A yellow phosphorus tail gas combustion system that reduces the generation of acidic substances

Abstract

This utility model discloses a yellow phosphorus tail gas combustion system that reduces the generation of acidic substances, belonging to the field of phosphorus chemical processing technology. It solves the problems of high cost, inefficiency, poor stability, and easy secondary pollution associated with existing technologies. The system includes three sequentially connected modules: tail gas pretreatment, combustion, and purification, forming a complete treatment pathway. The pretreatment module uses a centrifugal fan to transport the tail gas, a spray-filter desulfurization tower to remove sulfides, and a high-pressure backflush pipe to ensure stable airflow. The combustion module optimizes the air-fuel ratio, combines flue gas circulation and parameter monitoring to suppress nitrogen oxide generation, and is adapted to boiler waste heat utilization. The purification module is equipped with a waste heat recovery device before electrostatic precipitator to remove impurities. The system achieves desulfurization liquid regeneration and circulation, reduces equipment corrosion and treatment costs, ensures that exhaust gas emissions meet standards, and balances environmental protection and energy utilization efficiency.

Description

Technical Field

[0001] This utility model relates to the field of phosphorus chemical processing technology, specifically to a yellow phosphorus tail gas combustion system. Background Technology

[0002] The phosphorus furnace tail gas produced during the electric furnace phosphorus production process has a complex composition, with carbon monoxide as the main component, along with gases such as hydrogen sulfide, phosphine, and hydrogen fluoride. CO, the main component of the tail gas, can be used as fuel and has high utilization value, such as in raw material drying, steam preparation, phosphorus mud recovery, and the comprehensive utilization of fuel gas in hot water preparation processes. However, corrosive gases such as hydrogen sulfide, phosphine, and hydrogen fluoride, after being sprayed, cooled, and condensed, combine with some water vapor to form acid, which corrodes and damages the equipment and facilities of the entire production system. To address the series of adverse effects brought about by the waste heat utilization process, a technical solution is needed to reduce equipment corrosion during the waste heat utilization of yellow phosphorus tail gas.

[0003] We know that to reduce the corrosion of equipment by exhaust gases, we must understand how corrosion occurs and take appropriate countermeasures. Existing technologies mainly consider factors such as the residence time of exhaust gases in equipment, the removal of harmful components from exhaust gases, and the application of special materials.

[0004] While existing technologies can alleviate the problem of acid corrosion in phosphorus furnace tail gas, they still have significant shortcomings, mainly in terms of cost control, efficiency balance, and stability. Furthermore, the treatment process may be affected by fluctuations in tail gas flow and temperature, making it difficult to maintain a consistently high removal rate. The waste heat utilization process has poor adaptability: shortening the tail gas residence time can reduce corrosion, but it may reduce the waste heat exchange efficiency. Adding adsorption and spraying devices will increase tail gas resistance, requiring additional power from the induced draft fan, which indirectly consumes some of the recovered waste heat. If the adsorbent and wastewater after adsorption saturation are not treated properly, they may cause secondary pollution, and existing technologies lack low-cost, harmless supporting treatment solutions. Summary of the Invention

[0005] To address the problems in the background technology, this utility model provides a yellow phosphorus tail gas combustion system that reduces the generation of acidic substances, thereby solving many problems faced by the prior art. This system is used in the production process of yellow phosphorus to purify the exhaust gas emitted from the yellow phosphorus electric furnace and the flue gas generated after boiler combustion. The purpose is to remove sulfides from the exhaust gas, inhibit the generation of nitrogen oxides during combustion, and remove impurities; reduce the generation of acidic substances after exhaust gas combustion, so that the final exhaust gas meets environmental protection standards, and is also compatible with the use of boiler fuel gas.

[0006] The yellow phosphorus tail gas combustion system for reducing the generation of acidic substances described in this application includes three modules: tail gas pretreatment, combustion, and purification. The modules are connected in sequence to form a complete circuit. The exhaust gas pretreatment module is installed between the exhaust gas condensation tower 1 and the combustion module to desulfurize the electric furnace exhaust gas after it has been sprayed, washed, and cooled, preventing sulfides from entering the combustion module and causing secondary pollution or corrosion to the equipment. The combustion module is connected to the outlet of the exhaust gas pretreatment module to optimize the exhaust gas combustion mode and flue gas circulation mode, reducing the generation of nitrogen oxides during exhaust gas combustion and boiler heat exchange. The purification module is located after the combustion module to further remove fine impurities in the exhaust gas and improve the purification accuracy.

