A novel water-cooled bypass venting coupled SNCR system

Abstract

This invention discloses a novel water-cooled bypass venting coupled with SNCR (Synchronous Non-Chemical Reduction) system for treating flue gas in the flue gas chamber of a decomposition furnace. The system includes an ascent pipe, an SNCR ammonia injection device, a cyclone separator, a quenching assembly, a dust collector, and an exhaust fan. The flue gas in the flue gas chamber flows sequentially through the ascent pipe, cyclone separator, quenching assembly, and dust collector. The SNCR ammonia injection device is installed on the ascent pipe. Coarse ash separated by the cyclone separator is returned to the decomposition furnace, and after being purified by the dust collector to remove fine dust, it is discharged into the kiln tail chimney by the exhaust fan. This invention neutralizes excess harmful components in the cement kiln system, solving the problem of crusting and blockage caused by the accumulation of harmful components in the system. The water-cooled bypass venting system reduces the system gas volume, optimizes equipment selection, and compared to traditional processes, the cyclone separator is positioned before the quenching chamber, ensuring sufficient residence time for the SNCR reaction and minimizing the impact on kiln system output during the return of low-chlorinated coarse ash.

Description

Technical Field

[0001] This invention relates to the field of cement kiln co-processing technology, specifically a novel water-cooled bypass venting coupled SNCR system. Background Technology

[0002] In recent years, my country's cement industry has actively participated in the harmless and resource-based disposal of urban and rural solid waste. However, during the co-processing of urban and rural solid waste in cement kilns, the presence of numerous harmful components in the waste can have serious consequences for the normal operation of various systems and equipment within the cement kiln and for the quality of cement products. The waste from co-processing typically introduces significant amounts of harmful components such as potassium, sodium, sulfur, and chlorine. These harmful components not only circulate and accumulate within the system, causing crusting and blockages that affect the stable operation of the cement kiln production system, but also negatively impact clinker quality.

[0003] The traditional bypass ventilation system mainly involves the following process: high-temperature flue gas at 1100℃ is drawn from the flue gas chamber, cooled to 350℃ by mixing cold air or water in the quench chamber, then enters a cyclone separator to separate coarse and fine particles, and then enters a heat exchanger for secondary cooling before entering a bag filter for dust collection and purification, and finally discharged to the chimney by an exhaust fan. Some process routes add an SNCR device before the quench chamber.

[0004] Its disadvantages are as follows:

[0005] 1. In conventional processes, the high-temperature flue gas extracted from the smoke chamber is first rapidly cooled to 350°C and then sent to a cyclone separator. This rapid cooling process concentrates harmful elements onto the ash. The cyclone separator then returns over 80% of the coarse ash to the cement kiln, while over 20% of the fine ash is sent to a dust collector and discharged. Of this, 80% of the coarse ash contains Cl... - Harmful elements such as Cl have accumulated significantly due to the effects of rapid cooling. - If the ash content is ≥5%, returning it to the kiln will cause a cycle of harmful elements and reduce the ventilation effect. If it is not returned to the kiln, it will result in too much ash being discharged (due to the influence of specific surface area, fine ash has a greater impact on Cl- content than coarse ash). - The enrichment effect is better, and the Cl in the fine ash is better. - (Content exceeding 15%)

[0006] 2. Some process routes install the SNCR unit between the quench chamber and the smoke chamber. Due to the limited installation location of the quench chamber, the distance between it and the smoke chamber is very short, resulting in a very short SNCR reaction window time (less than 0.2s) and a denitrification efficiency of ≤10%. Furthermore, because a temperature control chamber is not provided, at a high temperature of 1100℃, some ammonia will be oxidized to NO. x Instead, it increased NO x Emissions.

[0007] 3. Traditional bypass ventilation systems require the introduction of a large amount of cold air, resulting in a larger selection of subsequent equipment. This not only increases equipment investment costs but also requires a certain amount of space, increasing the difficulty of design and layout. Furthermore, the heat exchange effect is generally poor.

[0008] 4. If the bypass ventilation system is equipped with SCR, it will greatly increase the investment and is not economical.

