Circulating fluidized bed gasifier, CO2 capture cement production line and gypsum decomposition system

Abstract

This utility model discloses a circulating fluidized bed gasifier, a CO2-captured cement production line, and a gypsum decomposition system. The cement production line, by modifying the decomposition furnace structure and adding a circulating feed pipe, a jacketed circulating fluidized bed gasifier, and a green hydrogen system, achieves high-concentration carbon dioxide capture and alternative fuel recycling. The industrial by-product gypsum decomposition system uses an electromagnetically heated decomposition furnace, gasification coupling, and a green hydrogen system for power supply, achieving co-production of sulfuric acid and lime with low carbon emissions. Both the cement production line and the industrial by-product gypsum decomposition system convert carbon dioxide into combustible gas for their own combustion through a jacketed circulating fluidized bed gasifier, combined with green electricity-to-hydrogen technology, completely solving the problems of fuel cost and carbon emissions. This system features high capture efficiency, low energy consumption, and compact equipment, making it suitable for large-scale industrial applications.

Description

Technical Field

[0001] This utility model relates to the field of carbon neutrality technology, and in particular to a circulating fluidized bed gasifier, a CO2-capturing cement production line, and a gypsum decomposition system. Background Technology

[0002] As a major industry characterized by high energy consumption and high emissions, the cement industry faces particular challenges in achieving carbon neutrality, making energy-saving and carbon-reduction technologies especially crucial. In particular, carbon dioxide capture technology in cement production processes currently faces several challenges and limitations. Firstly, traditional carbon dioxide capture processes such as MEA chemical absorption, pure oxygen combustion, and ammonia cooling methods, while differing in capture efficiency and energy consumption reduction, often require additional equipment investment and significant modifications, resulting in high capture costs and hindering widespread application.

[0003] Meanwhile, the current state of energy conservation and carbon reduction in the cement industry shows that energy-saving and carbon-reduction technologies cover multiple aspects, including low-energy firing, high-efficiency grinding, intelligent manufacturing, and fuel and raw material substitution. Different technologies have varying application effects and implementation difficulties in enterprises. Although a series of energy-saving and carbon-reduction policies and technical roadmap guidelines have been introduced, carbon capture technologies, such as carbon dioxide capture from cement kiln flue gas, have certain potential in "carbon capture and storage," but in practical applications, problems such as high initial investment and high energy consumption still exist.

[0004] Replacing fossil fuels with alternative fuels such as waste-derived fuels (RDF), biomass fuels, plastics, rubber, leather, and waste tires can reduce carbon emissions from fuels. However, these alternative fuels are scarce and more expensive than some types of coal. Their use requires specialized equipment, further increasing costs and making them difficult for cement companies to afford. Furthermore, they frequently cause safety accidents such as spontaneous combustion and injuries. Carbon dioxide, as a carbon-containing resource, is present in 1 Nm³ of... 3 Pure carbon dioxide can replace 0.54 kg of pure carbon, equivalent to 0.64 kg of standard coal; it can replace 1 Nm³ of pure oxygen. 3 This is equivalent to 0.21 kg of standard coal. In other words, every 1 Nm³... 3 Pure carbon dioxide can replace 0.85 kg of standard coal and should be converted and utilized.

[0005] Industrial by-product gypsum, a byproduct of chemical production such as phosphoric acid, faces dual pressures of environmental protection and economics in its treatment and utilization. Phosphogypsum, in particular, suffers from extremely high energy consumption in its pretreatment due to its wet storage characteristics. Furthermore, the high calcium sulfate content in phosphogypsum decomposes under oxygen-containing atmospheres, resulting in substantial energy consumption, and the heat requirement for calcination is almost twice that of calcium carbonate. This poses a challenge to industrial utilization and low-energy decomposition. These issues make the high energy consumption and difficulty in effectively controlling system energy consumption and costs in practical applications of industrial by-product gypsum decomposition systems a global challenge. Utility Model Content

[0006] This invention provides a circulating fluidized bed gasifier, a CO2-capturing cement production line, and a gypsum decomposition system.

[0007] The technical solution adopted in this utility model is as follows:

[0008] This utility model provides a circulating fluidized bed gasifier, including a coal bunker, a tubular screw feeder, a gasifier furnace, a two-stage cyclone separator, a second heat exchanger, a third high-temperature fan, and a slag cooler; the coal bunker is used to store lignite or low-priced coal; the feed end of the tubular screw feeder is connected to the coal bunker outlet, and the outlet end is connected to the gasifier furnace; the gasifier furnace has a double-layer cylindrical structure, with an inner and outer cylinder forming a sandwich layer, and a spirally wound air guide plate is provided in the sandwich layer; the air inlet of the two-stage cyclone separator is connected to the gas outlet of the gasifier furnace, and the outlet is connected to the gasifier furnace. The furnace has a feed inlet; the second heat exchanger's air inlet is connected to the two-stage cyclone separator's outlet; the third high-temperature blower's air inlet is connected to the gasifier's furnace jacket outlet, and the outlet is divided into two paths: one path connects to the gasifier's furnace jacket air inlet, and the other path is equipped with a third gas burner and then connects to the gasifier's furnace jacket air inlet; the slag cooler's feed inlet is connected to the waste outlet at the bottom of the gasifier's furnace; the circulating fluidized bed gasifier uses high-temperature carbon dioxide and steam as gasifying agents to gasify lignite into carbon monoxide and hydrogen, which are then used as alternative fuels for external equipment.

