Calculation method for co2 balance of gas-fired lime rotary kiln

Abstract

The present application relates to the field of metallurgy and chemical industry, and particularly relates to a kind of calculation method of CO2 balance of gas lime rotary kiln, which is calculated based on CO2 generated per unit product, and includes the following steps: a. calculating CO2 income based on the amount of CO2 released by the thermal decomposition of raw material limestone, the amount of CO2 brought by fuel and the amount of CO2 generated by fuel combustion; b. calculating CO2 expenditure based on the amount of CO2 carried by flue gas; and c. calculating the difference ratio based on CO2 income and CO2 expenditure. The present application clarifies the proportion of CO2 income and expenditure items to identify key carbon income and expenditure items, thereby developing targeted carbon reduction measures to control carbon emissions and meet environmental protection requirements.

Description

Technical Field

[0001] This invention relates to the fields of metallurgy and chemical engineering, to carbon emissions from industrial furnaces and kilns, and particularly to a method for calculating the CO2 balance of a gas-fired lime rotary kiln. Background Technology

[0002] A lime rotary kiln is a type of rotary kiln specifically designed for processing lime. It features simple operation and high production efficiency, and is widely used in industries such as cement, building materials, mining, and metallurgy.

[0003] Under the backdrop of achieving carbon peaking and carbon neutrality, energy conservation and carbon reduction in industrial furnaces and kilns are imperative. Since gas-fired rotary lime kilns introduce carbon into their fuels and raw materials, and generate significant amounts of CO2 through reactions within the kiln, they are a key area for carbon emission reduction. Therefore, it is necessary to calculate the CO2 balance of gas-fired rotary kiln systems, identify key carbon emission points, and develop targeted carbon reduction measures based on this analysis to contribute to achieving carbon peaking and carbon neutrality goals. Summary of the Invention

[0004] To develop targeted carbon reduction measures and contribute to the achievement of carbon peaking and carbon neutrality goals, this invention proposes a method for calculating the CO2 balance of a gas-fired lime rotary kiln. This method calculates the CO2 generated per unit product (e.g., the sum of 1 ton of lime and the amount of fly ash generated during the production of 1 ton of lime), and includes the following steps: a. Calculating CO2 revenue based on the amount of CO2 released from the thermal decomposition of raw limestone, the amount of CO2 introduced by fuel, and the amount of CO2 generated by fuel combustion; b. Calculating CO2 expenditure based on the amount of CO2 carried out by flue gas; and c. Calculating the difference ratio based on the CO2 revenue and CO2 expenditure.

[0005] In an embodiment of the present invention, in step a, the amount of CO2 released by the thermal decomposition of the raw material limestone is calculated based on the following formula:

[0006] Formula 1

[0007] in, This refers to the amount of CO2 released when the raw material limestone decomposes upon heating. △G 2 represents the loss on ignition of the clinker. △G 3 represents the loss on ignition of fly ash from the exhaust gas. △G 4 represents the loss on ignition of fly ash at the kiln head. G 2 represents the product output of lime clinker on a dry basis. G 3 represents the amount of fly ash in the exhaust gas on a dry basis.

[0008] In the embodiments of the present invention, calculations are performed based on the following formulas 2, 3, and 4, respectively. △G 2. △G 3 and △G4:

[0009] Formula 2

[0010] Formula 3

[0011] Formula 4

[0012] in, K 1 represents the loss on ignition rate of limestone entering the kiln. K 2 represents the loss on ignition rate of lime. K 3 represents the loss on ignition rate of fly ash in the exhaust gas. K 4 represents the loss on ignition rate of fly ash at the kiln head. G 4 represents the amount of fly ash at the kiln head on a dry basis.

[0013] In an embodiment of the present invention, in step a, the amount of CO2 carried in by the fuel is calculated based on the following formula five:

[0014] Formula 5

[0015] in, B represents the amount of CO2 introduced by the fuel, and B represents the amount of fuel consumed. This represents the CO2 content in the wet fuel gas.

[0016] In an embodiment of the present invention, calculations are based on the following formula six. :

[0017] Formula Six

[0018] in, This refers to the CO2 content in dry fuel gas. This refers to the moisture content of the wet gas.

