Desulfurization process for hot cement raw meal, and desulfurization device

Abstract

Disclosed in the present invention are a desulfurization process for hot cement raw meal, and a desulfurization device. The desulfurization process comprises: (1) discharging high-temperature solid hot raw meal from a discharge pipe of a C5 cyclone; (2) mixing the discharged high-temperature solid hot raw meal with a gas stream for primary cooling; (3) subjecting the hot raw meal, which has been mixed with gas, to gas-solid separation while simultaneously performing secondary cooling using atomized water to obtain low-temperature hot raw meal; (4) metering and then feeding the obtained low-temperature hot raw meal into a digester to perform a digestion reaction with digestion water in the digester, so as to produce calcium hydroxide; (5) conveying the digested material to a powder bin for temporary storage; and (6) metering and then feeding the material, which is temporarily stored in the powder bin, into a first air pipe between a C2 cyclone separator and a C1 cyclone separator, such that same undergoes a desulfurization treatment. The process method of the present invention has little influence on a preheater system and features low energy consumption, can adapt to working conditions in which an SO2 concentration undergoes large fluctuations, exhibits high desulfurization efficiency, involves the use of a small amount of desulfurizing agents, and provides a stable desulfurization effect.

Description

A desulfurization process and device for hot cement raw materials Technical Field

[0001] This invention relates to the field of desulfurization technology, specifically to a desulfurization process and device for hot cement raw materials. Background Technology

[0002] SO2 pollutants generated during cement production mainly originate from two sources: raw materials and fuel. Sulfur in raw materials primarily exists as organic sulfides, sulfides, or sulfates; sulfates in raw materials typically do not form SO2 in the preheater system and mostly enter the kiln system. Sulfides and organic sulfur in raw materials generate SO2 at 400℃-600℃, which is discharged with the exhaust gas. Traditional cement kiln flue gas desulfurization technologies mainly include wet desulfurization, dry desulfurization, and semi-dry desulfurization. Wet desulfurization technologies, such as limestone-gypsum wet desulfurization, although achieving high desulfurization efficiency (over 90%), suffer from drawbacks such as large equipment size, high investment costs, high water consumption during operation, and the potential for secondary wastewater pollution. Furthermore, the flue gas temperature after wet desulfurization is relatively low, usually requiring reheating to meet chimney emission requirements, further increasing energy consumption and operating costs.

[0003] Dry desulfurization technologies, such as the circulating fluidized bed dry desulfurization process using calcium-based desulfurizers, offer advantages such as system simplicity, small footprint, and no wastewater discharge. However, their desulfurization efficiency is relatively low, generally around 80-85%, making it difficult to meet increasingly stringent environmental emission standards. Furthermore, the limited contact time between the desulfurizer and flue gas during dry desulfurization results in insufficient reaction and low desulfurizer utilization, necessitating the replenishment of large amounts of desulfurizer and increasing operating costs.

[0004] Semi-dry desulfurization technology lies between wet and dry methods. For example, rotary spray semi-dry desulfurization overcomes some of the disadvantages of wet desulfurization to a certain extent. However, it still has problems such as easy scaling and clogging of equipment and poor adaptability to changes in flue gas flow and composition. This poses a challenge to the stable operation of the system and requires frequent equipment maintenance and repair, which affects the normal production of cement plants.

[0005] Furthermore, existing desulfurization technologies are insufficiently adaptable to situations where SO2 concentrations fluctuate significantly under different operating conditions when treating cement plant exhaust gases. When cement plants produce different types of cement or adjust their production processes, the SO2 concentration in the kiln tail exhaust gas may vary considerably. Traditional desulfurization processes struggle to quickly and effectively adjust desulfurization operating parameters, leading to unstable desulfurization results and sometimes resulting in SO2 emissions exceeding standards.

[0006] In summary, existing desulfurization technologies for cement plants still face challenges in simultaneously meeting multiple requirements, such as high-efficiency desulfurization, low-cost operation, stable and reliable operation, and adaptability to complex working conditions. Summary of the Invention

[0007] To address the aforementioned technical problems, this invention provides a desulfurization process and device for hot cement raw materials.

[0008] The technical solution adopted in this invention is:

[0009] A desulfurization process for hot cement raw materials includes the following steps:

[0010] (1) Take out the high-temperature solid hot raw material from the C5 grade cyclone discharge pipe;

[0011] (2) The extracted high-temperature solid thermal raw material is mixed with airflow for a first cooling process;

[0012] (3) The hot raw material mixed with gas is subjected to gas-solid separation and atomized water is used for secondary cooling to obtain low-temperature hot raw material;

[0013] (4) The obtained low-temperature hot raw material is metered and added to the digester. The calcium oxide in the hot raw material reacts with the digestion water in the digester to produce calcium hydroxide.

