A method for determining the carbon content in ash slag
By using synthetic carbon standards with low carbon content to calibrate and pre-treat the testing instrument, the problem of inaccurate carbon content measurement in ash and slag was solved, and more accurate carbon content measurement in ash and slag was achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- XIAN THERMAL POWER RES INST CO LTD
- Filing Date
- 2023-03-14
- Publication Date
- 2026-05-26
AI Technical Summary
Existing elemental analyzers cannot accurately measure the low carbon content in ash and slag, especially when the carbon content is below 1 wt%, which leads to inaccurate boiler heat balance calculations.
The testing instrument was calibrated using a synthetic carbon standard with low carbon content. A calibration curve was generated using a multi-point calibration method. The ash was pretreated by blending to ensure that the carbon content was within the range of the standard. The carbon content in the ash was then determined using the calibrated testing instrument.
This improves the accuracy and reliability of carbon content determination in ash and slag, ensuring that the measurement results are within the standard sample range and avoiding inaccurate measurement problems caused by carbon content exceeding or falling below the standard sample range.
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Abstract
Description
Technical Field
[0001] This application relates to the field of detection technology, and in particular to a method for determining the carbon content in ash. Background Technology
[0002] The determination of carbon content in fly ash and slag is mainly used for: 1. Determining the carbon content of fly ash and slag samples collected during the daily operation of coal-fired power plants, for monitoring boiler operation (assessing the completeness of coal combustion); 2. Determining the carbon content of fly ash and slag samples collected during coal-fired boiler heat balance tests, for boiler heat balance calculations. Currently, standards only cover the determination of combustible matter in fly ash and slag. In boiler heat balance calculations, combustible matter in fly ash and slag is equated with carbon content. However, in reality, combustible matter in fly ash and slag contains not only carbon but also small amounts of unburned sulfur and other substances. Therefore, the ability to accurately measure the carbon content in fly ash and slag is particularly important.
[0003] Because the carbon content in ash is very low, generally below 1 wt%, current elemental analyzer carbon measurement methods (calibration material carbon content between 40-70 wt%, measurement repeatability of 0.5%) cannot accurately measure such low carbon content. Summary of the Invention
[0004] In view of this, this application aims to provide a method for determining the carbon content in ash and slag, which uses a synthetic carbon standard with low carbon content to calibrate the testing instrument, thereby making the carbon content determination results more accurate.
[0005] To achieve the above objectives, embodiments of this application provide a method for determining the carbon content in ash, comprising:
[0006] Multiple synthetic carbon standards with different carbon contents were selected as calibration materials to calibrate the accuracy of the test instrument. The carbon content of the synthetic carbon standards was between 0.5% and 2.0 wt%.
[0007] The air-dried carbon content in the ash residue was determined using the calibrated testing instrument.
[0008] In some embodiments, the carbon content of the synthetic carbon standard is 0.5 wt%, 1.0 wt%, or 2.0 wt%.
[0009] In some embodiments, the carbon content of the ash is above 0.5 wt%.
[0010] In some embodiments, the carbon content of the ash is less than 0.5 wt%; the method for determining the carbon content in the ash further includes a step of pre-treating the ash with the synthetic carbon standard before determining the air-dried carbon content in the ash using the calibrated testing instrument.
[0011] In some embodiments, the mass ratio of the ash residue to the synthetic carbon standard is (3-7):(7-3).
[0012] In some embodiments, the carbon content of the synthetic carbon standard sample mixed with the ash is 2 wt%.
[0013] In some embodiments, the air-dried carbon content in the ash residue prior to the blending pretreatment is calculated using the following formula:
[0014]
[0015] In the formula:
[0016] C ad —Air-dried carbon content in ash residue before blending and pretreatment, expressed as mass fraction (%);
[0017] C yq —The carbon content of the ash residue after blending and pretreatment, as determined by the testing instrument, is expressed as a mass fraction (%).
[0018] C b —The carbon content of the synthesized carbon standard is expressed as a mass fraction (%);
[0019] m1—Mass of ash residue, mg;
[0020] m2 — the mass of the synthesized carbon standard, in mg.
[0021] In some embodiments, the method for calibrating the accuracy of the test instrument measurements is a multi-point calibration method.
