Oxy-fuel combustion cement clinker production device and method

Abstract

The invention provides a full-oxygen combustion cement clinker production device which comprises a rotary kiln, a decomposing furnace, an air cooling device and a carbon dioxide collecting device. Wherein the rotary kiln secondary tuyere is connected with a secondary air pipe, and a second oxygen inlet is formed in the secondary air pipe; the decomposing furnace is connected with a tertiary air pipe through the tertiary air port, and a third oxygen inlet is formed in the tertiary air pipe; a cooling gas inlet of the gas cooling device comprises a first oxygen inlet and a carbon dioxide inlet, and a cooling gas outlet of the gas cooling device is connected with the secondary air pipe and the tertiary air pipe. O2 and circulating CO2 flue gas are reasonably matched in the rotary kiln and the decomposing furnace, so that heat recovery is realized, the combustion conditions in the rotary kiln and the decomposing furnace are optimized, and the carbon capture cost of cement production is effectively reduced. The finally obtained flue gas containing high-concentration CO2 after combustion can be collected and adsorbed by adopting an adsorption rectification process, the operation cost of adsorption rectification can be reduced by 47%, and the investment cost can be reduced by 35%.

Description

Technical Field

[0001] The invention relates to the technical field of building materials, and in particular to a device and method for producing cement clinker by full oxygen combustion. Background Art

[0002] The cement industry is the world's third largest source of CO2 emissions. Its CO2 emissions mainly come from the large consumption of energy and resources used in cement production. In China, the cement industry's CO2 emissions are second only to the power industry and the steel industry. It is crucial to apply green and low-carbon technologies in the cement industry and promote net zero carbon emissions.

[0003] The cement industry usually uses air to assist combustion, resulting in a low CO2 concentration in flue gas (20-30%), so solvent absorption has to be used to capture CO2, which has a high operating cost. If high-purity oxygen is used instead of combustion air, and flue gas circulation is used to adjust the medium flow and heat transfer characteristics of the furnace, a high-concentration CO2 flue gas can be obtained, and CO2 can be captured by adsorption distillation. Compared with solvent absorption, the operating cost of adsorption distillation can be reduced by 47% and the investment cost can be reduced by 35%. Therefore, as a highly potential CO2 capture technology approach, the advantage of oxyfuel combustion technology is that it can produce a high-concentration CO2 flow, making CO2 capture more efficient and economical.

[0004] In the prior art, when the fuel burns under high CO2 concentration, the flame temperature is lower than the flame temperature of air combustion, and the combustion speed is slow. As the O2 concentration increases, the flame temperature rises rapidly, but too high an O2 concentration will cause the combustion flame temperature to be too high, and there is a risk of deflagration. In addition, due to the unreasonable O2 injection position, the mixing of O2 and fuel is uneven, forming local high temperature and low temperature areas, affecting the efficiency and stability of the combustion reaction. Improper O2 injection amount and position are one of the main problems facing the existing full oxygen combustion technology.

[0005] Therefore, the existing full oxygen combustion technology still has some deficiencies in the injection position and injection ratio of O2, which leads to an unstable combustion process and makes it difficult to give full play to the advantages of full oxygen combustion. In order to overcome the above problems, the present invention proposes a method for injecting oxygen in full oxygen combustion, which improves combustion stability while reducing carbon capture costs by optimizing the injection position of O2 and adjusting the mixing ratio of O2 and high CO2 flue gas. Summary of the invention

[0006] The present invention aims to solve the problem of high cost and low efficiency of carbon capture in cement production process by proposing a cement clinker production device and method by full oxygen combustion. The present invention is realized by adopting the following technical scheme:

[0007] A cement clinker production device using full oxygen combustion, comprising:

[0008] A rotary kiln for producing cement clinker; the rotary kiln comprises a rotary kiln feed port, a rotary kiln discharge port, a rotary kiln smoke outlet, a burner and a secondary air port; the secondary air port is connected to a secondary air duct, the secondary air duct is provided with a second oxygen inlet, and the second oxygen inlet is used to introduce oxygen into the secondary air duct;

[0009] A decomposition furnace is used to preheat raw materials and decompose carbonates in the raw materials; the decomposition furnace comprises a raw material inlet, a rotary kiln smoke inlet, a tertiary air port and a decomposition furnace outlet; the tertiary air port is connected to a tertiary air duct, and the tertiary air duct is provided with a third oxygen inlet, and the third oxygen inlet is used to introduce oxygen into the tertiary air duct; the rotary kiln smoke inlet is connected to the rotary kiln smoke outlet; the decomposition furnace outlet is connected to the rotary kiln feed port, and the decomposition furnace outlet is also connected to an exhaust gas outlet;