[0009] Therefore, it is necessary to provide a novel water-cooled bypass venting coupled SNCR system to solve the problems mentioned in the background art. Summary of the Invention

[0010] To achieve the above objectives, the present invention provides the following technical solution: a novel water-cooled bypass venting coupled SNCR system for treating flue gas in the flue gas chamber of a decomposition furnace, comprising an ascending pipe, an SNCR ammonia injection device, a cyclone separator, a quenching assembly, a dust collector, and an exhaust fan, wherein the flue gas in the flue gas chamber flows sequentially through the ascending pipe, the cyclone separator, the quenching assembly, and the dust collector.

[0011] The SNCR ammonia injection device is installed on the rising pipeline;

[0012] The coarse ash separated from the flue gas by the cyclone separator is sent back to the decomposition furnace, and then the fine dust is purified by the dust collector before being discharged into the kiln tail chimney by the exhaust fan.

[0013] Furthermore, as a preferred embodiment, the distance between the cyclone and the flue gas chamber is ≥20m, so as to ensure that the residence time of the flue gas in it is ≥2.5s.

[0014] Furthermore, as a preferred embodiment, the front end of the SNCR ammonia injection device is provided with a temperature regulating chamber to maintain the temperature inside the pipeline between 850°C and 920°C.

[0015] Furthermore, as a preferred embodiment, the reducing agent in the SNCR ammonia spraying device is ammonia water with a concentration of ≥20%, and the spray gun is an L-type dual-fluid spray gun.

[0016] Furthermore, as a preferred embodiment, the rapid cooling component is water-cooled and can rapidly cool the high-temperature flue gas to 180℃-220℃ within 2-4 seconds.

[0017] Furthermore, as a preferred embodiment, the quench assembly includes a quench chamber, an air intake pipe, a heat exchanger assembly, and a heat exchanger tube. The heat exchanger tube is embedded in the quench chamber, and the air inlet end of the heat exchanger tube is connected to the air intake pipe via the heat exchanger assembly. The heat exchanger assembly is located outside the quench chamber, and the air intake pipe is located inside the quench chamber. A spray pipe is provided at the top of the quench chamber for spraying coolant into the quench chamber, and a collection pipe for discharging coolant is provided at the bottom of the quench chamber.

[0018] Furthermore, as a preferred embodiment, the heat exchanger assembly includes an extension tube, a heat exchanger tube, and a sleeve. One end of the extension tube is connected to the air intake tube, and the other end is connected to the sleeve via the heat exchanger tube. The extension tube and the heat exchanger tube together form a U-shaped tube body with a notch. A portion of the sleeve body is fitted onto a portion of the heat exchanger tube body and is connected to the air inlet end of the heat exchanger tube.

[0019] Furthermore, as a preferred embodiment, the heat exchange tubes are configured as multiple vertically arranged tubes, with the tops of the multiple heat exchange tubes converging on a horizontal pipe serving as the air inlet of the heat exchange tubes, and the bottoms of the multiple heat exchange tubes passing through a quench chamber and converging on an exhaust pipe serving as the air outlet of the heat exchange tubes, the exhaust pipe being connected to a dust collector; an external cleaning component is slidably fitted on each heat exchange tube, the external cleaning component being able to float on the coolant.

[0020] Furthermore, as a preferred embodiment, the quench chamber is also horizontally equipped with a partition, which can separate the heat exchange tubes into upper and lower liquid control spaces. Each liquid control space is connected to the manifold by a liquid control pipe, and a valve body is provided on the liquid control pipe. The lower liquid control space is also supplied with liquid by an external liquid supply component.

[0021] Furthermore, as a preferred embodiment, the external cleaning component includes a cleaning sleeve, the inner surface of which has teeth, and a float ball is fixed on the outer surface of which the external cleaning component can float on the coolant. Multiple through-tubes are embedded through the middle of the cleaning sleeve.

[0022] Compared with the prior art, the present invention provides a novel water-cooled bypass venting coupled SNCR system, which has the following beneficial effects:

[0023] 1. The process is simple, equipment selection is optimized, and investment in project infrastructure is reduced;

[0024] 2. By placing the cyclone separator before the quench chamber, the reaction window time of SNCR is extended by taking advantage of the height of the cyclone separator, thereby improving the efficiency of SNCR.

[0025] 3. Using a water-cooled quench chamber to reduce flue gas temperature results in a better cooling rate and effect than air cooling.

[0026] 4. The cyclone separator is located before the quench chamber, resulting in a higher chlorine content in the hot flue gas from the pipeline and a lower chlorine content in the coarse ash sent back to the decomposition furnace. This significantly reduces the impact on the kiln system compared to traditional 350℃ high-chlorine coarse ash.

