Cement clinker preparation system

Abstract

The present invention provides a cement clinker preparation system, which comprises: a decomposing furnace configured to be a fluidized bed structure, the bottom of the decomposing furnace being provided with a plurality of fluidization air caps, the fluidization air caps being suitable for supplying primary air into a hearth of the decomposing furnace so as to pyrolyze a raw material passing through the decomposing furnace into a solid-phase decomposer and circulating flue gas enriched with carbon dioxide; the separator is communicated with the discharging end of the decomposing furnace and is suitable for separating solid-phase decomposers from circulating flue gas enriched with carbon dioxide; the material returning device is communicated with the solid phase output end of the separator and is provided with at least two material returning channels, and at least one material returning channel is communicated with the decomposing furnace, so that a part of solid phase decomposed products are returned to the decomposing furnace to be subjected to secondary pyrolysis; the rotary kiln is communicated with the other material returning channel of the material returning device and is suitable for firing the other part of the solid-phase decomposer entering the rotary kiln into the clinker; wherein the oxygen content of the primary air inlet of the decomposing furnace is configured to be greater than or equal to 75%.

Description

Technical Field

[0001] At least one embodiment of the present disclosure relates to the technical field of cement production, and more specifically, to a cement clinker preparation system. Background Art

[0002] In the industry, cement is mainly prepared by a dry production process, that is, particles such as limestone, clay, and iron ore are crushed and mixed to form raw meal, and then the clinker is prepared by high-temperature calcination and ground into powder. After being mixed with additives such as gypsum, cement is made.

[0003] The dry production process is characterized by high energy consumption and large carbon emissions. Among them, during the cement preparation process, the carbon dioxide generated by the decomposition furnace accounts for more than 80% of the total carbon dioxide emissions of the entire process. Therefore, how to capture the carbon dioxide generated by the decomposition furnace is the key to reducing the carbon emissions during the cement preparation process. On this basis, the local oxy-fuel combustion technology of the decomposition furnace (even if the rotary kiln in the system still operates in a normal air atmosphere, while the decomposition furnace operates in an oxygen and carbon dioxide atmosphere) has become the main research direction. The main advantage of this technology is that the mechanisms such as the rotary kiln, burner, grate cooler, and raw meal mill in the system can still maintain the existing structure without modification; and, 60%-75% of the total carbon dioxide generated by the decomposition furnace can be captured.

[0004] Currently, in the cement clinker preparation system based on the oxy-fuel combustion technology, the negative pressure environment of the system is generally configured by a circulation fan, so that the circulating flue gas generated in the decomposition furnace is evacuated and circulated between the raw meal preheating device, the oxygen production device, and the decomposition furnace. In this way, the oxygen content in the decomposition furnace can be maintained at 30%-40%, thus effectively preventing the local high temperature caused by the rapid combustion of solid fuel (such as pulverized coal) due to the excessive oxygen content at the inlet of the decomposition furnace.

[0005] In order to maintain the oxygen content in the precalciner at the above volume ratio, it is necessary to circulate the recycled flue gas in an amount 1.5 - 2.3 times the oxygen consumption for combustion in the precalciner. A large amount of recycled flue gas circulating in the negative pressure environment of the system will inevitably lead to air leakage, especially a large amount of air will leak into the inlet side of the circulation fan. The leaked air will introduce more nitrogen, resulting in a decrease in the carbon dioxide concentration at the outlet of the precalciner, increasing the difficulty of carbon dioxide capture and purification cost. Moreover, after the recycled flue gas leaves the precalciner, it is necessary to cool the recycled flue gas to remove most of the moisture in the recycled flue gas, and then the recycled flue gas is reheated again after returning to the precalciner, so the heat loss of the system is also increased. At the same time, in order to realize the circulation of the recycled flue gas in each device, corresponding pipelines, valves, detection mechanisms (such as flow detection mechanisms, pressure detection mechanisms, etc.) and circulation fans also need to be configured, which also increases the complexity of the system.

[0006] Therefore, how to provide a cement clinker preparation system that reduces the recycled flue gas and increases the oxygen concentration in the precalciner has become an urgent technical problem to be solved. Summary of the Invention

[0007] To solve at least one of the above and other technical problems in the prior art, the present disclosure provides a cement clinker preparation system. The fluidizing air caps configured in a fluidized bed structure are suitable for uniformly and adjustably supplying the primary air into the precalciner to reduce the flow rate of the gas in the precalciner and improve the mixing effect of the fuel and raw materials in the precalciner. Through the circulation of the solid phase decomposition products, the uniformity of the temperature distribution in the precalciner is improved, avoiding the occurrence of local high temperature, which is beneficial to increasing the oxygen content at the primary air inlet, reducing the air leakage of the recycled flue gas, thereby increasing the carbon dioxide concentration at the outlet of the precalciner and facilitating the capture of carbon dioxide. For this reason, it is not necessary to form a large-flow circulation of the recycled flue gas between the precalciner and other devices, and the system heat consumption can also be reduced.