[0010] An air cooling device is connected to the rotary kiln discharge port; the air cooling device is used to cool the material output from the rotary kiln discharge port; 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; the cooling gas outlet is respectively connected to the secondary air duct and the tertiary air duct;

[0011] A carbon dioxide collecting device is connected to the tail gas outlet; the carbon dioxide collecting device is used to collect carbon dioxide in the flue gas output from the tail gas outlet.

[0012] Optionally, the air cooling device adopts a grate cooler;

[0013] The first oxygen inlet and the carbon dioxide inlet are both located at the bottom of the grate cooler.

[0014] Optionally, the burner includes a burner carrier gas inlet, a fuel inlet and a burner outlet; the carrier gas inlet delivers a carrier gas containing oxygen and carbon dioxide into the burner and mixes with the fuel and then burns at the burner outlet; the volume fraction of oxygen in the carrier gas is 33-38%, and the volume fraction of carbon dioxide is 50-53%;

[0015] The secondary air duct supplies air to the burner outlet to assist combustion.

[0016] Optionally, the carbon dioxide collection device adopts a carbon dioxide adsorption distillation device.

[0017] Optionally, the tail gas outlet is connected to a circulating flue gas outlet, and the circulating flue gas outlet is connected to the burner and the air cooling device. The carbon dioxide inlet in the air cooling device uses the flue gas sent from the circulating flue gas outlet, and the carbon dioxide content is about 80%. In the burner, oxygen and the flue gas sent from the circulating flue gas outlet are mixed and burned as a carrier gas mixed with fuel.

[0018] Optionally, the third oxygen inlet is arranged on one end of the tertiary air duct close to the air cooling device;

[0019] The second oxygen air inlet is arranged on one end of the secondary air duct close to the air cooling device.

[0020] Optionally, the oxy-fuel combustion cement clinker production device further includes an oxygen preparation device, and the first oxygen inlet, the second oxygen inlet and the third oxygen inlet are all connected to the oxygen preparation device.

[0021] A method for producing cement clinker by oxyfuel combustion, using the above-mentioned cement clinker production device by oxyfuel combustion for production, comprises the following steps:

[0022] Step 1) oxygen is fed into the air cooling device through a first oxygen inlet; carbon dioxide is fed into the air cooling device through a carbon dioxide inlet; carbon dioxide and oxygen are mixed in the air cooling device to form a first mixed gas, and the first mixed gas is respectively fed to the secondary air duct and the tertiary air duct through a cooling gas outlet;

[0023] Step 2) oxygen is sent into the secondary air duct through the second oxygen inlet to mix with the first mixed gas in the secondary air duct to form a second mixed gas, and the second mixed gas is sent into the rotary kiln through the secondary air port to assist the burner; the flue gas in the rotary kiln enters the decomposition furnace through the rotary kiln flue gas outlet;

[0024] Step three) oxygen is sent into the tertiary air duct through the third oxygen inlet to mix with the first mixed gas to form a third mixed gas, and the third mixed gas is sent into the decomposition furnace from the tertiary air port; the flue gas and materials in the decomposition furnace are output from the decomposition furnace discharge port, the materials in the decomposition furnace enter the rotary kiln through the rotary kiln feed port, and the flue gas in the decomposition furnace enters the carbon dioxide collection device through the tail gas outlet to collect the carbon dioxide.

[0025] Optionally, the volume fraction of oxygen in the first mixed gas is 18-22%.

[0026] Optionally, the volume fraction of oxygen in the second mixed gas is 33-38%.

[0027] Optionally, the volume fraction of oxygen in the third mixed gas is 25-30%.

[0028] The fuels mentioned above are all coal.

[0029] The present invention has the following beneficial effects:

[0030] In the present invention, O2 and circulating CO2 flue gas are reasonably matched in the rotary kiln and the decomposition furnace, which not only realizes heat recovery, but also optimizes the combustion conditions in the rotary kiln and the decomposition furnace, and effectively reduces the carbon capture cost of cement production. The final flue gas obtained after combustion contains a high concentration of CO2, which can be collected and absorbed by the adsorption distillation process, and the operating cost of the adsorption distillation can be reduced by 47%, and the investment cost can be reduced by 35%.

