Petroleum coke calcination tail gas purification system and method

Abstract

The invention discloses a petroleum coke calcination tail gas purification system and method, and belongs to the technical field of tail gas treatment, the petroleum coke calcination tail gas purification system comprises a purification furnace body, a purification tank, a gas inlet flue, a water-gas separation grating, a flue gas distribution structure, a heat exchange coil, a catalyst module, a spraying system, a high-pressure back flushing pipeline and an alkaline liquid supply pipeline; the upper part of the purification tank is divided into a mixing chamber and a gas lifting chamber through a separation wall; a guide wall body is arranged between the mixing chamber and the purification tank; the gas inlet flue is communicated with the purification tank; the water-gas separation grating is correspondingly arranged at the top of the gas raising chamber; the flue gas distribution structure is correspondingly arranged above the water-gas separation grid; the heat exchange coil pipe is correspondingly arranged above the flue gas distribution structure; the catalyst module is of a honeycomb structure; the spraying system comprises a liquid inlet main pipe and a plurality of spraying heads; the high-pressure back flushing pipeline is connected to the liquid inlet main pipe in parallel, and the alkaline liquid supply pipe is connected to the liquid inlet main pipe. Through a multi-stage purification structure, deep removal of pollutants is ensured, and the purification efficiency and quality of petroleum coke tail gas are improved.

Description

Technical Field

[0001] This invention belongs to the field of exhaust gas treatment technology, specifically relating to a system and method for purifying exhaust gas from petroleum coke calcination. Background Technology

[0002] The tail gas generated during the preparation of petroleum coke powder mainly originates from the calcination stage, which involves calcining raw petroleum coke at high temperatures to remove volatiles and moisture, thereby increasing its carbon content and physicochemical properties. Secondly, it generates dust from physical processing stages such as crushing and grinding. Among these, the coke powder particles entrained in the calcination furnace tail gas are fine and highly concentrated, making them one of the most significant pollutants in the tail gas. Furthermore, the calcination tail gas also contains sulfur compounds (SO₄), a major pollutant. x ), nitrogen oxides (NO) x Petroleum coke, being highly acidic and corrosive, is a precursor to acid rain, photochemical smog, and ozone. To address these pollutants, petroleum coke production lines (especially the calcination section) typically employ combined processes in their tail gas treatment systems. These include baghouse dust collectors, electrostatic precipitators, limestone / lime-gypsum desulfurization, sodium alkali / dual alkali desulfurization, circulating fluidized bed desulfurization, and denitrification systems. This combination of dust removal, desulfurization, and denitrification, tail gas purification, is tail gas treated according to specific conditions (raw material sulfur content, volatile matter content, and emission standards). Baghouse dust collectors, wet desulfurization (limestone-gypsum method), and SCR denitrification are currently the most widely used technologies in large-scale, high-standard projects. However, petroleum coke calcination tail gas is a complex gas with multiple pollutants, high dust content, and high sulfur content. Existing calcination tail gas treatment systems suffer from low purification efficiency, easy catalyst clogging, lack of heat recovery, and high investment costs. Summary of the Invention

[0003] Technical problem solved: In view of the technical problems existing in the background technology, the present invention provides a calcination tail gas purification system and method that integrates physical separation, chemical absorption and catalytic reaction. Through multi-stage purification structure and heat energy recovery, the process flow is shortened and the purification efficiency and quality of petroleum coke tail gas are improved.