[0007] The exhaust gas pretreatment module includes two components connected in series: an exhaust gas delivery unit and a pre-combustion desulfurization treatment unit. The exhaust gas conveying unit uses a centrifugal fan 2 to stably introduce the exhaust gas into the pre-combustion desulfurization treatment unit while ensuring a uniform exhaust gas flow rate; the pre-combustion desulfurization treatment unit uses a spray filtration desulfurization tower, including a desulfurization spray box 3, a liquid storage tank 4, and a filter box 5.

[0008] The desulfurization spray box 3 is a square or cylindrical sealed box used for spraying desulfurizing agent. It has an air inlet pipe at the front end to introduce exhaust gas and a liquid supply pipe connected to the storage tank 4 on the side. The storage tank 4 is independent of the desulfurization spray box 3 and stores the desulfurizing agent solution inside. It has a conventional liquid level gauge and a dosing port on the outside. The storage tank 4 delivers the prepared desulfurizing agent solution to the desulfurization spray box 3 through the liquid supply pipe. Multiple sets of spray pipes are installed on the top of the desulfurization spray box 3. Atomizing nozzles 3-1 are evenly distributed on the spray pipes to atomize the desulfurizing agent solution into fine droplets, which fully contact the exhaust gas entering from the side and absorb the sulfur oxides in it.

[0009] The filter box 5 is a sealed box with a sealed door 5-1 on the side that can be opened and closed to clean and replace the filter assembly 5-3; the filter assembly 5-3 is fixed inside the filter box 5 by a fixing plate 5-2, and the installation direction of the filter assembly 5-3 is perpendicular to the exhaust gas intake direction; it includes a sealed door 5-1, a fixing plate 5-2 and a filter assembly 5-3.

[0010] A conveying pipe is installed at the outlet of the desulfurization spray box 3 and connected to the filter box 5 to convey the exhaust gas after preliminary desulfurization to the filter box 5. An exhaust pipe is installed at the tail of the filter box 5 to connect to the outlet of the filter box 5 and convey the exhaust gas after desulfurization and filtration to the rear.

[0011] In addition, a high-pressure backflush pipe 5-4 is installed on the back of the filter assembly 5-3 and fixed to the frame of the fixing plate 5-2. It is used to periodically remove the blockages on the surface of the filter assembly 5-3 to prevent the air volume from decreasing.

[0012] The combustion module is connected to the filter box 5 via an exhaust pipe and includes a main fan 6, a regulating damper, and a burner body 7. A temperature sensor is installed inside the burner body 7. The main fan 6 and the regulating damper are located on the air inlet pipe and are responsible for providing sufficient air to the burner body 7. A gas nozzle located inside the burner body 7 is connected to the exhaust pipe to control the injection volume of the desulfurized and filtered exhaust gas, ensuring optimal mixing with air. The burner body 7 is the core area where combustion occurs. Sensors are installed around the burner body 7 to monitor temperature and nitrogen oxide content, and adjust the combustion parameters accordingly. The supply of gas and air; a flue gas outlet is set at the rear end of the burner body 7, and a flue gas extraction pipe 7-1 is connected to the flue gas outlet, and an extraction fan 7-2 is provided to extract high-temperature flue gas from the flue gas outlet. The flue gas extraction pipe 7-1 is divided into two branches by a distribution valve 7-3. One branch is connected to a cooling device 7-4 and then back to the burner body 7 to reduce the oxygen concentration and flame temperature in the combustion zone and suppress the generation of nitrogen oxides; the other branch is connected to the air intake pipe where the main fan 6 is located, mixes with the intake air, and then sends it into the burner body 7 to reduce the oxygen concentration and further suppress the generation of nitrogen oxides.

[0013] The purification module is located behind the combustion module and is connected to the flue gas outlet of the burner body 7. It uses an electrostatic dust removal device 8 to remove fine dust and particulate matter remaining in the exhaust gas after desulfurization by utilizing the principle of electrostatic adsorption. Finally, it is connected to the chimney 9 for discharge.

[0014] A waste heat recovery device 10 is installed at the front end of the purification module to recover the heat in the flue gas before electrostatic dust removal.