[0009] This utility model also provides a cement production line with complete CO2 capture, including a cement kiln system, a kiln tail decomposition furnace, a preheater assembly, and a gas-solid separator, and further including the aforementioned circulating fluidized bed gasifier, a material distribution device, and a green hydrogen system; wherein: the inlet of the kiln tail decomposition furnace is connected to the outlet of the preheater assembly, and its outlet is connected to the inlet of the gas-solid separator; the outlet of the gas-solid separator is connected to a carbon dioxide circulation pipeline and a first high-temperature fan, the carbon dioxide circulation pipeline including a first branch connecting to the inlet of the kiln tail decomposition furnace and a second branch connecting to the jacketed inlet of the circulating fluidized bed gasifier; the outlet of the gas-solid separator... A first heat exchanger is installed between the gas inlet and the first high-temperature blower; a second high-temperature blower is installed between the gas outlet of the gas-solid separator and the gas inlet of the kiln tail decomposition furnace; a material distribution device is installed with its feed end connected to the discharge end of the gas-solid separator, and its discharge end is divided into two paths: one path returns to the feed inlet of the kiln tail decomposition furnace through a circulating material pipe, and the other path connects to the rotary kiln; a green hydrogen system includes an electrolyzer for generating oxygen and hydrogen, with its hydrogen outlet connected to the burner of the rotary kiln and its oxygen outlet connected to the pure oxygen combustion-supporting pipeline of the kiln tail decomposition furnace; the carbon monoxide and hydrogen combustible gases generated by the circulating fluidized bed gasifier are transported to the kiln tail decomposition furnace through pipelines as fuel for the decomposition furnace.

[0010] Furthermore, the preheater assembly includes preheaters C1, C2, C3, C4 and C5, wherein: preheater C1 is a downward exhaust cyclone; and the air inlet pipe of preheater C5 is equipped with a hydrogen fuel burner.

[0011] Furthermore, the inner wall of the kiln tail decomposition furnace is covered with heat-insulating material, and a second gas burner is provided at the bottom for introducing a mixture of carbon monoxide and hydrogen for combustion.

[0012] This utility model also provides a gypsum decomposition system, including a gypsum pretreatment system, a dual-atmosphere circulating material gypsum decomposition furnace and a cooling system, and further comprising the aforementioned circulating fluidized bed gasifier, separator, fourth high-temperature blower and green hydrogen system; wherein: the gypsum pretreatment system includes a drying crusher, a cyclone separator and a single-compartment air-swept mill, used for dehydrating, acid washing and grinding phosphogypsum; the feed inlet of the dual-atmosphere circulating material gypsum decomposition furnace is connected to the discharge outlet of the first multi-stage cyclone preheater and the second multi-stage cyclone preheater, and its furnace wall has a weak reducing zone The weak oxidation zone is equipped with an electromagnetic heating device; the air inlet of the separator is connected to the gas outlet of the dual-atmosphere circulating gypsum decomposition furnace, and the material outlet is connected to the cooling system; the fourth high-temperature fan is set at the bottom of the dual-atmosphere circulating gypsum decomposition furnace, and blows circulating air into the furnace through the air distribution plate; the hydrogen outlet of the green hydrogen system is connected to the burner of the dual-atmosphere circulating gypsum decomposition furnace, and the oxygen outlet is connected to the pure oxygen combustion pipeline of the decomposition furnace; the carbon monoxide and hydrogen generated by the circulating fluidized bed gasifier are transported to the burner of the first multi-stage cyclone preheater through pipelines.

[0013] Furthermore, the weak reduction zone of the dual-atmosphere circulating gypsum decomposition furnace is equipped with a sulfur injection device for injecting sulfur vapor to promote the decomposition of industrial by-product gypsum.

[0014] Furthermore, the cooling system is a fluidized bed cooler, and its hot air outlet is connected to the air inlet of the drying and crushing machine of the gypsum pretreatment system.

[0015] Furthermore, the first and second multi-stage cyclone preheaters include a weak reduction zone preheater and a weak oxidation zone preheater, which are respectively connected to the circulating fluidized bed gasifier and the green hydrogen system through pipelines.

[0016] Furthermore, the electromagnetic heating device is powered by green electricity, and the furnace temperature is controlled at 1060℃ in the weak reduction zone and 1100℃ in the weak oxidation zone.

[0017] Furthermore, the carbon dioxide outlet of the separator is connected to the jacketed air inlet of the circulating fluidized bed gasifier to form a closed-loop carbon dioxide circulation.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1. This utility model can significantly improve the raw material decomposition efficiency by adding heat insulation material inside the kiln tail decomposition furnace. At the same temperature, the decomposition rate is increased by 8%, the system heat consumption is reduced by 12%, and the amount of waste gas is reduced by 10%, thereby reducing the load on subsequent dust removal and desulfurization equipment.

[0020] 2. This utility model utilizes a jacketed circulating fluidized bed gasifier to generate carbon monoxide and hydrogen combustible gases by using high-concentration carbon dioxide (950℃~1100℃) from the decomposition furnace outlet as a heat carrier, combined with lignite or low-calorific-value coal gasification. This can replace 50% of the coal consumption of the decomposition furnace, significantly reducing fuel costs.

[0021] 3. This utility model provides hydrogen fuel to the rotary kiln at the kiln head through a green hydrogen system (hydrogen production by water electrolysis) and produces oxygen as a byproduct for combustion in the decomposition furnace. This enables zero carbon emissions during the rotary kiln combustion process and avoids the generation of nitrogen oxides, thus meeting environmental protection requirements.

[0022] 4. This utility model, through the electromagnetic heating device and sulfur dioxide enrichment design of the dual-atmosphere circulating material gypsum decomposition furnace, can increase the sulfur dioxide concentration of phosphogypsum decomposition to 80-85%, so that the sulfuric acid system can also adopt the "three-transformation and three-absorption" process after dilution, thereby reducing equipment investment and operating costs.