[0004] Technical solution: The petroleum coke calcination tail gas purification system of the present invention includes a purification furnace body, a calcination tail gas inlet end and a tail gas outlet end, and further includes: The purification tank is located at the bottom of the purification furnace body, and its upper part is divided into a mixing chamber and a rising chamber by an isolation wall. The top of the rising chamber is connected to the upper cavity of the purification furnace body. A guide wall is provided between the mixing chamber and the purification tank. The air intake flue is located adjacent to the outer wall of the purification furnace, and its inlet end is connected to the calcination tail gas inlet end and its outlet end is connected to the side of the purification tank and the mixing chamber respectively. A water-air separation grid is correspondingly installed at the top of the air-lifting chamber; The flue gas distribution structure includes a first flue gas distribution plate and a second flue gas distribution plate, which are sequentially arranged in the purification furnace body and located above the water-gas separation grid. The heat exchange coil is correspondingly installed above the flue gas distribution structure, and its two ends penetrate the furnace body and are respectively connected to the high-temperature heat exchange medium supply pipeline and the low-temperature heat exchange medium discharge pipeline. The catalyst module has a honeycomb structure and is installed between the upper support frame and the lower support frame. The spray system includes multiple liquid inlet pipes arranged circumferentially at the top of the purification furnace body. Each liquid inlet pipe is located inside the furnace body and is equipped with multiple spray heads corresponding to the catalyst module. A high-pressure backflush pipeline is connected in parallel to the liquid inlet main pipe and backflushs high-pressure gas to the catalyst module area. The alkaline liquid supply line is connected to the main inlet pipe and supplies alkaline liquid into the purification furnace. The drain end is located at the bottom of the purification furnace and is connected to the purification tank.

[0005] Preferably, the top of the guide wall is provided with an airflow channel connecting the mixing chamber and the rising chamber.

[0006] Preferably, the heat exchange coil is coiled around the inner circumference of the upper side of the furnace wall on the flue gas distribution plate.

[0007] Preferably, the high-pressure backflush line is connected to an external compressed air source to periodically remove dust from the catalyst module; The top of the purification furnace is equipped with a pressure relief valve.

[0008] Preferably, the spray heads are evenly distributed at the top of the inner cavity of the purification furnace, and spray alkaline liquid mist evenly toward the flue gas distribution plate.

[0009] Preferably, the water-air separation grid is composed of two layers of interlaced thin plates with a rectangular structure.

[0010] Preferably, the first flue gas distribution plate includes a grid structure composed of multiple partition plates distributed horizontally and vertically along the inner wall of the purification furnace; the second flue gas distribution plate adopts a mesh distribution structure.

[0011] This invention also discloses a purification method for a purification system, comprising the following steps: Step 1: The petroleum coke calciner sequentially passes through a bag filter and an electrostatic precipitator to remove large coke particles; then the dust-laden flue gas enters the calcination tail gas inlet and enters the alkaline liquid stored in the purification tank at high speed along the inlet flue. After the flue gas impacts the water surface at high speed, it enters the mixing chamber and passes through the guide wall to change the gas flow rate and flow pattern before entering the purification tank again, so that the unseparated dust and sulfur dioxide can fully contact the alkaline solution for humidification, separation and purification. Step 2: After the purified flue gas overflows from the purification tank solution, it flows upward from the rising chamber. During the process of passing through the rising chamber, the flue gas velocity decreases as the space increases. Under the action of water-gas separation grid and gravity, water droplets are separated from the flue gas, and the clean flue gas continues to flow upward. Step 3: As the clean flue gas flows upward along the inner cavity of the purification furnace, it is evenly distributed in the radial plane of the purification furnace body by the distribution effect of the first flue gas distribution plate and the second flue gas distribution plate, and the clean flue gas continues to rise. Step 4: As the clean flue gas flows through the heat exchange coil, it exchanges heat with the high-temperature heat exchange medium flowing through the heat exchange coil. The clean flue gas, heated to the preset temperature, undergoes a catalytic reaction with the catalyst module, causing nitrogen oxides to undergo oxidation-reduction and adsorption-denitrification with the alkaline solution. The denitrified flue gas enters the purified exhaust gas pipeline from the tail gas emission end at the top of the purification furnace. The denitrified liquid flows downward from the purification furnace until it enters the purification pool through the top of the gas riser chamber and reacts with sulfur dioxide in the flue gas. Finally, it is discharged through the liquid discharge end to enter the subsequent process.

