Calculation method for carbon emission intensity and carbon emissions of pure condensing coal-fired power generation units

Abstract

This invention discloses a method for calculating the carbon emission intensity and carbon emission amount of a pure condensing coal-fired power generation unit. It establishes a mathematical model to obtain a formula for calculating carbon emission intensity, calculates the as-received nitrogen and hydrogen content of coal using industrial analysis and calorific value data of coal from power plants, calculates the as-received carbon content of coal using empirical formulas, and calculates the standard coal carbon dioxide emission coefficient by combining data on the combustible content in ash. It obtains a relationship between the unit's power generation coal consumption and load rate by fitting coal consumption data under typical operating conditions. It calculates the power generation coal consumption for each statistical period based on the load rate, and combines this with the carbon dioxide emission coefficient to obtain the carbon emission intensity and carbon emission amount for each statistical period, thereby obtaining the cumulative carbon emission amount E. This invention does not require elemental analysis of the coal, uses readily available basic power plant monitoring data, is highly practical, and can promptly obtain carbon emission intensity and carbon emission amount for each statistical period. The data is accurate and timely, greatly facilitating carbon reduction management.

Description

Technical Field

[0001] This invention belongs to the field of coal-fired power generation, and more specifically relates to a method for calculating the carbon emission intensity and carbon emission amount of a pure condensing coal-fired power generation unit. Background Technology

[0002] To better promote carbon emission reduction, accurate calculation of carbon emissions from power generation units is crucial. The current conventional method for calculating carbon dioxide emissions is to estimate the actual amount of raw coal consumed by the power plant, multiplied by the emission factors of each type of coal. In practice, the amount of raw coal consumed is generally obtained based on daily measurements of coal fed into the furnace using belt scales or coal feeders. However, since the data obtained from belt scales and coal feeders are obtained through dynamic weighing processes and in complex working environments, inaccurate measurement data is unavoidable. Existing technologies use a standardized carbon oxidation rate to calculate carbon emissions, but this does not reflect the actual combustion level of the unit, and some units with good combustion performance may even lose their advantage. Under current technology, power plants conduct elemental analysis on coal by collecting daily fractional samples of coal fed into the furnace, mixing the daily fractional samples monthly to obtain a test sample, and then having a commissioned agency test the carbon content of the test sample. This process takes up to two months and suffers from problems such as lag, low monitoring efficiency, long cycle, high cost, and significant human interference. At the same time, methods that take the carbon oxidation rate of coal as 99% or 100% regardless of coal type, as well as methods that use default values ​​to simplify the calculation process, all contain errors that directly affect data quality.

[0003] Currently, power generation companies mainly collect data on unit carbon emissions for each month or even longer periods. They cannot accurately determine the carbon emission intensity of each unit's power generation load and operating conditions. Carbon emission intensity refers to the amount of carbon dioxide emitted by a unit per unit of power generation. Therefore, they cannot formulate reasonable carbon reduction targets and strategies in a timely manner, and cannot achieve refined management of power plant carbon reduction and carbon assets. Summary of the Invention

[0004] To avoid the problems existing in the prior art, this invention provides a method for calculating the carbon emission intensity and carbon emission amount of a pure condensing coal-fired power generation unit, so as to improve data accuracy, timely grasp the unit's carbon emission amount, and facilitate carbon management.

[0005] To achieve its objectives, the present invention employs the following technical solution:

[0006] The method for calculating carbon emission intensity and carbon emissions of pure condensing coal-fired power generating units in this invention is characterized by: establishing a mathematical model to obtain a formula for calculating carbon emission intensity; using industrial analysis and calorific value data of coal from power plants to calculate the nitrogen and hydrogen content of coal as received; calculating the carbon content of coal as received based on empirical formulas; and combining data on the combustible content in ash to calculate the standard coal carbon dioxide emission coefficient; obtaining a formula for the relationship between the unit's power generation coal consumption and load rate by fitting coal consumption data under typical operating conditions; calculating the power generation coal consumption in each statistical period based on the load rate; and combining the carbon dioxide emission coefficient to obtain the carbon emission intensity and carbon emissions in each statistical period, thereby obtaining the cumulative carbon emissions E.

[0007] The method for calculating the carbon emission intensity and carbon emissions of pure condensing coal-fired power generating units in this invention is characterized by the following steps:

[0008] Step 1: Based on the principle of carbon balance, the relationship between the unit's carbon emission intensity and coal consumption for power generation is obtained as shown in equation (1):

[0009]

[0010] In formula (1):

[0011] β CO2 Carbon emission intensity of the generating unit; B Coal M represents coal consumption. t This refers to the output power of the generator set.