[0014] (5) The digested material is temporarily stored in a powder silo;

[0015] (6) The material temporarily stored in the powder silo is metered and then added to the first air duct from the C2 cyclone separator to the C1 cyclone separator for desulfurization treatment.

[0016] Furthermore, a portion of the gas separated from the top of the cyclone separator is transported by a circulating fan to step (2) to be mixed with the high-temperature hot raw material for a cooling process, while the other portion is filtered by a dust collector and discharged from the desulfurization system by a tail exhaust fan.

[0017] Furthermore, the water vapor generated during the digestion reaction is extracted by the digestion blower, filtered through the filter inside the digester, and then discharged from the desulfurization system.

[0018] A desulfurization device for any of the above-mentioned cement hot raw material desulfurization processes includes a material receiving device, a disperser, a cyclone separator, a circulating fan, a first spiral weighing scale, a digester, a first conveying device, a powder silo, a second spiral weighing scale, and a second conveying device.

[0019] The C5-grade cyclone separator's feed pipe is connected to a disperser via a material handling device. The disperser has a feed inlet, an air inlet, and a discharge outlet. The disperser's feed inlet is connected to the material handling device via a pipe, and the disperser's discharge outlet is connected to a cyclone separator via a pipe. The top air outlet of the cyclone separator is connected to a circulating fan via an air duct, and the circulating fan is connected to the disperser's air inlet via an air duct. The cyclone separator's discharge outlet is connected to a digester via a first spiral weighing scale, and the digester's outlet is connected to a powder silo via a first conveying device. The powder silo's discharge outlet is connected to the first air duct via a second spiral weighing scale and a second conveying device.

[0020] Furthermore, it also includes a dust collector and an exhaust fan. The dust collector inlet is connected to the circulating fan outlet through a duct, and the exhaust fan inlet is connected to the dust collector outlet.

[0021] Furthermore, it also includes a digestion fan, which is connected to the outlet of the filter inside the digester.

[0022] Furthermore, the material handling device includes a three-way material handling pipe and a rotary feed valve. The inlet of the three-way material handling pipe is connected to the discharge pipe of the C5 grade cyclone separator, the first outlet of the three-way material handling pipe is connected to the smoke chamber, and the second outlet is connected to the inlet of the rotary feed valve.

[0023] Furthermore, the disperser includes a straight cylinder with a constricted middle section, a discharge port at the top of the cylinder and an air inlet at the bottom; a feed pipe is provided at the upper part of the straight cylinder, a feed port at the top of the feed pipe, and a spreading plate is provided on the inner surface of the lower end of the feed pipe, the spreading plate being radially distributed on the lower side of the inner surface of the feed pipe.

[0024] Furthermore, the cyclone separator is connected to the first spiral weighing scale via a double-layer airlock valve.

[0025] Furthermore, a spray gun is provided in the middle of the cyclone separator, which is used to spray atomized water into the cyclone separator.

[0026] The beneficial effects of this invention are:

[0027] 1. The cooling system adopts material intake and cooling from the C5 grade cyclone discharge pipe, resulting in low heat loss and minimal impact on the preheater system.

[0028] 2. The material is dispersed into the circulating airflow for a single cooling process. The circulating air volume is small and the energy consumption of the dispersed airflow is low.

[0029] 3. By using atomized water for secondary cooling of gas-solid mixtures through separation, the heat absorption of water through evaporation phase change is fully utilized. Compared with the method of collecting hot raw materials first and then cooling them with cooling water, the amount of cooling water used can be effectively reduced, the heat load of the circulating cooling water pool can be significantly reduced, energy consumption can be greatly saved, and the cooling load of the circulating water can be reduced.

[0030] 4. After digestion, CaO is converted into Ca(OH)2, which has better reactivity with SO2, making it easier to solidify and absorb SO2, resulting in high desulfurization efficiency and low desulfurization agent usage.

[0031] 5. The desulfurization device of the present invention can adapt to working conditions with large fluctuations in SO2 concentration and has a stable desulfurization effect. Attached Figure Description

[0032] Figure 1 is a flow chart of a cement hot raw material desulfurization process according to the present invention.

[0033] Figure 2 is a structural diagram of the disperser of the present invention.

