DEVICE AND METHOD FOR PRODUCING CEMENT CLINKER THROUGH COMPLETE OXYGEN COMBUSTION

Description

1 / 18 DEVICE AND METHOD FOR PRODUCING CEMENT CLINKER THROUGH COMPLETE OXYGEN COMBUSTION TECHNICAL FIELD [1] The disclosure relates to the technical field of building materials and, in particular, relates to a device and method for producing cement clinker through the complete combustion of oxygen. FUNDAMENTALS [2] The cement industry is the world’s third largest emitter of CO2. Its predominant CO2 emissions result from the high energy and resource consumption used in cement production. In China, CO2 emissions from the cement industry are second only to those from the electricity and steel industries. Green and low-carbon technologies applied to the cement industry promote net-zero carbon emissions and play a key role in achieving China’s dual goals of peak carbon emissions and carbon neutrality. [3] It is believed, both domestically and internationally, that the application of carbon capture, utilization and storage technologies is the only way for the cement industry to achieve carbon neutrality. However, air is typically used in the cement industry to support combustion, resulting in a low concentration (20%-30%) of CO2 in the flue gas. Thus, a solvent absorption method must be used to capture CO2, which is high in operational cost. If the combustion support air is replaced with high-purity oxygen and the medium flow and heat transfer characteristics of a kiln are adjusted through flue gas circulation, flue gas with high CO2 concentration can be obtained and the CO2 can be captured through adsorption and distillation. Compared to solvent absorption, the operational cost of adsorption and distillation can be reduced by 47% and the investment cost can be reduced by 35%.Thus, as a highly promising technological approach to capturing CO2, a total oxygen combustion technology has the advantage of producing high-concentration CO2 streams and capturing CO2 more efficiently and economically. Petition 870250022870, dated 03 / 24 / 2025, page 13 / 39 2 / 18 [4] In the prior art, when fuel is burned at a high CO2 concentration, the flame temperature is lower than that of air combustion and the combustion rate is slower. With an increase in O2 concentration, the flame temperature increases rapidly. However, an excessive O2 concentration will lead to an excessively high combustion flame temperature, as well as a risk of deflagration. Furthermore, due to an irrational O2 injection position, O2 and fuel cannot be uniformly mixed, thus forming a partial high temperature zone and a partial low temperature zone. These will influence the efficiency and stability of the combustion reaction. Incorrect injection dosage and an inadequate O2 injection position are the main problems faced by existing total oxygen combustion technology. [5] Since existing total oxygen combustion technology is still flawed in the injection position and O2 injection ratio, a combustion process is unstable and the full use of the advantages of total oxygen combustion is unattainable. In order to solve the above problems, the revelation provides a method for injecting oxygen during total oxygen combustion. By optimizing an O2 injection position and regulating an O2 to high-concentration CO2 combustion gas mixing ratio, combustion stability is improved while carbon capture costs are reduced. SUMMARY OF THE INVENTION [6] In order to solve problems of high cost of carbon capture and low efficiency in a cement production process, the revelation provides a device and method for producing cement clinker through total oxygen combustion. The revelation is implemented through the following technical solution: [7] A device for producing cement clinker through complete oxygen combustion includes: [8] a rotary kiln used to produce cement clinker, wherein the rotary kiln includes a rotary kiln feed door, a door Petition 870250022870, dated 03 / 24 / 2025, page 14 / 39 3 / 18 rotary kiln discharge, a rotary kiln flue gas outlet, a burner and a secondary duct port; and the secondary duct port is connected to a secondary duct, the secondary duct is provided with a second oxygen inlet and the second oxygen inlet is used to introduce oxygen into the secondary duct; [9] a decomposition furnace used to preheat a raw material and decompose carbonate in the raw material, wherein the decomposition furnace includes a raw material inlet, a rotary kiln flue gas inlet, a tertiary duct port and a decomposition furnace outlet; the tertiary duct port is connected to a tertiary duct and the tertiary duct is provided with a third oxygen inlet and the third oxygen inlet is used to introduce oxygen into the tertiary duct; the rotary kiln flue gas inlet is connected to the rotary kiln flue gas outlet; and the decomposition furnace outlet is connected to the rotary kiln feed port and the decomposition furnace outlet is further connected to an exhaust gas outlet;

[10] a gas cooling device, wherein the gas cooling device is connected to the discharge port of a rotary kiln; the gas cooling device is used to cool a material outlet from the discharge port of a rotary kiln; the cooling device includes a cooling gas inlet and a cooling gas outlet; the cooling gas inlet includes a first oxygen inlet and a carbon dioxide inlet; and the cooling gas outlet is connected to the secondary duct and the tertiary duct separately; and

[11] a carbon dioxide collection device, wherein the carbon dioxide collection device is connected to the exhaust gas outlet; and the carbon dioxide collection device is used to collect carbon dioxide in the combustion gas outlet from the exhaust gas outlet.