[0008] Embodiments of the present disclosure provide a cement clinker preparation system, including: a decomposition furnace configured as a fluidized bed structure, with a plurality of fluidizing air caps provided at the bottom of the decomposition furnace, suitable for supplying primary air into the furnace chamber of the decomposition furnace to fluidize the solid fuel and raw meal in the decomposition furnace, and enabling the solid fuel to burn in an oxygen atmosphere and a carbon dioxide atmosphere, so that the raw meal passing through the decomposition furnace is pyrolyzed into solid-phase decomposition products and circulating flue gas enriched with carbon dioxide; a separator communicating with the discharge end of the decomposition furnace, suitable for separating the solid-phase decomposition products and the circulating flue gas enriched with carbon dioxide; a return feeder communicating with the solid-phase output end of the separator and provided with at least two return channels, at least one of the return channels communicating with the decomposition furnace to enable a part of the solid-phase decomposition products to return to the decomposition furnace for secondary pyrolysis; and a rotary kiln communicating with the other return channel of the return feeder, suitable for firing the other part of the solid-phase decomposition products entering the rotary kiln into clinker; wherein the primary air includes pressurized oxygen or oxygen and a part of the circulating flue gas, so that the oxygen content at the primary air inlet of the decomposition furnace is configured to be greater than or equal to 75%.

[0009] According to an embodiment of the present disclosure, a material distribution mechanism is provided in the return feeder, suitable for adjusting the proportion of the solid-phase decomposition products entering different return channels.

[0010] According to an embodiment of the present disclosure, a wind locking mechanism is provided in the return channel of the return feeder communicating with the decomposition furnace, suitable for restricting the circulating flue gas from entering the return feeder.

[0011] According to an embodiment of the present disclosure, the cement clinker preparation system further includes a booster fan, the intake side of the booster fan communicating with the supply side of the oxygen and the circulating flue gas, and the proportion of the oxygen and the circulating flue gas supplied to the booster fan being adjustable, and the outlet side of the booster fan communicating with the fluidizing air caps.

[0012] According to an embodiment of the present disclosure, the cement clinker preparation system further includes a grate cooler communicating with the rotary kiln, suitable for exchanging heat between the externally input air and the clinker output from the rotary kiln to cool the clinker and generate high-temperature air.

[0013] According to an embodiment of the present disclosure, the cement clinker preparation system further includes: an oxygen production device communicating with the intake side of the booster fan, suitable for producing and supplying the oxygen to the booster fan; and a first heat exchanger, the hot side of the first heat exchanger communicating with the grate cooler, and the cold side of the first heat exchanger being disposed between the oxygen production device and the booster fan to use a part of the high-temperature air output from the grate cooler as a heat source to preheat the oxygen prepared by the oxygen production device.

[0014] According to an embodiment of the present disclosure, the cement clinker preparation system further includes a raw material preheating device connected to the feed side of the above-mentioned decomposition furnace, which is suitable for supplying the above-mentioned raw material to the above-mentioned decomposition furnace; wherein, the above-mentioned raw material preheating device is further connected to the gas-phase output end of the above-mentioned separator, and is suitable for preheating at least a part of the above-mentioned raw material with the above-mentioned recycled flue gas as a heat source.

[0015] According to an embodiment of the present disclosure, the above-mentioned raw material preheating device includes a first preheating part and a second preheating part that are isolated from each other; wherein, the above-mentioned first preheating part is connected to the gas-phase output end of the above-mentioned separator, and the above-mentioned second preheating part is connected to the above-mentioned rotary kiln.

[0016] According to an embodiment of the present disclosure, the cement clinker preparation system further includes a flue gas treatment mechanism, which is connected to the gas-phase output end of the above-mentioned separator, and is suitable for cooling the above-mentioned recycled flue gas enriched with carbon dioxide and preparing a carbon dioxide product.

[0017] According to an embodiment of the present disclosure, the above-mentioned flue gas treatment mechanism includes: a cooling device, which is connected to the gas-phase output end of the above-mentioned separator, and is suitable for cooling the above-mentioned recycled flue gas enriched with carbon dioxide so that at least a part of the water vapor in the above-mentioned recycled flue gas is condensed; and a purification and compression device, which is connected to the above-mentioned cooling device, and is suitable for extracting at least a part of the above-mentioned carbon dioxide from the above-mentioned recycled flue gas enriched with carbon dioxide after cooling to prepare a carbon dioxide product.