[0019] In an embodiment of the present invention, in step a, the amount of CO2 produced by fuel combustion is calculated based on the following formula:

[0020] Formula 7

[0021] in, The amount of CO2 produced by fuel combustion. This refers to the amount of CO2 produced by the combustion of CO in the fuel gas. This refers to the amount of CO2 produced by the combustion of CH4 in the fuel gas. C in gas m H n The amount of CO2 produced by combustion.

[0022] In embodiments of the present invention, calculations are performed based on the following formulas eight, nine, and ten, respectively. , and :

[0023] Formula 8

[0024] Formula Nine

[0025] Formula 10

[0026] in, The CO content in the wet fuel gas. This represents the CO content in the dry flue gas. This refers to the dry flue gas volume at the preheater outlet. The content of CH4 in the wet fuel gas. This refers to the CH4 content in dry flue gas. C in wet combustion gas m H n The content, C in dry flue gas m H n The content of.

[0027] In the embodiments of the present invention, calculations are performed based on the following formulas eleven and twelve, respectively. and :

[0028] Formula Eleven

[0029] Formula 12

[0030] in, The CO content in dry fuel gas. The moisture content of the wet fuel gas. The N2 content in the wet fuel gas. The content of N2 in dry flue gas. The content of O2, CO, H2, and CH4 in dry flue gas. 'b' represents the theoretical dry air volume, and 'b' represents the correction factor for the dry flue gas volume at the preheater outlet, which are calculated based on Formula XIII and Formula XIV, respectively. and b:

[0031]

[0032] Formula Thirteen

[0033] Formula Fourteen

[0034] in, The components of the wet fuel gas are CO, H2, CH4, and C. m H n The content of H2S and O2, m is Cm H n The number of C atoms in the C, n is the number of C atoms. m H n The number of H atoms in it.

[0035] In an embodiment of the present invention, in step a, the CO2 revenue is calculated based on the following formula fifteen:

[0036] Formula Fifteen

[0037] in, This refers to CO2 revenue.

[0038] In an embodiment of the present invention, in step b, the CO2 expenditure is calculated based on the following formula sixteen:

[0039] Formula Sixteen

[0040] in, CO2 expenditure This refers to the dry flue gas volume at the preheater outlet. This represents the CO2 content in the dry flue gas.

[0041] In an embodiment of the present invention, in step c, the difference ratio is calculated based on the following formula seventeen:

[0042] Formula 17

[0043] Where η is the difference ratio.

[0044] In an embodiment of the present invention, the method for calculating the CO2 balance of a gas-fired lime rotary kiln further includes the following steps: d. Generating a CO2 balance table based at least on the amount of CO2 released by the thermal decomposition of raw limestone, the amount of CO2 brought in by fuel, the amount of CO2 generated by fuel combustion, the amount of CO2 input, the amount of CO2 carried out by flue gas, the amount of CO2 output, and the difference ratio.

[0045] This invention application provides a method for calculating the CO2 balance of a gas-fired lime rotary kiln. It uses the principle of conservation of mass to obtain the CO2 income and expenditure of the rotary kiln, and calculates the proportion of CO2 income items and expenditure items, providing support for identifying key carbon income and carbon emission items and formulating carbon reduction measures. Attached Figure Description

[0046] Figure 1 The diagram shows a flowchart illustrating a method for calculating the CO2 balance in a gas-fired lime rotary kiln provided by the present invention. Detailed Implementation

[0047] It should be understood that the embodiments of the invention shown in the exemplary embodiments are merely illustrative. Although only a few embodiments have been described in detail in this invention, those skilled in the art will readily recognize that various modifications are possible without substantially departing from the teachings of the invention. Accordingly, all such modifications should be included within the scope of the invention. Other substitutions, modifications, variations, and deletions can be made to the design, operating conditions, and parameters of the following exemplary embodiments without departing from the spirit of the invention.