[0022] In some embodiments, the method for calibrating the accuracy of the test instrument measurement includes: using the test instrument to test the carbon content of each of the synthetic carbon standards multiple times according to a preset program, taking the average value of the multiple tests as the measured value of the corresponding synthetic carbon standard, and linearly fitting the measured values of each of the synthetic carbon standards to obtain a calibration curve.
[0023] In some embodiments, the testing instrument is one of a carbon-hydrogen-nitrogen elemental analyzer, a carbon-sulfur analyzer, a carbon-hydrogen analyzer, and a carbon-nitrogen analyzer.
[0024] The method for determining the carbon content in ash slag in this application has the following beneficial effects:
[0025] 1. Use a synthetic carbon standard with low carbon content (between 0.5-2 wt%) to calibrate the testing instrument. If the carbon content of the ash residue is within the range of the standard, the measurement results will be accurate and reliable.
[0026] 2. The ash residue with ultra-low carbon content (carbon content less than 0.5wt%) is pre-treated by blending to ensure that its carbon content does not exceed the range of the standard sample, thus making the measurement results more accurate.
[0027] 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
[0028] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein:
[0029] Figure 1 This is a flowchart illustrating a method for determining the carbon content in ash slag according to an exemplary embodiment.
[0030] Figure 2 This is a flowchart illustrating a method for determining the carbon content in ash according to another exemplary embodiment. Detailed Implementation
[0031] The embodiments of this application are described in detail below. These embodiments are exemplary and intended to explain this application, and should not be construed as limiting this application.
[0032] In the application, the disclosure of the numerical range includes all values throughout the range and the disclosure of further subdivisions of the range, including the endpoints and subranges given for these ranges.
[0033] Unless otherwise specified, all raw materials and equipment involved in the application are those that can be manufactured commercially or by known methods; and all methods involved are conventional methods unless otherwise specified.
[0034] Figure 1 This is a flowchart illustrating a method for determining the carbon content in ash slag according to an exemplary embodiment. Figure 1 As shown, the method for determining the carbon content in the ash includes:
[0035] S101, select multiple synthetic carbon standards with different carbon contents as calibration materials to calibrate the accuracy of the test instrument. The carbon content of the synthetic carbon standards is between 0.5-2.0 wt%.
[0036] In this application, the number of synthetic carbon standards is not limited, but is generally two or more. As a non-limiting example, the number of synthetic carbon standards includes, but is not limited to, three, four, five, or six. The carbon content of the synthetic carbon standards includes, but is not limited to, 0.5 wt%, 0.8 wt%, 1.0 wt%, 1.2 wt%, 1.5 wt%, 1.8 wt%, or 2.0 wt%. When the carbon content of the synthetic carbon standards is within the above range, the carbon content in most ash residues is within the upper and lower limits of the calibration curve, resulting in more accurate measurements. If the carbon content of the synthetic carbon standards is less than 0.5 wt%, the synthetic carbon standards are not easily completely burned and are prone to falling below the detection limit of the testing instrument. If the carbon content of the synthetic carbon standards is greater than 2.0 wt%, the carbon content of the synthetic carbon standards far exceeds the carbon content in most ash residues, and as the upper limit of the calibration curve, it will lead to inaccurate sample measurements.
[0037] As a possible example, three carbon standards were synthesized, each with a carbon content of 0.5 wt%, 1.0 wt%, or 2.0 wt%.
[0038] In some embodiments, the method for calibrating the accuracy of the testing instrument is a multi-point calibration method. The testing instrument is one of a carbon-hydrogen-nitrogen elemental analyzer, a carbon-sulfur analyzer, a carbon-hydrogen analyzer, and a carbon-nitrogen analyzer.
[0039] In some embodiments, a method for calibrating the accuracy of a testing instrument includes: using the testing instrument to test the carbon content of each synthetic carbon standard sample multiple times according to a preset program, taking the average value of the multiple tests as the measured value of the corresponding synthetic carbon standard sample, and performing curve fitting, specifically linear fitting, on the measured values of each synthetic carbon standard sample to obtain a calibration curve. The number of times the carbon content of each synthetic carbon standard sample is tested is more than three times, including but not limited to three, four, five, or six times. The more tests conducted, the closer the subsequent average value obtained is to the standard value of the carbon content of the synthetic carbon standard sample, i.e., the more accurate the measured value. During the testing process, to avoid environmental influences and loss due to the falling of the synthetic carbon standard material, the synthetic carbon standard material is securely encased in aluminum foil or similar material. As a possible example, the testing instrument is an elemental analyzer, and the calibration method is as follows: Weigh 70mg-100mg of calibration material, wrap it tightly with aluminum foil to prevent spillage, place it in the elemental analyzer, and follow the preset program of the elemental analyzer (which must meet the following requirements: high-purity oxygen flow rate ≥1.5L / min, combustion time ≥180s, quantitative extraction volume ≥10cm). 3 The carbon content is determined; each calibration substance is measured 4 times, and the average value of the 4 measurements is used as the measured value of the corresponding synthetic carbon standard calibration substance. The standard value of the calibration substance is input into the instrument to generate a calibration curve.
