A method and system for utilizing waste heat from cement kilns, reducing CO2 emissions, and co-producing CO.

Abstract

This invention provides a method and system for utilizing waste heat from cement kilns, reducing CO2 emissions, and co-producing CO. The method includes: preheating and decomposing cement raw materials in a decomposition furnace, and feeding the generated high-temperature flue gas into a CO reactor; injecting pulverized coal into the CO reactor to induce a reduction reaction, and sending the resulting reaction flue gas to various cyclone separators for countercurrent heat exchange with the raw materials; the heat-exchanged flue gas then enters a kiln tail boiler to recover waste heat and produce superheated steam; the superheated steam generated by the kiln head boiler and the kiln tail boiler is fed together into a back-pressure steam turbine, and the discharged medium-pressure steam is divided into two paths: the first path heats CO to purify the raw material gas, and the second path drives a generator to generate electricity; the low-temperature flue gas obtained after heat exchange in the kiln tail boiler is purified by dust collection, desulfurization, and dehydration, then pressurized by a booster fan, heated by the first path of medium-pressure steam, and sent to an adsorption device for purification to obtain industrial-grade CO products. This invention requires no additional heat source or catalyst, converting CO₂ in situ from cement kilns to co-produce high-value CO, achieving cascade utilization of waste heat and low-cost carbon emission reduction.

Description

Technical Field

[0001] This invention relates to the field of energy conservation and emission reduction technology in cement production, specifically to a method and system for utilizing waste heat from cement kilns, reducing CO2 emissions, and co-producing CO. Background Technology

[0002] The cement industry is a crucial foundation of the national economy, but it is also a typical high-energy-consuming and high-emission industry. Statistics show that producing one ton of cement clinker emits approximately 0.8-0.9 tons of CO2, with about 60% originating from limestone decomposition and 30% from coal combustion. With my country's proposed "dual carbon" targets, the cement industry faces immense pressure to reduce carbon emissions. CO2 capture, utilization, and storage (CCUS) technology is considered one of the key technologies for achieving deep decarbonization in the cement industry.

[0003] Currently, CO2 capture technology for cement kilns mainly relies on chemical absorption, which involves absorbing CO2 from the kiln tail gas using amine solution, then regenerating it through desorption to obtain high-purity CO2 gas, which is further purified and liquefied to produce food-grade or industrial-grade liquid CO2. However, this technical approach has encountered serious bottlenecks in practical application:

[0004] 1. Saturation of the CO2 product market: In recent years, with the successive launch of domestic CCUS projects, the supply of liquid CO2 has become saturated, and the CO2 consumption capacity is seriously insufficient, which seriously affects the economics of the projects.

[0005] 2. High energy consumption and cost: The chemical absorption method requires a large amount of steam for the desorption and regeneration of amine liquid. This part of the energy consumption usually accounts for more than 30% of the waste heat power generation of cement kiln, which greatly reduces the energy utilization efficiency of the system and increases the operating cost.

[0006] 3. High storage costs: If CO2 cannot be disposed of nearby and must be transported to a remote storage site for geological storage, the transportation and storage costs are extremely high.

[0007] To address the CO2 consumption problem, some existing technologies propose converting CO2 into syngas. For example, patent document CN116003004A discloses a cement production process coupling carbon dioxide capture, electrocatalysis, and oxygen-enriched combustion; however, this requires the introduction of an additional electrocatalytic system, increasing equipment investment and power consumption. Another patent, CN112321183B, proposes a zero-emission cement kiln system, but this requires large-scale modifications to existing cement production lines, resulting in significant changes, high costs, and difficulty in widespread adoption. Furthermore, in terms of waste heat utilization, most existing technologies still employ the traditional waste heat boiler + pure condensing power generation model, failing to perform cascade matching according to the energy needs of subsequent processes. This leads to the downgrading of high-grade steam energy, resulting in significant energy efficiency losses. Summary of the Invention

[0008] To address the problems of high energy consumption and insufficient market saturation and consumption capacity of the captured liquid CO2 in existing cement kiln carbon reduction technologies, which utilize traditional chemical adsorption methods for CO2 collection, this invention proposes a method for co-producing CO2 from waste heat in cement kilns, including:

[0009] Cement raw materials are preheated and decomposed in a decomposition furnace to generate high-temperature flue gas containing CO2 carrying hot raw materials. The high-temperature flue gas is then passed into a matching cyclone separator for gas-solid separation. The hot raw materials are separated and enter the kiln tail flue chamber, while the high-temperature flue gas containing CO2 enters a pre-set CO reactor.

[0010] Powdered coal is injected into the CO reactor, and the waste heat of the high-temperature flue gas is used as the heat source for the reaction. The CaO contained in the hot raw material that enters the CO reactor with the high-temperature flue gas is used as a catalyst to reduce the carbon in the powdered coal and the CO2 in the high-temperature flue gas to generate CO-containing reaction flue gas.

[0011] The reaction flue gas is sequentially fed into the cyclone separators of each stage of the preheater for countercurrent heat exchange with the raw materials. The flue gas after heat exchange enters the kiln tail boiler of the cement kiln to recover waste heat. At the same time, the waste heat of the hot air from the kiln head grate cooler is recovered by the kiln head boiler of the cement kiln. The two waste heat sources work together to produce superheated steam.

[0012] The superheated steam is fed into a back-pressure turbine, which drives the back-pressure turbine to drive the booster fan of the flue gas treatment system. The medium-pressure steam discharged from the back-pressure turbine is divided into two paths. The first path of medium-pressure steam is used to heat the CO purification feed gas, and the second path of medium-pressure steam is fed into a condensing turbine to drive a generator to generate electricity.

[0013] The low-temperature flue gas obtained after heat exchange in the kiln tail boiler is purified by dust collection, desulfurization, and dehydration in sequence. It is then pressurized by the booster fan, heated by the first medium-pressure steam, and sent to the CO pressure swing adsorption device for purification to obtain industrial-grade CO products.

[0014] Optionally, the cement raw meal is preheated and decomposed in a decomposition furnace to generate high-temperature flue gas containing CO2 carrying the hot raw meal, and the high-temperature flue gas is introduced into a pre-set CO reactor, including:

[0015] Cement raw materials undergo calcium carbonate decomposition in a decomposition furnace, generating high-temperature flue gas containing CO2.

[0016] The high-temperature flue gas carries the hot raw materials generated by decomposition into a matching cyclone separator for gas-solid separation, resulting in high-temperature flue gas after gas-solid separation.

[0017] The high-temperature flue gas after gas-solid separation is introduced into a pre-set CO reactor.

[0018] Optionally, the CO reactor is located in the high-temperature flue gas passage downstream of the decomposition furnace.

[0019] Optionally, the step of injecting pulverized coal into the CO reactor, utilizing the waste heat of the high-temperature flue gas as a reaction heat source, and using CaO contained in the hot raw material entering the CO reactor with the high-temperature flue gas as a catalyst, causes the carbon in the pulverized coal to undergo a reduction reaction with the CO2 in the high-temperature flue gas, generating CO-containing reaction flue gas, includes:

[0020] A set of coal powder injection devices are uniformly arranged circumferentially along the side wall of the CO reactor to inject coal powder into the CO reactor in a metered manner.

[0021] Based on the online monitoring data of CO2 in the flue gas at the inlet of the CO reactor, the coal powder injection rate is adjusted in real time to control the molar ratio of fixed carbon in the coal powder to CO2 in the flue gas to be within the range of 0.9-1.5.

[0022] The reaction temperature is maintained by utilizing the residual heat of the high-temperature flue gas, while the CaO contained in the hot raw material entering the CO reactor with the high-temperature flue gas is used for catalytic reduction, so that the carbon in the pulverized coal reacts fully with the CO2 in the high-temperature flue gas to generate CO-containing reaction flue gas.