[12] Optionally, a grate cooler is used as the gas cooling device.

[13] The first oxygen intake and the carbon dioxide intake Petition 870250022870, dated 03 / 24 / 2025, page 15 / 39 4 / 18 are both located at the bottom of the grate cooler.

[14] Optionally, the burner includes a burner carrier gas inlet, a fuel inlet and a burner outlet. The carrier gas containing oxygen and carbon dioxide is carried to the burner through the carrier gas inlet and is mixed with fuel and then burned at the burner outlet. The volume fraction of oxygen in the carrier gas is 33%-38%. The volume fraction of carbon dioxide is 50%-53%.

[15] Gas is supplied from the secondary duct to the burner outlet to support combustion.

[16] Optionally, a carbon dioxide adsorption and distillation device is used as the carbon dioxide collection device.

[17] Optionally, the exhaust gas outlet is connected to a circulating flue gas port. The circulating flue gas port is connected to the burner and the gas cooling device. The carbon dioxide inlet to the gas cooling device uses flue gas carried by the circulating flue gas port and a carbon dioxide content of about 80%. In the burner, the oxygen and flue gas carried by the circulating flue gas port are mixed to form carrier gas and then the carrier gas is mixed with fuel for combustion.

[18] Optionally, the third oxygen inlet is provided at one end of the tertiary duct near the gas cooling device.

[19] The second oxygen inlet is provided at one end of the secondary duct near the gas cooling device.

[20] Optionally, the device for producing cement clinker through total oxygen combustion also includes an oxygen preparation device. The first oxygen inlet, the second oxygen inlet and the third oxygen inlet are all connected to the oxygen preparation device.

[21] In a method for producing cement clinker through Petition 870250022870, dated 03 / 24 / 2025, page 16 / 39 5 / 18 complete oxygen combustion, production is conducted with the device to produce cement clinker through complete oxygen combustion. The method includes the following steps:

[22] step 1), transport oxygen to a gas cooling device through a first oxygen inlet; transport carbon dioxide to the gas cooling device through a carbon dioxide inlet; and mix the carbon dioxide and oxygen in the gas cooling device so as to form the first mixed gas and transport the first mixed gas to a secondary duct and a tertiary duct separately through a cooling gas outlet;

[23] step 2), transport oxygen to the secondary duct via a second oxygen inlet so as to mix with the first mixed gas in the secondary duct, form the second mixed gas and transport the second mixed gas to a rotary kiln via a secondary duct port so as to support combustion in a burner; and allow the combustion gas in the rotary kiln to enter a decomposition furnace via a rotary kiln combustion gas outlet; and

[24] step 3), transport oxygen to the tertiary duct through a third oxygen inlet so as to mix with the first mixed gas, form the third mixed gas and transport the third mixed gas to the decomposition furnace through a tertiary duct port; and discharge combustion gas and material into the decomposition furnace from a decomposition furnace discharge port, allowing the material in the decomposition furnace to enter the rotary kiln through a rotary kiln feed port, allowing the combustion gas in the decomposition furnace to enter a carbon dioxide collection device through an exhaust gas outlet and collect carbon dioxide.

[25] Optionally, a volume fraction of oxygen in the first gas mixture is 18%-22%.

[26] Optionally, a volume fraction of oxygen in the second gas mixture is 33%-38%.

[27] Optionally, a volume fraction of oxygen in the third gas Petition 870250022870, dated 03 / 24 / 2025, page 17 / 39 6 / 18 mixed is 25%-30%.

[28] All the fuel mentioned above is coal.

[29] Revelation has the following beneficial effects:

[30] In the development, the O2 and circulating CO2 flue gas are rationally combined in the rotary kiln and decomposition furnace, so that heat recovery is implemented, combustion conditions in the rotary kiln and decomposition furnace are optimized, and the carbon capture cost of cement production is effectively reduced. The flue gas finally obtained after combustion contains high concentration CO2 which can be collected and absorbed through adsorption and distillation. The operating cost of adsorption and distillation can be reduced by 47% and the investment cost can be reduced by 35%.