[0034] Figure 3 is a sectional view along the BB direction of Figure 2.

[0035] In the diagram: 1. Three-way feed pipe; 2. Slide valve; 3. Compressed air ring blower; 4. Rotary feed valve; 5. Disperser; 6. Cyclone separator; 7. Double-layer airlock valve; 8. First spiral weighing scale; 9. Digester; 10. Screw conveyor; 11. Airlock feeder; 12. FU chain conveyor; 13. Circulating fan; 14. Dust collector; 15. Tail exhaust fan; 16. Digestion fan; 17. Bucket elevator; 18. Powder silo; 19. Second spiral weighing scale; 20. Kiln inlet bucket elevator; 51. Cylinder; 52. Feed pipe; 53. Spreading plate; 501. Feed inlet; 502. Discharge outlet; 503. Air inlet; 511. Upper straight cylinder section; 512. Neck; 513. Lower straight cylinder section. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings and a preferred embodiment.

[0037] Referring to Figures 1-3; the present invention provides a desulfurization device, including a three-way feed pipe 1, a slide valve 2, a rotary feed valve 4, a disperser 5, a cyclone separator 6, a first spiral weighing scale 8, a digester 9, a spiral conveyor 10, an airlock feeder 11, a FU chain conveyor 12, a circulating fan 13, a dust collector 14, a tail exhaust fan 15, a digestion fan 16, a bucket elevator 17, a powder silo 18, a second spiral weighing scale 19, and a kiln inlet bucket elevator 20.

[0038] A three-way feed pipe 1, a slide gate valve 2, and a rotary feed valve 4 are connected in sequence to form a feeding device. The three-way feed pipe 1 is installed below the C5-grade cyclone discharge pipe. The inlet of the three-way feed pipe is connected to the C5-grade cyclone discharge pipe, the first outlet of the three-way feed pipe is connected to the smoke chamber, the second outlet is connected to the inlet of the slide gate valve 2, and the outlet of the slide gate valve 2 is connected to the inlet of the rotary feed valve 4. The solid hot raw material in the C5-grade cyclone discharge pipe flows into the rotary feed valve 4 through the three-way feed pipe 1 under the action of gravity. The amount of material taken out is controlled by the rotary feed valve 4. The inlet end of the rotary feed valve 4 is equipped with a compressed air ring blower 3, which uses compressed air to assist the flow of material in the material pipe above the rotary feed valve 4, promotes material flow, and avoids material blockage.

[0039] The disperser 5 includes a straight cylinder 51 with a constriction in the middle. The straight cylinder 51 consists of an upper straight cylinder 511, a middle constriction 512, and a lower straight cylinder 513. A discharge port 502 is formed at the top of the straight cylinder, and an air inlet 503 is formed at the bottom. A feed pipe 52 is obliquely connected to the upper straight cylinder 511. A feed inlet 501 is formed at the top of the feed pipe, and a spreading plate 53 is provided on the inner surface of the lower end of the feed pipe. The spreading plate 53 is radially distributed on the lower side of the inner surface of the feed pipe. The middle constriction 512 increases the gas flow rate, improves the dispersion effect of hot raw materials, and prevents the hot raw materials from slipping.

[0040] The feed inlet 501 of the disperser 5 is connected to the outlet of the rotary feed valve 4 via a pipeline, and the discharge outlet 502 is connected to the feed inlet of the cyclone separator 6 via a pipeline. The air outlet at the top of the cyclone separator is connected to the circulating fan 13 via an air duct.

[0041] The cyclone separator 6 has a spray gun in the middle ring, which is used to spray atomized cooling water into the interior of the separator.

[0042] The outlet of the circulating fan 13 is divided into two paths. One path connects to the disperser 5, providing a dispersing airflow to the disperser 5. The temperature of this airflow is the separator outlet temperature, which is much lower than the temperature of the hot raw material. The gas composition is a mixture of air and water vapor. This airflow has a high velocity in the disperser 5, and when it comes into contact with the hot raw material dispersed by the disperser 6, it can accelerate the hot raw material in a very short time, while simultaneously achieving heat exchange. Due to the highly efficient dispersing performance of the disperser 5, the amount of gas required by the disperser 5 can be minimized, thereby reducing the power consumption of the circulating fan 13 and lowering the overall system energy consumption.