[0023] Optionally, the reaction flue gas is sequentially fed into each stage of the preheater's cyclone separators for countercurrent heat exchange with the raw materials. The flue gas after heat exchange enters the kiln tail boiler of the cement kiln to recover waste heat. Simultaneously, the waste heat from the hot air of the kiln head grate cooler is recovered using the kiln head boiler of the cement kiln. The two sources of waste heat work together to produce superheated steam, including:

[0024] The CO-containing reaction flue gas is sequentially fed into each stage of the preheater cyclone separator, where it undergoes multi-stage countercurrent heat exchange with the cement raw material entering the preheater in the opposite direction, resulting in flue gas cooled by heat exchange.

[0025] The flue gas, after heat exchange and cooling, is discharged from the preheater outlet and enters the kiln tail boiler of the cement kiln. It then passes through the heat exchanger, evaporator, and economizer in sequence to complete heat exchange and generate the first stream of steam.

[0026] The high-temperature hot air discharged from the cement kiln head enters the kiln head boiler, and passes through the heater, evaporator and economizer in sequence to complete heat exchange and generate a second steam.

[0027] The first steam stream and the second steam stream are combined to form superheated steam.

[0028] Optionally, the superheated steam is fed into a back-pressure turbine to drive the turbine, which in turn drives the booster fan of the flue gas treatment system; the medium-pressure steam discharged from the back-pressure turbine is divided into two paths: the first path of medium-pressure steam is used to heat the CO purification feed gas, and the second path of medium-pressure steam is fed into a condensing turbine to drive a generator to generate electricity, including:

[0029] The superheated steam is fed into a back-pressure turbine to drive the back-pressure turbine to operate.

[0030] The back-pressure steam turbine directly drives the booster fan of the flue gas treatment system via a coaxial connection.

[0031] The back-pressure steam turbine discharges medium-pressure steam;

[0032] The medium-pressure steam is divided into two streams. The first stream of medium-pressure steam is sent to the heating device of the CO purification process, and the second stream of medium-pressure steam is sent to the condensing steam turbine to drive the condensing steam turbine to operate and drive the generator to generate electricity.

[0033] The discharge pressure of the back-pressure steam turbine is 0.5-1.2 MPa.

[0034] Optionally, the low-temperature flue gas obtained after heat exchange in the kiln tail boiler is successively purified by dust collection, desulfurization, and dehydration, then pressurized by the booster fan, heated by the first medium-pressure steam, and sent to a CO pressure swing adsorption unit for purification to obtain industrial-grade CO products, including:

[0035] The low-temperature flue gas, after being cooled by heat exchange in the kiln tail boiler, is then passed through a dust collector to remove dust, a desulfurization water washing tower to remove acidic gases, and a drying device to remove moisture, resulting in purified flue gas.

[0036] The purified flue gas is first pressurized by the first set of booster fans, and then the residual impurities are removed by the waste gas treatment device to obtain flue gas after impurity removal.

[0037] The flue gas after impurities are removed is pressurized a second time by the second set of booster fans to obtain pressurized flue gas.

[0038] The pressurized flue gas is heated by the first medium-pressure steam and then sent to a CO pressure swing adsorption device for selective adsorption and purification to obtain industrial-grade CO products.

[0039] Optionally, the CO product is fed into a pressure swing adsorption (PSA) unit for selective adsorption and purification to obtain an industrial-grade CO product, including:

[0040] The heated flue gas enters the adsorption tower of the CO pressure swing adsorption unit, where the alumina and copper-loaded composite adsorbent packed in the adsorption tower selectively adsorbs CO in the flue gas.

[0041] After adsorption is complete, the adsorption tower is evacuated by a vacuum pump to obtain CO product, which is then sent to the product storage tank.

[0042] A portion of the CO product gas is extracted from the product storage tank, pressurized, heated, and then returned to the adsorption tower as flushing gas to obtain industrial-grade CO product.

[0043] Based on the same inventive concept, this invention also provides a cement kiln waste heat utilization, CO2 emission reduction and CO co-production system, comprising:

[0044] The preheating and decomposition module is used to preheat and decompose cement raw materials in a decomposition furnace to generate high-temperature flue gas containing CO2 carrying the hot raw materials, and to introduce the high-temperature flue gas into a pre-set CO reactor.

[0045] The catalytic reduction module is used to inject pulverized coal into the CO reactor, using the waste heat of the high-temperature flue gas as the heat source for the reaction and the CaO contained in the hot raw material that enters the CO reactor with the high-temperature flue gas as the catalyst, so that the carbon in the pulverized coal reacts with the CO2 in the high-temperature flue gas to generate CO-containing reaction flue gas.

[0046] The countercurrent heat exchange module is used to sequentially send the reaction flue gas into the cyclone separators of each stage of the preheater for countercurrent heat exchange with the raw materials. The flue gas after heat exchange enters the kiln tail boiler of the cement kiln to recover waste heat. At the same time, the waste heat of the grate cooler is recovered by the kiln head boiler of the cement kiln. The two waste heat sources are used to produce superheated steam.

[0047] The fan drive module is used to send the superheated steam into the back pressure turbine and drive the back pressure turbine to drive the booster fan of the flue gas treatment system; the medium-pressure steam discharged from the back pressure turbine is divided into two paths, the first path of medium-pressure steam is used to heat the CO purification raw material gas, and the second path of medium-pressure steam is sent into the condensing turbine to drive the generator to generate electricity.

[0048] The CO generation module is used to purify the low-temperature flue gas obtained after heat exchange in the kiln tail boiler by sequentially collecting dust, desulfurizing, and dehydrating it. After being pressurized by the booster fan, it is heated by the first medium-pressure steam and sent to the CO pressure swing adsorption device for purification to obtain industrial-grade CO products.

[0049] Optionally, the preheating decomposition module includes:

[0050] The flue gas generation submodule is used to decompose cement raw materials into calcium carbonate in the decomposition furnace to generate high-temperature flue gas containing CO2.

[0051] The gas-solid separation submodule is used to carry the hot raw materials generated by the decomposition of the high-temperature flue gas into the matching cyclone separator for gas-solid separation, so as to obtain the high-temperature flue gas after gas-solid separation.

[0052] The gas inlet submodule is used to introduce the high-temperature flue gas after gas-solid separation into a pre-set CO reactor.

[0053] Optionally, the CO reactor is located in the high-temperature flue gas passage downstream of the decomposition furnace.

[0054] Optionally, the catalytic reduction module includes:

[0055] The pulverized coal injection submodule is used to quantitatively inject pulverized coal into the CO reactor through multiple sets of pulverized coal injection devices evenly arranged circumferentially along the sidewall of the CO reactor.

[0056] The CO2 monitoring submodule is used to adjust the coal powder injection rate in real time based on the online CO2 monitoring data of the flue gas at the inlet of the CO reactor, and control the molar ratio of fixed carbon in the coal powder to CO2 in the flue gas to be within the range of 0.9-1.5.

[0057] The high-temperature reaction submodule is used to maintain the reaction temperature by utilizing the residual heat of the high-temperature flue gas, and at the same time, to utilize the CaO contained in the hot raw material entering the CO reactor with the high-temperature flue gas for catalytic reduction reaction, so that the carbon in the coal powder reacts fully with the CO2 in the high-temperature flue gas to generate CO-containing reaction flue gas.

[0058] Optionally, the countercurrent heat exchange module includes:

[0059] The heat exchange and cooling submodule is used to sequentially send the CO-containing reaction flue gas into each stage of the preheater cyclone separator, and perform multi-stage countercurrent heat exchange with the cement raw material entering the preheater in the opposite direction to obtain the flue gas after heat exchange and cooling.