[0040] S102, the air-dried carbon content in ash was determined using calibrated testing instruments.
[0041] In some embodiments, the carbon content of the ash residue is 0.5 wt% or more, including but not limited to 1 wt% or more, 5 wt% or more, 10 wt% or more, 20 wt% or more, 30 wt% or more, 40 wt% or more, 50 wt% or more, 60 wt% or more, or 70 wt% or more. As a non-limiting example, the carbon content of the ash residue includes, but is not limited to, 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt%, 1.0 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, or 10 wt%. In some embodiments, during similar standard material testing, to avoid environmental impact and ash residue loss due to falling ash residue, the ash residue is tightly contained using aluminum foil or the like.
[0042] As a possible example, weigh 70mg-100mg of a general analytical test sample of ash residue, wrap it tightly with aluminum foil to prevent spillage, and place it in an elemental analyzer. Determine the carbon content according to the pre-set program of the elemental analyzer. The determined value is the air-dried carbon content in the ash residue. It should be noted that the pre-set program of the elemental analyzer here is consistent with the program used for testing the calibration material in step S101.
[0043] The method for determining the carbon content in ash slag in this application embodiment uses a synthetic carbon standard sample with low carbon content (between 0.5-2 wt%) to calibrate the testing instrument. The carbon content of the ash slag is within the range of the standard sample, and the measurement results are accurate and reliable.
[0044] Figure 2 This is a flowchart illustrating a method for determining the carbon content in ash slag according to another exemplary embodiment. Figure 2 As shown, the method for determining the carbon content in the ash includes:
[0045] S201, select multiple synthetic carbon standards with different carbon contents as calibration materials to calibrate the accuracy of the test instrument. The carbon content of the synthetic carbon standards is between 0.5-2.0 wt%.
[0046] It should be noted that, in this embodiment, the implementation process of step S201 can be referred to the description of the implementation process of step S101 above, and will not be repeated here.
[0047] S202 involves pre-treating ash residue with synthetic carbon standard samples by blending.
[0048] In some embodiments, the carbon content of the ash is less than 0.5 wt%, including but not limited to 0.5 wt%, 0.4 wt%, 0.3 wt%, 0.2 wt%, or 0.1 wt%.
[0049] In some embodiments, the mass ratio of ash to synthetic carbon standard is (3-7):(7-3). As a non-limiting example, the mass ratio of ash to synthetic carbon standard is 3:7, 4:6, 5:5, or 7:3, etc. Within the above range, the mass ratio allows for complete combustion of the sample, complete release of carbon, and effective differentiation between ash and synthetic carbon standard. If the mass ratio is too low, the carbon content in the ash is too low to be effectively distinguished from the synthetic carbon standard. If the mass ratio is too high, complete combustion is impossible, and the carbon content is below the lower limit of the calibration curve, resulting in inaccurate measurements.
[0050] In some embodiments, the carbon content of the synthetic carbon standard mixed with ash is between 0.5-2 wt%, including but not limited to 0.5 wt%, 0.8 wt%, 1.0 wt%, 1.2 wt%, 1.5 wt%, 1.8 wt%, or 2.0 wt%. This ensures that the carbon content after mixing is within the upper and lower limits of the calibration curve and is not significantly different from the carbon content in the ash, effectively distinguishing the ash from the synthetic carbon standard and making the measurement more accurate. If the carbon content of the synthetic carbon standard mixed with ash is too low, the synthetic carbon standard will not burn completely and is likely to fall below the detection limit of the testing instrument; if the carbon content of the synthetic carbon standard mixed with ash is too high, it will far exceed the carbon content in most of the ash, making it impossible to effectively distinguish the ash from the synthetic carbon standard and resulting in inaccurate measurements.