[0031] The invention performs oxygen-enriched injection in the air cooling device to enable O2 to be fully mixed with the high-CO2 flue gas before the combustion reaction, thereby avoiding high local O2 concentration and high local temperature, and improving the stability of the combustion process.

[0032] The present invention provides a control mechanism for the O2 concentration in the rotary kiln and the decomposition furnace, respectively, and can accurately control the O2 ratio to meet different oxygen concentration requirements in the decomposition furnace and the rotary kiln. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0034] Figure 1 It is a schematic diagram of the structure of the device of the present invention;

[0035] Figure 2 It is a schematic diagram of the burner structure in a rotary kiln;

[0036] Figure 3 It is a schematic diagram of an air cooling device. DETAILED DESCRIPTION

[0037] Now, various exemplary embodiments of the present invention are described in detail, and this detailed description should not be considered as a limitation of the present invention, but should be understood as a more detailed description of certain aspects, characteristics and embodiments of the present invention. It should be understood that the terms described in the present invention are only for describing specific embodiments and are not used to limit the present invention.

[0038] In addition, for the numerical range in the present invention, it is understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. The intermediate value in any stated value or stated range, and each smaller range between any other stated value or intermediate value in the range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0039] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the invention pertains. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of the present invention.

[0040] The terms "include", "comprising", "having", "containing", etc. used herein are all open-ended terms, which mean including but not limited to. The gas concentrations mentioned in the following embodiments are all measured by volume fraction.

[0041] Example 1

[0042] like Figures 1 to 3 The cement clinker production device shown in the figure uses full oxygen combustion, and comprises: a rotary kiln 1, a decomposition furnace 2, an air cooling device 3, and a carbon dioxide collecting device 4.

[0043] A 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 smoke outlet 13, a burner 14 and a secondary air port 15; the secondary air port 15 is connected to a secondary air duct 151, and a second oxygen air inlet 152 is provided on the secondary air duct 151, and the second oxygen air inlet is arranged on one end of the secondary air duct close to the air cooling device. The burner 14 is used to heat the rotary kiln, and the burner 14 includes a burner carrier gas inlet 141, a fuel inlet 142 and a burner outlet 143. The secondary air duct 15 supplies air to the burner outlet 143 to assist combustion. The carrier gas inlet 141 supplies carrier gas containing oxygen and carbon dioxide into the burner to mix with the fuel and then burn at the burner outlet.

[0044] The decomposition furnace 2 is used to preheat the raw material and decompose the carbonate in the raw material; the decomposition furnace comprises a raw material inlet (not shown in the figure), a rotary kiln smoke inlet 21, a tertiary air port 22 and a decomposition furnace outlet 23. During operation, a mixed raw material comprising raw material and fuel is added from the raw material inlet, burned in the decomposition furnace, preheated and decomposed the carbonate in the raw material. The tertiary air port 22 is connected to a tertiary air duct 221, and a third oxygen air inlet 222 is provided on the tertiary air duct 221. The third oxygen air inlet 222 is arranged on one end of the tertiary air duct near the air cooling device. The rotary kiln smoke inlet 21 is connected to the rotary kiln smoke outlet 13, so that the smoke in the rotary kiln can enter the decomposition furnace from the rotary kiln smoke inlet 21. The decomposition furnace outlet 23 is connected to the rotary kiln feed port, and the decomposition furnace outlet 23 is also connected to an exhaust gas outlet 231; the exhaust gas outlet 231 is connected to the carbon dioxide collection device 4. The tail gas outlet 231 is connected to a circulating flue gas outlet 232, which is connected to the burner 14 and the air cooling device 3, and is used to deliver the required carbon dioxide to the burner and the air cooling device. In the carrier gas formed by mixing oxygen and the circulating flue gas, the volume fraction of oxygen is 33-38%, and the volume fraction of carbon dioxide is 50-53%.

[0045] The air cooling device 3 adopts a grate cooler, and the air cooling device 3 is connected to the rotary kiln discharge port 12, and is used to cool the material output 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 respectively connected to the secondary air duct 151 and the tertiary air duct 221;

[0046] The carbon dioxide collecting device 4 adopts a carbon dioxide adsorption distillation device, and the carbon dioxide collecting device is connected to the tail gas outlet; the carbon dioxide collecting device 4 is used to collect carbon dioxide in the flue gas output from the tail gas outlet.