[0048] According to the present invention, a method for calculating the CO2 balance of a gas-fired lime rotary kiln is provided. This method is based on the CO2 generated per unit product (for example, the method described in this invention can be based on the sum of the amount of fly ash generated from producing 1 ton of lime and the amount of waste gas produced corresponding to the production of 1 ton of lime), and as follows... Figure 1 As shown, the method includes the following steps:

[0049] a. Calculate the CO2 intake based on the amount of CO2 released by the thermal decomposition of raw limestone, the amount of CO2 introduced by fuel, and the amount of CO2 produced by fuel combustion;

[0050] b. Calculate CO2 expenditure based on the amount of CO2 carried out by flue gas; and

[0051] c. Calculate the ratio of the difference between CO2 income and CO2 expenditure.

[0052] In an embodiment of the present invention, in step a, the amount of CO2 released by the thermal decomposition of the raw material limestone is calculated based on the following formula:

[0053] Formula 1

[0054] in, This refers to the amount of CO2 released by the thermal decomposition of raw limestone, expressed in t / t. 产品 ; △G 2 represents the loss on ignition of the product lime (commonly known as clinker), in t / h; △G 3 represents the loss on ignition of fly ash from the exhaust gas, in t / h; △G 4 represents the loss on ignition of fly ash at the kiln head, in t / h. G 2 represents the product lime production on a dry basis, in t / h, which is based on field statistics. G 3 represents the amount of fly ash from the exhaust gas on a dry basis, expressed in t / h. The fly ash is also treated as a product and is obtained through on-site statistics. In the embodiments of this invention, both clinker and fly ash are calculated on a dry basis. Clinker is the main product, while fly ash is simply dust collector ash, which is in small quantities and can be sold as a product.

[0055] In the embodiments of the present invention, calculations are performed based on the following formulas 2, 3, and 4, respectively. △G2. △G 3 and △G 4:

[0056] Formula 2

[0057] Formula 3

[0058] Formula 4

[0059] in, K 1 represents the loss on ignition rate of limestone entering the kiln, expressed in %, obtained through chemical analysis. K 2 represents the product's lime loss on ignition, expressed as a percentage, obtained through chemical analysis. K 3 represents the loss on ignition of fly ash in the exhaust gas, expressed as a percentage, obtained through chemical analysis and testing. K 4 represents the loss on ignition rate of kiln head fly ash, expressed in %, obtained through chemical analysis. G 4 represents the amount of fly ash at the kiln head on a dry basis, in t / h, which is based on field statistics.

[0060] In an embodiment of the present invention, in step a, the amount of CO2 carried in by the fuel is calculated based on the following formula five:

[0061] Formula 5

[0062] in, B represents the amount of CO2 introduced by the fuel, and B represents the fuel consumption, both in Nm³. 3 / h; The CO2 content in the wet fuel gas is expressed in units of %.

[0063] In an embodiment of the present invention, calculations are based on the following formula six. :

[0064] Formula Six

[0065] in, The CO2 content in dry gas is expressed as a percentage, obtained by testing with a gas analyzer. The moisture content of the fuel gas is expressed as a percentage (%), obtained by a moisture analyzer. In one embodiment, the moisture content of the fuel gas during the test was 4.51%. Instruments typically obtain dry-basis values ​​for composition analysis. Considering that fuel gas contains a certain amount of moisture, moisture needs to be factored in to obtain the accurate proportions. There are many types of fuel gas; in the embodiments of this invention, self-produced coke oven gas is generally used, therefore a gas analyzer can be used for relevant testing.

[0066] In an embodiment of the present invention, in step a, the amount of CO2 produced by fuel combustion is calculated based on the following formula:

[0067] Formula 7

[0068] in, This refers to the amount of CO2 produced by fuel combustion, expressed in tons per ton (t / t). This represents the amount of CO2 produced by the combustion of CO in fuel gas, expressed in t / t. This represents the amount of CO2 produced by the combustion of CH4 in fuel gas, expressed in t / t. C in gas m H n The amount of CO2 produced by combustion, expressed in t / t, C m H n It is a hydrocarbon substance.