[0023] 5. This utility model, through the diversion design of the carbon dioxide capture system (low-temperature distillation purification and gasification furnace recycling), can achieve industrial-grade carbon dioxide capture with a comprehensive power consumption of less than 200 kWh / t, reducing the direct cost to 130 yuan / ton CO2, which is significantly more economical than the traditional chemical absorption method.

[0024] 6. This utility model can reduce grinding power consumption by 15% by independently preheating cement additives and optimizing the fineness of raw material grinding, while also reducing the amount of system exhaust gas, further reducing energy consumption.

[0025] 7. This utility model, through the kiln tail decomposition furnace and the dual-atmosphere gypsum decomposition furnace system and their respective coordinated operation, can realize the co-production of cement clinker, industrial-grade carbon dioxide, sulfuric acid and lime, enabling enterprises to obtain multiple benefits through product diversification and carbon trading. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the structure of the circulating fluidized bed gasifier of this utility model;

[0027] Figure 2 This is a schematic diagram of the structure of the gasification furnace chamber of this utility model;

[0028] Figure 3 This is a schematic diagram of the green hydrogen system of this utility model;

[0029] Figure 4 This is a structural schematic diagram of a cement production line with complete CO2 capture according to this utility model;

[0030] Figure 5 This is a schematic diagram of the structure of the gypsum pretreatment system of this utility model;

[0031] Figure 6 This is a schematic diagram of the gypsum decomposition system of this utility model.

[0032] The component names corresponding to the reference numerals in the attached drawings are as follows:

[0033] 1. Kiln tail preheater; 2. Preheater assembly; 3. Gas-solid separator; 4. First heat exchanger; 5. First high-temperature blower; 6. Material distribution device; 7. Circulating feed pipe; 8. First gas burner; 9. Second gas burner; 10. First-stage cyclone separator; 11. Second high-temperature blower; 12. Hydrogen fuel burner; 13. Circulating fluidized bed gasifier; 1301. Coal bunker; 1302. Tubular screw feeder; 1303. Gasifier furnace chamber; 1304. Two-stage cyclone separator; 1305. Slag cooler; 1306. Second heat exchanger; 1307. Third high-temperature blower; 1308. Air guide plate; 1309. Third gas burner 14. Green Hydrogen System; 1401. Water Treatment System; 1402. Electrolyzer; 15. Cement Kiln System; 1501. Rotary Kiln; 1502. Tertiary Air Duct; 1503. Grate Cooler; 1504. AQC Boiler; 16. First Branch; 17. Second Branch; 18. Gypsum Pretreatment System; 19. Dual Atmosphere Gypsum Decomposition Furnace System; 1901. First Multistage Cyclone Preheater; 1902. Second Multistage Cyclone Preheater; 1903. Dual Atmosphere Circulating Material Gypsum Decomposition Furnace; 1904. Electromagnetic Heating Device; 1905. Separator; 20. Fourth High Temperature Fan; 21. Cooling System; 22. Fourth Gas Burner. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below in conjunction with specific embodiments and corresponding drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0035] Example 1

[0036] This embodiment provides a carbon dioxide capture system that can directly capture high-concentration carbon dioxide on existing cement production lines. Structurally, this embodiment mainly includes a kiln tail preheater 1, a preheater assembly 2, a gas-solid separator 3, a material distribution device 6, and a circulating material pipe 7. The feed end of the kiln tail preheater 1 is connected to the discharge end of the preheater assembly 2, and the air inlet end of the kiln tail preheater 1 is connected to the cement kiln system 15; the inlet end of the gas-solid separator 3 is connected to the outlet end of the kiln tail preheater 1. In this embodiment, the kiln tail preheater 1, preheater assembly 2, and gas-solid separator 3 are all existing equipment on the cement production line. In this embodiment, the preheater assembly 2 consists of preheaters C1-C5; the gas-solid separator 3 is a cyclone separator used to separate the gas-solid mixture transported from the kiln tail preheater 1.

[0037] Based on the original shape of the kiln tail decomposition furnace 1, the bottom of the kiln tail decomposition furnace 1 is bent and extended downward to increase its volume. The material distribution device 6 has a "three-way" structure. The inlet end of the material distribution device 6 is connected to the outlet end of the gas-solid separator 3. One end of the outlet end of the material distribution device 6 is connected to the kiln tail decomposition furnace 1 through the circulating material pipe 7, and the other end is connected to the rotary kiln 1501. A new first-stage cyclone separator 10 is added to the original preheater assembly 2. The first-stage cyclone separator 10 is the preheater C2. The inlet end of the preheater C2 is connected to the outlet end of the preheater C1, and the outlet end of the preheater C2 is connected to the inlet end of the preheater C3. The preheater C1 is a downward exhaust cyclone separator. The material distribution device 6, the circulating material pipe 7, and the preheater C2 are all new devices added to the original cement production line.

[0038] In addition, the outlet end of the gas-solid separator 3 is connected to a first heat exchanger 4, and the outlet end of the first heat exchanger 4 is also connected to a first high-temperature fan 5.

[0039] The kiln tail decomposition furnace 1 is equipped with heat insulation material. A second high-temperature fan 11 is also connected to the bottom of the kiln tail decomposition furnace 1. A first gas burner 8 is installed between the kiln tail decomposition furnace 1 and the second high-temperature fan 11; a second gas burner 9 is installed inside the bottom of the kiln tail decomposition furnace 1; and a hydrogen fuel burner 12 is installed at the air inlet pipe of the preheater C5.