[0018] According to an embodiment of the present disclosure, the above-mentioned flue gas treatment mechanism further includes a second heat exchanger, and the hot side of the above-mentioned second heat exchanger is arranged between the gas-phase output end of the above-mentioned separator and the above-mentioned cooling device to exchange heat between the above-mentioned recycled flue gas enriched with carbon dioxide as a heat source and the air input to the cold side of the above-mentioned second heat exchanger externally.

[0019] According to the cement clinker preparation system provided by the present disclosure, the fluidizing air cap configured as a fluidized bed structure is suitable for uniformly and adjustably supplying primary air into the decomposition furnace to reduce the flow rate of the gas in the decomposition furnace. Through the circulation of the solid-phase decomposition products, the uniformity of the temperature distribution in the decomposition furnace is improved, the occurrence of local high temperature is avoided, which is beneficial to increasing the oxygen content at the primary air inlet, thereby increasing the carbon dioxide concentration at the outlet of the decomposition furnace and facilitating the capture of carbon dioxide. Description of the Drawings

[0020] Figure 1 is a schematic diagram of a cement clinker preparation system according to an exemplary embodiment of the present disclosure;

[0021] Figure 2 is Figure 1 a schematic diagram of the decomposition furnace of the exemplary embodiment shown;

[0022] Figure 3It is a schematic diagram of a cement clinker preparation system according to another exemplary embodiment of the present disclosure, showing an implementation manner in which the gas-phase output end of the separator is directly connected to the flue gas treatment mechanism; and

[0023] Figure 4 It is a schematic diagram of a cement clinker preparation system according to still another exemplary embodiment of the present disclosure, showing an implementation manner in which the raw material preheating device includes only one preheating section.

[0024] In the said drawings, the meanings of the reference numerals are specifically as follows:

[0025] 1. Raw material preheating device;

[0026] 1A. First preheating section;

[0027] 1B. Second preheating section;

[0028] 2. Calciner;

[0029] 3. Separator;

[0030] 4. Return feeder;

[0031] 5. Rotary kiln;

[0032] 6. Grate cooler;

[0033] 7. Oxygen production device;

[0034] 8. First heat exchanger;

[0035] 9. First waste heat boiler;

[0036] 10. Booster fan;

[0037] 11. Second waste heat boiler;

[0038] 12. Raw material preparation device;

[0039] 13. Flue gas purification device;

[0040] 14. Second heat exchanger;

[0041] 15. Cooling device; and

[0042] 16. Purification and compression device. Detailed implementation manners

[0043] To make the objectives, technical solutions and advantages of the present disclosure more clear and understandable, the following further describes the present disclosure in detail with reference to specific embodiments and the accompanying drawings.

[0044] The terms used herein are for describing specific embodiments only and are not intended to limit the present disclosure. The terms "including", "comprising" and the like used herein indicate the presence of the described features, steps, operations and / or components, but do not preclude the presence or addition of one or more other features, steps, operations or components.

[0045] All terms used herein, including technical and scientific terms, have the meanings commonly understood by those of ordinary skill in the art, unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification and should not be interpreted in an idealized or overly rigid manner.

[0046] In cases where expressions such as "at least one of A, B, and C, etc." are used, generally, it should be interpreted according to the meaning commonly understood by those of ordinary skill in the art. For example, a "system having at least one of A, B, and C" should include, but is not limited to, a system having only A, only B, only C, having A and B, having A and C, having B and C, and / or having A, B, and C. In cases where expressions such as "at least one of A, B, or C, etc." are used, generally, it should be interpreted according to the meaning commonly understood by those of ordinary skill in the art. For example, a "system having at least one of A, B, or C" should include, but is not limited to, a system having only A, only B, only C, having A and B, having A and C, having B and C, and / or having A, B, and C.

[0047] Figure 1 It is a schematic diagram of a cement clinker preparation system according to an exemplary embodiment of the present disclosure.

[0048] The cement clinker preparation system provided according to the present disclosure, as Figure 1As shown, it includes a precalciner 2, a separator 3, a return feeder 4 and a rotary kiln 5. The precalciner 2 is configured as a fluidized bed structure, and a plurality of fluidizing tuyeres are arranged at the bottom of the precalciner 2, which is suitable for supplying primary air into the furnace chamber of the precalciner 2, so that the solid fuel and raw meal in the precalciner 2 are fluidized, and the solid fuel burns in an oxygen atmosphere and a carbon dioxide atmosphere, so that the raw meal passing through the precalciner 2 is pyrolyzed into solid phase decomposition products and recycled flue gas enriched with carbon dioxide. The separator 3 is communicated with the discharge end of the precalciner 2, and is suitable for separating the solid phase decomposition products and the recycled flue gas enriched with carbon dioxide. The return feeder 4 is communicated with the solid phase output end of the separator 3, and is provided with at least two return channels, and at least one return channel is communicated with the precalciner 2, so that a part of the solid phase decomposition products are returned to the precalciner 2 for secondary pyrolysis. The rotary kiln 5 is communicated with another return channel of the return feeder 4, and is suitable for firing another part of the solid phase decomposition products entering the rotary kiln 5 into clinker. Among them, the primary air includes pressurized oxygen or oxygen and a part of recycled flue gas, so that the oxygen content at the primary air inlet of the precalciner 2 is configured to be greater than or equal to 75%.