[0012] C ar The carbon content of the coal received; A ar The ash content of the coal received;

[0013] The average carbon content of ash residue is the percentage of the average carbon content of ash residue to the total amount of coal ash.

[0014] Using equation (1), we can construct the expression for the unit's carbon emission intensity as represented by equation (2):

[0015]

[0016] In equation (2): B f Q represents the unit's coal consumption rate for power generation. net,ar The lower heating value of coal is calculated based on the base calorific value.

[0017] Equation (2) can be simplified to Equation (3):

[0018] β CO2 =k×B f (3)

[0020] In equation (3): k is the CO2 emission coefficient of standard coal;

[0021] Step 2: Calculate the standard coal CO2 emission coefficient k using formula (4) based on the data of coal quality and combustible content in ash:

[0022]

[0023] In formula (4): the average carbon content of ash slag It is calculated using equation (5) based on the carbon content data of the ash residue from the power plant's laboratory tests:

[0024]

[0025] In equation (5):

[0026] ω s The mass fraction of slag in the total ash content of the fuel; ω as The mass fraction of fly ash in the total ash content of fuel;

[0027] ω c.s ω represents the mass fraction of combustibles in the slag. c.as This represents the mass fraction of combustibles in fly ash.

[0028] The carbon content (C) of the coal received as a basis was obtained using an empirical formula. ar As represented by equation (6):

[0029]

[0030] In formula (6):

[0031] H ar The hydrogen content of the coal received; M ar The total water content of the coal received;

[0032] S ar The basic sulfur content of the coal received; N ar The basic nitrogen content of the coal;

[0033] The coal received has a basic nitrogen content of N. ar The hydrogen content (H) of coal received ar It is calculated from industrial analysis data using equations (7) and (8):

[0034] N ar =0.016V daf +0.9 (7)

[0036]

[0037] V daf Q is the ash-free volatile matter obtained from dried coal through industrial analysis; gr,ar The higher calorific value of coal is received.

[0038] Step 3: Establish a mathematical model to obtain the relationship between unit power generation coal consumption and load factor.

[0039] Based on the coal consumption data from typical operating condition tests of the unit, and through quadratic polynomial fitting, the empirical formula for the relationship between the unit's power generation coal consumption and load factor is obtained as shown in equation (9):

[0040]

[0041] In equation (9): ρ e , where a is the unit load rate; a, b, and c are the coal consumption characteristic coefficients related to the unit;

[0042] Step 4: Carbon emission intensity and carbon emission volume of the computer group

[0043] The load factor ρ is calculated by taking the average load over a 1-hour period. e Let j represent the j-th hour period, and calculate the coal consumption for power generation in the j-th hour according to formula (9);

[0044] The carbon emission intensity of the j-th hour is calculated using equation (3);

[0045] The carbon emissions E for the j-th hour are calculated using equation (10). j for:

[0046]

[0047] In equation (10): P0 is the rated power of the coal-fired power generation unit;

[0048] The unit carbon emissions E from time 0 to the end of hour n, calculated using equation (11), are as follows:

[0049]

[0050] In equation (11): j = 1, 2…n, thus realizing the calculation of the unit's carbon emissions.

[0051] Furthermore, based on the fluctuations in unit load, the calculation of unit carbon emissions in step 4 is replaced by calculating the load rate ρ by taking the average load over a 15-minute period. e Let x represent the xth 15-minute period, and calculate the coal consumption for power generation in the xth 15-minute period according to formula (9);

[0052] The carbon emission intensity of the xth 15-minute period is calculated using equation (3);

[0053] The carbon emissions E' for the xth 15-minute period are calculated using equation (12). x :

[0054]

[0055] The unit carbon emissions E' from time 0 to the end of the m-th 15-minute period are calculated using equation (13):

[0056]

[0057] In equation (13): x = 1, 2…m, thus realizing the calculation of the unit's carbon emissions.

[0058] Compared with existing technologies, the beneficial effects of this invention are reflected in:

[0059] 1. This invention calculates the carbon emission intensity and carbon emissions of power plants based on the reverse balance method, which solves the problem of inaccurate coal consumption measurement when calculating carbon emission intensity and carbon emissions of power plants. It also takes into account the actual carbon oxidation rate, which effectively improves the accuracy of the data.

[0060] 2. This invention solves the current problem that power plants cannot timely grasp the elemental content of coal. It calculates the received carbon content of coal based on testable industrial analysis and calorific value data, which facilitates timely grasp of unit emission intensity and carbon emission, and enables carbon management.