[0040] The process for capturing high-concentration carbon dioxide in this embodiment is as follows:

[0041] 1. Initially, high-temperature kiln gas is introduced into the kiln tail decomposition furnace 1 of the cement kiln system 15. The high-temperature kiln gas enters the preheater assembly 2 through the kiln tail decomposition furnace 1 and the gas-solid separator 3, and flows according to the path "C5→C4→C3→C2→C1". At the same time, cement raw meal (mainly a mixture of limestone and cement additives) is introduced into the preheater assembly 2 and preheated using high-temperature kiln gas. The specific preheating process is as follows: cement raw meal is fed into the air inlet pipe of preheater C1. Under the action of high-temperature kiln gas, cement raw meal is preheated and carried into preheater C1. Then, cement raw meal and airflow swirl in C1, resulting in gas-solid separation. Cement raw meal enters the air inlet pipe of preheater C2 through the discharge port of C1. The cement raw meal entering the C2 inlet duct of the preheater undergoes the same process as described above under the action of high-temperature kiln gas, namely, “C2 inlet duct—C2—C2 outlet—C3 inlet duct—C3—C4 inlet duct—C4—C5 inlet duct—C5”. The cement raw meal is preheated to 800-830℃ by the cement kiln tail preheater C5-C1, and finally enters the kiln tail decomposition furnace 1 through the C5 outlet. The high-temperature kiln gas in the preheater assembly 2 is discharged through C1 after cooling, and is then processed by the downstream system and equipment (such as SP boiler) for the next step.

[0042] 2. The heat source for the kiln tail decomposition furnace 1 is provided by the combustion of carbon monoxide and hydrogen gas with pure oxygen. Kiln gas and part of the tertiary air are directly mixed with the kiln gas through the C5 air inlet pipe and fed into the cement kiln preheater for heat energy reuse. The airflow exchanges heat with the raw materials through C6-C1, and is cooled down step by step. The outlet temperature of the preheater C1 is <320℃. The gas-solid mixture from the kiln tail decomposition furnace 1 is separated by the gas-solid separator 3. The high-concentration carbon dioxide gas (carbon dioxide concentration 92-95%) obtained from the decomposition of calcium carbonate is cooled by the first heat exchanger 4 and then sent to the carbon dioxide purification system by the first high-temperature fan 5. Part of the mixture of calcium oxide and other substances obtained from the decomposition of calcium carbonate enters the rotary kiln 1501 for calcination to form cement clinker, and the other part returns to the kiln tail decomposition furnace 1 through the material distribution device 6 and the circulating material pipe 7. The circulating air is drawn from the outlet pipe of the gas-solid separator 3 and sent to the upstream of the kiln tail decomposition furnace 1 by the second high-temperature fan 11. The first gas burner 8 is added to the outlet pipe of the fan to heat the carbon dioxide gas to about 1000℃.

[0043] Example 2

[0044] like Figure 1 As shown, unlike Example 1, in this example, the cement production line is also equipped with a circulating fluidized bed gasifier 13, including a coal bunker 1301, a tubular screw feeder 1302, a gasifier furnace 1303, a two-stage cyclone separator 1304, a slag cooler 1305, a second heat exchanger 1306, and a third high-temperature fan 1307.

[0045] The discharge end of the coal bunker 1301 is connected to the tubular screw feeder 1302, and the tubular screw feeder 1302 is connected to the feed end of the gasifier furnace 1303. Figure 2 As shown, the gasifier furnace 1303 has a double-layer cylindrical structure, with an interlayer between the inner cylinder (lining) and the outer cylinder. A guide plate 1308 is installed in the interlayer, one end of which is connected to a third high-temperature blower 1307 and spirally wound around the inner cylinder. The outer cylinder is made of heat-insulating and refractory materials for thermal insulation, while the inner cylinder is made of high-temperature resistant materials. The discharge end of the gasifier furnace 1303 is connected to the feed end of a two-stage cyclone separator 1304, and the waste discharge port of the gasifier furnace 1303 is connected to a slag cooler 1305. The gas outlet end of the two-stage cyclone separator 1304 is connected to a second heat exchanger 1306, and the gas outlet end of the gasifier furnace 1303 is connected to the third high-temperature blower 1307. A third gas burner 1309 is also installed between the gas outlet end of the gasifier furnace 1303 and the third high-temperature blower 1307.

[0046] The working process of the circulating fluidized bed gasifier 13 in this embodiment is as follows:

[0047] Lignite or other low-calorific-value coal, after being crushed and screened to the required fineness, is stored in coal bunker 1301. After metering, it enters the gasifier furnace 1303 via tubular screw feeder 1302. Gasifying agent steam is supplied by the kiln head AQC boiler 1504, while carbon dioxide is extracted from the outlet of the kiln tail decomposition furnace 1 and enters the gasifier furnace 1303 via the third high-temperature blower 1307 and guide plate 1308. High-concentration carbon dioxide gas is diverted by the third high-temperature blower 1307, heated to over 1000℃ by the third gas burner 1309, and enters the jacket to insulate the gasifier furnace 1303 and transfer heat into its interior, ensuring that the carbon consumption for CO2 conversion is close to the theoretical value. The combustible gas obtained through gasification, mainly composed of carbon monoxide and hydrogen, is separated by a two-stage cyclone separator 1304 and then cooled to 700℃ by a second heat exchanger 1306 to become hot coal gas, which is directly supplied to the cement kiln's decomposition furnace and kiln head system. This system is preferably built at the kiln tail.

[0048] Example 3

[0049] Unlike Embodiments 1 or 2, in this embodiment, a green hydrogen system 14 is also installed on the cement production line, such as... Figure 3 As shown, the system includes a water treatment system 1401, green electricity, and an electrolyzer 1402. Electricity is generated using (self-built) green energy sources such as wind and solar power, while also incorporating grid-connected power grid technology. After being treated by the water treatment system 1401, the water enters the electrolyzer 1402 to produce hydrogen and oxygen. The produced hydrogen is used for combustion (air-assisted combustion) in the rotary kiln 1501 at the kiln head, and the combustion product is water vapor, which can be directly vented. The byproduct oxygen is used as an auxiliary for the oxygen-based combustion in the decomposition furnace system.