[0027] 5. This invention renders excessive harmful components in the cement kiln system harmless, solving the problem of crusting and blockage caused by the accumulation of harmful components in the system.

[0028] 6. The position of the external cleaning component can be controlled by adjusting the coolant level in the quench chamber, thereby driving the external cleaning component to move up and down, cleaning the outside of the heat exchange tubes and reducing the reduction in heat exchange efficiency caused by dirt adhesion.

[0029] 7. By configuring baffles, the heat exchange tubes can be separated into different liquid control spaces. This allows for individual control of the coolant level in each space, ensuring that at least one liquid control space is filled with coolant. This enables position adjustment of external cleaning components during real-time cooling, thereby achieving real-time descaling. Attached Figure Description

[0030] Figure 1 A schematic diagram of the overall structure of a novel water-cooled bypass venting coupled SNCR system;

[0031] Figure 2 This is a schematic diagram of the quenching component in a novel water-cooled bypass venting coupled SNCR system.

[0032] Figure 3 for Figure 2 A partially enlarged structural diagram;

[0033] Figure 4 This is a schematic diagram of the external cleaning component in a novel water-cooled bypass venting coupled SNCR system.

[0034] In the diagram: 1. Decomposition furnace; 2. Flue gas chamber; 3. Flip valve; 4. Cyclone separator; 5. Temperature control chamber; 6. SNCR ammonia injection device; 7. Quenching assembly; 8. Dust collector; 9. Exhaust fan; 10. Kiln tail chimney; 11. Scraper conveyor; 12. Ash silo; 71. Quenching chamber; 72. Air intake pipe; 73. Heat exchanger pipe; 74. Liquid supply pipe; 75. Spray pipe; 76. Baffle plate; 77. Collection pipe; 78. Heat soaking pipe assembly; 79. External cleaning assembly; 781. Extension pipe; 782. Heat soaking pipe; 783. Sleeve; 784. Air inlet; 791. Cleaning sleeve; 792. Through pipe; 793. Float ball. Detailed Implementation

[0035] Example: Please refer to Figures 1-4 In this embodiment of the invention, a novel water-cooled bypass venting coupled SNCR system is used to treat the flue gas in the flue gas chamber 2 of the decomposition furnace 1. The system includes an ascending pipe, an SNCR ammonia injection device 6, a cyclone 4, a quench assembly 7, a dust collector 8, and an exhaust fan 9. The flue gas in the flue gas chamber 2 flows sequentially through the ascending pipe, the cyclone 4, the quench assembly 7, and the dust collector 8.

[0036] The SNCR ammonia injection device 6 is installed on the riser pipe;

[0037] The coarse ash separated in the flue gas by the cyclone separator 4 is sent back to the decomposition furnace 1. After being purified by the dust collector 8, the fine dust is discharged into the kiln tail chimney 10 by the exhaust fan 9.

[0038] In other words, a certain proportion of high-temperature flue gas is drawn from the front of flue gas chamber 2, and an SNCR ammonia injection device 6 is installed on the rising pipe to denitrify the high-temperature flue gas. At the same time, a temperature regulating chamber 5 is installed to control the temperature of the rising pipe within the optimal reaction temperature range for denitrification. The hot flue gas first enters the cyclone separator 4 for coarse ash-fine ash separation. The coarse ash with low chlorine content is sent back to the decomposition furnace 1. Specifically, the coarse ash returns to the decomposition furnace 1 through the feeding pipeline, which is equipped with a flap valve 3. The high-chlorine hot flue gas enters the water-cooled rapid cooling component 7 for rapid cooling to 200°C, which meets the inlet temperature requirements of the dust collector 8. After being purified by the dust collector 8, it is discharged into the kiln tail chimney 10 through the exhaust fan 9. The dust collector 8 can intercept fine ash, and the collected kiln ash is sent to the ash silo 12 through the scraper conveyor 11 for further processing.

[0039] In a preferred embodiment, the distance between the cyclone 4 and the flue gas chamber 2 is ≥20m, so as to ensure that the residence time of the flue gas therein is ≥2.5s;

[0040] The front end of the SNCR ammonia injection device 6 is equipped with a temperature regulating chamber to maintain the temperature inside the pipeline between 850℃ and 920℃.

[0041] The reducing agent in the SNCR ammonia spraying device is ammonia water with a concentration of ≥20%, and the spray gun is an L-type dual-fluid spray gun.