[31] In the revelation, oxygen-enriched injection is conducted into the gas cooling device, so that O2 can be fully mixed with high CO2 combustion gas before the combustion reaction, the high partial temperature caused by a high partial concentration of O2 is avoided and the stability of a combustion process is improved.

[32] According to the disclosure, a regulation mechanism is provided for an O2 concentration in the rotary kiln and in the decomposition furnace separately, so that an O2 ratio can be precisely controlled and different oxygen concentration requirements in the decomposition furnace and in the rotary kiln can be met. BRIEF DESCRIPTION OF THE FIGURES

[33] In order to illustrate more clearly technical solutions in specific embodiments of the development or in the state of the art, the accompanying drawings necessary for the description of the specific embodiments or the state of the art will be briefly introduced below. Obviously, the accompanying drawings in the following description are some embodiments of the development, and those skilled in the art may still derive other drawings from these accompanying drawings without any creative effort.

[34] FIG. 1 is a schematic structural diagram of a developing device; Petition 870250022870, dated 03 / 24 / 2025, page 18 / 39 7 / 18

[35] FIG. 2 is a schematic structural diagram of a burner in a rotary kiln; and

[36] FIG. 3 is a schematic diagram of a gas cooling device. DETAILED DESCRIPTION

[37] Several illustrative embodiments of the disclosure are described in detail. Such detailed description should not be considered a limitation of the disclosure and should be understood as a more detailed description of some aspects, features and implementation solutions of the disclosure. It should be understood that the terms described in the disclosure are merely used to describe specific embodiments and are not intended to limit the disclosure.

[38] Furthermore, it should be understood that each intermediate value between an upper limit and a lower limit of a numerical range in the disclosure is further specifically disclosed. Any stated value or any intermediate value within a stated range, as well as any other stated value or each smaller range between intermediate values ​​within the range, are also included in the disclosure. The upper limit and the lower limit of the smaller ranges may be independently included or excluded from the range.

[39] Unless otherwise specified, all technical and scientific terms used in this document have the same meanings as commonly understood by those skilled in the subject matter to which the disclosure relates. Although the disclosure only describes preferred methods and materials, any methods and materials similar or equivalent to those described in this document may also be used in implementing or testing the disclosure.

[40] The words include, comprehend, have, contain, etc. used in this document are all open words and indicate including, but not limited to. The gas concentrations mentioned in the following examples are all measured by volume fraction. EXAMPLE 1

[41] A device for producing cement clinker through Petition 870250022870, dated 03 / 24 / 2025, p. 19 / 39 8 / 18 complete oxygen combustion, as shown in FIGS. 1-3 includes: a rotary kiln 1, a decomposition furnace 2, a gas cooling device 3 and a carbon dioxide collection device 4.

[42] Rotary kiln 1 is used to produce cement clinker. The rotary kiln includes a rotary kiln feed port 11, a rotary kiln discharge port 12, a rotary kiln flue gas outlet 13, a burner 14, and a secondary duct port 15. The secondary duct port 15 is connected to a secondary duct 151. The secondary duct 151 is provided with a second oxygen inlet 152. The second oxygen inlet is provided at one end of the secondary duct near the gas cooling device. The burner 14 is used to heat the rotary kiln. The burner 14 includes a burner carrier gas inlet 141, a fuel inlet 142, and a burner outlet 143. Gas is supplied from the secondary duct 151 to the burner outlet 143 to support combustion.The carrier gas containing oxygen and carbon dioxide is transported to the burner through carrier gas inlet 141 and is mixed with fuel and then burned at the burner outlet.