[0061] 3. Based on the test data of unit power generation coal consumption under typical operating conditions, this invention fits the empirical formula of load and power generation coal consumption, constructs a simplified calculation model of carbon emission intensity and power generation coal consumption, and obtains the carbon emission intensity of the unit under different load rates. Compared with the existing method of directly calculating carbon emissions without considering carbon emission intensity, the method of this invention reflects the carbon emission intensity.

[0062] 4. The method of the present invention helps to better calculate the carbon emission intensity and carbon emission of coal-fired power units. The calculation process is simple and the results are highly accurate. It can effectively avoid human interference, has a short time delay, and is low in cost. Detailed Implementation

[0063] In this embodiment, the method for calculating the carbon emission intensity and carbon emissions of a pure condensing coal-fired power generation unit is as follows: First, a mathematical model is established to obtain the carbon emission intensity calculation formula. Then, the nitrogen and hydrogen content of the coal as received are calculated using industrial analysis and calorific value data of the power plant's coal. Next, the carbon content of the coal as received is calculated according to empirical formulas. The standard coal carbon dioxide emission coefficient is calculated by combining the combustible content data in the ash and slag. The relationship between the unit's power generation coal consumption and load rate is obtained by fitting the coal consumption data under typical operating conditions of the unit. Finally, the power generation coal consumption within the statistical period is calculated based on the load rate. The carbon emission intensity and carbon emissions for each statistical period are obtained by combining the carbon dioxide emission coefficient, thereby obtaining the cumulative carbon emissions E.

[0064] In this embodiment, the calculation method for carbon emission intensity and carbon emissions of pure condensing coal-fired power generation units is carried out according to the following steps:

[0065] Step 1: Based on the principle of carbon balance, the relationship between the unit's carbon emission intensity and coal consumption for power generation is obtained as shown in equation (1):

[0066]

[0067] In formula (1):

[0068] Carbon emission intensity of the generating unit, g / (kW·h); B Coal This refers to coal consumption, expressed in tons per hour (t / h).

[0069] M t C represents the generator set's output power, in MW; ar The carbon content of the coal received is expressed as a percentage.

[0070] A ar The ash content of the coal received is %, in %.

[0071] The average carbon content of ash is denoted as , which is the percentage of the average carbon content of ash to the total amount of coal ash.

[0072] Using equation (1), we can construct the expression for the unit's carbon emission intensity as represented by equation (2):

[0073]

[0074] B f Q represents the unit's coal consumption rate for power generation, expressed in g / (kW·h); net,ar The lower heating value of coal is given by the received basis, kJ / kg; Equation (2) is simplified to Equation (3):

[0075]

[0076] In equation (3): k is the CO2 emission coefficient of standard coal;

[0077] Step 2: Using formula (4) based on coal quality and ash data, the standard coal CO2 emission coefficient k is calculated as follows:

[0078]

[0079] In equation (4):

[0080] Average carbon content of ash It is calculated using equation (5) based on the carbon content data of the ash residue from the power plant's laboratory tests:

[0081]

[0082] In equation (5):

[0083] ω sThe percentage of slag in the total ash content of the fuel is taken as a conventional value.

[0084] ω as The percentage of fly ash in the total ash content of fuel is taken as a conventional value.

[0085] ω c.s The mass fraction of combustibles in the slag, expressed as a percentage, is taken from power plant laboratory data.

[0086] ω c.as The mass fraction of combustibles in fly ash, expressed as a percentage, is taken from power plant laboratory data.

[0087] The carbon content (C) of the coal received as a basis was obtained using an empirical formula. ar As represented by equation (6):

[0088]

[0089] In formula (6):

[0090] H ar The hydrogen content of the coal received is %, %; M ar The total water content of the coal received is %, in %.

[0091] S ar The basic sulfur content of the coal received is %, %; N ar The nitrogen content of the coal received is %, in %.

[0092] Coal received with basic nitrogen content N ar The hydrogen content (H) of coal received ar It is calculated from equations (7) and (8) based on industrial analysis and calorific value data:

[0093] N ar =0.016V daf +0.9 (7)

[0095]

[0096] V daf The volatile matter content (%) of dried coal (ash-free basis) was obtained through industrial analysis.

[0097] Q gr,ar The higher heating value of coal is given by the received amount, in kJ / kg.

[0098] Step 3: Establish a mathematical model to obtain the relationship between unit power generation coal consumption and load factor.