[0049] In a schematic embodiment, as Figure 1 shown, the cement clinker preparation system further includes a raw meal preparation device 12. Specifically, the raw meal preparation device 12 includes, but is not limited to, a feeding mechanism, a silo, a crusher, a pre-homogenization mechanism, a raw meal mill, etc., and is suitable for crushing and grinding large materials such as limestone, clay, iron ore, etc. for entering the raw meal preheating device 1 for treatment.

[0050] In a schematic embodiment, the primary air introduced through the fluidizing tuyeres is configured to maintain the flue gas velocity in the furnace chamber of the precalciner at 3-6 m / s. Further, in the primary air formed by the oxygen (O2) and recycled flue gas introduced by the fluidizing tuyeres, the volume fraction of oxygen (O2) includes, but is not limited to, being configured to be 75%-100%, and the oxygen (O2) can be adjusted according to the actual pyrolysis process.

[0051] In such an embodiment, the pressurized primary air is evenly supplied into the decomposition furnace 2 through the fluidizing air caps to form a local positive pressure inside the furnace chamber of the decomposition furnace 2. Compared with the current system with a negative pressure condition formed by a high-temperature blower among various devices (including the decomposition furnace, raw material preheating device, and rotary kiln), the occurrence of air leakage can be reduced, thereby preventing the uncontrollable introduction of nitrogen (N2) in the air into the decomposition furnace, which is beneficial to increasing the concentration of carbon dioxide (CO2) in the gaseous decomposition products generated in the decomposition furnace 2 for subsequent capture. Moreover, under positive pressure conditions, the ratio of oxygen (O2) and recycled flue gas in the supplied primary air is more sensitive and accurate in adjustment compared to the uncontrollable large air volume generated under negative pressure conditions; with the distribution function of the fluidizing air caps, the gas flow rate inside the decomposition furnace 2 can be effectively controlled and reduced, enabling the primary air to be evenly distributed inside the decomposition furnace. Further, based on the ratio of oxygen and recycled flue gas in the primary air, the proportion of the recycled flue gas circulating inside the decomposition furnace 2 can be significantly reduced, and even the recycling of the flue gas is not required (i.e., the state where the volume fraction of oxygen (O2) is 100%), thereby reducing the heat consumption of the system and per unit product.

[0052] Further, in response to at least one of the temperature, gas flow rate, and working state inside the decomposition furnace 2, the proportion of the solid-phase decomposition products returned to the decomposition furnace 2 can be correspondingly configured, so that a part of the heated solid-phase decomposition products returns to the decomposition furnace 2 again, mixes with the raw materials that have not been pyrolyzed or have not been completely pyrolyzed in the furnace, and is recycled again, thereby enabling the raw materials to be gently heated in the decomposition furnace 2. In this way, through the combined action of air distribution and mixing of the solid-phase decomposition products, the temperature of each part inside the decomposition furnace 2 is made uniform. Compared with the current method of circulating the flue gas among various devices based on negative pressure conditions, not only the content of oxygen (O2) inside the decomposition furnace 2 is increased, but also the occurrence of local high-temperature inside the decomposition furnace 2 is effectively avoided.

[0053] Figure 2 Yes Figure 1 It is a schematic diagram of the decomposition furnace of the illustrated exemplary embodiment.

[0054] According to an embodiment of the present disclosure, as Figure 2 shown, a material distribution mechanism is provided inside the return feeder 4, which is suitable for adjusting the proportion of the solid-phase decomposition products entering the two return channels.

[0055] In an exemplary embodiment, as Figure 2 shown, the return feeder 4 is configured with two return channels. One return channel is connected to the decomposition furnace 2 (such as Figure 2 the return channel located on the left shown), and the other return channel is connected to the rotary kiln 5 (such as Figure 2The return material channel located on the right as shown). Further, the material distribution mechanism includes a baffle plate disposed between the two return material channels. The baffle plate is connected to the output end of a driving part (such as a motor) and is adapted to swing at the material inlet positions of the two return material channels, so that the solid phase decomposition products output from the separator 3 are respectively guided into the two return material channels under the action of the baffle plate. Among them, the solid phase decomposition products returned to the decomposition furnace 2 account for 20%-80% of the total amount.