[0069] In embodiments of the present invention, calculations are performed based on the following formulas eight, nine, and ten, respectively. , and :

[0070] Formula 8

[0071] Formula Nine

[0072] Formula 10

[0073] in, The CO content in wet fuel gas is expressed as % (%). The CO content in dry flue gas is expressed as a percentage, obtained from a flue gas analyzer test. This refers to the dry flue gas volume at the preheater outlet, in Nm³. 3 / Nm 3 ; The CH4 content in wet fuel gas, expressed in Nm³. 3 / Nm 3 It is calculated based on the CH4 content and water content of the dry fuel gas. The percentage (%) represents the CH4 content in dry flue gas, obtained from a flue gas analyzer. C in wet combustion gas m H n The content, in Nm 3 / Nm 3 According to dry gas C m H n The content and moisture content of the gas were calculated. C in dry flue gas m H nThe content, expressed as a percentage, is obtained by testing with a flue gas analyzer. For ease of distinction, here and elsewhere in this invention, superscripts with apostrophes indicate flue gas, those without apostrophes indicate fuel gas, superscript 's' indicates wet components, and superscript 'g' indicates dry components.

[0074] In the embodiments of the present invention, calculations are performed based on the following formulas eleven and twelve, respectively. and :

[0075] Formula Eleven

[0076] Formula 12

[0077] in, The CO content in dry fuel gas. The moisture content of the wet fuel gas is expressed as %, measured by a moisture meter. The N2 content in wet fuel gas is expressed as % (%). The N2 content in dry flue gas is expressed as a percentage, obtained by testing with a gas analyzer. The content of O2, CO, H2, and CH4 in dry flue gas, expressed in %, is obtained by testing with a flue gas analyzer. Theoretical dry air volume, unit: Nm³ 3 / Nm 3 b is the correction coefficient for the dry flue gas volume at the preheater outlet, which is calculated based on Formula XIII and Formula XIV respectively. and b:

[0078]

[0079] Formula Thirteen

[0080] Formula Fourteen

[0081] in, The components of the wet fuel gas are CO, H2, CH4, and C. m H n The content of H2S and O2, in Nm 3 / Nm 3 It is calculated based on the content of each component of the dry gas and the water content of the gas; m is C m H n The number of C atoms in the C, n is the number of C atoms. m H n The number of H atoms in it.

[0082] In an embodiment of the present invention, in step a, the CO2 revenue is calculated based on the following formula fifteen:

[0083] Formula Fifteen

[0084] in, This refers to CO2 revenue.

[0085] In an embodiment of the present invention, in step b, the CO2 expenditure is calculated based on the following formula sixteen:

[0086] Formula Sixteen

[0087] in, CO2 expenditure, in tons per ton (t / t). This refers to the dry flue gas volume at the preheater outlet. This represents the CO2 content in the dry tobacco.

[0088] In an embodiment of the present invention, in step c, the difference ratio is calculated based on the following formula seventeen:

[0089] Formula 17

[0090] Where η is the difference ratio.

[0091] In embodiments of the present invention, such as Figure 1 As shown, the calculation method for the CO2 balance of a gas-fired lime rotary kiln further includes the following steps: d. A CO2 balance sheet is generated based at least on the amount of CO2 released by the thermal decomposition of the raw material limestone, the amount of CO2 introduced by the fuel, the amount of CO2 produced by fuel combustion, the CO2 intake, the amount of CO2 carried out by the flue gas, the CO2 expenditure, and the ratio of these differences. A blank example of this balance sheet is shown in Table 1:

[0092] Table 1 CO2 Balance Table

[0093]

[0094] The present invention is further illustrated below with reference to specific embodiments:

[0095] Thermal tests were conducted on a lime rotary kiln in a certain factory, and the CO2 balance of the kiln was calculated through the following steps.