[0050] In addition, to further reduce costs, PSA pressure swing adsorption technology is used to separate a portion of the hydrogen during the conversion of carbon dioxide into carbon monoxide and hydrogen combustible gas, which is then used as fuel for the kiln head and preheater components.

[0051] Example 4

[0052] This embodiment provides a cement production line with complete CO2 capture throughout the process, mainly comprising three parts: a cement kiln system 15, a high-concentration carbon dioxide capture system, a circulating fluidized bed gasifier 13, a green hydrogen system 14, and a carbon dioxide circulation pipeline. Figure 4 As shown, the cement kiln system 15 is the same as the prior art, mainly consisting of a rotary kiln 1501, a tertiary air duct 1502, a grate cooler 1503, and an AQC boiler 1504; the high-concentration carbon dioxide capture system is the same as in Example 1.

[0053] The carbon dioxide circulation pipeline includes a first branch 16 and a second branch 17 connected to the outlet of the gas-solid separator 3. A first high-temperature fan 5 is installed at the outlet of the gas-solid separator 3 to control the pressure in the decomposition furnace to a slightly negative pressure. The high-concentration carbon dioxide flue gas is divided into two paths: the first branch 16, after being cooled, dusted, and desulfurized by the first heat exchanger 4, enters the low-temperature carbon dioxide distillation purification process to be processed into various carbon dioxide products. After being treated by the low-temperature distillation purification process, the carbon dioxide meets the quality requirements of industrial-grade and above carbon dioxide products; the second branch 17, without going through the purification system, is connected from the gas outlet of the kiln tail decomposition furnace 1 and directly enters the circulating fluidized bed gasifier 13. Under the action of high temperature and catalyst, it reacts with the carbon in the low-calorific-value coal to generate combustible gas with carbon monoxide and hydrogen as the main components, which is then circulated for use in the cement kiln decomposition furnace system. In summary, in a cement production line with complete CO2 capture, the kiln tail decomposition furnace mainly burns CO, while the kiln head uses H2 as fuel.

[0054] Example 5

[0055] This embodiment provides an industrial by-product gypsum decomposition system with complete CO2 capture, such as... Figure 5 and Figure 6 As shown, it mainly includes a gypsum pretreatment system 18, a dual-atmosphere gypsum decomposition furnace system 19, a cooling system 21, a circulating fluidized bed gasifier 13, and a green hydrogen system 14.

[0056] The dual-atmosphere gypsum decomposition furnace system 19 includes a first multi-stage cyclone preheater 1901, a second multi-stage cyclone preheater 1902, a dual-atmosphere circulating gypsum decomposition furnace 1903, an electromagnetic heating device 1904, a separator 1905, and a fourth high-temperature fan 20; the discharge port of the gypsum pretreatment system 18 is connected to the inlet of the first multi-stage cyclone preheater 1901 and the second multi-stage cyclone preheater 1902, and the discharge ports of the first multi-stage cyclone preheater 1901 and the second multi-stage cyclone preheater 1902 are connected to... The feed inlet of the dual-atmosphere circulating gypsum decomposition furnace 1903 is connected to the feed outlet of the dual-atmosphere circulating gypsum decomposition furnace 1903. The feed outlet of the separator 1905 is connected to the feed inlet of the dual-atmosphere circulating gypsum decomposition furnace 1903. The feed outlet of the separator 1905 is connected to the feed inlet of the cooling system 21. The fourth high-temperature fan 20 is located at the bottom of the feed inlet of the dual-atmosphere circulating gypsum decomposition furnace 1903. In addition, an air distribution plate and an air cap are provided.

[0057] The circulating fluidized bed gasifier 13 is connected to the dual-atmosphere gypsum decomposition furnace system 19. The oxygen outlet of the green hydrogen system 14 is connected to the first multi-stage cyclone preheater 1901, and the hydrogen outlet of the green hydrogen system 14 is connected to the dual-atmosphere circulating material gypsum decomposition furnace 1903. The exhaust outlet of the cooling system 21 is connected to the drying and crushing machine in the gypsum pretreatment system 18, and a fourth gas burner 22 is installed at the air inlet of the drying and crushing machine.

[0058] The process flow of the industrial by-product gypsum decomposition device in this embodiment is as follows:

[0059] (i) The phosphogypsum raw material is transported from the raw material silo to the pre-homogenization stockpile, where 0.5% lime (CaO) is added, mechanically mixed, and aged for 24 hours to neutralize soluble phosphorus (P2O5) and soluble fluorine (F). - The process involves the formation of insoluble Ca3(PO4)2 and CaF2 precipitates, removing 93% of soluble phosphorus and 29% of soluble fluorine. The neutralized phosphogypsum then enters a drying and crushing mill, where it is dehydrated into hemihydrate gypsum under the action of hot air (from exhaust gas from cooling system 21). Subsequently, it undergoes concentrated sulfuric acid spray washing in a cyclone separator. The sulfuric acid reacts with residual insoluble phosphorus (Ca3(PO4)2), eutectic phosphorus (CaHPO4), and fluoride (CaF2), generating CaSO4, H3PO4, and HF gas. After washing, the phosphogypsum crystal structure changes from blocky to flake-like, and the eutectic phosphorus removal rate is ≥95%.

[0060] After pickling, the hemihydrate gypsum enters a single-compartment air-swept mill (speed increased by 20%), where grinding in the steel section inside the mill ensures that the gypsum's specific surface area is ≥250 m². 2 / kg, shortening subsequent decomposition time.