[0060] The first heat exchange submodule is used to discharge the cooled flue gas from the preheater outlet and enter the kiln tail boiler of the cement kiln, where it passes through the heat exchanger, evaporator and economizer in sequence to complete the heat exchange and generate the first steam.

[0061] The second heat exchange submodule is used to introduce the high-temperature hot air discharged from the kiln head grate cooler into the kiln head boiler, and then pass through the heat exchanger, evaporator and economizer in sequence to complete the heat exchange and generate the second steam.

[0062] The steam merging submodule is used to merge the first steam stream with the second steam stream to form superheated steam.

[0063] Optionally, the wind turbine drive module includes:

[0064] The turbine drive submodule is used to send the superheated steam into the back pressure turbine and drive the back pressure turbine to operate;

[0065] The coaxial booster submodule is used to directly drive the booster fan of the flue gas treatment system via the back pressure turbine through a coaxial connection.

[0066] The waste heat utilization submodule is used to utilize the medium-pressure steam discharged from the back-pressure steam turbine; the medium-pressure steam is divided into two paths, the first path of medium-pressure steam is sent to the heating device of the CO purification process, and the second path of medium-pressure steam is sent into the condensing steam turbine to drive the condensing steam turbine to operate and drive the generator to generate electricity.

[0067] The discharge pressure of the back-pressure steam turbine is 0.5-1.2 MPa.

[0068] Optionally, the CO generation module includes:

[0069] The flue gas purification submodule is used to process the low-temperature flue gas after heat exchange and cooling in the kiln tail boiler through a dust collector to remove dust, a desulfurization water washing tower to remove acidic gases, and a drying device to remove moisture, thereby obtaining purified flue gas.

[0070] The first-stage booster submodule is used to first boost the purified flue gas through the first set of booster fans, and then remove residual impurities through the waste gas treatment device to obtain flue gas after impurity removal.

[0071] The secondary booster submodule is used to boost the impurity-removed flue gas a second time through a second set of booster fans to obtain boosted flue gas.

[0072] The CO purification submodule is used to heat the pressurized flue gas through the first medium-pressure steam path and then send it to a CO pressure swing adsorption device for selective adsorption and purification to obtain industrial-grade CO products.

[0073] Optionally, the CO purification submodule includes:

[0074] The CO adsorption unit is used to introduce heated flue gas into the adsorption tower of the CO pressure swing adsorption device. The alumina and copper-loaded composite adsorbent packed in the adsorption tower selectively adsorbs CO in the flue gas.

[0075] The vacuum desorption unit is used to evacuate the adsorption tower by a vacuum pump after adsorption is completed, obtain CO product, and send it to the product storage tank.

[0076] The CO output unit is used to extract CO product gas from the product storage tank, pressurize and heat it, and then return it to the adsorption tower as flushing gas to obtain industrial-grade CO product.

[0077] In another aspect, the present invention also provides an electronic device, comprising: at least one processor and a memory; the memory and the processor are connected via a bus;

[0078] The memory is used to store one or more programs;

[0079] When the one or more programs are executed by the at least one processor, a method for utilizing waste heat from a cement kiln, reducing CO2 emissions, and co-producing CO, as described above, is implemented.

[0080] In another aspect, the present invention also provides a computer device readable storage medium having an executable program stored thereon, wherein when the executable program is executed, it implements the aforementioned method for utilizing waste heat of a cement kiln, reducing CO2 emissions, and co-producing CO.

[0081] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0082] This invention provides a method and system for utilizing waste heat from a cement kiln, reducing CO2 emissions, and co-producing CO. The method includes: heating and decomposing cement raw materials in a decomposition furnace to generate high-temperature flue gas containing CO2 and carrying the hot raw materials; passing the high-temperature flue gas into a matching cyclone separator for gas-solid separation; separating the hot raw materials and allowing them to enter the kiln tail flue chamber; and injecting pulverized coal into the CO reactor, utilizing the waste heat of the high-temperature flue gas as a reaction heat source, and injecting the pulverized coal into the hot raw materials that enter the CO reactor along with the high-temperature flue gas. The CaO contained within acts as a catalyst, causing the carbon in the pulverized coal to undergo a reduction reaction with the CO2 in the high-temperature flue gas, generating CO-containing reactive flue gas. This reactive flue gas is sequentially fed into each stage of the preheater's cyclone separators for counter-current heat exchange with the raw materials. The flue gas after heat exchange enters the kiln tail boiler of the cement kiln to recover waste heat. Simultaneously, the waste heat from the grate cooler is recovered from the kiln head boiler of the cement kiln, and the two sources of waste heat work together to produce superheated steam. This superheated steam is then fed into a back-pressure turbine, which drives the back-pressure turbine to power the booster fan of the flue gas treatment system. The discharged medium-pressure steam is divided into two streams. The first stream of medium-pressure steam is used to heat the raw gas for CO purification, and the second stream of medium-pressure steam is sent to a condensing steam turbine to drive a generator to generate electricity. The low-temperature flue gas obtained after heat exchange in the kiln tail boiler is purified by dust collection, desulfurization, and dehydration. After being pressurized by the booster fan, it is heated by the first stream of medium-pressure steam and sent to a CO pressure swing adsorption device for purification to obtain industrial-grade CO products. This invention integrates a CO reactor into the cement kiln flue gas process, utilizing the waste heat of the high-temperature flue gas at the decomposition furnace outlet to provide heat for the CO2 reduction reaction. The system utilizes CaO naturally carried in the hot raw materials of the flue gas as a catalyst, eliminating the need for additional heating devices and special catalysts, thus reducing energy consumption and operating costs in CO2 conversion. Simultaneously, by prioritizing the use of superheated steam generated from waste heat recovery at the kiln tail and kiln head for the booster fan of the back-pressure turbine direct-drive flue gas treatment system, and then distributing the discharged medium-pressure steam for heating CO purification feed gas and waste heat power generation, precise cascade matching of different grades of thermal energy can be achieved. This helps reduce the conversion loss between electrical and mechanical energy, improving energy utilization efficiency. Attached Figure Description

[0083] Figure 1 A schematic diagram of a method for utilizing waste heat from a cement kiln, reducing CO2 emissions, and co-producing CO, provided by the present invention;

[0084] Figure 2 This is a schematic diagram of the overall device upon which the method for utilizing waste heat from a cement kiln and reducing CO2 emissions to co-produce CO provided by this invention is applied to the carbon emission reduction retrofit process of a specific cement production line.

[0085] Figure 3 This invention provides a schematic diagram of the structural composition of a cement kiln waste heat utilization, CO2 emission reduction and CO co-production system;

[0086] In the diagram, 1-Cement calcination and CO2 cracking system; 1a-Kiln tail flue; 1b-Decomposition furnace; 1c-5-stage cyclone separator; 1d-CO reactor; 1e-Pulverized coal injection system; 1f-4-stage cyclone separator; 1g-1-stage cyclone separator; 2-Kiln tail boiler; 2a-Kiln tail superheater; 2b-Kiln tail evaporator; 2c-Kiln tail steam drum; 2d-Kiln tail economizer; 3-Kiln head boiler; 3a-Kiln head superheater; 3b-Kiln... 3-Evaporator at the kiln head; 3-Steam drum at the kiln head; 3-Economizer at the kiln head; 3-Common economizer; 4-Dust collector; 5-Induced draft fan; 6-Desulfurization water washing tower; 7-Steam turbine drive system; 7a-First booster fan; 7b-Back pressure steam turbine; 7c-Second booster fan; 8-Waste gas treatment device; 8a-Adsorption bed; 8b-Drying bed; 9-First heater; 10-CO pressure swing adsorption device; 10a-CO adsorption tower; 10b-CO adsorption tower inlet; 10c-CO adsorption tower outlet; 11-Vacuum pump; 12-Storage tank; 13-Compressor; 14-Second heater; 15-Steam turbine; 16-Generator; 17-Condenser; 18-Water pump; A-Waste gas emission; B-As raw material for industrial production. Detailed Implementation

[0087] This invention proposes a method and system for utilizing waste heat from cement kilns, reducing CO2 emissions, and co-producing CO. The specific embodiments of this invention will be further described in detail below with reference to the accompanying drawings.