[0056] In a schematic embodiment, as Figure 2 shown, the solid fuel is input into the decomposition furnace 2 through, but not limited to, the furnace wall of the decomposition furnace 2 and / or the return material channel. Among them, the solid fuel includes, but is not limited to, pulverized coal. Specifically, the solid fuel and the solid phase decomposition products returned to the decomposition furnace are fluidized under the action of the fluidizing air caps to burn in an oxygen (O2) and carbon dioxide (CO2) atmosphere in the decomposition furnace 2.

[0057] According to an embodiment of the present disclosure, as Figure 2 shown, a wind locking mechanism is provided in the return material channel of the return feeder 4 communicating with the decomposition furnace 2, which is adapted to restrict the entry of circulating flue gas into the return feeder 4.

[0058] In a schematic embodiment, not shown in the figure, the wind locking mechanism includes, but is not limited to, a wind locking valve. Specifically, the return material channel of the return feeder 4 communicating with the decomposition furnace 2 (such as Figure 2 the return material channel located on the left as shown) is preferably configured with multiple stages of wind locking valves, including but not limited to two stages.

[0059] In such an embodiment, through the configured wind locking mechanism, a gas-solid isolation can be formed between the decomposition furnace 2 and the separator 3, thereby preventing the circulating flue gas enriched with carbon dioxide generated in the decomposition furnace 2 from entering the separator 3 and affecting the separation efficiency of the separator 3.

[0060] According to an embodiment of the present disclosure, as Figure 1 and 2 shown, the cement clinker preparation system further includes a booster fan 10. The intake side of the booster fan 10 is communicated with the supply side of oxygen and circulating flue gas, and the ratio of oxygen and circulating flue gas supplied to the booster fan 10 is adjustable. The outlet side of the booster fan 10 is communicated with the fluidizing air caps.

[0061] In a schematic embodiment, an adjustable valve is configured on the intake side of the booster fan 10 (i.e., the supply side of oxygen and circulating flue gas), and the valve is adapted to adjust the ratio of oxygen and circulating flue gas input by the booster fan 10 during the operation of the decomposition furnace 2. Among them, the ratio of the circulating flue gas is configured to be less than or equal to 15%. Further, the ratio of the circulating flue gas can be configured to be close to zero.

[0062] In such an embodiment, compared with the system under the negative pressure condition formed by the circulating fan, since the proportion of the circulating flue gas that is re-distributed and enters the decomposition furnace 2 is very small or even close to zero, therefore, the heat loss of the system caused by the reheating of the cooled circulating flue gas entering the decomposition furnace 2 again can be effectively avoided.

[0063] According to an embodiment of the present disclosure, as Figure 1 shown, the cement clinker preparation system further includes a grate cooler 6 connected to the rotary kiln 5, which is suitable for exchanging heat between the externally input air and the clinker output from the rotary kiln 5 to cool the clinker and generate high-temperature air.

[0064] According to an embodiment of the present disclosure, as Figure 1 shown, the cement clinker preparation further includes an oxygen production device 7 and a first heat exchanger 8. The oxygen production device 7 is connected to the intake side of the booster fan 10 and is suitable for producing and supplying oxygen to the booster fan 10. The hot side of the first heat exchanger 8 is connected to the grate cooler 6, and the cold side of the first heat exchanger 8 is arranged between the oxygen production device 7 and the booster fan 10 to use a part of the high-temperature air output from the grate cooler 6 as a heat source to preheat the oxygen prepared by the oxygen production device 7.

[0065] In a schematic embodiment, the oxygen production device 7 includes but is not limited to an air separation device. Specifically, the air separation device is suitable for producing high-concentration oxygen from air through compression cycle, deep refrigeration and rectification. Among them, the oxygen concentration supplied to the decomposition furnace 2 via the air separation device includes but is not limited to being greater than or equal to 95%, and preferably can be configured to supply oxygen with a concentration greater than or equal to 99%.

[0066] In a schematic embodiment, as Figure 1 shown, the cement clinker preparation system further includes a first waste heat boiler 9 (such as a waste heat boiler at the kiln head). Specifically, the high-temperature flue gas output from the grate cooler 6 includes but is not limited to supplying heat to at least one of the first waste heat boiler 9, the first heat exchanger 8 and the rotary kiln 5. Among them, the high-temperature air returned to the rotary kiln 5 can be used as combustion-supporting air for the rotary kiln 5; the high-temperature air entering the first heat exchanger 8 can be used for indirect heat exchange of the oxygen generated by the oxygen production device 7; the high-temperature air entering the first waste heat boiler 9 can be used for heat exchange of the circulating medium in the first waste heat boiler 9 to enable the circulating medium to expand and do work (such as generating electricity externally).