[43] Decomposition furnace 2 is used to preheat a feedstock and decompose carbonate in the feedstock. The decomposition furnace includes a feedstock inlet (not shown in the figure), a rotary kiln flue gas inlet 21, a tertiary duct port 22, and a decomposition furnace outlet 23. During operation, a mixed feedstock, including the feedstock and fuel, is added from the feedstock inlet and burned in the decomposition furnace. The carbonate in the feedstock is preheated and decomposed. The tertiary duct port 22 is connected to a tertiary duct 221. The tertiary duct 221 is provided with a third oxygen inlet 222. The third oxygen inlet is provided at one end of the tertiary duct near the gas cooling device.The rotary kiln flue gas inlet 21 is connected to the rotary kiln flue gas outlet 13, so that the flue gas in the rotary kiln can enter the furnace. Petition 870250022870, dated 03 / 24 / 2025, page 20 / 39 9 / 18 Decomposition from rotary kiln combustion gas inlet 21. The decomposition furnace outlet 23 is connected to the rotary kiln feed port, and the decomposition furnace outlet 23 is further connected to an exhaust gas outlet 231. The exhaust gas outlet 231 is connected to the carbon dioxide collection device 4. The exhaust gas outlet 231 is connected to a circulating combustion gas port 232. The circulating combustion gas port 232 is connected to the burner 14 and the gas cooling device 3 and is used to transport the carbon dioxide required for the burner and the gas cooling device. In the carrier gas formed by the mixture of oxygen and circulating combustion gas, the volume fraction of oxygen is 33%-38% and the volume fraction of carbon dioxide is 50%-53%.

[44] Gas cooling device 3 is arranged. A grate cooler is used as the gas cooling device 3. The gas cooling device 3 is connected to the rotary kiln discharge port 12 and is used to cool a material outlet from the rotary kiln discharge port 12. The cooling device 3 includes a cooling gas inlet and a cooling gas outlet 33. The cooling gas inlet includes a first oxygen inlet 32 ​​and a carbon dioxide inlet 31. The first oxygen inlet and the carbon dioxide inlet are both located at the bottom of the grate cooler. The cooling gas outlet is connected to the secondary duct 151 and the tertiary duct 221 separately.

[45] Carbon dioxide collection device 4 is provided. A carbon dioxide adsorption and distillation device is used as the carbon dioxide collection device 4. The carbon dioxide collection device is connected to the exhaust gas outlet. The carbon dioxide collection device 4 is used to collect carbon dioxide in the combustion gas outlet from the exhaust gas outlet.

[46] All the fuel mentioned above is coal.

[47] One implementation process of the disclosure is as follows: in a method for producing cement clinker through the complete combustion of Petition 870250022870, dated 03 / 24 / 2025, page 21 / 39 10 / 18 oxygen, production is conducted with a device to produce cement clinker through complete oxygen combustion. The method includes the following steps:

[48] ​​Step 1), oxygen is transported to a gas cooling device through a first oxygen inlet; the circulating combustion gas is transported to the gas cooling device through a carbon dioxide inlet; and the carbon dioxide and oxygen are mixed in the gas cooling device so as to form the first mixed gas, and the first mixed gas is transported to a secondary duct and a tertiary duct separately through a cooling gas outlet.

[49] Step 2), oxygen is transported to the secondary duct through a second oxygen inlet so as to mix with the first mixed gas in the secondary duct, the second mixed gas is formed and the second mixed gas is transported to a rotary kiln through a secondary duct port so as to support combustion in a burner; and the combustion gas in the rotary kiln enters a decomposition furnace through a rotary kiln combustion gas outlet.

[50] Step 3), oxygen is transported to the tertiary duct through a third oxygen inlet so as to mix with the first mixed gas, the third mixed gas is formed and the third mixed gas is transported to the decomposition furnace through a tertiary duct port; and the combustion gas and material in the decomposition furnace are emitted from a decomposition furnace discharge port, the material in the decomposition furnace enters the rotary kiln through a rotary kiln feed port, the combustion gas in the decomposition furnace enters a carbon dioxide collection device through an exhaust gas outlet and the carbon dioxide is collected.

[51] The volume fraction of oxygen in the first gas mixture is 18%-22%. The volume fraction of oxygen in the second gas mixture is 33%-38%. The volume fraction of oxygen in the third gas mixture is 25%-30%. Petition 870250022870, dated 03 / 24 / 2025, p. 22 / 39 11 / 18

[52] Through the device, a concentration of carbon dioxide in the flue gas transported to the carbon dioxide collection device can reach about 80%. Due to the high concentration, an adsorption and distillation method can be used for carbon dioxide recovery. In the previous technique, a CO2 concentration in the flue gas is 20%-30%, and the CO2 is usually captured through a solvent absorption method. The method is suitable for recovering carbon dioxide from flue gases containing low concentration carbon dioxide and is complicated in process and high in investment and operating cost. Adsorption and distillation must separate carbon dioxide from other gases according to the differences between carbon dioxide and other gases in boiling point.Heavy components with a boiling point higher than carbon dioxide are removed with different adsorbents, and light components are extracted by distillation, leaving carbon dioxide with a purity of 99.99% or more. It is estimated that operating and investment costs can be reduced by 45.7% and 36.4%, respectively, by recovering carbon dioxide with an adsorption and distillation apparatus instead of a solvent absorption apparatus.