[0051] S203, the air-dried carbon content in ash was determined using calibrated testing instruments.
[0052] It should be noted that the ash here is the ash that has undergone the blending and pretreatment in step S202, which is a mixture of ash and synthetic carbon standard.
[0053] It should be noted that, in this embodiment, the implementation process of step S203 can be referred to the description of the implementation process of step S102 above, and will not be repeated here.
[0054] In some embodiments, in step S203, the air-dried carbon content in the ash is determined using a calibrated testing instrument. This is the carbon content in the pretreated ash, which is also the carbon content in the mixture of ash and synthetic carbon standard. The actual air-dried carbon content in the ash before pretreatment is calculated according to formula ①:
[0055]
[0056] In formula ①:
[0057] C ad —Air-dried carbon content in ash residue before blending and pretreatment, expressed as mass fraction (%);
[0058] C yq—The carbon content of the ash residue after blending and pretreatment, as determined by the testing instrument, is expressed as a mass fraction (%).
[0059] C b —The carbon content of the synthesized carbon standard is expressed as a mass fraction (%);
[0060] m1—Mass of ash residue, mg;
[0061] m2 — the mass of the synthesized carbon standard, in mg.
[0062] The method for testing the carbon content in ash slag of this application will be further illustrated below with specific embodiments.
[0063] Example 1
[0064] The method for determining the carbon content in ash slag in this embodiment includes the following steps:
[0065] (1) Calibration: Synthetic carbon standards with carbon contents of 0.5wt%, 1.0wt%, and 2.0wt% were selected as calibration materials. The calibration method was multi-point calibration, and the curve fitting method was linear fitting. The mass of the synthetic carbon standard with a carbon content of 0.5wt% was weighed four times, with masses of 82mg, 80mg, 76mg, and 75mg respectively; the mass of the synthetic carbon standard with a carbon content of 1.0wt% was weighed four times, with masses of 72mg, 86mg, 77mg, and 73mg respectively; and the mass of the synthetic carbon standard with a carbon content of 2.0wt% was weighed four times, with masses of 88mg, 88mg, 79mg, and 76mg respectively. The carbon standard was wrapped tightly with aluminum foil to prevent spillage and placed in the carbon, hydrogen, and nitrogen elemental analyzer in sequence. The test conditions were: high-purity oxygen flow rate of 1.5L / min, combustion time of 180s, and quantitative extraction volume of 10cm³. 3 The carbon content was determined. Each mass of each synthetic carbon standard sample was measured once, and the average of the four measurements was used as the measured value for that synthetic carbon calibrator. The results are shown in Table 1. Finally, the measured values of the three synthetic carbon standard calibrators were input into the instrument to generate a calibration curve y = 0.9055x - 0.2127.
[0066] Table 1. Results and values of carbon content determination for three synthetic carbon standards.
[0067]
[0068] (2) Measurement: Weigh 88 mg of fly ash from origin 1 for general analysis test, wrap it tightly with tin foil to prevent spillage, and place it in a carbon, hydrogen, and nitrogen element analyzer. Follow the preset program of the carbon, hydrogen, and nitrogen element analyzer (test conditions: high-purity oxygen flow rate of 1.5 L / min, combustion time of 180 s, and quantitative extraction volume of 10 cm).3 The carbon content was determined, and the measured carbon content of the fly ash on an air-dried basis was 1.22 wt%.
[0069] Example 2
[0070] The method for determining the carbon content in ash slag in this embodiment includes the following steps:
[0071] (1) Calibration: Synthetic carbon standards with carbon contents of 0.5wt%, 1.0wt%, and 2.0wt% were selected as calibration materials. The calibration method was multi-point calibration, and the curve fitting method was linear fitting. The mass of the synthetic carbon standard with a carbon content of 0.5wt% was weighed four times, with masses of 82mg, 80mg, 76mg, and 75mg respectively; the mass of the synthetic carbon standard with a carbon content of 1.0wt% was weighed four times, with masses of 72mg, 86mg, 77mg, and 73mg respectively; and the mass of the synthetic carbon standard with a carbon content of 2.0wt% was weighed four times, with masses of 88mg, 88mg, 79mg, and 76mg respectively. The carbon standard was wrapped tightly with aluminum foil to prevent spillage and placed in the carbon, hydrogen, and nitrogen elemental analyzer in sequence. The test conditions were: high-purity oxygen flow rate of 1.5L / min, combustion time of 180s, and quantitative extraction volume of 10cm³. 3 The carbon content was determined. Each mass of each synthetic carbon standard sample was measured once, and the average of the four measurements was used as the measured value for that synthetic carbon calibrator. The results are shown in Table 2. Finally, the measured values of the three synthetic carbon standard calibrators were input into the instrument to generate a calibration curve y = 0.9055x - 0.2127.