[0012] Compared with the prior art, the present invention has at least the following beneficial effects: 1. The purification system of the present invention ensures deep removal of pollutants through a multi-stage purification structure and multi-stage treatment, shortens the process flow, and improves the purification efficiency and quality of petroleum coke tail gas. 2. The heat exchange coil structure is designed to work in conjunction with the catalyst module. The heat exchange coil can recover the waste heat of the high-temperature flue gas, preheat the clean flue gas to meet the needs of the subsequent denitrification reaction, and reduce energy consumption. 3. The catalyst module adopts a modular structure and is equipped with a spray system and a high-pressure backflushing pipeline. The catalyst module realizes catalytic denitrification of calcination tail gas. The catalyst module is easy to maintain and replace components, and the high-pressure backflushing extends the service life of the catalyst. Attached Figure Description

[0013] Figure 1 This is a cross-sectional view of the internal structure of the purification furnace body of the present invention; Figure 2 This is a flowchart of the purification system of the present invention; Figure 3 for Figure 1 Cross-sectional view of the central purification tank along the AA direction; Figure 4 for Figure 1 Top view of the structure of the purification furnace body from direction A; Figure 5 for Figure 1 Top view of the central purification furnace body along the BB direction; Figure 6 for Figure 1 Top view of the purification furnace body along the CC direction.

[0014] Attached reference numerals: 100, Purification system; 1, Furnace body; 2, Calcination tail gas inlet; 3, Inlet flue; 4, Purification tank; 5, Partition wall; 6, Mixing chamber; 7, Gas rising chamber; 8, Water-gas separation grid; 9, First flue gas distribution plate; 10, Second flue gas distribution plate; 11, Heat exchange coil; 12, Lower support frame; 13, Honeycomb catalyst module; 14, Upper support frame; 15, Liquid inlet main pipe; 16, Spray head; 17, Tail gas emission end; 18, Liquid discharge end; 19, Pressure relief valve; 20, High-pressure backflush pipeline; 21, Alkaline liquid supply pipeline; 22, Purified tail gas emission pipeline; 23, High-temperature heat exchange medium supply pipeline; 24, Low-temperature heat exchange medium discharge pipeline. Detailed Implementation

[0015] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the following will be described in conjunction with the accompanying drawings. Figures 1-6 The technical solutions of the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention are within the scope of protection of the present invention.

[0016] Example 1: As Figure 1 and Figure 2As shown, this invention discloses a petroleum coke calcination tail gas purification system. The purification system 100 includes a purification furnace body 1, a calcination tail gas inlet end 2, a tail gas outlet end 17, and a liquid outlet end 18. It also includes an inlet flue duct 3, a purification tank 4, a water-gas separation grid 8, a flue gas distribution structure, a heat exchange coil 11, a catalyst module 13, a spray system, a high-pressure backflushing pipeline 20, and an alkaline liquid supply pipeline 21. The purification tank 4 is located at the bottom of the purification furnace body 1, and its cross-sectional structure is a V-shaped groove structure. The upper part of the purification tank 4 is divided into a mixing chamber 6 and a rising gas chamber 7 by an isolation wall. The top of the mixing chamber 6 is a closed structure and is not connected to the upper cavity of the purification furnace body 1. The top of the rising gas chamber 7 is connected to the upper cavity of the purification furnace body 1. A guide wall 5 is provided between the mixing chamber 6 and the purification tank 4. The top of the guide wall 5 is provided with an airflow channel connecting the mixing chamber 6 and the rising chamber 7. The inlet flue 3 is located adjacent to the outer wall of the purification furnace body 1, and its inlet end is connected to the calcination tail gas inlet end 2, and its outlet end is connected to the corresponding side of the purification tank 4 and the mixing chamber 6. When the dust-laden flue gas enters the alkaline liquid stored in the purification tank 4 at high speed along the inlet flue 3, the flue gas enters the mixing chamber 6 after being blocked by the guide wall 5 after impacting the water surface at high speed. The gas flow rate and flow state are changed by the guide wall 5 and it re-enters the purification tank 4, so that the unseparated dust, sulfur dioxide and alkaline solution can fully contact each other for humidification, separation and purification. After being purified and dust-removed, the clean flue gas overflows and enters the rising chamber 7.