[0061] The air inlet of the drying and crushing machine is equipped with a fourth gas burner 22 (fuel is green hydrogen or CO / H2) to supplement heat when starting up.

[0062] Pickling waste gas (containing SO2 / HF) is fed into the acid production system to recover sulfuric acid.

[0063] (ii) The pretreated gypsum powder is fed into the first multi-stage cyclone preheater 1901 (weak reduction zone preheating) and the second multi-stage cyclone preheater 1902 (weak oxidation zone preheating) in two separate streams, and is heated to 750°C by utilizing the waste heat of the decomposition furnace exhaust gas.

[0064] Weak reducing zone (1060℃): Gypsum (CaSO4) reacts with H2 provided by the green hydrogen system 14 and the CO / H2 mixture generated by the gasifier to produce CaO and SO2 (CaSO4 and H2 / CO → CaO and SO2↑ and H2O / CO2↑). The electromagnetic heating device 1904 (green electric drive) directly heats the furnace wall to 1000℃, which can reduce fuel consumption and oxygen consumption.

[0065] Weak oxidation zone (1100℃): Introduce 14 byproducts of the green hydrogen system, O2 (purity ≥95%), to ensure complete decomposition and suppress the reverse reaction (CaO and SO2 and O2 → CaSO4).

[0066] Air distribution plate and air cap: The fourth high-temperature fan 20 blows in circulating air to accelerate gas flow and avoid local melting and blockage.

[0067] The decomposed gas-solid mixture enters separator 1905 (cyclone separator), where high-concentration sulfur dioxide gas (85-90%) and solid products (CaO) are separated.

[0068] The carbon dioxide gas is cooled to 200°C by a heat exchanger and then sent to a low-temperature distillation unit by the fourth high-temperature fan 20 for purification and liquefaction, or returned to the jacket layer of the gasifier for recycling.

[0069] A blower is installed at the bottom of the decomposition furnace to force air supply and maintain the oxygen concentration in the weak oxidation zone at ≤5%. Sulfur vapor (reducing agent) is injected into the weak reduction zone to enhance the decomposition efficiency of CaSO4.

[0070] (III) Circulating fluidized bed gasification and green hydrogen energy supply

[0071] Lignite enters the gasifier furnace 1303 from the coal bunker 1301 via a tubular screw feeder 1302, where it reacts with carbon dioxide (950℃) and water vapor returned from the CO2 capture system to produce a CO / H2 mixture (calorific value ≥2500 kcal / Nm³). 3 ).

[0072] Jacket layer: High-temperature carbon dioxide flows along the furnace wall jacket to maintain the furnace temperature ≥1000℃.

[0073] After the gasified gas is dedusted by a two-stage cyclone separator 1304, 50% is supplied to the decomposition furnace for combustion and 50% is returned to the cement kiln system 15.

[0074] The gasification residue (ash) is cooled by the slag cooler 1305 and then transported as a cement admixture.

[0075] Green Hydrogen System 14 Synergy: Electrolyzer 1402 (Green Electric Driven) produces H2 and O2:

[0076] H2: It is directly fed into the weak reducing zone of the decomposition furnace for combustion, replacing fossil fuels and serving as a reducing agent for the decomposition of CaSO4.

[0077] O2: Provides full oxygen to the weak oxidation zone of the decomposition furnace to aid combustion and improve combustion efficiency.

[0078] (iv) Waste heat recovery and resource utilization

[0079] After the decomposition furnace residue (CaO) is cooled by the cooling system 21, the 500℃ waste gas is returned to the industrial by-product gypsum drying and crushing machine as a heat source, reducing drying energy consumption by 30%.

[0080] The waste heat from the gasifier jacket layer is circulated to the decomposition furnace via the third high-temperature blower 1307 to maintain a stable temperature field.

[0081] Product utilization:

[0082] SO2 gas: concentration ≥28%, is converted into industrial sulfuric acid through a "three-transformation and three-absorption" acid production system.

[0083] CaO: Purity ≥ 95%, sold as active lime or used in cement clinker production.

[0084] (v) Carbon emissions:

[0085] With closed-loop carbon dioxide recycling (capture concentration ≥85%) and green hydrogen combustion, the system's net carbon emissions approach zero.

[0086] Technical advantages: gypsum decomposition rate ≥99%, energy consumption reduced by 40% compared to traditional processes.

[0087] In summary, the process of pretreatment → decomposition → capture → gasification → green hydrogen energy supply forms a closed loop, achieving the goals of removing harmful components, co-producing high-value products, and achieving near-zero carbon emissions. This provides an innovative solution for the resource utilization of industrial by-product gypsum.

[0088] Features: In the first preheater system, full oxygen combustion and CO2 enrichment to a concentration of ≥85% are achieved; in the second preheater and dual-atmosphere gypsum decomposition furnace system, full oxygen combustion and SO2 enrichment to a concentration of over 85% are achieved.

[0089] In summary, the fuel and air distribution for the industrial by-product gypsum decomposition system with complete CO2 capture is as follows: CO is used as fuel in the first multi-stage cyclone preheater; H2 is used as fuel in the gypsum decomposition furnace of the second multi-stage cyclone preheater; and high-temperature hot air recovered from lime (cement clinker) is used for drying the industrial by-product gypsum.

[0090] The beneficial effects of this utility model are as follows:

[0091] I. Cement Production Line

[0092] 1. This utility model introduces hydrogen production through water electrolysis (with byproduct oxygen used as combustion aid to achieve full oxygen combustion in the decomposition furnace) by classifying fuels for use in the calcination zone of the cement rotary kiln 1501. Simultaneously, a circulating fluidized bed gasifier 13 is added to convert captured carbon dioxide into combustible gas for recycling in the decomposition furnace (this gasifier can use large quantities of biomass fuel or be jacketed with a green electric heating device), achieving full capture of carbon dioxide and low carbon emissions throughout the entire cement clinker production process.