[0072] Table 2. Results and values of carbon content determination for three synthetic carbon standards.
[0073]
[0074]
[0075] (2) Measurement: Weigh 41 mg of general analysis test sample of slag from origin 2, mix it with 50 mg of 2.0 wt% synthetic carbon standard, and after mixing evenly, wrap it tightly with tin foil to prevent spillage. Place it in the elemental analyzer and perform the test according to the preset program of the carbon, hydrogen and nitrogen elemental analyzer (test conditions: high-purity oxygen flow rate of 1.5 L / min, combustion time of 180 s, quantitative extraction volume of 10 cm). 3 The carbon content was determined by a carbon, hydrogen and nitrogen elemental analyzer and found to be 1.18 wt%. According to formula ①, the air-dried carbon content in the slag before blending was calculated to be 0.18 wt%.
[0076] Example 3
[0077] This embodiment is basically the same as Embodiment 1, except that the test sample is fly ash from origin 3, and the measured air-dried carbon content of the fly ash from origin 3 is 0.96 wt%.
[0078] Example 4
[0079] This embodiment is basically the same as embodiment 1, except that the test sample is fly ash from origin 4, and the measured air-dried carbon content of fly ash from origin 4 is 0.75 wt%.
[0080] Example 5
[0081] This embodiment is basically the same as Embodiment 1, except that the test sample is fly ash from origin 5, and the measured air-dried carbon content of the fly ash from origin 5 is 0.88 wt%.
[0082] Example 6
[0083] This embodiment is basically the same as Embodiment 1, except that the test sample is fly ash from origin 6, and the measured air-dried carbon content of the fly ash from origin 6 is 0.93 wt%.
[0084] Example 7
[0085] This embodiment is basically the same as embodiment 2, except that the test sample is fly ash from origin 7, and the measured air-dried carbon content of fly ash from origin 7 is 0.14 wt%.
[0086] Example 8
[0087] This embodiment is basically the same as embodiment 2, except that the test sample is fly ash from origin 8, and the measured air-dried carbon content of fly ash from origin 8 is 0.09 wt%.
[0088] Comparative Example 1
[0089] The combustible matter of fly ash from origin 1 in Example 1 was measured using the commonly used method for measuring ash combustible matter (drying oven + muffle furnace method). The combustible matter was equated with the carbon content of fly ash from origin 1 in Example 1, and the total sulfur content of fly ash was determined using the Eska method. The test results are shown in Table 3.
[0090] Comparative Example 2
[0091] This comparative example is basically the same as comparative example 1, except that the test sample is slag from origin 2 in example 2.
[0092] Comparative Example 3
[0093] This comparative example is basically the same as comparative example 1, except that the test sample is fly ash from place 3 in example 3.
[0094] Comparative Example 4
[0095] This comparative example is basically the same as comparative example 1, except that the test sample is fly ash from origin 4 in example 4.
[0096] Comparative Example 5
[0097] This comparative example is basically the same as comparative example 1, except that the test sample is fly ash from origin 5 in example 5.
[0098] Comparative Example 6
[0099] This comparative example is basically the same as comparative example 1, except that the test sample is fly ash from place 6 in example 6.
[0100] Comparative Example 7
[0101] This comparative example is basically the same as comparative example 1, except that the test sample is fly ash from place 7 in example 7.
[0102] Comparative Example 8
[0103] This comparative example is basically the same as comparative example 1, except that the test sample is fly ash from place 8 in example 8.
[0104] Table 3 Comparison of test results between Examples 1-8 and Comparative Examples 1-8
[0105]
[0106] As can be seen from Table 3, the commonly used drying oven + muffle furnace method for determining the combustibles in ash is not equivalent to the carbon content of ash, and also includes a small amount of total sulfur in ash. This indicates that the carbon content determination method in ash of this application measures the carbon content of ash more accurately.