[0017] like Figure 3 As shown, the water-gas separation grid 8 is correspondingly installed at the top of the rising chamber 7. The water-gas separation grid 8 is composed of multiple thin plates with two layers of rectangular structure that are interlaced. When the purified flue gas overflows from the solution in the purification tank 4, it flows upward from the rising chamber 7. During the process of passing through the rising chamber 7, the flue gas velocity decreases as the space increases. Under the action of passing through the water-gas separation grid 8 and gravity, water droplets are separated from the flue gas, and the clean flue gas continues to flow upward. The water-gas separation grid 8 is conducive to the separation of water and gas in the flue gas.

[0018] like Figure 6 As shown, the flue gas distribution structure includes a first flue gas distribution plate 9 and a second flue gas distribution plate 10, which are sequentially arranged inside the purification furnace body 1 and above the water-gas separation grid 8. The first flue gas distribution plate 9 includes a grid structure composed of multiple partition plates distributed horizontally and vertically along the inner wall of the purification furnace body 1. The second flue gas distribution plate 10 adopts a mesh distribution structure. When the clean flue gas flows upward along the inner cavity of the purification furnace body 1, it is evenly distributed in the radial plane of the purification furnace body 1 by the distribution effect of the first flue gas distribution plate 9 and the second flue gas distribution plate 10, and the clean flue gas continues to rise for purification and denitrification.

[0019] like Figure 1As shown, the heat exchange coil 11 is positioned above the flue gas distribution structure, with both ends penetrating the furnace body and connected to the high-temperature heat exchange medium supply pipeline 23 and the low-temperature heat exchange medium discharge pipeline 24, respectively. The heat exchange coil 11 is coiled circumferentially around the inner side of the furnace wall above the flue gas distribution plate. Specifically, as shown... Figure 2 As shown, the calcination flue gas flows through the outside of the heat exchange coil 11. The high-temperature heat exchange medium can be high-temperature flue gas. During the process of the high-temperature flue gas flowing through the heat exchange coil 11, it exchanges heat with the clean flue gas flowing outside the heat exchange coil 11, heating the clean flue gas passing through the heat exchange coil 11 to a specific temperature window (usually 300-400℃). Then, when it passes through the catalyst module 13, a denitrification reaction occurs to remove nitrogen oxides.

[0020] like Figure 1 , Figure 4 and Figure 5 As shown, the catalyst module 13 has a honeycomb structure and is installed between the upper support frame 14 and the lower support frame 12. The spray system includes multiple liquid inlet pipes 15 arranged circumferentially at the top of the purification furnace body 1. Each liquid inlet pipe 15 is located inside the furnace body and has multiple spray nozzles 16 corresponding to the catalyst module 13. The spray nozzles 16 are evenly distributed at the top of the inner cavity of the purification furnace body and spray alkaline liquid mist evenly toward the flue gas distribution plate. During the process of clean flue gas flowing through the catalyst module 13, under the action of the catalyst, a reducing agent (usually ammonia water or urea solution) is sprayed into the clean flue gas through the spray nozzles 16, and NO is reduced within a specific temperature window (usually 300-400℃). x The catalyst module 13 needs to be replaced periodically to reduce it to N2 and H2O.

[0021] like Figure 2 As shown, the high-pressure backflush pipeline 20 is connected in parallel to the liquid inlet main pipe 15. The high-pressure backflush pipeline 20 is connected to an external compressed air source to backflush high-pressure gas into the catalyst module area to periodically remove dust accumulated in the catalyst module 13. It should be noted that during the purification process of the catalyst module 13, the liquid inlet main pipe 15 and the spray head 16 are used. A pressure relief valve 19 is equipped at the top of the purification furnace body 1, and the pressure can be released through the pressure relief valve 19 after the dust removal is completed.

[0022] like Figure 2 As shown, the alkaline liquid supply pipeline 21 is connected to the main liquid inlet 15 and supplies alkaline liquid into the purification furnace body 1. In a specific embodiment, to meet the requirements for nitrogen oxide removal, the alkaline liquid is ammonia water. The alkaline liquid supply pipeline 21 is connected to an ammonia water tanker, and its pipeline is connected to an ammonia water unloading pump, an ammonia water storage tank, and an ammonia water transfer pump, etc., to meet the ammonia water supply requirements.