[0096] (1) CO2 revenue calculation

[0097] ① The amount of CO2 released when raw limestone decomposes upon heating

[0098] (6-1)

[0099] in:

[0100] min1—Amount of CO2 released by the decomposition reaction of limestone, t / t of product;

[0101] —Loss on ignition of lime clinker, t / h;

[0102] (6-2)

[0103] In the formula: G2—product clinker output (dry basis), which was 21.58 t / h during the test period;

[0104] K1—Loss on ignition rate of limestone entering the kiln, %, the sample analysis during the test period was 41.53%;

[0105] K2—Loss on ignition rate of clinker lime, %, the sample analysis during the test was 5.19%;

[0106] Therefore,

[0107]

[0108]

[0109] (6-3)

[0110] In the formula:

[0111] G3—Fly ash content in exhaust gas (dry basis), 2.21 t / h during the test period;

[0112] K3—Loss on ignition of fly ash in exhaust gas, %, the sample analysis during the test showed 12.13%;

[0113] Substituting the data into equation (6-3), we get:

[0114]

[0115]

[0116] (6-4)

[0117] In the formula:

[0118] G4—Kiln head fly ash content (dry basis), 0.1t / h during the test period;

[0119] K4—Kiln head fly ash loss on ignition, %, during the test, K4=K3=12.13%;

[0120] Substituting the data into equation (6-4), we get:

[0121]

[0122] Substituting the data of △G2, △G3, and △G4 into equation (6-1), we get:

[0123]

[0124] ② Amount of CO2 introduced by fuel

[0125] The dry, moisture, and wet components of the gas (specifically coke oven gas) during the test are shown in Table 6-1.

[0126] Table 6-1 Dry, Moisture and Wet Components of Coke Oven Gas

[0127]

[0128] (6-5)

[0129] ;

[0130] B—Gas consumption, 7927 Nm during the test period. 3 / h;

[0131] —CO2 content in wet fuel gas, %

[0132] —CO2 content in dry fuel gas, %

[0133] —Moisture content of the wet fuel gas, measured by a moisture meter, was 4.51% during the test period;

[0134] Substituting the above data into equation (6-5), we get:

[0135]

[0136] ③ Amount of CO2 produced by fuel combustion

[0137] (6-6)

[0138]

[0139] ;

[0140] (6-7)

[0141] —Preheater outlet dry flue gas volume, Nm3 / Nm3

[0142] (6-8)

[0143] The contents of O2, CO, H2, and CH4 in the dry flue gas, expressed as a percentage, are obtained from flue gas analyzer tests, as shown in Table 6-2.

[0144] Table 6-2 Dry, Moisture and Wet Components of Flue Gas

[0145]

[0146] —Theoretical dry air volume, Nm3 / Nm3

[0147] (6-9)

[0148] Substituting the wet component content into Table 6-1, we get:

[0149]

[0150] b—Correction factor for dry flue gas volume at preheater outlet

[0151] (6-10)

[0152] Substituting the dry components of the flue gas into equation (6-10), we get:

[0153]

[0154] The dry flue gas volume at the preheater outlet is:

[0155]

[0156]

[0157] ;

[0158] (6-11)

[0159] Substituting the known data, we get

[0160]

[0161]

[0162] (6-12)

[0163] Substituting the data, we get:

[0164]

[0165]

[0166] ③ Total CO2 revenue

[0167] (6-13)

[0168] Substituting the data, we get:

[0169]

[0170] (2) CO2 expenditure calculation

[0171] ① Amount of CO2 carried out by flue gas , t / t

[0172] (6-14)

[0173] Substituting the data, we get:

[0174]

[0175] (3) Calculation of the ratio η between CO2 income and expenditure

[0176]

[0177] (4) CO2 balance table

[0178] Table 6-3 CO2 Balance Table

[0179]

[0180] This patent application proposes a method for calculating the CO2 balance of a gas-fired lime rotary kiln. By clarifying the proportion of CO2 income and expenditure items, the method identifies key carbon income and expenditure items, thereby enabling targeted carbon reduction measures to be formulated and carbon emissions controlled to meet environmental protection requirements.

[0181] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of the present invention. Any modifications or equivalent substitutions made to the present invention without departing from the spirit and scope thereof should be covered within the protection scope of the claims of the present invention.