[0047] The fuels mentioned above are all coal.

[0048] The implementation process of the present invention is as follows: A method for producing cement clinker by oxyfuel combustion, using the above-mentioned cement clinker production device by oxyfuel combustion for production, comprises the following steps:

[0049] Step 1) oxygen is fed into the air cooling device through a first oxygen inlet; circulating flue gas is fed into the air cooling device through a carbon dioxide inlet; carbon dioxide and oxygen are mixed in the air cooling device to form a first mixed gas, and the first mixed gas is respectively fed to the secondary air duct and the tertiary air duct through a cooling gas outlet;

[0050] Step 2) oxygen is sent into the secondary air duct through the second oxygen inlet to mix with the first mixed gas in the secondary air duct to form a second mixed gas, and the second mixed gas is sent into the rotary kiln through the secondary air port to assist the burner; the flue gas in the rotary kiln enters the decomposition furnace through the rotary kiln flue gas outlet;

[0051] Step three) oxygen is sent into the tertiary air duct through the third oxygen inlet to mix with the first mixed gas to form a third mixed gas, and the third mixed gas is sent into the decomposition furnace from the tertiary air port; the flue gas and materials in the decomposition furnace are output from the decomposition furnace discharge port, the materials in the decomposition furnace enter the rotary kiln through the rotary kiln feed port, and the flue gas in the decomposition furnace enters the carbon dioxide collection device through the tail gas outlet to collect the carbon dioxide.

[0052] The volume fraction of oxygen in the first mixed gas is 18-22%, the volume fraction of oxygen in the second mixed gas is 33-38%, and the volume fraction of oxygen in the third mixed gas is 25-30%.

[0053] The above device can make the concentration of carbon dioxide in the flue gas sent to the carbon dioxide collection device reach about 80%. Due to its high concentration, the adsorption distillation method can be used to recover carbon dioxide. The CO2 concentration of flue gas in the prior art is 20-30%. Generally, a solvent absorption method is used to capture CO2. This method is suitable for recovering carbon dioxide from low-concentration carbon dioxide flue gas. The process is complex and the investment and operating costs are high. Adsorption distillation uses the boiling point of carbon dioxide to separate from other gases. The heavy components with higher boiling points than carbon dioxide are removed by different adsorbents, and the light components are extracted by distillation. Finally, the remaining carbon dioxide has a purity of more than 99.99%. According to calculations, the use of adsorption distillation equipment instead of solvent absorption equipment for carbon dioxide recovery can reduce operating costs by 45.7% and investment costs by 36.4%.

[0054] The invention performs oxygen-enriched injection in the air cooling device to fully mix O2 with high CO2 flue gas before the combustion reaction, thereby avoiding high local O2 concentration and high local temperature, and improving the stability of the combustion process. If the oxygen and flue gas are not mixed in advance in the air cooling device, the oxygen is mixed with the flue gas in the secondary and tertiary air ducts, which will cause uneven mixing, high local oxygen concentration, high temperature, and is not conducive to fuel burnout.

[0055] Embodiment 2:

[0056] Based on the device in Example 1, full oxygen combustion cement clinker production is implemented to reduce the cost of CO2 capture and improve the combustion stability of the rotary kiln and the decomposition furnace. The specific steps are as follows:

[0057] Step 1) oxygen is fed into the air cooling device through the first oxygen inlet; circulating flue gas is fed into the air cooling device through the carbon dioxide inlet; carbon dioxide and oxygen are mixed in the air cooling device to form a first mixed gas, the O2 concentration in the first mixed gas is 21.2%, and the first mixed gas is divided into two paths through the cooling gas outlet and respectively fed to the secondary air duct and the tertiary air duct;

[0058] Step 2) oxygen is sent into the secondary air duct through the second oxygen inlet to mix with the first mixed gas in the secondary air duct to form a second mixed gas, the O2 concentration in the second mixed gas is 35.4%, and the second mixed gas is sent into the rotary kiln through the secondary air port to assist the burner; the flue gas in the rotary kiln enters the decomposition furnace through the rotary kiln flue gas outlet;

[0059] Step three) oxygen is sent into the tertiary air duct through the third oxygen inlet to be mixed with the first mixed gas to form a third mixed gas, the O2 concentration in the third mixed gas is 27.0%, and the third mixed gas is sent into the decomposition furnace from the tertiary air port; the flue gas and materials in the decomposition furnace are output from the decomposition furnace discharge port, the materials in the decomposition furnace enter the rotary kiln through the rotary kiln feed port, and the flue gas in the decomposition furnace enters the carbon dioxide collection device through the tail gas outlet to collect the carbon dioxide.