[0088] Example 1:

[0089] This invention provides a method for utilizing waste heat from cement kilns, reducing CO2 emissions, and co-producing CO. A schematic flow diagram is shown below. Figure 1 As shown, it includes:

[0090] Step 1: Cement raw materials are preheated and decomposed in the decomposition furnace to generate high-temperature flue gas containing CO2 carrying hot raw materials. The high-temperature flue gas is then passed into a matching cyclone separator (e.g., a 5th stage cyclone separator) for gas-solid separation. The hot raw materials are separated and enter the kiln tail flue chamber, while the high-temperature flue gas containing CO2 enters the pre-set CO reactor.

[0091] Step 2: Powdered coal is injected into the CO reactor. The waste heat of the high-temperature flue gas is used as the heat source for the reaction, and the CaO contained in the hot raw material that enters the CO reactor with the high-temperature flue gas is used as a catalyst. The carbon in the powdered coal reacts with the CO2 in the high-temperature flue gas to generate CO-containing reaction flue gas.

[0092] Step 3: The reaction flue gas is sequentially fed into the cyclone separators of each stage of the preheater for countercurrent heat exchange with the raw materials. The flue gas after heat exchange enters the kiln tail boiler of the cement kiln to recover waste heat. At the same time, the waste heat of the grate cooler is recovered by the kiln head boiler of the cement kiln. The two waste heat sources are used to produce superheated steam.

[0093] Step 4: The superheated steam is fed into the back-pressure turbine to drive the back-pressure turbine to drive the booster fan of the flue gas treatment system (for example, it can drive the two-stage booster fan of the flue gas treatment system); the medium-pressure steam discharged from the back-pressure turbine is divided into two paths. The first path of medium-pressure steam is used to heat the CO purification raw material gas, and the second path of medium-pressure steam is sent into the condensing turbine to drive the generator to generate electricity.

[0094] Step 5: The low-temperature flue gas obtained after heat exchange in the kiln tail boiler is purified by dust collection, desulfurization and dehydration in sequence. After being pressurized by the booster fan, it is heated by the first medium-pressure steam and sent to the CO pressure swing adsorption device for purification to obtain industrial-grade CO product.

[0095] In one implementation, in step 1 above, the cement raw meal is preheated and decomposed in a decomposition furnace to generate high-temperature flue gas containing CO2 carrying the hot raw meal. The high-temperature flue gas is then passed into a matching cyclone separator for gas-solid separation. The separated hot raw meal enters the kiln tail flue chamber. The process of the high-temperature flue gas containing CO2 entering a pre-set CO reactor may include:

[0096] Cement raw materials undergo calcium carbonate decomposition in a decomposition furnace, generating high-temperature flue gas containing CO2.

[0097] The high-temperature flue gas carries the hot raw materials generated by decomposition into a matching cyclone separator for gas-solid separation, resulting in high-temperature flue gas after gas-solid separation.

[0098] The high-temperature flue gas after gas-solid separation is introduced into a pre-set CO reactor.

[0099] For example, the CO reactor can be located in the high-temperature flue gas passage downstream of the decomposition furnace (high temperature refers to a flue gas passage with a temperature not lower than 800°C).

[0100] In this implementation, by utilizing the existing preheating and separation process of the cement kiln, no additional flue gas pretreatment unit is required. This enables precise separation and transport of high-temperature flue gas and hot raw materials, ensuring that the flue gas entering the reactor has stable high-temperature reaction conditions and natural catalytic components. Furthermore, the reactor is located downstream of the decomposer in the high-temperature flue gas path, reusing the thermal gradient of the existing flue gas system and avoiding heat loss during long-distance transport of the high-temperature flue gas. Additionally, a micro-positive pressure control unit (specifically, a pressure sensor, electric regulating valve, and control unit can be installed on the duct between the CO reactor outlet and the inlet of the 4-stage cyclone separator) can be considered. The controller adjusts the opening of the electric regulating valve according to the detection signal of the pressure sensor to maintain the pressure in this section of the duct slightly higher than the ambient pressure of the preheater system (e.g., maintaining the pressure in the duct 50-100 Pa higher than the ambient pressure of the preheater). The reason is that the existing technology generally adopts negative pressure operation to prevent the overflow of high-temperature flue gas and pollution of the environment. However, this implementation method is designed for the characteristics of high concentration of CO in the reaction flue gas. It actively sets a micro positive pressure in the local key section, which can prevent the risk of CO oxidation reaction with oxygen caused by air leakage in the preheater. This not only avoids the unnecessary loss of CO products, but also eliminates the safety hazard of local oxidation and overheating damage to the equipment.

[0101] In one implementation, the process of injecting pulverized coal into the CO reactor in step 2 above, using the waste heat of the high-temperature flue gas as a reaction heat source, and the CaO contained in the hot raw material entering the CO reactor with the high-temperature flue gas as a catalyst, allows the carbon in the pulverized coal to undergo a reduction reaction with the CO2 in the high-temperature flue gas to generate CO-containing reaction flue gas. This process may include:

[0102] A set of coal powder injection devices are uniformly arranged circumferentially along the side wall of the CO reactor to inject coal powder into the CO reactor in a metered manner.

[0103] Based on the online monitoring data of CO2 in the flue gas at the inlet of the CO reactor, the coal powder injection rate is adjusted in real time to control the molar ratio of fixed carbon in the coal powder to CO2 in the flue gas to be within the range of 0.9-1.5.

[0104] The reaction temperature is maintained by utilizing the residual heat of the high-temperature flue gas, while the CaO contained in the hot raw material entering the CO reactor with the high-temperature flue gas is used for catalytic reduction, so that the carbon in the coal powder reacts fully with the CO2 in the high-temperature flue gas to generate CO-containing reaction flue gas.

[0105] For example, the temperature of the above reduction reaction can be controlled at 850~950℃, and the flue gas residence time is ≥2s;

[0106] In this implementation, multiple sets of pulverized coal injection devices arranged circumferentially can achieve full mixing and contact between pulverized coal and flue gas. The amount of pulverized coal injection can be dynamically adjusted based on online monitoring data of CO2 in the inlet flue gas, ensuring the stable progress of the reduction reaction. No additional special catalyst or external heating source is required, which helps to significantly reduce material consumption and operating energy consumption in the CO2 conversion process. At the same time, in-situ catalysis is achieved by reusing the waste heat of the high-temperature flue gas already present in the cement kiln and the natural CaO component generated by the decomposition of raw materials, without the need for additional catalyst. This not only reduces costs but also significantly improves the CO2 conversion efficiency, allowing the reaction to be completed in a very short time, meeting the needs of continuous industrial production.

[0107] In one implementation, step 3 above involves sequentially feeding the reaction flue gas into each stage of the preheater's cyclone separators for countercurrent heat exchange with the raw materials. The flue gas after heat exchange then enters the kiln tail boiler of the cement kiln to recover waste heat. Simultaneously, the waste heat from the grate cooler is recovered using the kiln head boiler of the cement kiln. The process of using both waste heat sources to jointly produce superheated steam may include:

[0108] The CO-containing reaction flue gas is sequentially fed into each stage of the preheater cyclone separator, where it undergoes multi-stage countercurrent heat exchange with the cement raw material entering the preheater in the opposite direction, resulting in flue gas cooled by heat exchange.