[0107] Comparative Example 9
[0108] The carbon, hydrogen, and nitrogen elemental analyzer was used to determine the carbon content in fly ash from origin 1 in Example 1. The carbon content was determined by using EDTA as a calibration substance (carbon content 41.098 wt%) and no pretreatment was performed on the test sample. The test results are shown in Table 4.
[0109] Example 10
[0110] This comparative example is basically the same as comparative example 9, except that the test sample is the slag from origin 2 in example 2, and no pretreatment is performed on the test sample.
[0111] Comparative Example 11
[0112] This comparative example is basically the same as comparative example 9, except that the test sample is fly ash from origin 3 in example 3.
[0113] Comparative Example 12
[0114] This comparative example is basically the same as comparative example 9, except that the test sample is fly ash from origin 4 in example 4.
[0115] Comparative Example 13
[0116] This comparative example is basically the same as comparative example 9, except that the test sample is fly ash from origin 5 in example 5.
[0117] Comparative Example 14
[0118] This comparative example is basically the same as comparative example 9, except that the test sample is fly ash from origin 6 in example 6.
[0119] Comparative Example 15
[0120] This comparative example is basically the same as comparative example 9, except that the test sample is fly ash from origin 7 in example 7.
[0121] Comparative Example 16
[0122] This comparative example is basically the same as comparative example 9, except that the test sample is fly ash from origin 8 in example 8.
[0123] Table 4 Comparison of test results between Examples 1-8 and Comparative Examples 9-16
[0124]
[0125]
[0126] As can be seen from Table 4, the existing elemental analyzer method for determining the carbon content in ash slag has a significantly higher measured value because the calibration substance EDTA differs greatly from the carbon content in the ash slag. However, the method for determining the carbon content in ash slag in this application uses a synthetic carbon standard with low carbon content for calibration, ensuring that the carbon content in the ash slag is within the range of the standard, thus making the measurement results more accurate and reliable.
[0127] In this application, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which 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. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.
[0128] 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 determining the carbon content in ash, characterized in that, include: Multiple synthetic carbon standards with different carbon contents were selected as calibration materials to calibrate the accuracy of the test instrument. The carbon content of the synthetic carbon standards was between 0.5% and 2.0 wt%. The air-dried carbon content in the ash residue was determined using the calibrated testing instrument. The carbon content of the ash is below 1.22 wt%, and when the carbon content of the ash is less than 0.5 wt%, the method for determining the carbon content in the ash further includes a step of pre-treating the ash with the synthetic carbon standard by blending before determining the air-dried carbon content in the ash using the calibrated testing instrument; the blending mass ratio of the ash to the synthetic carbon standard is (3-7):(7-3). The testing instrument is one of the following: a carbon-hydrogen-nitrogen elemental analyzer, a carbon-sulfur analyzer, a carbon-hydrogen analyzer, and a carbon-nitrogen analyzer. The air-dried carbon content in the ash residue before blending and pretreatment is calculated using the following formula: In the formula: —Air-dried carbon content in ash residue before blending and pretreatment, expressed as mass fraction (%); —The carbon content of the ash residue after blending and pretreatment, as determined by the testing instrument, is expressed as a mass fraction (%). —The carbon content of the synthesized carbon standard is expressed as a mass fraction (%); — Ash mass, mg; —The mass of the synthesized carbon standard, in mg.
2. The method for determining the carbon content in ash slag according to claim 1, characterized in that, The carbon content of the synthetic carbon standard is 0.5 wt%, 1.0 wt%, or 2.0 wt%.
3. The method for determining the carbon content in ash slag according to claim 1, characterized in that, The carbon content of the synthetic carbon standard sample mixed with the ash slag is 2 wt%.
4. The method for determining the carbon content in ash slag according to claim 1, characterized in that, The method for calibrating the accuracy of the test instrument measurements is the multi-point calibration method.
5. The method for determining the carbon content in ash slag according to claim 4, characterized in that, The method for calibrating the accuracy of measurements taken by the testing instrument includes: The carbon content of each of the synthetic carbon standards is tested multiple times using the aforementioned testing instrument according to a preset program. The average value of the multiple tests is taken as the measured value of the corresponding synthetic carbon standard. The measured values of each of the synthetic carbon standards are linearly fitted to obtain a calibration curve.