[0043] Another outlet of the circulating fan 13 is connected to the dust collector 14, and the outlet of the dust collector 14 is connected to the tail exhaust fan 15. As needed, the tail exhaust fan 15 discharges the gas containing moisture from the desulfurization system. The volume of the gas discharged from the system is the system's air leakage and the volume of water vapor generated by the vaporization of the atomized water injected into the cyclone separator 6. This volume can be determined by pressure balance within the system. Specifically, a pressure gauge is installed at the outlet of the circulating fan 13 for pressure monitoring. When the outlet pressure of the circulating fan 13 is too high, it indicates that the amount of circulating gas in the system is too large. The frequency of the tail exhaust fan 15 can be increased to increase the exhaust volume until the outlet pressure of the circulating fan 13 reaches the set value. When the outlet pressure of the circulating fan 13 is too low, it indicates that the amount of circulating gas in the system is too low. The frequency of the tail exhaust fan 15 can be decreased to reduce the exhaust volume until the outlet pressure of the circulating fan 13 reaches the set value.

[0044] The lower outlet of the cyclone separator 6 is connected to a double-layer airlock valve 7 via a pipe. The outlet of the double-layer airlock valve 7 is connected to a first spiral weighing scale 8 via a pipe. The outlet of the first spiral weighing scale 8 is connected to a digester 9 via a pipe. The digester 9 is equipped with a dust collector and a digestion water injection unit. The outlet of the dust collector is connected to a digestion blower 16 via a duct. The digestion water injection unit is used to inject digestion water into the digester.

[0045] The outlet of the digester 9 is connected to the screw conveyor 10 via a pipe. The outlet of the screw conveyor 10 is equipped with an airlock feeder 11. The airlock feeder 11 is connected to the FU chain conveyor 12 via a pipe. The outlet of the FU chain conveyor 12 is connected to the bucket elevator 17. The outlet of the bucket elevator 17 is connected to the powder silo 18. The outlet of the powder silo 18 is connected to the second screw weighing scale 19. The outlet of the second screw weighing scale 19 is connected to the kiln inlet bucket elevator 20 via a pipe. The outlet of the kiln inlet bucket elevator is connected to the first air duct.

[0046] The screw conveyor 10, the airlock feeder 11, the FU chain conveyor 12, and the bucket elevator 17 constitute the first conveying device; the kiln inlet bucket elevator 20 serves as the second conveying device.

[0047] The following describes the desulfurization process for hot cement raw materials according to the present invention. This desulfurization process uses the aforementioned desulfurization device and specifically includes the following steps:

[0048] (1) A material handling device is used to remove high-temperature solid hot raw material from the C5 grade cyclone discharge pipe;

[0049] (2) The high-temperature hot raw material extracted by the material taking device enters the disperser 5 through the feed pipe 52. Under the action of the spreading plate 53, it enters the airflow from the air inlet 503 in a dispersed state, mixes fully with the airflow and moves with the airflow, and is discharged from the outlet 502. During the mixing process, the high-temperature hot raw material and the airflow exchange heat, the temperature drops, and a cooling is completed.

[0050] (3) The hot raw material after the first cooling and the airflow flow together into the cyclone separator 6 at high speed. In the cyclone separator 6, it is fully mixed with the atomized cooling water and heat exchanged to achieve the second cooling of the hot raw material. The cooled hot raw material is separated from the airflow under the action of the separator and discharged from the bottom outlet of the separator. The atomized water absorbs heat and vaporizes into water vapor, which is discharged from the top outlet of the separator with the gas that has completed the heat exchange and enters the circulating fan 13.

[0051] The circulating fan 13 delivers a portion of the gas to step (2) to mix with the high-temperature hot raw material for a cooling process, and another portion of the gas is delivered to the dust collector. After being filtered by the dust collector, the gas is discharged from the desulfurization system through the tail exhaust fan.

[0052] (4) The hot raw material discharged from the lower outlet of the cyclone separator 6 is discharged into the first spiral weighing scale 8 through the double-layer air lock valve 7. After being weighed in the spiral weighing scale 8, it is discharged into the digester 9. The calcium oxide in the hot raw material reacts fully with the sprayed water to generate calcium hydroxide. The water vapor generated during the reaction is extracted by the digestion blower 16, filtered by the dust collector installed in the digester 9, and discharged from the desulfurization system. The amount of sprayed water is given quantitatively according to the weight of the hot raw material weighed by the spiral weighing scale.