[0109] The flue gas, after heat exchange and cooling, is discharged from the preheater outlet and enters the kiln tail boiler of the cement kiln. It then passes through the heat exchanger, evaporator, and economizer in sequence to complete heat exchange and generate the first stream of steam.

[0110] The high-temperature hot air discharged from the cement kiln grate cooler enters the kiln head boiler, and passes through the heat exchanger, evaporator and economizer in sequence to generate a second stream of steam.

[0111] The first stream of steam is combined with the second stream of steam to form superheated steam;

[0112] In this implementation, by recirculating the flue gas after the CO conversion reaction to the preheater system for countercurrent heat exchange with the raw materials, the waste heat from the conversion reaction is directly reused in the core preheating stage of cement clinker production, rather than being directly sent to the waste heat boiler, thus achieving cascaded synergistic recovery of reaction waste heat.

[0113] In one implementation, step 4 above involves feeding the superheated steam into a back-pressure turbine to drive the turbine and power the booster fan of the flue gas treatment system. The intermediate-pressure steam discharged from the back-pressure turbine is divided into two paths: the first path is used to heat the CO purification feed gas, and the second path is fed into a condensing turbine to drive a generator to generate electricity.

[0114] The superheated steam is fed into a back-pressure turbine to drive the back-pressure turbine to operate.

[0115] The back-pressure steam turbine directly drives the booster fan of the flue gas treatment system via a coaxial connection.

[0116] The back-pressure steam turbine discharges medium-pressure steam;

[0117] The medium-pressure steam is divided into two streams. The first stream of medium-pressure steam is sent to the heating device of the CO purification process, and the second stream of medium-pressure steam is sent to the condensing steam turbine to drive the condensing steam turbine to operate and drive the generator to generate electricity.

[0118] The discharge pressure of the back-pressure steam turbine is 0.5-1.2 MPa.

[0119] In this implementation, by prioritizing the use of high-grade superheated steam to directly drive the booster fan of the flue gas treatment system, the secondary conversion between electrical and mechanical energy can be eliminated, which helps to reduce the plant's power consumption. At the same time, the medium-grade steam discharged from the back-pressure turbine is precisely matched to the heating requirements of the CO purification process, and the remaining steam is used for power generation, which enables the on-demand allocation and full utilization of thermal energy of different grades.

[0120] In one implementation, the low-temperature flue gas obtained after heat exchange in the kiln tail boiler in step 5 above is successively purified by dust collection, desulfurization, and dehydration, then pressurized by the booster fan, heated by the first medium-pressure steam, and sent to a CO pressure swing adsorption device for purification to obtain industrial-grade CO products. This process may include:

[0121] The low-temperature flue gas, after being cooled by heat exchange in the kiln tail boiler, is then passed through a dust collector to remove dust, a desulfurization water washing tower to remove acidic gases, and a drying device to remove moisture, resulting in purified flue gas.

[0122] The purified flue gas is first pressurized by the first set of booster fans, and then the residual impurities are removed by the waste gas treatment device to obtain flue gas after impurity removal.

[0123] The flue gas after impurities are removed is pressurized a second time by the second set of booster fans to obtain pressurized flue gas.

[0124] The pressurized flue gas is heated by the first medium-pressure steam and then sent to a CO pressure swing adsorption device for selective adsorption and purification to obtain industrial-grade CO products.

[0125] In this implementation, the process of selectively adsorbing and purifying CO using a pressure swing adsorption (PSA) unit to obtain industrial-grade CO products may include:

[0126] The heated flue gas enters the adsorption tower of the CO pressure swing adsorption unit (at least two adsorption towers in parallel alternately perform adsorption, desorption and production). The alumina and copper-loaded composite adsorbent packed in the adsorption tower selectively adsorbs CO in the flue gas.

[0127] After adsorption is complete, the adsorption tower is evacuated by a vacuum pump to obtain CO product, which is then sent to the product storage tank.

[0128] A portion of the CO product gas is extracted from the product storage tank, pressurized, heated, and then returned to the adsorption tower as flushing gas to improve the CO desorption effect.

[0129] In the above implementation method, the quality and pressure conditions of the flue gas entering the adsorption device are ensured by multi-stage purification and two-stage pressurization process. High selective adsorption of CO can be achieved by using alumina and copper-loaded composite adsorbent. The desorption efficiency and product purity can be improved by rinsing with partial product gas recirculation. Furthermore, the entire purification process does not require the introduction of additional chemical reagents, which can avoid secondary pollution and ensure the quality stability of industrial-grade CO products.

[0130] In summary, this invention addresses the problems of high energy consumption and insufficient market saturation and absorption capacity of the captured liquid CO2 in existing cement kiln carbon reduction technologies, which rely on traditional chemical adsorption methods for CO2 collection. This invention proposes a method for co-producing CO2 from cement kiln waste heat, reducing CO2 emissions, and generating CO. By deeply coupling the material and energy flows of the entire cement production process with the CO2 conversion process, it achieves in-situ CO2 carbon conversion and cascade utilization of waste heat resources. This method requires no additional energy input or specialized catalysts, transforming previously difficult-to-absorb greenhouse gases into high-value-added industrial raw materials. This significantly improves the economic feasibility of cement kiln carbon reduction projects while requiring minimal modifications to existing cement production line equipment, facilitating rapid and large-scale application across the entire industry.

[0131] Example 2:

[0132] A specific embodiment demonstrates the application of the cement kiln waste heat utilization, CO2 emission reduction, and CO co-production method proposed in this invention to the carbon emission reduction retrofit of a cement production line. A schematic diagram of the underlying equipment is shown below. Figure 2 As shown, the device includes a cement calcination and CO2 cracking system 1, a flue gas treatment system, a CO pressure swing adsorption system, and a waste heat recovery and utilization system. The cement calcination and CO2 cracking system 1 may include a preheater system consisting of a kiln tail flue chamber 1a, a decomposition furnace 1b, a 5-stage cyclone separator 1c, a CO reactor 1d, a pulverized coal injection system 1e, a 4-stage cyclone separator 1f, a 1-stage cyclone separator 1g, and matching ductwork. The bottom two stages of the original 5-stage preheater are disconnected and inserted into the CO reactor 1d. The outlet of the decomposition furnace 1b is connected to the inlet of the 5-stage cyclone separator 1c, the outlet of the 5-stage cyclone separator 1c is connected to the inlet of the CO reactor 1d, and the outlet of the CO reactor 1d is connected to the inlet of the 4-stage cyclone separator 1f. Multiple sets of pulverized coal injection systems 1e are evenly arranged along the circumference of the CO reactor 1d on the reactor sidewall.

[0133] The flue gas treatment system includes a dust collector 4, an induced draft fan 5, a desulfurization water washing tower 6, a turbine drive system 7, and a waste gas treatment device 8. The turbine drive system 7 includes a first booster fan 7a, a back-pressure turbine 7b, and a second booster fan 7c. The waste gas treatment device 8 includes an adsorption bed 8a and a drying bed 8b. The flue gas from the outlet of the first-stage cyclone separator 1g is cooled by the kiln tail boiler 2 and then enters the dust collector 4. It is then sent to the desulfurization water washing tower 6 by the induced draft fan 5, and subsequently passes through the first booster fan 7a, the adsorption bed 8a, the drying bed 8b, and the second booster fan 7c in sequence. The adsorption bed 8a is filled with alumina, silica gel adsorbent, and activated carbon in sequence, and the drying bed 8b is filled with alumina and molecular sieve in sequence. Both the first booster fan 7a and the second booster fan 7c are directly driven by the back-pressure turbine 7b. The CO pressure swing adsorption system includes a first heater 9, a CO pressure swing adsorption device 10, a vacuum pump 11, a storage tank 12, a compressor 13, and a second heater 14. The CO pressure swing adsorption device 10 includes a CO adsorption tower 10a, a CO adsorption tower inlet 10b, and a CO adsorption tower outlet 10c. The flue gas, after being pressurized by the second booster fan 7c, enters the first heater 9, and then enters the CO adsorption tower 10a through the CO adsorption tower inlet 10b. The vacuum pump 11 is connected to the CO adsorption tower 10a, and the inlet of the storage tank 12 is connected to the outlet of the vacuum pump 11. The compressor 13 and the second heater 14 are connected sequentially between the storage tank 12 and the CO adsorption tower 10a. The CO adsorption tower 10a is sequentially filled with alumina and copper-loaded adsorbent. The heat source for both the first heater 9 and the second heater 14 comes from the exhaust steam of the back pressure turbine 7b.

