction vessel 20 is constructed as a crucible, which includes a crucible body 21, a height limiting member 22, and a blocking member 23. The bottom plate 211 and the side wall 212 of the crucible body 21 are respectively provided with vent holes; the height limiting member 22 is disposed inside the crucible body 21; the blocking member 23 is disposed at the top opening of the crucible body 21; wherein, the crucible body 21 is used to hold the mixed sample, the height limiting member 22 is used to limit the filling thickness of the mixed sample, and the blocking member 23 is used to prevent the mixed sample from escaping.
[0076] In this embodiment, the reaction vessel 20 is constructed as a crucible. The crucible body 21 is used to hold the sample. The bottom plate 211 and sidewalls 212 of the crucible body 21 are respectively provided with vent holes, allowing high-temperature gas to pass through the sample from the bottom and sides, thereby improving the uniformity of heat and mass transfer. The height limiter 22 is used to limit the filling thickness of the mixed sample, preventing excessive thickness from causing localized oxygen deficiency and delayed heating. The barrier 23 is used to block the top opening of the crucible body 21 to prevent sample escape; specifically, it is used to suppress the lifting, curling, and scattering of fibrous biomass during high-speed gas flow or volatile matter release.
[0077] The crucible can be made of one or more of the following materials: quartz, alumina ceramic, corundum, heat-resistant alloy, or other high-temperature stable materials. The crucible body 21 has a shallow cylindrical or shallow disc-cylindrical structure, with a height-to-diameter ratio of less than 1:4, to reduce sample buildup thickness and minimize inter-particle obstruction. The specific dimensions of the crucible body 21 should be determined based on the longest dimension of the biomass particles. The maximum diameter of the crucible should not be less than 80% of the biomass sample being tested, and the trapezoidal angle of the crucible should be greater than 30 degrees. For different types of samples, the size of the vent holes, the porosity, and the sample loading depth can be adjusted according to the particle characteristics. For coarse particle mixed samples, the height of the height limiter 22 and the diameter of the vent holes at the bottom of the crucible can be adjusted to ensure the uniform distribution of the mixed sample during testing.
[0078] Furthermore, the bottom plate 211 of the crucible body 21 is constructed as a bottom permeable support layer, which can be a perforated bottom plate, a metal mesh, a ceramic porous plate, or a high-temperature resistant grid structure to facilitate the passage and flow of high-temperature gas through the sample. The side wall 212 of the crucible body 21 is constructed as a permeable structural wall, and its permeable holes can be constructed as through holes, slots, or mesh openings to improve the ventilation conditions of coarse particles and fibrous biomass during the heating process.
[0079] Specifically, the barrier element 23 can be a mesh cover or a strip-shaped pressure frame structure to effectively prevent fibrous biomass from being lifted, curled, and scattered.
[0080] The reaction vessel 20 of the above embodiment is highly adaptable to coarse particles and fibrous samples, which can ensure that the samples do not stack, have little obstruction, and are heated evenly, thus avoiding test deviations.
[0081] like Figure 3As shown, according to some embodiments of this application, the reaction apparatus 100 further includes an atmosphere control component 50, which is connected to the test chamber. The atmosphere control component 50 is used to input reactant gases and simulated flue gas into the test chamber 10 to control the atmosphere within the test chamber 10. In this embodiment, the atmosphere control component 50 is connected to the test chamber 10 to input reactant gases and simulated flue gas into the test chamber 10 to ensure the normal progress of the combustion reaction and to recreate the atmospheric environment of boiler combustion, thereby improving the accuracy and reference value of the test. Furthermore, the atmosphere control component 50 is also used to simultaneously input air into the test chamber 10 to more realistically simulate the atmospheric environment of boiler combustion. In addition, the atmosphere control component 50 can control the flow rate and velocity of the reactant gases, simulated flue gas, and / or air.
[0082] In some embodiments, the test chamber 10 includes an upper sample inlet area, a constant-temperature reaction area, and a lower exhaust area arranged sequentially from top to bottom. The constant-temperature reaction area is the main test area; a heating device 30 is correspondingly arranged in the constant-temperature reaction area to achieve a stable high-temperature heating environment; the reaction vessel 20 and the mixed sample are placed in the constant-temperature reaction area for combustion reaction. The upper sample inlet area is connected to the atmosphere control component 50 to achieve the input of the required gas. The lower exhaust area is connected to a gas extraction or flue gas treatment device to stabilize the flow field inside the furnace and discharge the reaction generated gas.
[0083] In some embodiments, the reaction apparatus 100 further includes a conveying assembly for conveying the mixed sample and the reaction vessel 20 to the isothermal reaction zone of the test chamber 10. Based on this, the reaction apparatus 100 of this application can perform either rapid heating tests or slow heating tests. Specifically, before heating the test chamber 10, the reaction vessel 20 and the mixed sample are placed into their corresponding positions in the isothermal reaction zone using the conveying assembly, and then the heating device 30 is turned on to perform a slow heating test; conversely, by first heating the isothermal reaction zone of the test chamber 10 to a preset temperature, and then placing the reaction vessel 20 and the mixed sample into their corresponding positions in the isothermal reaction zone using the conveying assembly, a rapid heating test can be performed. In practice, a suitable testing method can be selected based on the boiler operating conditions or testing requirements.