[0060] After testing, in the flue gas at the tail gas outlet, the O2 concentration was 2.8%, the CO2 concentration was 78.4%, the temperature in the rotary kiln and the decomposition furnace remained within the expected range, there was no local high temperature and drastic temperature fluctuation, the combustion process was stable, and the average NOx concentration inside the decomposition furnace was 330mg / m 3 The average NOx concentration inside the rotary kiln is 900 mg / m 3 .

[0061] Embodiment 3:

[0062] Based on the structure of Example 1, a cement production line was transformed into full oxygen combustion, with the aim of reducing the cost of CO2 capture and improving the combustion stability of the rotary kiln and the decomposition furnace. The specific steps are as follows:

[0063] Step 1) oxygen is fed into the air cooling device through the first oxygen inlet; circulating flue gas is fed into the air cooling device through the carbon dioxide inlet; carbon dioxide and oxygen are mixed in the air cooling device to form a first mixed gas, the O2 concentration in the first mixed gas is 19.6%, and the first mixed gas is divided into two paths through the cooling gas outlet and respectively fed to the secondary air duct and the tertiary air duct;

[0064] Step 2) oxygen is sent into the secondary air duct through the second oxygen inlet to mix with the first mixed gas in the secondary air duct to form a second mixed gas, the O2 concentration in the second mixed gas is 33.7%, and the second mixed gas is sent into the rotary kiln through the secondary air port to assist the burner; the flue gas in the rotary kiln enters the decomposition furnace through the rotary kiln flue gas outlet;

[0065] Step three) oxygen is sent into the tertiary air duct through the third oxygen inlet to mix with the first mixed gas to form a third mixed gas, the O2 concentration in the third mixed gas is 25.2%, and the third mixed gas is sent into the decomposition furnace from the tertiary air port; the flue gas and materials in the decomposition furnace are output from the decomposition furnace discharge port, the materials in the decomposition furnace enter the rotary kiln through the rotary kiln feed port, and the flue gas in the decomposition furnace enters the carbon dioxide collection device through the tail gas outlet to collect the carbon dioxide.

[0066] After testing, in the flue gas at the tail gas outlet, the O2 concentration was 2.4%, the CO2 concentration was 80.5%, the temperature in the rotary kiln and the decomposition furnace remained within the expected range, there was no local high temperature and drastic temperature fluctuation, the combustion process was stable, and the average NOx concentration inside the decomposition furnace was 320mg / m 3 The average NOx concentration inside the rotary kiln is 940 mg / m 3 .

[0067] Example 4

[0068] Based on the device in Example 1, full oxygen combustion cement clinker production is implemented to reduce the cost of CO2 capture and improve the combustion stability of the rotary kiln and the decomposition furnace. The specific steps are as follows:

[0069] Step 1) oxygen is fed into the air cooling device through the first oxygen inlet; circulating flue gas is fed into the air cooling device through the carbon dioxide inlet; carbon dioxide and oxygen are mixed in the air cooling device to form a first mixed gas, the O2 concentration in the first mixed gas is 18.2%, and the first mixed gas is divided into two paths through the cooling gas outlet and respectively fed to the secondary air duct and the tertiary air duct;

[0070] Step 2) oxygen is sent into the secondary air duct through the second oxygen inlet to mix with the first mixed gas in the secondary air duct to form a second mixed gas, the O2 concentration in the second mixed gas is 33.5%, and the second mixed gas is sent into the rotary kiln through the secondary air port to assist the burner; the flue gas in the rotary kiln enters the decomposition furnace through the rotary kiln flue gas outlet;

[0071] Step three) oxygen is sent into the tertiary air duct through the third oxygen inlet to mix with the first mixed gas to form a third mixed gas, the O2 concentration in the third mixed gas is 25.1%, and the third mixed gas is sent into the decomposition furnace from the tertiary air port; the flue gas and materials in the decomposition furnace are output from the decomposition furnace discharge port, the materials in the decomposition furnace enter the rotary kiln through the rotary kiln feed port, and the flue gas in the decomposition furnace enters the carbon dioxide collection device through the tail gas outlet to collect the carbon dioxide.