[53] In the development, oxygen-enriched injection is conducted in the gas cooling device so that O2 can be fully mixed with high CO2 combustion gas before the combustion reaction, the high partial temperature caused by a high partial concentration of O2 is avoided and the stability of a combustion process is improved. If oxygen and combustion gas are not mixed beforehand in the gas cooling device, all the oxygen can mix with the combustion gas in the secondary and tertiary ducts, leading to uneven mixing. In this case, a high partial concentration of oxygen and a high partial temperature can occur, and complete combustion of the fuel is not facilitated. EXAMPLE 2

[54] Based on the device in Example 1, cement clinker is Petition 870250022870, dated 03 / 24 / 2025, page 23 / 39 12 / 18 produced through the complete combustion of oxygen, so that the cost of CO2 capture is reduced and, meanwhile, the combustion stability of a rotary kiln and a decomposition furnace is improved. The specific steps are as follows:

[55] Step 1), oxygen is transported to a gas cooling device through a first oxygen inlet; the circulating combustion gas is transported to the gas cooling device through a carbon dioxide inlet; and the carbon dioxide and oxygen are mixed in the gas cooling device so as to form the first mixed gas, an O2 concentration in the first mixed gas is 21.2% and the first mixed gas is transported to a secondary duct and a tertiary duct separately through a cooling gas outlet.

[56] Step 2), oxygen is transported to the secondary duct through a second oxygen inlet so as to mix with the first mixed gas in the secondary duct, the second mixed gas is formed, an O2 concentration in the second mixed gas is 35.4% and the second mixed gas is transported to a rotary kiln through a secondary duct port so as to support combustion in a burner; and the combustion gas in the rotary kiln enters a decomposition furnace through a rotary kiln combustion gas outlet.

[57] Step 3), oxygen is transported to the tertiary duct through a third oxygen inlet so as to mix with the first mixed gas, the third mixed gas is formed, an O2 concentration in the third mixed gas is 27.0% and the third mixed gas is transported to the decomposition furnace through a tertiary duct port; and combustion gas and material in the decomposition furnace are emitted from a decomposition furnace discharge port, the material in the decomposition furnace enters the rotary kiln through a rotary kiln feed port, the combustion gas in the decomposition furnace enters a carbon dioxide collection device through an exhaust gas outlet and the carbon dioxide is collected. Petition 870250022870, dated 03 / 24 / 2025, page 24 / 39 13 / 18

[58] Through measurement, in the combustion gas at the waste gas outlet, an O2 concentration of 2.8% and a CO2 concentration of 78.4%. The temperatures in the rotary kiln and decomposition furnace are maintained within an expected range, and no partial high temperatures or severe temperature fluctuations appear. The combustion process is stable. An average NOx concentration in the decomposition furnace is 330 mg / m3 and an average NOx concentration in the rotary kiln is 900 mg / m3. EXAMPLE 3

[59] Based on the structure of Example 1, a cement production line undergoes total oxygen combustion transformation in order to reduce the cost of CO2 capture and improve the combustion stability of a rotary kiln and a decomposition furnace. The specific steps are as follows:

[60] Step 1), oxygen is transported to a gas cooling device through a first oxygen inlet; the circulating combustion gas is transported to the gas cooling device through a carbon dioxide inlet; and the carbon dioxide and oxygen are mixed in the gas cooling device so as to form the first mixed gas, an O2 concentration in the first mixed gas is 19.6% and the first mixed gas is transported to a secondary duct and a tertiary duct separately through a cooling gas outlet.

[61] Step 2), oxygen is transported to the secondary duct through a second oxygen inlet so as to mix with the first mixed gas in the secondary duct, the second mixed gas is formed, an O2 concentration in the second mixed gas is 33.7% and the second mixed gas is transported to a rotary kiln through a secondary duct port so as to support combustion in a burner; and the combustion gas in the rotary kiln enters a decomposition furnace through a rotary kiln combustion gas outlet.