[0099] Based on the coal consumption data of the unit under typical operating conditions, after quadratic polynomial fitting, the empirical formula of the unit's power generation coal consumption and load rate is obtained as shown in formula (9). The typical operating conditions of the unit can be selected as 100%, 75% and 50% of the rated load.

[0100]

[0101] ρ e , where is the unit load rate, %; a, b, and c are the coal consumption characteristic coefficients related to the unit;

[0102] Step 4: Carbon emission intensity and carbon emission volume of the computer group

[0103] The load factor ρ is calculated by taking the average load over a 1-hour period. e Let j represent the j-th hour period, and calculate the coal consumption for power generation in the j-th hour according to formula (9);

[0104] The carbon emission intensity of the j-th hour is calculated using equation (3);

[0105] The carbon emissions E for the j-th hour are calculated using equation (10). j for:

[0106]

[0107] In equation (10): P0 is the rated power of the coal-fired power generation unit;

[0108] The unit carbon emissions E from time 0 to the end of hour n, calculated using equation (11), are as follows:

[0109]

[0110] In equation (11): j = 1, 2…n, thus realizing the calculation of the unit's carbon emissions.

[0111] In practice, based on the fluctuations in unit load, the calculation of unit carbon emissions in step 4 can be replaced by calculating the load rate ρ by taking the average load over a 15-minute period. e Let x represent the xth 15-minute period, and calculate the coal consumption for power generation in the xth 15-minute period according to formula (9);

[0112] The carbon emission intensity of the xth 15-minute period is calculated using equation (3);

[0113] The carbon emissions E' for the xth 15-minute period are calculated using equation (12). x for:

[0114]

[0115] The unit carbon emissions E' calculated from time 0 to the end of the m-th 15-minute period is as follows:

[0116]

[0117] In equation (13): x = 1, 2…m, thus realizing the calculation of the unit's carbon emissions.

[0118] The test data for the coal consumption of a 660MW pure condensing ultra-supercritical coal-fired power generating unit under 100%, 75%, and 50% rated load conditions are 264.7g / (kW·h), 267.7g / (kW·h), and 275.2g / (kW·h), respectively. The fitted binomial formula for the coal consumption is as shown in equation (9-1):

[0119]

[0120] Within one hour, the unit maintained a 600MW operation with a load factor of 90.91%. The calculated coal consumption for power generation under the current load factor was 265.27g / (kW·h). The industrial analysis of the coal fed into the furnace, the lower heating value, the higher heating value, the combustibles in fly ash, the combustibles in slag, and the sulfur content are shown in Table 1.

[0121] Based on the conversion of different coal quality standards, V is obtained. daf The value was 37.64%;

[0122] N is calculated from equations (7) and (8). ar and H ar They were 1.50% and 3.44% respectively;

[0123] C is obtained by calculating from equation (6) ar It is 58.00%;

[0124] Calculated from equation (5) It is 1.14%;

[0125] The standard coal CO2 emission coefficient k was calculated to be 2.79 using equation (4);

[0126] The carbon emission intensity of the unit within 1 hour is calculated to be 740.10 g / (kW·h) using equation (3);

[0127] The carbon emissions of the unit within 1 hour are calculated using equation (10) to be 444.07t.

[0128] Considering the load fluctuations and further refining the time period, with a statistical period of 15 minutes, the load rates of the unit in the first to fourth periods were 89.24%, 90.61%, 91.52%, and 92.42%, respectively.

[0129] According to equation (9), the coal consumption for power generation in the first to fourth cycles of the unit is 265.44 g / (kW·h), 265.30 g / (kW·h), 265.21 g / (kW·h), and 265.13 g / (kW·h), respectively.

[0130] According to equation (3), the carbon emission intensity of the unit during the first to fourth cycles is 740.58 g / (kW·h), 740.19 g / (kW·h), 739.95 g / (kW·h), and 739.72 g / (kW·h), respectively.

[0131] The carbon emissions of the unit during the first to fourth 15-minute cycles, calculated using equation (12), are as follows:

[0132] E'1=109.05; E'2=110.66; E'3=111.73; E'4=112.81

[0133] Therefore, the carbon emissions of this unit in 1 hour are calculated to be 444.25 tons, that is:

[0134] A 15-minute calculation will be more accurate than a 1-hour calculation. When the total statistical time span is large and the complexity of the calculation is a concern, it is advisable to choose a 1-hour calculation.