[0072] After testing, in the flue gas at the tail gas outlet, the O2 concentration was 2.3%, the CO2 concentration was 79.1%, the temperature in the rotary kiln and the decomposition furnace was kept within the expected range, there was no local high temperature and drastic temperature fluctuation, the combustion process was stable, and the average NOx concentration inside the decomposition furnace was 325mg / m 3 The average NOx concentration inside the rotary kiln is 890 mg / m 3 .

[0073] Example 5

[0074] Based on the device in Example 1, full oxygen combustion cement clinker production is implemented to reduce the cost of CO2 capture and improve the combustion stability of the rotary kiln and the decomposition furnace. The specific steps are as follows:

[0075] Step 1) oxygen is fed into the air cooling device through the first oxygen inlet; circulating flue gas is fed into the air cooling device through the carbon dioxide inlet; carbon dioxide and oxygen are mixed in the air cooling device to form a first mixed gas, the O2 concentration in the first mixed gas is 21.7%, and the first mixed gas is divided into two paths through the cooling gas outlet and respectively fed to the secondary air duct and the tertiary air duct;

[0076] Step 2) oxygen is sent into the secondary air duct through the second oxygen inlet to mix with the first mixed gas in the secondary air duct to form a second mixed gas, the O2 concentration in the second mixed gas is 37.6%, and the second mixed gas is sent into the rotary kiln through the secondary air port to assist the burner; the flue gas in the rotary kiln enters the decomposition furnace through the rotary kiln flue gas outlet;

[0077] Step three) oxygen is sent into the tertiary air duct through the third oxygen inlet to mix with the first mixed gas to form a third mixed gas, the O2 concentration in the third mixed gas is 29.8%, and the third mixed gas is sent into the decomposition furnace from the tertiary air port; the flue gas and materials in the decomposition furnace are output from the decomposition furnace discharge port, the materials in the decomposition furnace enter the rotary kiln through the rotary kiln feed port, and the flue gas in the decomposition furnace enters the carbon dioxide collection device through the tail gas outlet to collect the carbon dioxide.

[0078] After testing, in the flue gas at the tail gas outlet, the O2 concentration was 2.9%, the CO2 concentration was 80.3%, the temperature in the rotary kiln and the decomposition furnace remained within the expected range, there was no local high temperature and drastic temperature fluctuation, the combustion process was stable, and the average NOx concentration inside the decomposition furnace was 340mg / m 3 The average NOx concentration inside the rotary kiln is 950 mg / m 3 .

[0079] Comparative Example 1

[0080] In Example 2, the amount of oxygen added to the second oxygen inlet was increased, and the oxygen ratio of the second mixed gas was increased to 40%. The remaining steps were the same as in Example 2. As a result, the oxygen concentration of the rotary kiln was too high, and local high temperature would occur, increasing the NOx concentration. The average NOx concentration inside the decomposition furnace was 450 mg / m 3 The average NOx concentration inside the rotary kiln is 1090 mg / m 3 The increase in nitrogen oxide concentration increases the pressure and cost of denitrification equipment.

[0081] Comparative Example 2

[0082] In Example 2, the amount of oxygen added to the third oxygen inlet was increased, and the oxygen ratio of the third mixed gas was increased to 33%. The remaining steps were the same as in Example 2. As a result, the oxygen concentration in the decomposition furnace was too high, and local high temperature would occur, increasing the NOx concentration. The average NOx concentration inside the decomposition furnace was 530 mg / m 3 The average NOx concentration inside the rotary kiln is 950 mg / m 3 The increase in nitrogen oxide concentration increases the pressure on the denitrification unit and the denitrification cost.

[0083] According to the comparison between the embodiment and the comparative example, the present invention provides a control mechanism for the O2 concentration in the rotary kiln and the decomposition furnace, respectively, which can accurately control the O2 ratio to meet the different oxygen concentration requirements in the decomposition furnace and the rotary kiln. The use of an appropriate amount of oxygen addition can effectively prevent the generation of excessive nitrogen oxides, and can reduce the pressure and denitrification cost of the denitrification device.

[0084] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the invention.