[62] Step 3), oxygen is transported to the tertiary duct through a third oxygen inlet so as to mix with the first gas. Petition 870250022870, dated 03 / 24 / 2025, page 25 / 39 14 / 18 mixed, the third mixed gas is formed, an O2 concentration in the third mixed gas is 25.2% and the third mixed gas is transported to the decomposition furnace through a tertiary duct port; and combustion gas and material in the decomposition furnace are emitted from a decomposition furnace discharge port, the material in the decomposition furnace enters the rotary kiln through a rotary kiln feed port, the combustion gas in the decomposition furnace enters a carbon dioxide collection device through an exhaust gas outlet and the carbon dioxide is collected.

[63] Through measurement, in the combustion gas at the waste gas outlet, an O2 concentration of 2.4% and a CO2 concentration of 80.5%. The temperatures in the rotary kiln and decomposition furnace are maintained within an expected range, and no partial high temperature and severe temperature fluctuation appear. A stable combustion process. An average NOx concentration in the decomposition furnace is 320 mg / m3 and an average NOx concentration in the rotary kiln is 940 mg / m3. EXAMPLE 4.

[64] Based on the device in Example 1, cement clinker is produced through complete oxygen combustion, so that the cost of CO2 capture is reduced and, meanwhile, the combustion stability of a rotary kiln and a decomposition furnace is improved. The specific steps are as follows:

[65] Step 1), oxygen is transported to a gas cooling device through a first oxygen inlet; the circulating combustion gas is transported to the gas cooling device through a carbon dioxide inlet; and the carbon dioxide and oxygen are mixed in the gas cooling device so as to form the first mixed gas, an O2 concentration in the first mixed gas is 18.2% and the first mixed gas is transported to a secondary duct and a tertiary duct separately through a cooling gas outlet.

[66] Step 2), oxygen is transported to the secondary duct through Petition 870250022870, dated 03 / 24 / 2025, page 26 / 39 15 / 18 of a second oxygen inlet so as to mix with the first mixed gas in the secondary duct, the second mixed gas is formed, an O2 concentration in the second mixed gas is 33.5% and the second mixed gas is transported to a rotary kiln through a secondary duct port so as to support combustion in a burner; and the combustion gas in the rotary kiln enters a decomposition furnace through a rotary kiln combustion gas outlet.

[67] Step 3), oxygen is transported to the tertiary duct through a third oxygen inlet so as to mix with the first mixed gas, the third mixed gas is formed, an O2 concentration in the third mixed gas is 25.1% and the third mixed gas is transported to the decomposition furnace through a tertiary duct port; and combustion gas and material in the decomposition furnace are emitted from a decomposition furnace discharge port, the material in the decomposition furnace enters the rotary kiln through a rotary kiln feed port, the combustion gas in the decomposition furnace enters a carbon dioxide collection device through an exhaust gas outlet and the carbon dioxide is collected.

[68] Through measurement, in the combustion gas at the waste gas outlet, an O2 concentration of 2.3% and a CO2 concentration of 79.1%. The temperatures in the rotary kiln and decomposition furnace are maintained within an expected range, and no partial high temperatures or severe temperature fluctuations appear. The combustion process is stable. An average NOx concentration in the decomposition furnace is 325 mg / m3 and an average NOx concentration in the rotary kiln is 890 mg / m3. EXAMPLE 5

[69] Based on the device in Example 1, cement clinker is produced through complete oxygen combustion, so that the cost of CO2 capture is reduced and, meanwhile, the combustion stability of a rotary kiln and a decomposition furnace is improved. The specific steps are as follows:

[70] Step 1), oxygen is transported to a device of Petition 870250022870, dated 03 / 24 / 2025, page 27 / 39 16 / 18 Gas cooling via a first oxygen inlet; the circulating combustion gas is transported to the gas cooling device via a carbon dioxide inlet; and the carbon dioxide and oxygen are mixed in the gas cooling device so as to form the first mixed gas, an O2 concentration in the first mixed gas is 21.7% and the first mixed gas is transported to a secondary duct and a tertiary duct separately via a cooling gas outlet.

[71] Step 2), oxygen is transported to the secondary duct through a second oxygen inlet so as to mix with the first mixed gas in the secondary duct, the second mixed gas is formed, an O2 concentration in the second mixed gas is 37.6% and the second mixed gas is transported to a rotary kiln through a secondary duct port so as to support combustion in a burner; and the combustion gas in the rotary kiln enters a decomposition furnace through a rotary kiln combustion gas outlet.