[0042] The rapid cooling component is water-cooled and can rapidly cool high-temperature flue gas to 180℃-220℃ within 2-4 seconds.

[0043] like Figure 1 As shown, a temperature control chamber 5 is installed before the SNCR ammonia injection device to ensure that the reaction window is maintained at 850℃~920℃, and the ammonia water injection rate of the system is controlled at 0.1~0.2m³. 3 / h, the reaction residence time is maintained at ≥2.5s, achieving a denitrification efficiency of ≥70%. Using this example, the Cl in the coarse ash... - The content is 1.6%, which is lower than the Cl content in the coarse ash after the quench chamber in the traditional air-cooled bypass system process. - The content is much lower at 5-7%; in this embodiment, the ash is first passed through a cyclone separator and then cooled to 200°C by a rapid cooling device, reducing the Cl content in the fine ash. - With a content of >20%, the air volume is reduced by 35% compared to traditional air-cooled bypass systems.

[0044] In this embodiment, as Figure 2-4The quenching assembly 7 includes a quenching chamber 71, an air intake pipe 72, a heat exchanger assembly 78, and a heat exchanger pipe 73. The heat exchanger pipe 73 is embedded in the quenching chamber 71. The air inlet of the heat exchanger pipe 73 is connected to the air intake pipe 72 via the heat exchanger assembly 78. The heat exchanger assembly is located outside the quenching chamber 71, and the air intake pipe 72 is located inside the quenching chamber 71. A spray pipe 75 is provided at the top of the quenching chamber for spraying coolant into the quenching chamber 71. The spray pipe 75 is connected to an external coolant supply assembly via a coolant supply pipe 74. A collection pipe 77 for discharging coolant is also provided at the bottom of the quenching chamber 71.

[0045] In this embodiment, the heat exchanger tube assembly 78 includes an extension tube 781, a heat exchanger tube 782, and a sleeve 783. One end of the extension tube is connected to the air intake tube 781, and the other end is connected to the sleeve 783 via the heat exchanger tube 782. The extension tube and the heat exchanger tube 782 together form a U-shaped tube body with a notch. A portion of the sleeve 783 is fitted onto a portion of the heat exchanger tube and is connected to the air inlet end of the heat exchanger tube 73.

[0046] In this embodiment, the heat exchange tubes 73 are configured as multiple vertically arranged tubes. The tops of the multiple heat exchange tubes 73 converge on a horizontal pipe that serves as the air inlet of the heat exchange tubes 73, and the bottoms of the multiple heat exchange tubes 73 pass through the quench chamber and converge on an exhaust pipe that serves as the air outlet of the heat exchange tubes 73. The exhaust pipe is connected to the dust collector 8. An external cleaning component 79 is slidably sleeved on each heat exchange tube 73. The external cleaning component 79 can float on the coolant.

[0047] In addition, the external cleaning component 79 includes a cleaning sleeve 791, the inner surface of which has teeth, and a float ball 793 is fixed on the outer surface of which the external cleaning component 799 can float on the coolant. A plurality of through pipes 792 are embedded through the middle of the cleaning sleeve.

[0048] In other words, the float ball 793 allows the external cleaning component 79 to float on the coolant. Thus, by controlling the coolant level in the quench chamber, the position of the external cleaning component 79 can be controlled, thereby driving the external cleaning component 79 to rise and fall, achieving cleaning of the outside of the heat exchange tube and reducing the reduction in heat exchange efficiency caused by dirt adhesion.

[0049] Furthermore, during implementation, the number of heat exchange tubes 73 can be configured according to specific circumstances;

[0050] In a preferred embodiment, only two heat exchange tubes 73 are configured.

[0051] In addition, a partition 76 is horizontally arranged in the quench chamber 71. The heat exchange tube 73 can be divided into two liquid control spaces, and each liquid control space is connected to the manifold 77 by a liquid control pipe. A valve body is provided on the liquid control pipe, and the liquid control space below is also supplied with liquid by an external liquid supply component.

[0052] It should be explained that by configuring the baffle 76, the heat exchange tube 73 can be separated into different liquid control spaces. In this way, the liquid level of the coolant in different spaces can be controlled individually, thereby ensuring that at least one liquid control space is full of coolant. This enables the position adjustment of the external cleaning component 79 during real-time cooling, thereby achieving real-time descaling.