[0023] like Figure 3As shown, the drain end 18 is located at the bottom of the purification furnace body 1 and is connected to the purification tank 4. When the alkaline solution stored in the purification tank reacts with the sulfur oxides in the flue gas, it can be discharged through the drain end 18.

[0024] Example 2: The present invention also discloses a purification method for a purification system, comprising the following steps: (1) The petroleum coke calciner sequentially passes through a bag filter and an electrostatic precipitator to remove large coke particles; then the dust-laden flue gas enters the calcination tail gas inlet 2 and enters the alkaline liquid stored in the purification tank 4 at high speed along the inlet flue 3. After the flue gas impacts the water surface at high speed, it enters the mixing chamber 6 and enters the purification tank 4 again through the guide wall 5 to change the gas flow rate and flow state, so that the unseparated dust and sulfur dioxide can fully contact the alkaline solution for humidification, separation and purification; the alkaline solution can be limestone (CaCO3) or slaked lime (Ca(OH)2) slurry that can achieve good absorption of SO2, or NaOH or Na2CO3 solution can be used to absorb SO2.

[0025] (2) After the purified flue gas overflows from the solution in the purification tank 4, it flows upward from the rising chamber 7. During the process of passing through the rising chamber 7, the flue gas velocity decreases as the space increases. Under the action of passing through the water-gas separation grid 8 and gravity, water droplets are separated from the flue gas, and the clean flue gas continues to flow upward.

[0026] (3) As the clean flue gas flows upward along the inner cavity of the purification furnace body 1, it is evenly distributed in the radial plane of the purification furnace body 1 by the distribution effect of the first flue gas distribution plate 9 and the second flue gas distribution plate 10. After the clean flue gas is evenly distributed, it continues to rise and passes through the heat exchange coil 11 for heat exchange.

[0027] (4) As the clean flue gas flows through the heat exchange coil 11, it exchanges heat with the high-temperature heat exchange medium flowing through the heat exchange coil 11. The clean flue gas, heated to the preset temperature, undergoes a catalytic reaction with the catalyst module 13, causing the nitrogen oxides to undergo oxidation-reduction and adsorption-denitration with the alkaline solution. The denitrified flue gas enters the purified tail gas discharge pipeline 22 from the tail gas discharge end 17 at the top of the purification furnace body 1. The denitrified liquid flows downward from the purification furnace body 1 until it enters the purification pool 4 through the top of the rising chamber 7 and reacts with the sulfur dioxide in the flue gas. Finally, it is discharged through the liquid discharge end 18 into the subsequent process.

[0028] The above are preferred embodiments 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 should also be considered within the scope of protection of the present invention.

Claims

1. A petroleum coke calcination tail gas purification system, comprising a purification furnace body (1), a calcination tail gas inlet (2), and a tail gas outlet (17), characterized in that, Also includes: Purification tank (4) is located at the bottom of purification furnace body (1), and is divided into mixing chamber (6) and rising chamber (7) above it by an isolation wall. The top of rising chamber (7) is connected to the upper cavity of purification furnace body (1). A guide wall (5) is provided between mixing chamber (6) and purification tank (4). The air intake flue (3) is located adjacent to the outer wall of the purification furnace body (1), and its inlet end is connected to the calcination tail gas inlet end (2) and its outlet end is connected to the side corresponding to the purification pool (4) and the mixing chamber (6). Water-air separation grid (8) is disposed on the top of the air-lift chamber (7); The flue gas distribution structure includes a first flue gas distribution plate (9) and a second flue gas distribution plate (10), which are arranged in sequence inside the purification furnace body (1) and above the water-gas separation grid (8). Heat exchange coil (11) is arranged above the flue gas distribution structure, and its two ends pass through the furnace body and are respectively connected to the high temperature heat exchange medium supply pipeline (23) and the low temperature heat exchange medium discharge pipeline (24). Catalyst module (13), which has a honeycomb structure, is installed between the upper support frame (14) and the lower support frame (12); The spray system includes multiple liquid inlet pipes (15) arranged in the circumferential direction at the top of the purification furnace body (1). Each liquid inlet pipe (15) is located in the furnace body and is equipped with multiple spray heads (16) corresponding to the catalyst module (13). High-pressure backflush line (20), which is connected in parallel to the liquid inlet main line (15) and backflushs high-pressure gas to the catalyst module area; The alkaline liquid supply line (21) is connected to the liquid inlet pipe (15) and supplies alkaline liquid into the purification furnace body (1); The drain end (18) is located at the bottom of the purification furnace body (1) and is connected to the purification tank (4).