[0093] 2. Due to the high initial concentration of carbon dioxide captured by this system (92-95%), ultra-low capture cost is achieved. The power consumption of the downstream purification system is 170±5 kWh / tCO2, plus the power consumption of the dust removal fan is 15 kWh / tCO2, for a total power consumption of less than 200 kWh / tCO2, with a direct capture cost of 130 RMB / tCO2. Simultaneously, the capture equipment is synchronized with the cement production system, fully realizing large-scale, high-volume, and ultra-low-cost carbon dioxide capture.

[0094] 3. Due to the large-scale use of lignite or low-calorific-value coal to replace high-quality coal, a significant price difference exists, thereby achieving low-cost cement production. Simultaneously, "coal-to-gas" conversion has been implemented, achieving the clean and efficient use of coal.

[0095] 4. Cement companies can produce cement and carbon dioxide together. Due to the ultra-low cost, both products can generate profits simultaneously. They can also sell carbon assets.

[0096] 5. Coal ash (coal-based kaolin) produced after the combustion of lignite or other low-calorific-value coal is used as a cement admixture to produce LC3 cement, further reducing cement costs.

[0097] 6. The reconstructed cement production system of this utility model can also bring about the following beneficial changes: Due to the effect of the circulating decomposition system, the decomposition rate of the kiln feed is increased, reducing the proportion of fuel used at the kiln head to 35-30% and increasing the proportion of fuel used at the kiln tail to 65-70%. This helps to reduce the amount of hydrogen used, reduce the heat load of the kiln, and is very beneficial to reducing heat consumption.

[0098] II. Industrial By-product Gypsum Decomposition System

[0099] 1. This utility model introduces hydrogen production through water electrolysis (using byproduct oxygen as a combustion aid to achieve full oxygen combustion in the decomposition furnace) by classifying fuels for use in the decomposition system of gypsum byproducts in the industry. Simultaneously, a circulating fluidized bed gasifier is invented to convert captured carbon dioxide into combustible gas for recycling in the first multi-stage preheater (this gasifier can use large quantities of biomass fuel or be jacketed with a green electric heating device), achieving 100% capture and zero carbon emissions of carbon dioxide throughout the entire gypsum decomposition production process.

[0100] 2. Due to the high initial concentration of carbon dioxide captured by this system, ultra-low cost is achieved. The power consumption of the downstream purification system is 170±5 kWh / t carbon dioxide, plus the power consumption of the dust removal fan of 25 kWh / t carbon dioxide, the total power consumption is below 210 kWh / t carbon dioxide, and the direct capture cost is 130 yuan / t carbon dioxide. At the same time, the capture equipment is synchronized with the gypsum decomposition system, fully realizing large-scale, large-scale, and ultra-low cost carbon dioxide capture.

[0101] 3. Due to the large-scale use of lignite or low-calorific-value coal to replace high-quality coal, a significant price difference exists, achieving low-cost gypsum decomposition. Simultaneously, "coal-to-gas" conversion is realized, achieving the clean and efficient use of coal.

[0102] 4. The company can produce sulfuric acid along with lime and carbon dioxide. Due to the ultra-low cost, all three products are profitable at the same time. It can also sell carbon assets.

[0103] 5. Hydrogen is produced by electrolysis of water (green electricity) and used as fuel for the 1903 dual-atmosphere circulating feed gypsum decomposition furnace; the by-product oxygen is fully utilized as a combustion-supporting gas; electromagnetic heating (green electricity) is installed on the inner wall of the gypsum decomposition furnace to reduce the amount of hydrogen used and lower costs.

[0104] In summary, this utility model, with equipment structure improvement as its core (radiation enhancement of the decomposition furnace, jacket of the gasification furnace, and electromagnetic heating device), combined with process system optimization (green hydrogen power supply, carbon dioxide diversion, and independent preheating of auxiliary materials), solves key problems in the cement industry such as high energy consumption for carbon dioxide capture, high cost of alternative fuels and existing safety hazards, and difficulties in gypsum treatment. It achieves technological breakthroughs such as a reduction of capture cost by more than 60%, a fuel substitution rate of 100%, and a reduction of gypsum decomposition energy consumption by 30%, while meeting the needs of large-scale industrial application and possessing significant economic and environmental benefits.

[0105] The above description is merely a preferred embodiment of the present utility model and is not intended to limit the present utility model in any way. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present utility model. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present utility model without departing from the scope of the present utility model shall still fall within the scope of the present utility model.

Claims

1. A circulating fluidized bed gasifier, characterized in that, It includes a coal bunker (1301), a tubular screw feeder (1302), a gasifier furnace (1303), a two-stage cyclone separator (1304), a second heat exchanger (1306), a third high-temperature fan (1307), and a slag cooler (1305). The coal bunker (1301) is used to store lignite or low-priced coal; the feed end of the tubular screw feeder (1302) is connected to the discharge port of the coal bunker (1301), and the discharge end is connected to the gasifier furnace (1303); the gasifier furnace (1303) has a double-layer cylindrical structure, with an interlayer formed between the inner and outer cylinders, and a spirally wound air guide plate (1308) is provided in the interlayer; the air inlet of the two-stage cyclone separator (1304) is connected to the air outlet of the gasifier furnace (1303), and the discharge port is connected to the feed inlet of the gasifier furnace (1303); the air inlet of the second heat exchanger (1306) is connected to the two-stage cyclone separator. (1304) Air outlet; The air inlet of the third high-temperature blower (1307) is connected to the interlayer outlet of the gasifier furnace (1303), and the air outlet is divided into two paths: one path is connected to the interlayer air inlet of the gasifier furnace (1303), and the other path is equipped with a third gas burner (1309) and then connected to the interlayer air inlet of the gasifier furnace (1303); The feed inlet of the slag cooler (1305) is connected to the waste outlet at the bottom of the gasifier furnace (1303); The circulating fluidized bed gasifier (13) uses high-temperature carbon dioxide and water vapor as gasifying agents to gasify lignite to generate carbon monoxide and hydrogen, which are used as alternative fuels for external equipment.