[0134] The waste heat recovery system includes a kiln tail boiler 2, a kiln head boiler 3, a steam turbine 15, a generator 16, a condenser 17, and a water pump 18. The kiln tail boiler 2 includes a kiln tail superheater 2a, a kiln tail evaporator 2b, a kiln tail steam drum 2c, and a kiln tail economizer 2d. The kiln head boiler 3 includes a kiln head superheater 3a, a kiln head evaporator 3b, a kiln head steam drum 3c, a kiln head economizer 3d, and a common economizer 3e. The steam outlets of both the kiln tail boiler 2 and the kiln head boiler 3 are connected to the inlet of the back-pressure steam turbine 7b. The exhaust port of the back-pressure steam turbine 7b is connected to the first heater 9, the second heater 14, and the inlet of the steam turbine 15, respectively. The steam turbine 15 is coaxially connected to the generator 16. The condenser 17 and the water pump 18 are sequentially connected between the outlet of the condenser 17 and the boiler feedwater inlet.

[0135] The device can be operated in the following steps:

[0136] (1) In-situ CO2 transformation

[0137] Cement raw materials are heated and decomposed in decomposition furnace 1b, generating high-temperature flue gas (e.g., 880℃). The flue gas carries the hot raw materials into a 5-stage cyclone separator 1c for gas-solid separation. The separated high-temperature flue gas enters CO reactor 1d. The pulverized coal injection system 1e injects pulverized coal according to the online monitoring data of CO2 in the inlet flue gas, controlling the molar ratio of carbon to CO2 to be 1.1. The high-temperature flue gas provides the heat source for the reaction. The CaO in the small amount of hot raw materials (10-35g / Nm3) that enter the reactor with the flue gas acts as a catalyst, causing the carbon in the pulverized coal to undergo a reduction reaction with CO2 to generate CO.

[0138] (2) Waste heat recovery

[0139] After the above-mentioned conversion reaction, the flue gas passes through the 4th to 1st stage cyclone separators in sequence. After countercurrent heat exchange with the raw materials to complete the preheater waste heat recovery, it enters the kiln tail boiler 2 and passes through the kiln tail superheater 2a, kiln tail evaporator 2b, and kiln tail economizer 2d in sequence to generate the first path of superheated steam. At the same time, the hot air from the kiln head grate cooler enters the kiln head boiler 3 and passes through the kiln head superheater 3a, kiln head evaporator 3b, kiln head economizer 3d, and common economizer 3e in sequence to generate the second path of superheated steam.

[0140] (3) Steam cascade utilization

[0141] After the two superheated steam streams merge, they enter the back-pressure turbine 7b, which drives the first booster fan 7a and the second booster fan 7c directly. The 0.8MPa, 170℃ medium-pressure steam discharged from the back-pressure turbine 7b is divided into two streams. One stream is sent to the first heater 9 and the second heater 14 to heat the raw material gas, and the other stream is sent to the turbine 15 to expand and do work, driving the generator 16 to generate electricity.

[0142] (4) Flue gas purification and upgrading

[0143] The low-temperature flue gas (e.g., 180°C) after heat exchange in the kiln tail boiler 2 is successively filtered by the dust collector 4, pressurized by the induced draft fan 5, and desulfurized by the desulfurization water washing tower 6 to remove SO2. After being pressurized by the first booster fan 7a, it enters the adsorption bed 8a to remove residual impurities. After being dehydrated by the drying bed 8b, it is pressurized to 1.0MPa by the second booster fan 7c. Finally, it is heated to 50°C by the first heater 9 and sent to the CO pressure swing adsorption device 10.

[0144] (5) CO purification and output

[0145] The CO pressure swing adsorption (PSA) unit 10 may include three CO adsorption towers 10a connected in parallel. By sequentially controlling the adsorption, vacuum desorption, and product gas rinsing processes, continuous purification and production of CO can be achieved. Flue gas enters the CO adsorption tower 10a through the CO adsorption tower inlet 10b. The copper-loaded adsorbent selectively adsorbs CO, while gases such as N2 and O2 are discharged from port A through the CO adsorption tower outlet 10c. After adsorption is completed, the vacuum pump 11 is turned on to evacuate and desorb the CO adsorption tower 10a. The obtained CO product is sent to the storage tank 12. A small amount of CO product gas is extracted from the storage tank 12, pressurized by the compressor 13, heated to 90°C by the second heater 14, and then returned to the CO adsorption tower 10a as rinsing gas. The final industrial-grade CO product is output from port B as a raw material for chemical production.

[0146] This embodiment illustrates that the method for utilizing waste heat from cement kilns, reducing CO2 emissions, and co-producing CO proposed in this invention achieves in-situ CO2 conversion without additional heat sources or catalysts by reusing the existing high-temperature flue gas waste heat from the cement kiln itself and the natural CaO components generated from the decomposition of raw materials. This significantly reduces the energy consumption for CO2 conversion and solves the problem of CO2 disposal after capture. Moreover, it can be implemented simply by inserting a CO reactor between the two-stage cyclone separators of the existing preheater, requiring minimal modification work and low investment, thus making the cement kiln carbon emission reduction project significantly economically feasible.

[0147] Example 3:

[0148] Based on the same inventive concept, this invention also provides a cement kiln waste heat utilization, CO2 emission reduction and CO co-production system, the structural composition of which is shown in the schematic diagram below. Figure 3 As shown, it includes:

[0149] The preheating decomposition module is used to heat and decompose cement raw materials in the decomposition furnace to generate high-temperature flue gas containing CO2 carrying hot raw materials. The high-temperature flue gas is then passed into a matching cyclone separator for gas-solid separation. The hot raw materials are separated and enter the kiln tail flue chamber, while the high-temperature flue gas containing CO2 enters the pre-set CO reactor.

[0150] The catalytic reduction module is used to inject pulverized coal into the CO reactor, using the waste heat of the high-temperature flue gas as the heat source for the reaction and the CaO contained in the hot raw material that enters the CO reactor with the high-temperature flue gas as the catalyst, so that the carbon in the pulverized coal reacts with the CO2 in the high-temperature flue gas to generate CO-containing reaction flue gas.

[0151] The countercurrent heat exchange module is used to sequentially send the reaction flue gas into the cyclone separators of each stage of the preheater for countercurrent heat exchange with the raw materials. The flue gas after heat exchange enters the kiln tail boiler of the cement kiln to recover waste heat. At the same time, the waste heat of the grate cooler is recovered by the kiln head boiler of the cement kiln. The two waste heat sources are used to produce superheated steam.

[0152] The fan drive module is used to send the superheated steam into the back pressure turbine and drive the back pressure turbine to drive the booster fan of the flue gas treatment system; the medium-pressure steam discharged from the back pressure turbine is divided into two paths, the first path of medium-pressure steam is used to heat the CO purification raw material gas, and the second path of medium-pressure steam is sent into the condensing turbine to drive the generator to generate electricity.