[0015] System workflow: After exiting the condenser, the exhaust gas from the yellow phosphorus electric furnace enters the desulfurization unit via the exhaust gas fan. In the desulfurization tower, sulfides are removed through a combined spray and filtration process. The desulfurization liquid is regenerated and recycled. The desulfurized exhaust gas then enters the low-NOx burner for combustion. The resulting high-temperature flue gas undergoes heat exchange in the boiler. Part of the flue gas is circulated back to the boiler and burner via the secondary fan and main fan 6, reducing the oxygen concentration and flame temperature in the combustion zone and inhibiting the formation of nitrogen oxides. The flue gas produced after combustion enters the purification module, is discharged after electrostatic precipitator treatment, and is then discharged through the chimney 9. Before entering the electrostatic precipitator, a waste heat recovery device 10 is installed to recover heat from the flue gas that does not participate in the main burner 7 circulation. The waste heat recovery device 10 then sends the flue gas into the electrostatic precipitator, and finally discharges it through the chimney 9, completing the entire process. Beneficial effects

[0016] The yellow phosphorus tail gas combustion system described in this application, which reduces the generation of acidic substances, effectively addresses the shortcomings of existing yellow phosphorus tail gas treatment technologies in terms of cost control, efficiency balance, stability, and secondary pollution, offering comprehensive benefits in multiple aspects. The system forms a complete treatment pathway through three sequentially connected modules: "tail gas pretreatment - combustion - purification." In the pretreatment module, a centrifugal fan stably delivers tail gas, and a spray-filter desulfurization tower atomizes the desulfurizing agent solution through atomizing nozzles in the desulfurization spray box, ensuring full contact with the tail gas to absorb sulfur oxides. The gas is then filtered by filter components in the filter box, and a high-pressure backflush pipe ensures stable airflow, efficiently removing sulfides from the tail gas and preventing them from entering subsequent modules and causing secondary pollution or equipment corrosion. The combustion module precisely controls the air supply through a main fan and regulating dampers, and the gas nozzles control the amount of tail gas injected to achieve optimal performance. The system features optimized air-fuel ratio, and through the design of flue gas extraction ducts, cooling devices, and branch pipe circulation, combined with sensor monitoring and parameter adjustment of temperature and nitrogen oxide content, it effectively reduces oxygen concentration and flame temperature in the combustion zone, significantly suppressing nitrogen oxide formation. It also adapts to the boiler fuel gas usage requirements, ensuring efficient waste heat exchange and avoiding the additional consumption of recovered waste heat due to increased exhaust gas resistance from additional devices. The waste heat recovery device installed before the purification module fully recovers heat from the flue gas, and the subsequent electrostatic precipitator efficiently removes residual fine dust and particulate matter after desulfurization, ultimately ensuring that the emitted exhaust gas meets environmental standards. Furthermore, the desulfurization liquid in the system can be regenerated and recycled, reducing the risk of secondary pollution caused by improper treatment of adsorbents and wastewater. Overall, it improves the stability of exhaust gas treatment, reduces equipment corrosion, balances environmental protection and energy utilization efficiency, and controls treatment costs, providing a superior technical solution for the utilization of waste heat from yellow phosphorus exhaust gas. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the yellow phosphorus tail gas combustion system described in Example 1.

[0018] Figure 2 This is a schematic diagram of the exhaust gas pretreatment module.

[0019] Figure 3 This is a schematic diagram of the structure of the filter box.

[0020] Figure 4 This is a schematic diagram of the yellow phosphorus tail gas combustion system described in Example 2.

[0021] Figure 5 This is a schematic diagram of the yellow phosphorus tail gas combustion system described in Example 2.

[0022] In the diagram: 1. Tail gas condenser tower; 2. Centrifugal fan; 3. Desulfurization spray box; 3-1. Atomizing nozzle; 4. Liquid storage tank; 5. Filter box; 5. Sealing door; 5-1. Fixing plate; 5-2. Filter assembly; 5-3. High-pressure backflush pipe; 5-4. Main fan; 6. Burner body; 7. Smoke extraction duct; 7-1. Exhaust fan; 7-2. Distribution valve; 7-3. Cooling device; 7-4. Electrostatic dust removal device; 8. Chimney; 9. Waste heat recovery device; 10. Detailed Implementation

[0023] The present invention will be further described in detail below with reference to specific embodiments. Example 1

[0024] refer to Figure 1 , 2 3. The yellow phosphorus tail gas combustion system for reducing the generation of acidic substances described in this embodiment includes a tail gas pretreatment module, a combustion module and a purification module connected in sequence, forming a closed-loop treatment pathway.

[0025] The exhaust gas pretreatment module is installed between the exhaust gas condensation tower and the combustion module, and consists of an exhaust gas conveying unit and a pre-combustion desulfurization treatment unit connected in series. The exhaust gas conveying unit uses a centrifugal fan, and the pre-combustion desulfurization treatment unit is a spray-filtration type desulfurization tower, which includes a desulfurization spray box, a storage tank, and a filter box. The desulfurization spray box is a square, sealed box with multiple sets of spray pipes installed on the top, with atomizing nozzles evenly distributed on the pipes; the storage tank is independent of the desulfurization spray box, with a level gauge and a dosing port on the outside, and is connected to the desulfurization spray box through a supply pipe; the filter box is a sealed box with a sealable door that can be opened and closed on the side, and the filter assembly is fixed inside by a fixing plate perpendicular to the exhaust gas inlet direction, with a high-pressure backflush pipe on the back of the filter assembly.