[0084] In this embodiment of the application, the test is conducted according to the evaluation method and system for the co-combustion characteristics of biomass and coal of this application. The specific process is as follows: S11. Select biomass raw materials and coal raw materials, process the biomass raw materials and coal raw materials to obtain biomass samples and coal samples; S12. Determine the blending ratio of biomass and coal, and prepare the corresponding mixed sample according to the blending ratio; multiple blending ratios can be determined, and steps S13-S18 are performed to test and analyze the corresponding mixed samples respectively. S13. Determine the test conditions, heat the empty reaction vessel, and collect reference mass data during the heating process; S14. The mixed sample, biomass sample, and coal sample are heated under the same test conditions as in step S13 to induce combustion reactions. During the combustion reaction, the original mass data of the mixed sample, the first mass data of the biomass sample, and the second mass data of the coal sample are collected respectively. The same test conditions mean that the heating temperature, atmosphere composition, atmosphere flow rate, and test time are all the same, and the initial mass of the mixed sample, biomass sample, and coal sample is also the same. S15. Using the benchmark mass data and the above formula (1), the original mass data, the first mass data, and the second mass data are corrected respectively; and the original conversion rate data and the original reaction rate data of the mixed sample, the first conversion rate data of the biomass sample, and the second conversion rate data and the second reaction rate data of the coal sample are calculated and analyzed according to the corrected data and the above formulas (2) and (3). S16. Based on the first conversion rate data, the second conversion rate data and the corresponding blending ratio, calculate the corresponding theoretical conversion rate data using the above formula (4); and generate the synergistic combustion index using the above formula (5) or (6) based on the theoretical conversion rate data and the original conversion rate data. S17. Extract combustion characteristic data based on the original conversion rate data and the original reaction rate data, extract benchmark characteristic parameters based on the second conversion rate data and the second reaction rate data, and calculate the combustion deviation index using the above formula (8). S18. Determine the evaluation result of the corresponding blending ratio based on the combustion deviation index and the synergistic combustion index; S19. Determine the optimal blending ratio based on the evaluation results corresponding to the blending ratio.
[0085] The evaluation method and system for the co-combustion characteristics of biomass and coal according to this application have the following technical effects: Combustion testing can accurately, quickly, and stably reflect the reaction characteristics of mixed fuels; an evaluation system directly serving raw material acceptance and boiler blending is constructed, and the compatibility of biomass and coal co-combustion in the field is rapidly evaluated through joint judgment using pure coal benchmarks and synergistic combustion indicators; a testing and evaluation technology for the co-combustion characteristics of biomass-coal particles with industrial application value is formed, which can be directly used for raw material acceptance, blending optimization, and boiler stable combustion decisions; and the problem that existing evaluation methods are difficult to accurately evaluate the co-combustion of mixed fuels under actual working conditions is solved. Compared with existing technologies, this invention emphasizes the representativeness of field samples, is more applicable to coarse particle or fibrous samples, is closer to actual production conditions, and can be practically deployed and applied; this application is of great significance for improving the level of biomass raw material control at the plant, optimizing co-combustion schemes, and ensuring the safe and stable operation of boilers.
[0086] In the description of this application, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.
[0087] In the description of this application, "first feature" and "second feature" may include one or more of the features.
[0088] In the description of this application, "multiple" means two or more.
[0089] In the description of this application, the first feature being "above" or "below" the second feature may include the first and second features being in direct contact, or the first and second features being in contact through another feature between them.
[0090] In the description of this application, the terms "above," "over," and "on top" for the first feature and the second feature include the first feature being directly above or diagonally above the second feature, or simply indicate that the first feature is at a higher horizontal level than the second feature.
[0091] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.
[0092] Although embodiments of this application have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the claims and their equivalents.
Claims
1. A method for evaluating the characteristics of biomass and coal co-combustion, characterized in that, include: Determine the blending ratio of biomass and coal, and prepare a mixed sample according to the blending ratio; The mixed sample is heated to induce a combustion reaction, and the raw mass data of the mixed sample is collected during the combustion reaction. The original mass data are analyzed and calculated to obtain the actual conversion rate data and combustion characteristic data of the mixed sample combustion reaction; Acquire the first conversion rate data of the biomass combustion reaction, the second conversion rate data of the coal combustion reaction, and the baseline characteristic data and baseline fluctuation range of the coal combustion reaction; The first conversion rate data and the second conversion rate data are analyzed and calculated to obtain the theoretical conversion rate data of the combustion reaction of the mixed sample; and the synergistic combustion index of the mixed sample is generated based on the actual conversion rate data and the theoretical conversion rate data. Based on the combustion characteristic data, the baseline characteristic data, and the baseline fluctuation range, a combustion deviation index for the mixed sample is generated. The evaluation result of the blending ratio is determined based on the synergistic combustion index and the combustion deviation index.