[0153] The CO generation module is used to purify the low-temperature flue gas obtained after heat exchange in the kiln tail boiler by sequentially collecting dust, desulfurizing, and dehydrating it. After being pressurized by the booster fan, it is heated by the first medium-pressure steam and sent to the CO pressure swing adsorption device for purification to obtain industrial-grade CO products.

[0154] In one implementation, the preheating decomposition module may include:

[0155] The flue gas generation submodule is used to decompose cement raw materials into calcium carbonate in the decomposition furnace to generate high-temperature flue gas containing CO2.

[0156] The gas-solid separation submodule is used to carry the hot raw materials generated by the decomposition of the high-temperature flue gas into the matching cyclone separator for gas-solid separation, so as to obtain the high-temperature flue gas after gas-solid separation.

[0157] The gas inlet submodule is used to introduce the high-temperature flue gas after gas-solid separation into a pre-set CO reactor.

[0158] For example, the CO reactor may be located in the high-temperature flue gas passage downstream of the decomposition furnace.

[0159] In one implementation, the catalytic reduction module may include:

[0160] The pulverized coal injection submodule is used to quantitatively inject pulverized coal into the CO reactor through multiple sets of pulverized coal injection devices evenly arranged circumferentially along the sidewall of the CO reactor.

[0161] The CO2 monitoring submodule is used to adjust the coal powder injection rate in real time based on the online CO2 monitoring data of the flue gas at the inlet of the CO reactor, and control the molar ratio of fixed carbon in the coal powder to CO2 in the flue gas to be within the range of 0.9-1.5.

[0162] The high-temperature reaction submodule is used to maintain the reaction temperature by utilizing the residual heat of the high-temperature flue gas, and at the same time, to utilize the CaO contained in the hot raw material entering the CO reactor with the high-temperature flue gas for catalytic reduction reaction, so that the carbon in the coal powder reacts fully with the CO2 in the high-temperature flue gas to generate CO-containing reaction flue gas.

[0163] In one implementation, the countercurrent heat exchange module may include:

[0164] The heat exchange and cooling submodule is used to sequentially send the CO-containing reaction flue gas into each stage of the preheater cyclone separator, and perform multi-stage countercurrent heat exchange with the cement raw material entering the preheater in the opposite direction to obtain the flue gas after heat exchange and cooling.

[0165] The first heat exchange submodule is used to discharge the cooled flue gas from the preheater outlet and enter the kiln tail boiler of the cement kiln, where it passes through the heat exchanger, evaporator and economizer in sequence to complete the heat exchange and generate the first steam.

[0166] The second heat exchange submodule is used to introduce the high-temperature hot air discharged from the cement kiln grate cooler into the kiln head boiler, and then pass through the heat exchanger, evaporator and economizer in sequence to complete the heat exchange and generate a second steam.

[0167] The steam merging submodule is used to merge the first steam stream with the second steam stream to form superheated steam.

[0168] In one implementation, the wind turbine drive module may include:

[0169] The turbine drive submodule is used to send the superheated steam into the back pressure turbine and drive the back pressure turbine to operate;

[0170] The coaxial booster submodule is used to directly drive the booster fan of the flue gas treatment system via the back pressure turbine through a coaxial connection.

[0171] The waste heat utilization module is used to utilize the medium-pressure steam discharged from the back-pressure steam turbine. The medium-pressure steam is divided into two paths: the first path of medium-pressure steam is sent to the heating device of the CO purification process, and the second path of medium-pressure steam is sent to the condensing steam turbine to drive the condensing steam turbine to operate and drive the generator to generate electricity.

[0172] The discharge pressure of the back-pressure steam turbine is 0.5-1.2 MPa.

[0173] In one implementation, the CO generation module may include:

[0174] The flue gas purification submodule is used to process the low-temperature flue gas after heat exchange and cooling in the kiln tail boiler through a dust collector to remove dust, a desulfurization water washing tower to remove acidic gases, and a drying device to remove moisture, thereby obtaining purified flue gas.

[0175] The first-stage booster submodule is used to first boost the purified flue gas through the first set of booster fans, and then remove residual impurities through the waste gas treatment device to obtain flue gas after impurity removal.

[0176] The secondary booster submodule is used to boost the impurity-removed flue gas a second time through a second set of booster fans to obtain boosted flue gas.

[0177] The CO purification submodule is used to heat the pressurized flue gas through the first medium-pressure steam path and then send it to a CO pressure swing adsorption device for selective adsorption and purification to obtain industrial-grade CO products.

[0178] In this implementation, the CO purification submodule may include:

[0179] The CO adsorption unit is used to introduce heated flue gas into the adsorption tower of the CO pressure swing adsorption device. The alumina and copper-loaded composite adsorbent packed in the adsorption tower selectively adsorbs CO in the flue gas.

[0180] The vacuum desorption unit is used to perform vacuum desorption on the adsorption tower after adsorption is completed by a vacuum pump to obtain CO product and send it to the product storage tank; the CO product gas is extracted from the product storage tank, pressurized and heated and then returned to the adsorption tower as flushing gas to improve the CO desorption effect.

[0181] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0182] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0183] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0184] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0185] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit its protection scope. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that after reading the present invention, they can still make various changes, modifications or equivalent substitutions to the specific implementation of the present application, but these changes, modifications or equivalent substitutions are all within the protection scope of the claims of the present application.

Claims

1. A method for utilizing waste heat from a cement kiln, reducing CO2 emissions, and co-producing CO, characterized in that, include: Cement raw materials are heated and decomposed in a decomposition furnace to generate high-temperature flue gas containing CO2 carrying the hot raw materials. The high-temperature flue gas is then passed into a matching cyclone separator for gas-solid separation. The hot raw materials are separated and enter the kiln tail flue chamber, while the high-temperature flue gas containing CO2 enters a pre-set CO reactor. Powdered coal is injected into the CO reactor, and the waste heat of the high-temperature flue gas is used as the heat source for the reaction. The CaO contained in the hot raw material that enters the CO reactor with the high-temperature flue gas is used as a catalyst to reduce the carbon in the powdered coal and the CO2 in the high-temperature flue gas to generate CO-containing reaction flue gas. The reaction flue gas is sequentially fed into the preheater and each stage of the cyclone separator to exchange heat with the raw material in a countercurrent manner. The flue gas after heat exchange enters the kiln tail boiler of the cement kiln. At the same time, the kiln head boiler of the cement kiln is set up. The waste heat boilers at the kiln head and the kiln tail recover their respective waste heat to produce superheated steam. The superheated steam is fed into a back-pressure turbine, which drives the back-pressure turbine to drive the booster fan of the flue gas treatment system. The medium-pressure steam discharged from the back-pressure turbine is divided into two paths. The first path of medium-pressure steam is used to heat the CO purification feed gas, and the second path of medium-pressure steam is fed into a condensing turbine to drive a generator to generate electricity. The low-temperature flue gas obtained after heat exchange in the kiln tail boiler is purified by dust collection, desulfurization, and dehydration in sequence. It is then pressurized by the booster fan, heated by the first medium-pressure steam, and sent to the CO pressure swing adsorption device for purification to obtain industrial-grade CO products.

2. The method as described in claim 1, characterized in that, The cement raw meal is heated and decomposed in a decomposition furnace, generating high-temperature flue gas containing CO2 and carrying the hot raw meal. This high-temperature flue gas is then passed into a matching cyclone separator for gas-solid separation. The separated hot raw meal enters the kiln tail flue chamber, while the CO2-containing high-temperature flue gas enters a pre-set CO reactor, including: Cement raw materials undergo calcium carbonate decomposition in a decomposition furnace, generating high-temperature flue gas containing CO2. The high-temperature flue gas carries the hot raw material into the matching cyclone separator for gas-solid separation, and obtains high-temperature flue gas after gas-solid separation. The high-temperature flue gas after gas-solid separation is introduced into a pre-set CO reactor.