[0067] According to an embodiment of the present disclosure, as Figure 1 shown, the cement clinker preparation system further includes a raw material preheating device 1 connected to the feed side of the decomposition furnace 2, which is suitable for supplying raw materials to the decomposition furnace 2. Among them, the raw material preheating device 1 is also connected to the gas-phase output end of the separator 3 and is suitable for preheating at least a part of the raw materials using the circulating flue gas as a heat source.

[0068] Figure 3It is a schematic diagram of a cement clinker preparation system according to another exemplary embodiment of the present disclosure, showing an implementation manner in which the gas-phase output end of the separator is directly connected to the flue gas treatment mechanism.

[0069] According to an embodiment of the present disclosure, as Figure 1 and Figure 3 shown, the raw material preheating device 1 includes a first preheating part 1A and a second preheating part 1B that are isolated from each other. Among them, the first preheating part 1A is connected to the gas-phase output end of the separator 3, and the second preheating part 1B is connected to the rotary kiln 5.

[0070] In an exemplary embodiment, as Figure 1 and Figure 3 shown, the raw material preheating device 1 is configured as a dual series having a first preheating part 1A and a second preheating part 1B. Specifically, a cascade heat exchange structure of 3 to 5 stages can be configured in each preheating part (that is, the first preheating part 1A and the second preheating part 1B), and among them, a 4-stage heat exchange mechanism is a preferred implementation manner.

[0071] In an exemplary embodiment, as Figure 1 and Figure 3 shown, the first preheating part 1A of the raw material preheating device 1 is connected to the gas-phase output end of the separator 3 (including direct connection as Figure 1 shown and indirect connection as Figure 3 shown). Further, the second preheating part 1B of the raw material preheating device 1 is connected to the rotary kiln 5. In this way, the first preheating part 1A preheats the raw material to be treated with the circulating flue gas separated by the separator 3, and the second preheating part 1B preheats the raw material with the rotary kiln combustion flue gas generated by burning fuel in the rotary kiln 5.

[0072] In an exemplary embodiment, as Figure 1 and Figure 3 shown, the raw material entering the first preheating part 1A and the second preheating part 1B of the raw material preheating device 1 via the raw material preparation device 12 can be distributed. Specifically, the distribution methods include but are not limited to configuring according to the flow rate and / or temperature of the circulating flue gas entering the first preheating part 1A and the rotary kiln combustion flue gas entering the second preheating part 1B.

[0073] For example, if the temperature of the circulating flue gas at the outlet of the first preheating part 1A is higher than the temperature of the rotary kiln combustion flue gas at the outlet of the second preheating part 1B, then more raw material is distributed to enter the first preheating part 1A for preheating.

[0074] Similarly, if the temperature of the rotary kiln combustion flue gas at the outlet of the second preheating part 1B is higher than the temperature of the circulating flue gas at the outlet of the first preheating part 1A, then more raw material is distributed to enter the second preheating part 1B for preheating.

[0075] In such an embodiment, the raw meal is pre-distributed and pre-heated according to the temperatures of the flue gases (i.e., the recycled flue gas and the rotary kiln combustion flue gas) at the outlets of different pre-heating sections, so that the temperatures of the raw meal pre-heated by the two pre-heating sections are approximately the same, and thus the raw meal can be uniformly heated in the decomposition furnace 2.

[0076] According to an embodiment of the present disclosure, as Figure 1 shown, the cement clinker preparation system further includes a flue gas treatment mechanism. The flue gas treatment mechanism is connected to the gas-phase output end of the separator 3 and is suitable for cooling the recycled flue gas enriched with carbon dioxide and preparing carbon dioxide products.

[0077] According to an embodiment of the present disclosure, as Figure 1 shown, the flue gas treatment mechanism includes a cooling device 15 and a purification and compression device 16. The cooling device 15 is connected to the gas-phase output end of the separator 3 and is suitable for cooling the recycled flue gas enriched with carbon dioxide so that at least a part of the water vapor in the recycled flue gas is condensed. The purification and compression device 16 is connected to the cooling device 15 and is suitable for extracting at least a part of the carbon dioxide from the cooled recycled flue gas enriched with carbon dioxide to prepare carbon dioxide products.

[0078] According to an embodiment of the present disclosure, as Figure 1 shown, the flue gas treatment mechanism further includes a second heat exchanger 14. The hot side of the second heat exchanger 14 is arranged between the gas-phase output end of the separator 3 and the cooling device 15 to exchange heat between the recycled flue gas enriched with carbon dioxide as a heat source and the air input to the cold side of the second heat exchanger 14 from the outside.