[72] Step 3), oxygen is transported to the tertiary duct through a third oxygen inlet so as to mix with the first mixed gas, the third mixed gas is formed, an O2 concentration in the third mixed gas is 29.8% and the third mixed gas is transported to the decomposition furnace through a tertiary duct port; and combustion gas and material in the decomposition furnace are emitted from a decomposition furnace discharge port, the material in the decomposition furnace enters the rotary kiln through a rotary kiln feed port, the combustion gas in the decomposition furnace enters a carbon dioxide collection device through an exhaust gas outlet and the carbon dioxide is collected.

[73] Through measurement, in the combustion gas at the waste gas outlet, an O2 concentration of 2.9% and a CO2 concentration of 80.3%. The temperatures in the rotary kiln and decomposition furnace are maintained within an expected range, and no high partial temperatures or severe temperature fluctuations appear. A combustion process is Petition 870250022870, dated 03 / 24 / 2025, pp. 28 / 39 17 / 18 stable. An average NOx concentration in the decomposition furnace is 340 mg / m3 and an average NOx concentration in the rotary kiln is 950 mg / m3. COMPARATIVE EXAMPLE 1

[74] The amount of oxygen added from the second oxygen inlet in Example 2 is increased, and the oxygen ratio of the second mixed gas in Example 2 is increased to 40%. The other steps are the same as in Example 2. As a result, the oxygen concentration in a rotary kiln is excessive, causing a high partial temperature and increasing the NOx concentration. Through measurement, an average NOx concentration in a decomposition furnace is 450 mg / m3, and an average NOx concentration in the rotary kiln is 1090 mg / m3. The increase in nitrogen oxide concentration causes the pressure and cost of denitrification of a denitrification device to be higher. COMPARATIVE EXAMPLE 2

[75] The amount of oxygen added from the third oxygen inlet in Example 2 is increased, and the oxygen ratio of the third mixed gas in Example 2 is increased to 33%. The other steps are the same as in Example 2. As a result, the oxygen concentration in a decomposition furnace is excessive, causing a high partial temperature and increasing the NOx concentration. Through measurement, an average NOx concentration in a decomposition furnace is 530 mg / m3, and an average NOx concentration in the rotary kiln is 950 mg / m3. The increase in nitrogen oxide concentration causes the pressure and cost of denitrification of a denitrification device to be higher.

[76] Through comparison of examples and comparative examples, according to the revelation, a regulation mechanism is provided for an O2 concentration in the rotary kiln and in the decomposition furnace separately, so that an O2 ratio can be precisely controlled and different oxygen concentration requirements in the decomposition furnace and in the rotary kiln can be met. An adequate amount of oxygen addition can effectively prevent the generation of excessive nitrogen oxides and reduce the pressure and cost of Petition 870250022870, dated 03 / 24 / 2025, pp. 29 / 39 18 / 18 denitrification of a denitrification device.

[77] Obviously, the examples are merely examples given for clear illustration and are not intended to limit the modalities. Those skilled in the art may make modifications or variations in other forms based on the above description. There is no need and no way to exhaust all modalities. Obvious modifications or variations derived from the modalities must still be within the scope of disclosure protection. Petition 870250022870, dated 03 / 24 / 2025, pp. 30 / 39

Claims

1 / 4 CLAIMS 1. Device for producing cement clinker through total oxygen combustion, CHARACTERIZED by comprising: a rotary kiln used to produce cement clinker, wherein the rotary kiln comprises a rotary kiln feed port, a rotary kiln discharge port, a rotary kiln flue gas outlet, a burner and a secondary duct port; and the secondary duct port is connected to a secondary duct, the secondary duct is provided with a second oxygen inlet and the second oxygen inlet is used to introduce oxygen into the secondary duct; a decomposition furnace used to preheat a raw material and decompose carbonate in the raw material, wherein the decomposition furnace comprises a raw material inlet, a rotary kiln flue gas inlet, a tertiary duct port and a decomposition furnace outlet;The tertiary duct port is connected to a tertiary duct, and the tertiary duct is provided with a third oxygen inlet, and the third oxygen inlet is used to introduce oxygen into the tertiary duct; the rotary kiln combustion gas inlet is connected to the rotary kiln combustion gas outlet; and the decomposition furnace outlet is connected to the rotary kiln feed port, and the decomposition furnace outlet is further connected to an exhaust gas outlet; a gas cooling device, wherein the gas cooling device is connected to the rotary kiln discharge port; the gas cooling device is used to cool a material outlet from the rotary kiln discharge port; the cooling device comprises a cooling gas inlet and a cooling gas outlet; the cooling gas inlet comprises a first oxygen inlet and a carbon dioxide inlet;and the cooling gas outlet is connected to the secondary and tertiary ducts separately; and a carbon dioxide collection device, wherein the carbon dioxide collection device is connected to the exhaust gas outlet; and the carbon dioxide collection device is used to collect carbon dioxide from the combustion gas outlet.