Claims

1. A method for calculating the CO2 balance of a gas-fired lime rotary kiln, characterized in that, The CO2 balance is calculated on a unit product basis, and the method comprises the following steps: a. The CO2 income amount is calculated based on the following Formula Fifteen: Equation fifteen wherein, is the amount of CO2income, CO2amounts explained from thermal decomposition of raw material limestone, CO2amounts brought in as fuel, CO2amounts produced from combustion of fuel; b. The CO2 expenditure amount is calculated based on the following Formula Sixteen: Formula Sixteen wherein, Bco2is the CO2emission, Bdrygas is the dry flue gas at the preheater outlet, Bco2is the CO2content in the dry flue gas, B is the fuel gas consumption, G 2is the product lime output on a dry basis, G 3is the waste gas fly ash on a dry basis; c. The difference ratio is calculated based on the following Formula Seventeen: Formula 17 wherein η is the difference ratio; and d. A CO2 balance table is generated based on at least the amount of CO2 released by thermal decomposition of raw limestone, the amount of CO2 brought in by fuel, and the amount of CO2 generated by combustion of fuel, the CO2 income amount, the CO2 expenditure amount, and the difference ratio.

2. The method of calculating the CO2 balance of a gas-fired lime rotary kiln according to claim 1, characterized in that In step a, the amount of CO2 released by thermal decomposition of raw limestone is calculated based on the following Formula One: Formula 1 wherein, △G 2 is the loss on ignition of the product lime, △G 3 is the loss on ignition of the exhaust gas fly ash, △G 4 is the loss on ignition of the kiln head fly ash.

3. The method of calculating the CO2 balance of a gas-fired lime rotary kiln according to claim 2, characterized in that, Equations Two, Three and Four, respectively △G 2、 △G 3 and △G 4: Formula 2 Formula 3 Formula 4 wherein, K 1 is the limestone burn rate into the kiln, K 2 is the product lime burn rate, K 3 is the off-gas fly ash burn rate, K 4 is the kiln head fly ash burn rate, G 4 is the kiln head fly ash amount on a dry basis.

4. The method of calculating the CO2 balance of a gas-fired lime rotary kiln according to claim 2, characterized in that, In step a, the amount of CO2 brought in by fuel is calculated based on the following Formula Five: Formula 5 wherein is the content of CO2in the wet combustion gas.

5. The method of calculating the CO2 balance of a gas-fired lime rotary kiln according to claim 4, characterized in that Based on the following equation six calculation : Formula Six wherein is the content of CO2in dry gas, Wet gas moisture content, in %.

6. The method of calculating the CO2 balance of a gas-fired lime rotary kiln according to claim 4, characterized in that In step a, the amount of CO2 generated by combustion of fuel is calculated based on the following Formula Seven: Formula 7 wherein is the amount of CO2 produced by the combustion of CO in the fuel gas, is the amount of CO2 produced by the combustion of CH4 in the fuel gas, is the amount of CO2 produced by the combustion of C m H n combustion.

7. The method of calculating the CO2 balance of a gas-fired lime rotary kiln according to claim 6, characterized in that, are calculated based on the following Equations Eight, Nine and Ten, respectively , and : Formula 8 Formula Nine Formula 10 wherein is the content of CO in the wet flue gas, is the content of CO in the dry flue gas, is the content of CH4 in the wet flue gas, is the content of CH4 in the dry flue gas, is the content of C m H n in the wet flue gas, is the content of C m H n in the dry flue gas.

8. The method of calculating the CO2 balance of a gas-fired lime rotary kiln according to claim 7, characterized in that are calculated based on the following Equation Eleven, Equation Twelve, respectively and : Formula Eleven Official Twelve wherein, is the content of CO in the dry combustion gas, is the water content of the wet combustion gas, is the content of N2 in the wet combustion gas, is the content of N2 in the dry flue gas, is the content of O2, CO, H2, CH4 in the dry flue gas, is the theoretical dry air amount, b is the correction coefficient of the dry flue gas amount at the outlet of the preheater, wherein b is calculated based on the following Formula XIII and Formula XIV respectively and b: Formula Thirteen Formula Fourteen wherein, CO, H2, CH4, C m H n , H2S, O2, m is the number of C m H n atoms in C, n is the number of C m H n atoms in H.

Images