[0079] In a schematic embodiment, as Figure 1 shown, the gas-phase output end of the separator 3 is connected to the first pre-heating section 1A of the raw meal pre-heating device 1. Further, the first pre-heating section 1A is connected to the hot side of the second heat exchanger 14, and the cold side of the second heat exchanger 14 is suitable for introducing external air to indirectly exchange heat between the recycled flue gas enriched with carbon dioxide (CO2) after heat exchange through the first pre-heating section 1A and the air. In this way, the preliminary cooling of the recycled flue gas enriched with carbon dioxide (CO2) is realized, and the waste heat in the recycled flue gas is recovered. Further, the high-temperature air after heat exchange with the recycled flue gas sequentially passes through the second waste heat boiler 11 (such as the waste heat boiler at the kiln tail), the raw meal preparation device 12 and the flue gas purification device 13, so as to exchange heat with the circulating medium in the second waste heat boiler 11, so that the circulating medium expands to do work (such as generating electricity externally), and finally the tail gas in the second waste heat boiler 11 is purified and discharged by the flue gas purification device 13.

[0080] Figure 4 is a schematic diagram of a cement clinker preparation system according to another schematic embodiment of the present disclosure, showing an embodiment in which the raw meal pre-heating device only includes one pre-heating section.

[0081] In a schematic embodiment, as Figure 3 and Figure 4 shown, the gas-phase output end of the separator 3 is communicated with the hot side of the second heat exchanger 14, and the cold side of the second heat exchanger 14 is adapted to introduce external air. Further, the cold side of the second heat exchanger 14 is communicated with the raw material preheating device 1. In this way, after the recycled flue gas enriched with carbon dioxide (CO2) separated by the separator 3 is indirectly heat-exchanged with air, it is further cooled by the cooling device 15, and the high-temperature air after heat exchange is adapted to preheat the raw materials in the raw material preheating device 1.

[0082] In a schematic embodiment, as Figure 4 shown, the raw material preheating device 1 is an integral structure. Specifically, the raw material preheating device 1 is respectively communicated with the cold side of the second heat exchanger 14 and the rotary kiln 5. In this way, high-temperature air and the rotary kiln combustion flue gas generated by the rotary kiln 5 can be respectively introduced into the raw material preheating device 1 to preheat the raw materials in the raw material preheating device 1.

[0083] In such an embodiment, as Figure 3 and Figure 4 shown, the recycled flue gas enriched with carbon dioxide (CO2) output from the gas-phase output end of the separator 3 is directly treated by the recycled flue gas treatment mechanism. Compared with Figure 1 the embodiment shown, the air leakage caused by the flow of the recycled flue gas can be further reduced to avoid the introduction of nitrogen (N2) into the decomposition furnace 2 due to air leakage.

[0084] In a schematic embodiment, the cooling device 15 in the flue gas treatment mechanism is configured with two pipelines. One pipeline is communicated with the purification and compression device 16, and the other pipeline is communicated with the decomposition furnace 2 through the booster fan 10 to serve as the supply side of the recycled flue gas of the decomposition furnace 2. Among them, valve bodies are configured in both pipelines to control the flow rate of the cooled recycled flue gas passing through each pipeline. Preferably, in the cooled recycled flue gas, the recycled flue gas returned to the decomposition furnace 2 includes but is not limited to being configured to account for 15% or less of the total amount. For example, 10% of the recycled flue gas is returned to the decomposition furnace 2, and 90% of the recycled flue gas is compressed and purified.

[0085] In such an embodiment, the recycled flue gas enriched with carbon dioxide ((CO2) is gradually cooled via the second heat exchanger 14 and the cooling device 15 to remove at least a part of the moisture in the recycled flue gas. The cooled recycled flue gas is distributed by the cooling device 15, and a small amount of the low-temperature recycled flue gas can be returned to the decomposition furnace 2 to rapidly cool the flue gas in the decomposition furnace 2, thereby avoiding the local high temperature in the decomposition furnace 2 caused by a special operating environment. The purification and compression device 16 is adapted to adsorb (including physical adsorption and / or chemical adsorption) at least a part of other gases in the recycled flue gas except carbon dioxide, and then compress the carbon dioxide gas (including at least one of absorption compression, mechanical compression and liquefaction compression) to form a high-pressure carbon dioxide (CO2) product.

[0086] It should also be noted that the directional terms mentioned in the embodiments, such as "up", "down", "front", "back", "left", "right", etc., are only references to the directions in the drawings and are not used to limit the protection scope of the present disclosure. Throughout the drawings, the same elements are denoted by the same or similar reference numerals. When it may cause confusion in the understanding of the present disclosure, the conventional structures or configurations will be omitted.

[0087] The embodiments of the present disclosure have been described above. However, these embodiments are only for illustrative purposes and not for limiting the scope of the present disclosure. Although the embodiments have been described separately above, this does not mean that the measures in each embodiment cannot be used advantageously in combination. The scope of the present disclosure is defined by the appended claims and their equivalents. Without departing from the scope of the present disclosure, those skilled in the art can make various substitutions and modifications, and these substitutions and modifications should all fall within the scope of the present disclosure.