Claims

1. A cement clinker production device using full oxygen combustion, characterized in that: include: A rotary kiln for producing cement clinker; the rotary kiln comprises a rotary kiln feed port, a rotary kiln discharge port, a rotary kiln smoke outlet, a burner and a secondary air port; the secondary air port is connected to a secondary air duct, the secondary air duct is provided with a second oxygen inlet, and the second oxygen inlet is used to introduce oxygen into the secondary air duct; A decomposition furnace is used to preheat raw materials and decompose carbonates in the raw materials; the decomposition furnace comprises a raw material inlet, a rotary kiln smoke inlet, a tertiary air port and a decomposition furnace outlet; the tertiary air port is connected to a tertiary air duct, and the tertiary air duct is provided with a third oxygen inlet, and the third oxygen inlet is used to introduce oxygen into the tertiary air duct; the rotary kiln smoke inlet is connected to the rotary kiln smoke outlet; the decomposition furnace outlet is connected to the rotary kiln feed port, and the decomposition furnace outlet is also connected to an exhaust gas outlet; An air cooling device is connected to the rotary kiln discharge port; the air cooling device is used to cool the material output from the rotary kiln discharge port; 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; the cooling gas outlet is respectively connected to the secondary air duct and the tertiary air duct; A carbon dioxide collecting device is connected to the tail gas outlet; the carbon dioxide collecting device is used to collect carbon dioxide in the flue gas output from the tail gas outlet.

2. The oxyfuel combustion cement clinker production device according to claim 1, characterized in that: The air cooling device adopts a grate cooler; The first oxygen inlet and the carbon dioxide inlet are both located at the bottom of the grate cooler.

3. The oxyfuel combustion cement clinker production device according to claim 1, characterized in that: The burner comprises a burner carrier gas inlet, a fuel inlet and a burner outlet; the carrier gas inlet delivers a carrier gas containing oxygen and carbon dioxide into the burner and mixes with the fuel, and then burns at the burner outlet; the volume fraction of oxygen in the carrier gas is 33-38%, and the volume fraction of carbon dioxide is 50-53%; The secondary air duct supplies air to the burner outlet to assist combustion.

4. The oxyfuel combustion cement clinker production device according to claim 1, characterized in that: The carbon dioxide collection device adopts a carbon dioxide adsorption distillation device; Preferably, the tail gas outlet is connected to a circulating flue gas outlet, and the circulating flue gas outlet is connected to a burner and an air cooling device.

5. The oxyfuel combustion cement clinker production device according to claim 1, characterized in that: The third oxygen inlet is arranged on one end of the tertiary air duct close to the air cooling device; The second oxygen air inlet is arranged on one end of the secondary air duct close to the air cooling device.

6. The oxyfuel combustion cement clinker production device according to claim 1, characterized in that: The oxy-fuel combustion cement clinker production device further comprises an oxygen preparation device, and the first oxygen inlet, the second oxygen inlet and the third oxygen inlet are all connected to the oxygen preparation device.

7. A method for producing cement clinker by oxyfuel combustion, characterized in that: The production of cement clinker using the oxyfuel combustion device according to any one of claims 1 to 5 comprises the following steps: Step 1) oxygen is fed into the air cooling device through a first oxygen inlet; carbon dioxide is fed into the air cooling device through a carbon dioxide inlet; carbon dioxide and oxygen are mixed in the air cooling device to form a first mixed gas, and the first mixed gas is respectively fed to the secondary air duct and the tertiary air duct through a cooling gas outlet; Step 2) oxygen is sent into the secondary air duct through the second oxygen inlet to mix with the first mixed gas in the secondary air duct to form a second mixed gas, and the second mixed gas is sent into the rotary kiln through the secondary air port to assist the burner; the flue gas in the rotary kiln enters the decomposition furnace through the rotary kiln flue gas outlet; Step three) oxygen is sent into the tertiary air duct through the third oxygen inlet to mix with the first mixed gas to form a third mixed gas, and the third mixed gas is sent into the decomposition furnace from the tertiary air port; the flue gas and materials in the decomposition furnace are output from the decomposition furnace discharge port, the materials in the decomposition furnace enter the rotary kiln through the rotary kiln feed port, and the flue gas in the decomposition furnace enters the carbon dioxide collection device through the tail gas outlet to collect the carbon dioxide.

8. The method according to claim 7, characterized in that The volume fraction of oxygen in the first mixed gas is 18-22%.

9. The method according to claim 7, characterized in that: The volume fraction of oxygen in the second mixed gas is 33-38%.

10. The method according to claim 7, characterized in that The volume fraction of oxygen in the third mixed gas is 25-30%.

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