[0053] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A novel water-cooled bypass venting coupled SNCR system for treating flue gas in the flue gas chamber (2) of a decomposition furnace (1), characterized in that: It includes an uplift pipe, an SNCR ammonia injection device (6), a cyclone separator (4), a quenching assembly (7), a dust collector (8), and an exhaust fan (9). The flue gas in the flue gas chamber (2) flows sequentially through the uplift pipe, the cyclone separator (4), the quenching assembly (7), and the dust collector (8). The rising pipe is equipped with the SNCR ammonia injection device (6), and the front end of the SNCR ammonia injection device (6) is equipped with a temperature regulating chamber; The coarse ash separated by the cyclone separator (4) in the flue gas is sent back to the decomposition furnace (1), and then the fine dust is purified by the dust collector (8) and discharged into the kiln tail chimney (10) by the exhaust fan (9). The quenching assembly (7) includes a quenching chamber (71), an air intake pipe (72), a heat exchanger assembly (78), and a heat exchanger pipe (73). The heat exchanger pipe (73) is embedded in the quenching chamber (71). The air inlet of the heat exchanger pipe (73) is connected to the air intake pipe (72) via the heat exchanger assembly (78). The heat exchanger assembly is located outside the quenching chamber (71). The air intake pipe (72) is located inside the quenching chamber (71). A spray pipe (75) is provided at the top of the quenching chamber for spraying coolant into the quenching chamber (71). The spray pipe (75) is connected to an external liquid supply assembly via a liquid supply pipe (74). A collection pipe (77) for discharging coolant is also provided at the bottom of the quenching chamber (71). The quench chamber (71) is also horizontally equipped with a partition (76), which can separate the heat exchange tube (73) into two liquid control spaces. Each liquid control space is connected to the manifold (77) by a liquid control pipe. A valve body is provided on the liquid control pipe. The liquid control space below is also supplied with liquid by an external liquid supply component.

2. The novel water-cooled bypass venting coupled SNCR system according to claim 1, characterized in that: The distance between the cyclone (4) and the flue gas chamber (2) is ≥20m, so as to ensure that the residence time of the flue gas in it is ≥2.5s.

3. The novel water-cooled bypass venting coupled SNCR system according to claim 1, characterized in that: The temperature control chamber is used to maintain the temperature inside the pipeline between 850℃ and 920℃.

4. The novel water-cooled bypass venting coupled SNCR system according to claim 1, characterized in that: The reducing agent in the SNCR ammonia spraying device is ammonia water with a concentration of ≥20%, and the spray gun is an L-type dual-fluid spray gun.

5. A novel water-cooled bypass venting coupled SNCR system according to claim 1, characterized in that: The rapid cooling component is water-cooled and can rapidly cool high-temperature flue gas to 180℃-220℃ within 2-4 seconds.

6. A novel water-cooled bypass venting coupled SNCR system according to claim 1, characterized in that: The heat exchanger assembly (78) includes an extension tube (781), a heat exchanger tube (782), and a sleeve (783). One end of the extension tube is connected to the air intake tube (72), and the other end is connected to the sleeve (783) via the heat exchanger tube (782). The extension tube and the heat exchanger tube (782) together form a U-shaped tube body with a notch. Part of the sleeve (783) is fitted onto part of the heat exchanger tube and is connected to the air inlet end of the heat exchanger tube (73).

7. A novel water-cooled bypass venting coupled SNCR system according to claim 1, characterized in that: The heat exchange tubes (73) are configured as a plurality of vertically arranged tubes. The tops of the plurality of heat exchange tubes (73) converge on a horizontal tube that serves as the air inlet of the heat exchange tubes (73). The bottoms of the plurality of heat exchange tubes (73) pass through a quench chamber and converge on an exhaust pipe that serves as the air outlet of the heat exchange tubes (73). The exhaust pipe is connected to a dust collector (8). An external cleaning component (79) is slidably fitted on each heat exchange tube (73). The external cleaning component (79) can float on the coolant.

8. A novel water-cooled bypass venting coupled SNCR system according to claim 7, characterized in that: The external cleaning assembly (79) includes a cleaning sleeve (791), the inner surface of which has teeth, and a float (793) is fixed on the outer surface of which the external cleaning assembly (791) can float on the coolant. A plurality of through pipes (792) are embedded in the middle of the cleaning sleeve.

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