Claims

1. A cement clinker preparation system, characterized in that, Comprising: A precalciner (2) configured as a fluidized bed structure, with a plurality of fluidizing tuyeres provided at the bottom of the precalciner (2), suitable for supplying primary air into the furnace chamber of the precalciner (2) to fluidize the solid fuel and raw meal in the precalciner (2), and enabling the solid fuel to burn in an oxygen atmosphere and a carbon dioxide atmosphere, so that the raw meal passing through the precalciner (2) is pyrolyzed into solid phase decomposition products and circulating flue gas enriched in carbon dioxide; A separator (3) communicating with the discharge end of the precalciner (2), suitable for separating the solid phase decomposition products and the circulating flue gas enriched in carbon dioxide; A return feeder (4) communicating with the solid phase output end of the separator (3) and provided with at least two return channels, at least one of the return channels communicating with the precalciner (2) to enable a part of the solid phase decomposition products to return to the precalciner (2) for secondary pyrolysis; And A rotary kiln (5) communicating with another return channel of the return feeder (4), suitable for firing another part of the solid phase decomposition products entering the rotary kiln (5) into clinker; Wherein, the primary air includes pressurized oxygen or oxygen and a part of the circulating flue gas, so that the oxygen content at the primary air inlet of the precalciner (2) is configured to be greater than or equal to 75%.

2. The system according to claim 1, wherein A material distribution mechanism is provided in the return feeder (4), suitable for adjusting the proportion of the solid phase decomposition products entering different return channels.

3. The system according to claim 1, wherein A air lock mechanism is provided in the return channel of the return feeder (4) communicating with the precalciner (2), suitable for restricting the circulating flue gas from entering the return feeder (4).

4. The system according to any one of claims 1 to 3, characterized in that, It further includes a booster fan (10), the intake side of the booster fan (10) communicates with the supply side of the oxygen and the circulating flue gas, and the proportion of the oxygen and the circulating flue gas supplied to the booster fan (10) is adjustable, and the outlet side of the booster fan (10) communicates with the fluidizing tuyeres.

5. The system according to claim 4, characterized in that, It further includes a grate cooler (6) communicating with the rotary kiln (5), suitable for exchanging heat between the externally input air and the clinker output from the rotary kiln (5) to cool the clinker and generate high-temperature air.

6. The system according to claim 5, wherein It further includes: An oxygen production device (7) communicating with the intake side of the booster fan (10), suitable for producing and supplying the oxygen to the booster fan (10); And A first heat exchanger (8), the hot side of the first heat exchanger (8) communicates with the grate cooler (6), and the cold side of the first heat exchanger (8) is arranged between the oxygen production device (7) and the booster fan (10) to use a part of the high-temperature air output from the grate cooler (6) as a heat source to preheat the oxygen prepared by the oxygen production device (7).

7. The system according to any one of claims 1 to 3, characterized in that It further includes a raw meal preheating device (1) communicating with the feed side of the precalciner (2), suitable for supplying the raw meal to the precalciner (2); Wherein, the raw meal preheating device (1) also communicates with the gas phase output end of the separator (3), suitable for preheating at least a part of the raw meal with the circulating flue gas as a heat source.

8. The system according to claim 7, characterized in that, The raw material preheating device (1) includes a first preheating part (1A) and a second preheating part (1B) that are isolated from each other; wherein, the first preheating part (1A) is communicated with the gas-phase output end of the separator (3), and the second preheating part (1B) is communicated with the rotary kiln (5).

9. The system according to any one of claims 1 to 3, characterized in that, It further includes a flue gas treatment mechanism, which is communicated with the gas-phase output end of the separator (3) and is applicable to cooling the recycled flue gas enriched with carbon dioxide and preparing carbon dioxide products.

10. The system according to claim 9, wherein The flue gas treatment mechanism includes: a cooling device (15), which is communicated with the gas-phase output end of the separator (3) and is applicable to cooling the recycled flue gas enriched with carbon dioxide so that at least a part of the water vapor in the recycled flue gas is condensed; and a purification and compression device (16), which is communicated with the cooling device (15) and is applicable to extracting at least a part of the carbon dioxide from the recycled flue gas enriched with carbon dioxide after cooling to prepare the carbon dioxide products.

11. The system according to claim 10, wherein The flue gas treatment mechanism further includes a second heat exchanger (14), and the hot side of the second heat exchanger (14) is arranged between the gas-phase output end of the separator (3) and the cooling device (15) to exchange heat between the recycled flue gas enriched with carbon dioxide as a heat source and the air input to the cold side of the second heat exchanger (14) from outside.

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