2. The evaluation method for the co-combustion characteristics of biomass and coal according to claim 1, characterized in that, The analysis and calculation of the original mass data to obtain the actual conversion rate data and combustion characteristic data of the mixed sample combustion reaction includes: An empty reaction vessel is heated to collect baseline mass data of the reaction vessel; The original mass data is corrected based on the baseline mass data to obtain the corrected mass data of the combustion reaction of the mixed sample; The corrected quality data is analyzed and calculated to obtain the actual conversion rate data and the combustion characteristic data.
3. The evaluation method for the co-combustion characteristics of biomass and coal according to claim 1, characterized in that, The combustion characteristic data includes multiple combustion characteristic parameters, the reference characteristic data includes reference characteristic parameters corresponding one-to-one with the combustion characteristic parameters, and the reference fluctuation range includes allowable fluctuation amounts corresponding one-to-one with the combustion characteristic parameters; wherein, generating the combustion deviation index of the mixed sample based on the combustion characteristic data, the reference characteristic data, and the reference fluctuation range includes: Based on the combustion characteristic parameters, the corresponding benchmark characteristic parameters, and the allowable fluctuation amount, the deviation value corresponding to the combustion characteristic parameters is calculated; Determine the weight corresponding to each of the combustion characteristic parameters; The combustion deviation index is calculated based on the weight and deviation value corresponding to each combustion characteristic parameter.
4. The evaluation method for the co-combustion characteristics of biomass and coal according to claim 1, characterized in that, The evaluation result of determining the blending ratio based on the synergistic combustion index and the combustion deviation index includes: Obtain the combustion deviation threshold and co-combustion threshold of the mixed sample; The combustion deviation index and the combustion deviation threshold are calculated and analyzed, and the synergistic combustion index and the synergistic combustion threshold are also calculated and analyzed to obtain the evaluation results of the blending ratio.
5. The evaluation method for the co-combustion characteristics of biomass and coal according to claim 1, characterized in that, Also includes: Based on the evaluation results of the blending ratio, the optimal blending ratio of the mixed sample is determined.
6. The evaluation method for the co-combustion characteristics of biomass and coal according to claim 1, characterized in that, The preparation of the mixed sample according to the said co-firing ratio includes: Biomass and coal raw materials were processed separately while maintaining their original main particle size distribution to obtain biomass and coal samples respectively. The biomass sample and the coal sample are blended according to the blending ratio to obtain the mixed sample.
7. An evaluation system for the co-combustion characteristics of biomass and coal, used to implement the evaluation method for the co-combustion characteristics of biomass and coal as described in any one of claims 1-6, characterized in that, include: A sample configuration unit, wherein the sample configuration unit is used to configure the mixed sample; A reaction apparatus for causing the mixed sample to undergo a combustion reaction; A data acquisition unit is connected to the reaction device to acquire raw mass data of the combustion reaction of the mixed sample, and to obtain first conversion rate data of the biomass combustion reaction, second conversion rate data of the coal combustion reaction, and baseline characteristic data and baseline fluctuation range of the coal combustion reaction. A data processing unit is connected to the data acquisition unit; the data processing unit is used to calculate and analyze the original quality data, the first conversion rate data, the second conversion rate data, the benchmark characteristic data, and the benchmark fluctuation range to obtain the evaluation results of the mixed sample.
8. The evaluation system for the co-combustion characteristics of biomass and coal according to claim 7, characterized in that, The reaction apparatus includes: The testing chamber is equipped with a heating device; A reaction vessel, wherein the reaction vessel is disposed within the test chamber; A weighing assembly is disposed below and connected to the reaction vessel; wherein, The reaction vessel is used to hold the mixed sample, the heating device is used to heat the test chamber so that the mixed sample undergoes a combustion reaction; the weighing component is used to monitor the weight change of the mixed sample during the combustion reaction process to obtain the original mass data.
9. The evaluation system for the co-combustion characteristics of biomass and coal according to claim 8, characterized in that, The reaction vessel is constructed as a crucible, and the crucible includes: The crucible body has ventilation holes on its bottom plate and side walls. A height limiting component is disposed inside the crucible body; A blocking element is provided at the top opening of the crucible body; wherein, The crucible body is used to hold the mixed sample, the height limiting member is used to limit the filling thickness of the mixed sample, and the barrier member is used to prevent the mixed sample from escaping.
10. The evaluation system for the co-combustion characteristics of biomass and coal according to claim 8, characterized in that, The reaction apparatus further includes: An atmosphere control component is connected to the test chamber; wherein the atmosphere control component is used to input reactive gases and simulated flue gas into the test chamber to control the atmosphere within the test chamber.