[0053] (5) The digested hot raw material is fed into the powder silo 18 by the first conveying device for temporary storage;

[0054] (6) The material stored in the powder silo 18 is fed into the raw material feeding bucket elevator at the kiln tail after being metered by the second screw feeder 19, i.e., into the kiln bucket elevator 20. It is transported together with the raw material into the kiln bucket elevator to the first air duct of C2-C1. Under the action of the high-speed airflow in the air duct, it is quickly dispersed and fully mixed with the airflow, and reacts with SO2 in the airflow to absorb SO2.

[0055] The measurement value of the second spiral weighing scale 19 is dynamically controlled by the sulfur value detected by the sulfide detection device in the preheater system. When the sulfur value increases, the amount of raw material fed into the digester is increased; when the sulfur value decreases, the amount of raw material fed into the digester is decreased, so as to keep the sulfur content discharged from the system within the required range.

[0056] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications are also within the protection scope of the present invention.

Claims

1. A process for desulphurization of cement hot raw meal, characterized in that, Includes the following steps: (1) Take out the high-temperature solid hot raw material from the C5 grade cyclone discharge pipe; (2) The extracted high-temperature solid thermal raw material is mixed with airflow for a first cooling process; (3) The hot raw material mixed with gas is subjected to gas-solid separation and atomized water is used for secondary cooling to obtain low-temperature hot raw material; (4) The obtained low-temperature hot raw material is metered and added to the digester. The calcium oxide in the hot raw material reacts with the digestion water in the digester to produce calcium hydroxide. (5) The digested material is temporarily stored in a powder silo; (6) The material temporarily stored in the powder silo is metered and then added to the first air duct from the C2 cyclone separator to the C1 cyclone separator for desulfurization treatment.

2. A process for hot raw cement desulphurization according to claim 1, characterized in that, The gas separated from the top of the cyclone separator is partially transported to step (2) by a circulating fan to be mixed with the high-temperature hot raw material for a cooling process, and the other part is filtered by the dust collector and discharged from the desulfurization system by the tail exhaust fan.

3. A process for the hot raw meal desulphurization of cement according to claim 1, characterized in that, The water vapor generated during the digestion process is extracted by the digestion blower, filtered through the filter inside the digester, and then discharged from the desulfurization system.

4. A desulphurization device for use in a hot cement kiln desulphurization process according to any one of claims 1 to 3, characterized in that It includes a material handling device, a disperser, a cyclone separator, a circulating fan, a first spiral weighing scale, a digester, a first conveying device, a powder silo, a second spiral weighing scale, and a second conveying device; The C5 grade cyclone discharge pipe is connected to the disperser via a material handling device. The disperser has a feed inlet, an air inlet, and a discharge outlet. The disperser inlet is connected to the material receiving device via a pipeline, the disperser outlet is connected to the cyclone separator via a pipeline, the top outlet of the cyclone separator is connected to the circulating fan via an air duct, and the circulating fan is connected to the disperser inlet via an air duct; the cyclone separator outlet is connected to the digester via the first spiral weighing scale, the digester outlet is connected to the powder silo via the first conveying device, and the powder silo outlet is connected to the first air duct via the second spiral weighing scale and the second conveying device in sequence.

5. The desulfurizing apparatus according to claim 4, characterized by It also includes a dust collector and an exhaust fan. The dust collector inlet is connected to the circulating fan outlet through a duct, and the exhaust fan inlet is connected to the dust collector outlet.

6. The desulfurizing apparatus according to claim 4, characterized by It also includes a digestion fan, which is connected to the outlet of the filter inside the digester.

7. The desulfurizing apparatus according to claim 4, characterized by The material handling device includes a three-way material handling pipe and a rotary feed valve. The inlet of the three-way material handling pipe is connected to the discharge pipe of the C5 grade cyclone separator. The first outlet of the three-way material handling pipe is connected to the smoke chamber, and the second outlet is connected to the inlet of the rotary feed valve.

8. The desulfurizing apparatus according to claim 4, characterized by The disperser includes a straight cylinder with a constricted middle section, a discharge port at the top of the cylinder and an air inlet at the bottom; a feed pipe is provided at the upper part of the straight cylinder, a feed port at the top of the feed pipe, and a spreading plate is provided on the inner surface of the lower end of the feed pipe, the spreading plate being radially distributed on the lower side of the inner surface of the feed pipe.

9. The desulfurizing apparatus according to claim 8, characterized by The cyclone separator is connected to the first spiral weighing scale via a double-layer airlock valve.

10. The desulfurizing apparatus according to claim 4, characterized by A spray gun is installed in the middle of the cyclone separator, which is used to spray atomized water into the cyclone separator.

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