3. The method as described in claim 1 or 2, characterized in that, The CO reactor is located in the high-temperature flue gas passage downstream of the decomposition furnace.

4. The method as described in claim 1, characterized in that, The process involves injecting pulverized coal into the CO reactor, utilizing the waste heat of the high-temperature flue gas as a reaction heat source, and using CaO contained in the hot raw material entering the CO reactor with the high-temperature flue gas as a catalyst. This causes the carbon in the pulverized coal to undergo a reduction reaction with the CO2 in the high-temperature flue gas, generating CO-containing reaction flue gas. The process includes: A set of coal powder injection devices are uniformly arranged circumferentially along the side wall of the CO reactor to inject coal powder into the CO reactor in a metered manner. Based on the online monitoring data of CO2 in the flue gas at the inlet of the CO reactor, the coal powder injection rate is adjusted in real time to control the molar ratio of fixed carbon in the coal powder to CO2 in the flue gas to be within the range of 0.9-1.

5. The reaction temperature is maintained by utilizing the residual heat of the high-temperature flue gas, while the CaO contained in the hot raw material entering the CO reactor with the high-temperature flue gas is used for catalytic reduction, so that the carbon in the pulverized coal reacts fully with the CO2 in the high-temperature flue gas to generate CO-containing reaction flue gas.

5. The method as described in claim 1, characterized in that, The process involves sequentially feeding the reaction flue gas into each stage of the preheater's cyclone separators for countercurrent heat exchange with the raw materials. The heat-exchanged flue gas then enters the kiln tail boiler of the cement kiln. Simultaneously, a kiln head boiler is installed at the kiln head. Both the kiln head and kiln tail waste heat boilers recover their respective waste heat to produce superheated steam. This includes: The CO-containing reaction flue gas is sequentially fed into each stage of the preheater cyclone separator, where it undergoes multi-stage countercurrent heat exchange with the cement raw material entering the preheater in the opposite direction, resulting in flue gas cooled by heat exchange. The flue gas, after heat exchange and cooling, is discharged from the preheater outlet and enters the kiln tail boiler of the cement kiln. It then passes through the heat exchanger, evaporator, and economizer in sequence to complete heat exchange and generate the first stream of steam. The hot air discharged from the kiln head grate cooler enters the kiln head boiler, and passes through the heat exchanger, evaporator and economizer in sequence to generate a second stream of steam. The first steam stream and the second steam stream are combined to form superheated steam.

6. The method as described in claim 1, characterized in that, The superheated steam is fed into a back-pressure turbine, which drives the turbine to power the booster fan of the flue gas treatment system. The medium-pressure steam discharged from the back-pressure turbine is divided into two paths: the first path is used to heat the CO purification feed gas, and the second path is fed into a condensing turbine to drive a generator to generate electricity. The superheated steam is fed into a back-pressure turbine to drive the back-pressure turbine to operate. The back-pressure steam turbine directly drives the booster fan of the flue gas treatment system via a coaxial connection. The back-pressure steam turbine discharges medium-pressure steam; The medium-pressure steam is divided into two streams. The first stream of medium-pressure steam is sent to the heating device of the CO purification process, and the second stream of medium-pressure steam is sent to the condensing steam turbine to drive the condensing steam turbine to operate and drive the generator to generate electricity. The discharge pressure of the back-pressure steam turbine is 0.5-1.2 MPa.

7. The method as described in claim 1, characterized in that, The low-temperature flue gas obtained after heat exchange in the kiln tail boiler is successively purified by dust collection, desulfurization, and dehydration. It is then pressurized by the booster fan, heated by the first medium-pressure steam, and sent to a CO pressure swing adsorption unit for purification to obtain industrial-grade CO products, including: The low-temperature flue gas, after being cooled by heat exchange in the kiln tail boiler, is then passed through a dust collector to remove dust, a desulfurization water washing tower to remove acidic gases, and a drying device to remove moisture, resulting in purified flue gas. The purified flue gas is first pressurized by the first set of booster fans, and then the residual impurities are removed by the waste gas treatment device to obtain flue gas after impurity removal. The flue gas after impurities are removed is pressurized a second time by the second set of booster fans to obtain pressurized flue gas. The pressurized flue gas is heated by the first medium-pressure steam and then sent to a CO pressure swing adsorption device for selective adsorption and purification to obtain industrial-grade CO products.

8. The method as described in claim 7, characterized in that, The CO product is selectively adsorbed and purified by a pressure swing adsorption (PSA) unit to obtain industrial-grade CO products, including: The heated flue gas enters the adsorption tower of the CO pressure swing adsorption unit, where the alumina and copper-loaded composite adsorbent packed in the adsorption tower selectively adsorbs CO in the flue gas. After adsorption is complete, the adsorption tower is evacuated by a vacuum pump to obtain CO product, which is then sent to the product storage tank. A portion of the CO product gas is extracted from the product storage tank, pressurized, heated, and then returned to the adsorption tower as flushing gas to obtain industrial-grade CO product.

9. A system for utilizing waste heat from a cement kiln, reducing CO2 emissions, and co-producing CO, characterized in that, include: The preheating and decomposition module is used to preheat and decompose cement raw materials in the decomposition furnace to generate high-temperature flue gas containing CO2 carrying hot raw materials. The high-temperature flue gas is then passed into a matching cyclone separator for gas-solid separation. The hot raw materials are separated and enter the kiln tail flue chamber, while the high-temperature flue gas containing CO2 enters the pre-set CO reactor. The catalytic reduction module is used to inject pulverized coal into the CO reactor, using the waste heat of the high-temperature flue gas as the heat source for the reaction and the CaO contained in the hot raw material that enters the CO reactor with the high-temperature flue gas as the catalyst, so that the carbon in the pulverized coal reacts with the CO2 in the high-temperature flue gas to generate CO-containing reaction flue gas. The countercurrent heat exchange module is used to sequentially send the reaction flue gas into the cyclone separators of each stage of the preheater for countercurrent heat exchange with the raw materials. The flue gas after heat exchange enters the kiln tail boiler of the cement kiln to recover waste heat. At the same time, the hot air waste heat of the kiln head grate cooler is recovered by the kiln head boiler of the cement kiln. The two waste heat sources work together to produce superheated steam. The fan drive module is used to send the superheated steam into the back pressure turbine and drive the back pressure turbine to drive the booster fan of the flue gas treatment system; the medium-pressure steam discharged from the back pressure turbine is divided into two paths, the first path of medium-pressure steam is used to heat the CO purification raw material gas, and the second path of medium-pressure steam is sent into the condensing turbine to drive the generator to generate electricity. The CO generation module is used to purify the low-temperature flue gas obtained after heat exchange in the kiln tail boiler by sequentially collecting dust, desulfurizing, and dehydrating it. After being pressurized by the booster fan, it is heated by the first medium-pressure steam and sent to the CO pressure swing adsorption device for purification to obtain industrial-grade CO products.

10. The system as described in claim 9, characterized in that, The preheating decomposition module includes: The flue gas generation submodule is used to decompose cement raw materials into calcium carbonate in the decomposition furnace to generate high-temperature flue gas containing CO2. The gas-solid separation submodule is used to carry the hot raw materials generated by the decomposition of the high-temperature flue gas into the matching cyclone separator for gas-solid separation, so as to obtain the high-temperature flue gas after gas-solid separation. The gas inlet submodule is used to introduce the high-temperature flue gas after gas-solid separation into a pre-set CO reactor.

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