[0026] The combustion module is connected to the filter box via an exhaust pipe and includes a main fan, a regulating damper, and a burner body. A temperature sensor is installed inside the burner body, and sensors monitoring temperature and nitrogen oxide levels are located around it. The main fan and regulating damper are mounted on the air inlet duct. The gas nozzle inside the burner body is connected to the exhaust pipe. The flue gas outlet at the rear of the burner body connects to a smoke extraction duct, which is equipped with an extraction fan. The exhaust duct is divided into two branches by a distribution valve. One branch connects to the cooling device and then back to the burner body; the other branch connects to the air inlet duct where the main fan is located.

[0027] The purification module is located behind the combustion module and is connected to the flue gas outlet of the burner body. It is equipped with a waste heat recovery device at the front end, an electrostatic dust removal device in the main body, and a chimney at the end.

[0028] Workflow After the exhaust gas from the yellow phosphorus electric furnace is discharged from the condenser tower, it is stably introduced into the desulfurization spray box by a centrifugal fan. The desulfurizing agent solution in the storage tank is transported to the spray pipe through the supply pipe, where it is atomized into fine droplets by the atomizing nozzles, making full contact with the exhaust gas to absorb sulfur oxides. The exhaust gas after preliminary desulfurization enters the filter box, where impurities are removed by the filter components. The high-pressure backflush pipe regularly cleans the surface of the filter components to ensure stable airflow.

[0029] After desulfurization and filtration, the exhaust gas enters the burner body through the exhaust pipe. The main fan and regulating damper precisely supply air, and the gas nozzle controls the amount of exhaust gas injected to achieve the optimal air-fuel ratio. During combustion, sensors monitor the temperature and nitrogen oxide content in real time. The exhaust fan draws in high-temperature flue gas, which is then distributed by the distribution valve. Part of the flue gas is cooled by the cooling device and returned to the burner body, while the other part is mixed with the air in the air inlet duct and sent to the burner body. This reduces the oxygen concentration and flame temperature in the combustion zone, thus inhibiting the formation of nitrogen oxides.

[0030] The flue gas generated by combustion first enters the waste heat recovery device to recover heat, then enters the electrostatic precipitator to remove residual fine dust and particulate matter, and finally is discharged through the chimney in compliance with standards. Example 2

[0031] refer to Figure 2 , 3 4, 5. The yellow phosphorus tail gas combustion system for reducing the generation of acidic substances described in this embodiment is also composed of a tail gas pretreatment module, a combustion module and a purification module connected in sequence. The core component functions remain unchanged, and only some structural adjustments are made for adaptability.

[0032] The overall layout is the same as in Embodiment 1, except that a waste heat recovery device 10 is provided at the front end of the purification module, and the connection method and function of the other components are the same as in Embodiment 1.

[0033] Workflow The exhaust gas treatment process is basically the same as in Example 1: After the exhaust gas from the yellow phosphorus electric furnace is discharged through the condenser tower, it is sent into the cylindrical desulfurization spray box by a centrifugal fan. After the sulfur oxides are absorbed by the atomized desulfurizing agent solution, it enters the filter box for filtration and impurity removal, and the air volume is guaranteed by the high-pressure backflush pipe.

[0034] The desulfurized exhaust gas enters the main body of the burner, where it is fully combusted under the optimized air-fuel ratio and flue gas recirculation. Sensors adjust parameters in real time to suppress the formation of nitrogen oxides. The flue gas after combustion first recovers heat through a waste heat recovery device, then is purified by an electrostatic precipitator, and finally discharged through a chimney. The entire process achieves the goals of reducing the formation of acidic substances, recovering and utilizing waste heat, and ensuring that the exhaust gas meets emission standards.

Claims

1. A yellow phosphorus tail gas combustion system for reducing the generation of acidic substances, characterized in that, It includes three modules: exhaust gas pretreatment module, combustion module, and purification module. These modules are connected in sequence to form a complete circuit. Among them, the exhaust gas pretreatment module is installed between the exhaust gas condensation tower (1) and the combustion module to desulfurize the electric furnace exhaust gas after it has been sprayed, washed and cooled; the combustion module is connected to the outlet of the exhaust gas pretreatment module to optimize the exhaust gas combustion mode and flue gas circulation mode; and the purification module is set after the combustion module to further remove fine impurities in the exhaust gas.