2. Device for producing cement clinker through complete oxygen combustion, according to claim 1, CHARACTERIZED in that a grate cooler is used as the gas cooling device; and the first oxygen inlet and the carbon dioxide inlet are both located at the bottom of the grate cooler.

3. Device for producing cement clinker through total oxygen combustion, according to claim 1, CHARACTERIZED in that the burner comprises a burner carrier gas inlet, a fuel inlet and a burner outlet; carrier gas containing oxygen and carbon dioxide is transported to the burner by the carrier gas inlet and is mixed with fuel and then burned at the burner outlet; and a volume fraction of oxygen in the carrier gas is 33%-38% and a volume fraction of carbon dioxide is 50%-53%; and gas is supplied from the secondary duct to the burner outlet to support combustion.

4. Device for producing cement clinker through complete oxygen combustion, according to claim 1, CHARACTERIZED in that a carbon dioxide adsorption and distillation device is used as the carbon dioxide collection device; and preferably, the exhaust gas outlet is connected to a circulating combustion gas port and the circulating combustion gas port is connected to the burner and gas cooling device.

5. Device for producing cement clinker through complete oxygen combustion, according to claim 1, CHARACTERIZED in that the third oxygen inlet is provided at one end of the tertiary duct near the gas cooling device; and the second oxygen inlet is provided at one end of the secondary duct near the gas cooling device. Petition 870250022870, dated 03 / 24 / 2025, pp. 32 / 39 3 / 4 6. Device for producing cement clinker through complete oxygen combustion, according to claim 1, CHARACTERIZED by further comprising an oxygen preparation device, wherein the first oxygen inlet, the second oxygen inlet and the third oxygen inlet are all connected to the oxygen preparation device.

7. Method for producing cement clinker by complete oxygen combustion, CHARACTERIZED in that the production is conducted with the device for producing cement clinker by complete oxygen combustion, as defined in any one of claims 1 to 5, and the method comprises the following steps: step 1), transporting oxygen to a gas cooling device through a first oxygen inlet; transporting carbon dioxide to the gas cooling device through a carbon dioxide inlet; and mixing the carbon dioxide and oxygen in the gas cooling device so as to form the first mixed gas and transporting the first mixed gas to a secondary duct and a tertiary duct separately through a cooling gas outlet;Step 2) Transport oxygen to the secondary duct through a second oxygen inlet so as to mix with the first mixed gas in the secondary duct, form the second mixed gas, and transport the second mixed gas to a rotary kiln through a secondary duct port so as to support combustion in a burner; and allow the combustion gas in the rotary kiln to enter a decomposition furnace through a rotary kiln combustion gas outlet; and Step 3) Transport oxygen to the tertiary duct through a third oxygen inlet so as to mix with the first mixed gas, form the third mixed gas, and transport the third mixed gas to the decomposition furnace through a tertiary duct port;and to emit combustion gas and material in the decomposition furnace from a decomposition furnace discharge port, allowing the material in the decomposition furnace to enter the rotary kiln through a feed port of Petition 870250022870, dated 03 / 24 / 2025, page 33 / 39 4 / 4 rotary kiln, allowing the combustion gas in the decomposition furnace to enter a carbon dioxide collection device through an exhaust gas outlet and collect carbon dioxide.; 8. Method according to claim 7, characterized in that the volume fraction of oxygen in the first gas mixture is 18%-22%.

9. Method according to claim 7, characterized in that the volume fraction of oxygen in the second gas mixture is 33%-38%.

10. Method according to claim 7, CHARACTERIZED in that the volume fraction of oxygen in the third gas mixture is 25%-30%. Petition 870250022870, dated 03 / 24 / 2025, pp. 34 / 39

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