[0135] Table 1

[0136]

[0137] This embodiment is only intended to illustrate the technical concept and features of the present invention, and its purpose is to enable those skilled in the art to understand the method and core idea of ​​the present invention and to implement it accordingly. It should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A method for calculating the carbon emission intensity and carbon emissions of a pure condensing coal-fired power generation unit, characterized by: A mathematical model was established to calculate carbon emission intensity. The as-received nitrogen and hydrogen content of coal was calculated using industrial analysis and calorific value data from power plant coal. The as-received carbon content of coal was calculated using empirical formulas. The standard coal carbon dioxide emission coefficient was calculated by combining data on combustible matter content in ash and slag. The relationship between unit power generation coal consumption and load factor was obtained by fitting coal consumption data under typical unit operating conditions. Power generation coal consumption for each statistical period was calculated based on the load factor. Combined with the carbon dioxide emission coefficient, the carbon emission intensity and carbon emission amount for each statistical period were obtained, thus yielding the cumulative carbon emissions. The calculation method for the carbon emission intensity and carbon emission amount of the pure condensing coal-fired power generation unit is carried out according to the following steps: Step 1: Based on the principle of carbon balance, the relationship between the unit's carbon emission intensity and coal consumption for power generation is obtained as shown in equation (1): （1）； In formula (1): Carbon emission intensity of the generating unit; This refers to coal consumption. This refers to the output power of the generator set. The carbon content of the coal received; The ash content of the coal received; The average carbon content of ash residue is the percentage of the average carbon content of ash residue to the total amount of coal ash. Using equation (1), we can construct the expression for the unit's carbon emission intensity as represented by equation (2): （2）； In formula (2): The unit's coal consumption rate for power generation; The lower heating value of coal is calculated based on the base calorific value. Equation (2) can be simplified to Equation (3): （3）； In formula (3): k The standard coal CO2 emission factor; Step 2: Calculate the standard coal CO2 emission coefficient using formula (4) based on the data on coal quality and combustible content in ash. k : （4）； In equation (4): Average carbon content of ash It is calculated using equation (5) based on the carbon content data of the ash residue from the power plant's laboratory tests: （5）； In equation (5): The mass fraction of furnace slag relative to the total ash content of the fuel; The mass fraction of fly ash in the total ash content of fuel; This represents the mass fraction of combustibles in the slag. This represents the mass fraction of combustibles in fly ash. The carbon content of coal as received by the base was obtained using an empirical formula. As represented by equation (6): （6）； In formula (6): The hydrogen content of the coal is the basic value. The total water content of the coal received; The base sulfur content of the coal; The basic nitrogen content of the coal; The coal received basic nitrogen content and the hydrogen content received by coal It is calculated from industrial analysis data using equations (7) and (8): （7）； （8）； in: It is the ash-free volatile matter obtained through industrial analysis of dried coal; The higher calorific value of coal is received. Step 3: Establish a mathematical model to obtain the relationship between unit power generation coal consumption and load factor. Based on the coal consumption data from typical operating condition tests of the unit, and through quadratic polynomial fitting, the empirical formula for the relationship between the unit's power generation coal consumption and load factor is obtained as shown in formula (9): （9）； In equation (9): Unit load rate; , and Coal consumption characteristic coefficients related to the unit; Step 4: Carbon emission intensity and carbon emission volume of the computer group The load factor is calculated by taking the average load over a 1-hour period. ,by j Indicates the first j The hourly time period is calculated according to formula (9) to obtain the first hour. j Hourly coal consumption for power generation; The first one is obtained by calculating from equation (3). j Carbon emission intensity per hour; The first one is obtained by calculating from equation (10). j carbon emissions per hour for: （10）； In formula (10): This refers to the rated power of the coal-fired power generation unit. The unit carbon emissions from time 0 to the end of hour n are calculated using equation (11). for: （11）； In equation (11): j = 1,2…n, thus realizing the calculation of the unit's carbon emissions.

2. The method for calculating carbon emission intensity and carbon emission amount of pure condensing coal-fired power generating units according to claim 1, characterized in that: Based on the fluctuations in unit load, the calculation of unit carbon emissions in step 4 is replaced by calculating the load rate by taking the average load over a 15-minute period. Let x represent the xth 15-minute period, and calculate the coal consumption for power generation in the xth 15-minute period according to formula (9); The carbon emission intensity of the xth 15-minute period is calculated using equation (3); The carbon emissions for the xth 15-minute period are calculated using equation (12). for: （12）； The unit carbon emissions from time 0 to the end of the m-th 15-minute period are calculated using equation (13). for: （13）； In equation (13): x = 1,2…m, thus realizing the calculation of the unit's carbon emissions.

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