2. The petroleum coke calcination tail gas purification system according to claim 1, characterized in that, The top of the guide wall (5) is provided with an airflow channel connecting the mixing chamber (6) and the air-lifting chamber (7).

3. The petroleum coke calcination tail gas purification system according to claim 1, characterized in that, The heat exchange coil (11) is coiled around the inner circumference of the upper side of the furnace wall on the flue gas distribution plate.

4. The petroleum coke calcination tail gas purification system according to claim 1, characterized in that, The high-pressure backflush line (20) is connected to an external compressed air source to periodically remove dust from the catalyst module (13); The top of the purification furnace body (1) is equipped with a pressure relief valve (19).

5. The petroleum coke calcination tail gas purification system according to claim 1, characterized in that, The spray heads (16) are evenly distributed on the top of the inner cavity of the purification furnace, and spray alkaline liquid mist evenly toward the flue gas distribution plate.

6. The petroleum coke calcination tail gas purification system according to claim 1, characterized in that, The water-air separation grid (8) is composed of two layers of interlaced thin plates with a rectangular structure.

7. The petroleum coke calcination tail gas purification system according to claim 1, characterized in that, The first flue gas distribution plate (9) includes a grid structure composed of multiple partition plates distributed horizontally and vertically along the inner wall of the purification furnace body (1); the second flue gas distribution plate (10) adopts a mesh distribution structure.

8. A purification method for a purification system according to any one of claims 1 to 7, characterized in that, Includes the following steps: Step 1: The petroleum coke calciner passes through a bag filter and an electrostatic precipitator in sequence to remove large coke particles; then the dust-laden flue gas enters the calcination tail gas inlet (2) and enters the alkaline liquid stored in the purification tank (4) at high speed along the inlet flue (3). After the flue gas impacts the water surface at high speed, it enters the mixing chamber (6) and changes the gas flow rate and flow state through the guide wall (5) and enters the purification tank (4) again, so that the unseparated dust and sulfur dioxide can fully contact the alkaline solution for humidification, separation and purification. Step 2: After the purified flue gas overflows from the solution in the purification tank (4), it flows upward from the rising chamber (7). During the process of passing through the rising chamber (7), the flue gas velocity decreases as the space increases. Under the action of water-gas separation grid (8) and gravity, water droplets are separated from the flue gas, and the clean flue gas continues to flow upward. Step 3: As the clean flue gas flows upward along the inner cavity of the purification furnace body (1), it is evenly distributed in the radial plane of the purification furnace body (1) by the distribution effect of the first flue gas distribution plate (9) and the second flue gas distribution plate (10), and the clean flue gas continues to rise. Step 4: As the clean flue gas flows through the heat exchange coil (11), it exchanges heat with the high-temperature heat exchange medium flowing through the heat exchange coil (11). The clean flue gas, heated to the preset temperature, undergoes a catalytic reaction with the catalyst module (13), causing nitrogen oxides to undergo oxidation-reduction and adsorption-denitrification with the alkaline solution. The denitrified flue gas enters the purified tail gas discharge pipeline (22) from the tail gas discharge end (17) at the top of the purification furnace body (1). The denitrified liquid flows downward from the purification furnace body (1) until it enters the purification pool (4) through the top of the rising chamber (7) and reacts with sulfur dioxide in the flue gas. Finally, it is discharged through the liquid discharge end (18) into the subsequent process.

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