2. The yellow phosphorus tail gas combustion system for reducing the generation of acidic substances according to claim 1, characterized in that, The exhaust gas pretreatment module includes two components connected in series: an exhaust gas delivery unit and a pre-combustion desulfurization treatment unit. The exhaust gas conveying unit uses a centrifugal fan (2) to stably introduce the exhaust gas into the pre-combustion desulfurization treatment unit; the pre-combustion desulfurization treatment unit uses a spray filtration desulfurization tower, including a desulfurization spray box (3), a liquid storage tank (4), and a filter box (5). The desulfurization spray box (3) is a square or cylindrical sealed box used for spraying desulfurizing agent. An air inlet pipe is set at the front end to introduce tail gas, and the side is connected to the liquid supply pipe of the storage tank (4). The storage tank (4) is independent of the desulfurization spray box (3) and stores the desulfurizing agent solution inside. A level gauge and a dosing port are set on its outside. The storage tank (4) transports the prepared desulfurizing agent solution to the desulfurization spray box (3) through the liquid supply pipe. Multiple sets of spray pipes are installed on the top of the desulfurization spray box (3). Atomizing nozzles (3-1) are evenly distributed on the spray pipes to atomize the desulfurizing agent solution into fine droplets, which fully contact the tail gas entering from the side. The filter box (5) is a sealed box with a sealed door (5-1) on the side that can be opened and closed to clean and replace the filter assembly (5-3); the filter assembly (5-3) is fixed inside the filter box (5) by a fixing plate (5-2), and the installation direction of the filter assembly (5-3) is perpendicular to the air intake direction of the exhaust gas; it includes a sealed door (5-1), a fixing plate (5-2) and a filter assembly (5-3). A conveying pipe is set at the outlet of the desulfurization spray box (3) and connected to the filter box (5) to convey the tail gas after preliminary desulfurization to the filter box (5). An exhaust pipe is set at the tail of the filter box (5) to connect to the outlet of the filter box (5) and convey the tail gas after desulfurization and filtration to the rear. In addition, a high-pressure backflush pipe (5-4) is installed on the back of the filter assembly (5-3) and fixed on the frame of the fixing plate (5-2) to periodically remove the blockage on the surface of the filter assembly (5-3) and prevent the air volume from decreasing.

3. The yellow phosphorus tail gas combustion system for reducing the generation of acidic substances according to claim 1, characterized in that, The combustion module is connected to the filter box (5) via an exhaust pipe and includes a main fan (6), a regulating damper, and a burner body (7). A temperature sensor is installed inside the burner body (7). The main fan (6) and the regulating damper are installed on the air inlet pipe and are responsible for supplying air to the burner body (7). The gas nozzle installed inside the burner body (7) is connected to the exhaust pipe and controls the amount of exhaust gas injected after desulfurization and filtration. The burner body (7) is the core area where combustion occurs. Sensors are installed around the burner body (7) to monitor the temperature. The nitrogen oxide content is adjusted according to the parameters to control the supply of gas and air. A flue gas outlet is set at the rear end of the burner body (7). A smoke extraction pipe (7-1) is connected to the flue gas outlet, and an exhaust fan (7-2) is provided to extract high-temperature flue gas from the flue gas outlet. The smoke extraction pipe (7-1) is divided into two branches by a distribution valve (7-3). One branch is connected to a cooling device (7-4) and then back to the burner body (7). The other branch is connected to the air inlet pipe where the main fan (6) is located, where it is mixed with the intake air and then sent into the burner body (7).

4. A yellow phosphorus tail gas combustion system for reducing the generation of acidic substances according to claim 1, 2, or 3, characterized in that, The purification module is located behind the combustion module and is connected to the flue gas outlet of the burner body (7). It uses an electrostatic dust removal device (8) to remove fine dust and particulate matter remaining in the exhaust gas after desulfurization by utilizing the principle of electrostatic adsorption. Finally, it is connected to the chimney (9) for discharge.

5. A yellow phosphorus tail gas combustion system for reducing the generation of acidic substances according to claim 1, 2, or 3, characterized in that, A waste heat recovery device (10) is installed at the front end of the purification module to recover the heat in the flue gas before electrostatic dust removal.

6. The yellow phosphorus tail gas combustion system for reducing the generation of acidic substances according to claim 4, characterized in that, A waste heat recovery device (10) is installed at the front end of the purification module to recover the heat in the flue gas before electrostatic dust removal.

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