2. A CO2-captured cement production line, comprising a cement kiln system (15), a kiln tail decomposition furnace (1), a preheater assembly (2), and a gas-solid separator (3), characterized in that, It also includes the circulating fluidized bed gasifier (13), the feed distribution device (6), and the green hydrogen system (14) as described in claim 1; wherein: The feed inlet of the kiln tail decomposition furnace (1) is connected to the discharge outlet of the preheater assembly (2), and its discharge outlet is connected to the feed inlet of the gas-solid separator (3); the gas outlet of the gas-solid separator (3) is connected to a carbon dioxide circulation pipeline and a first high-temperature fan (5), the carbon dioxide circulation pipeline includes a first branch (16) connected to the gas inlet of the kiln tail decomposition furnace (1) and a second branch (17) connected to the jacketed gas inlet of the circulating fluidized bed gasifier (13); a first heat exchanger (4) is provided between the gas outlet of the gas-solid separator (3) and the first high-temperature fan (5); a second high-temperature fan (11) is provided between the gas outlet of the gas-solid separator (3) and the gas inlet of the kiln tail decomposition furnace (1). The feeding device (6) is connected to the outlet of the gas-solid separator (3) at the feed end. The discharge end is divided into two paths: one path returns to the feed inlet of the kiln tail decomposition furnace (1) through the circulating material pipe (7), and the other path is connected to the rotary kiln (1501). The green hydrogen system (14) includes an electrolyzer (1402) for generating oxygen and hydrogen, with its hydrogen outlet connected to the burner of the rotary kiln (1501) and its oxygen outlet connected to the pure oxygen combustion pipeline of the kiln tail decomposition furnace (1). The carbon monoxide and hydrogen combustible gases generated by the circulating fluidized bed gasifier (13) are transported through pipelines to the kiln tail decomposition furnace (1) as fuel for the decomposition furnace.

3. The CO2 full capture cement production line according to claim 2, characterized in that, The preheater assembly (2) includes preheaters C1, C2, C3, C4 and C5, wherein: preheater C1 is a downward exhaust cyclone; the air inlet pipe of preheater C5 is equipped with a hydrogen fuel burner (12).

4. The CO2 full capture cement production line according to claim 2, characterized in that, The inner wall of the kiln tail decomposition furnace (1) is covered with heat insulation material, and a second gas burner (9) is provided at the bottom for introducing a mixture of carbon monoxide and hydrogen for combustion.

5. A gypsum decomposition system, comprising a gypsum pretreatment system (18), a dual-atmosphere circulating gypsum decomposition furnace (1903), and a cooling system (21), characterized in that, It also includes the circulating fluidized bed gasifier, separator (1905), fourth high-temperature blower (20), and green hydrogen system (14) as described in claim 1; wherein: The gypsum pretreatment system (18) includes a drying crusher, a cyclone separator and a single-compartment air-swept mill, used to dehydrate, acid wash and grind phosphogypsum; The feed inlet of the dual-atmosphere circulating material gypsum decomposition furnace (1903) is connected to the discharge outlet of the first multi-stage cyclone preheater (1901) and the second multi-stage cyclone preheater (1902), and the weak reduction zone and weak oxidation zone of its furnace wall are equipped with electromagnetic heating devices (1904). The air inlet of the separator (1905) is connected to the air outlet of the dual-atmosphere circulating gypsum decomposition furnace (1903), and the discharge outlet is connected to the cooling system (21). The fourth high-temperature blower (20) is located at the bottom of the dual-atmosphere circulating material gypsum decomposition furnace (1903), and blows circulating air into the furnace through the air distribution plate; The hydrogen outlet of the green hydrogen system (14) is connected to the burner of the dual-atmosphere circulating gypsum decomposition furnace (1903), and the oxygen outlet is connected to the pure oxygen combustion pipeline of the dual-atmosphere circulating gypsum decomposition furnace (1903). The carbon monoxide and hydrogen generated by the circulating fluidized bed gasifier (13) are transported through pipelines to the burner of the first multi-stage cyclone preheater (1901).

6. The gypsum decomposition system according to claim 5, characterized in that, The weak reduction zone of the dual-atmosphere circulating gypsum decomposition furnace (1903) is equipped with a sulfur injection device, which is used to inject sulfur vapor to promote the decomposition of industrial by-product gypsum.

7. The gypsum decomposition system according to claim 5, characterized in that, The cooling system (21) is a fluidized bed cooler, whose hot air outlet is connected to the air inlet of the drying and crushing machine of the gypsum pretreatment system (18).

8. The gypsum decomposition system according to claim 5, characterized in that, The first multi-stage cyclone preheater (1901) and the second multi-stage cyclone preheater (1902) include a weak reduction zone preheater and a weak oxidation zone preheater, which are respectively connected to the circulating fluidized bed gasifier (13) and the green hydrogen system (14) through pipelines.

9. The gypsum decomposition system according to claim 5, characterized in that, The electromagnetic heating device (1904) is powered by green electricity, and the furnace temperature is controlled at 1060℃ in the weak reduction zone and 1100℃ in the weak oxidation zone.

10. The gypsum decomposition system according to claim 5, characterized in that, The carbon dioxide outlet of the separator (1905) is connected to the jacket inlet of the circulating fluidized bed gasifier (13) to form a closed-loop carbon dioxide circulation.

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