Yellow phosphorus tail gas gas-fired boiler flue gas treatment method and treatment system

Abstract

The invention discloses a yellow phosphorus tail gas gas-fired boiler flue gas treatment method which comprises the following steps: S1, carrying out first-stage deacidification treatment on flue gas in a flue of a boiler at the flue gas temperature of 300-500 DEG C, and carrying out dry-process flue gas treatment; and S2, flue gas exhausted from the tail of the flue of the boiler is subjected to second-stage deacidification treatment, and tail gas subjected to second-stage deacidification treatment is exhausted from a chimney. According to the flue gas treatment method for the yellow phosphorus tail gas gas-fired boiler, the concentration of acid pollutants in the flue gas is greatly reduced, corrosion of flue gas condensation to a flue is reduced, the boiler can stably operate for a long time, and the efficiency of the boiler is improved. The invention further discloses a flue gas treatment system for the yellow phosphorus tail gas gas-fired boiler.

Description

Technical Field

[0001] The present invention relates to the technical field of yellow phosphorus tail gas treatment, and particularly relates to a method and a system for treating yellow phosphorus tail gas boiler flue gas. Background Art

[0002] Yellow phosphorus is an important chemical raw material and is indispensable in industries such as electronic-grade chemicals, pharmaceuticals, pesticides, extractants, military industry, and battery materials.

[0003] Yellow phosphorus tail gas is a by-product in the yellow phosphorus production process. The main components are combustible substances, including CO, H 2 , CH 4 . The remaining impurities are inorganic sulfur (H 2 S), organic sulfur (COS, CS 2 ), arsenic compounds, HF, HCN, elemental phosphorus, phosphine, etc. Because of its relatively high calorific value, it can be used as fuel. The main products after the combustion of yellow phosphorus tail gas are SO 2 , SO 3 , HF, P 2 O 5 , As 2 O 3 , etc. The concentration of the main pollutant SO 2 is usually 8000 - 15000 mg / Nm 3 ; the concentration of the main corrosive substance P 2 O 5 is about 1500 mg / Nm 3 theoretically. According to the boiler emission requirements, the SO 2 emission concentration should be ≤ 35 mg / Nm 3 , and the soot emission concentration should be ≤ 10 mg / Nm 3 . Therefore, the SO 2 removal rate needs to be ≥ 99%. In order to avoid serious corrosion, the removal efficiency of P 2 O 5 needs to reach more than 90%. Due to the existence of phosphides, the flue gas after the combustion of yellow phosphorus tail gas has strong corrosiveness. In the early days, many yellow phosphorus industries directly burned yellow phosphorus tail gas as fuel or waste gas, but this would cause pollutant emissions and serious corrosion of subsequent equipment.

[0004] Currently, in the operating yellow phosphorus tail gas combustion boilers, the post-furnace flue gas purification mainly relies on the wet spray flue gas purification technology. Through the wet spray process, this technology can effectively remove phosphides and SO 2, its significant advantage lies in its high desulfurization efficiency when applied to the treatment of high-sulfur flue gas. However, acid condensation begins to occur in the range of 300°C to 500°C of the flue gas temperature in the boiler's tail flue. After acid condensation, it will cause serious corrosion to the downstream flue and equipment. Since this process involves strong liquid-phase reactions, phosphorus corrosion is inevitable. Even if preventive measures are taken, such as using expensive spray anti-corrosion treatment or stainless steel materials for the flue and absorption tower, the relevant equipment components still need to be frequently replaced, and generally need to be shut down for maintenance and replacement within 2 to 3 months, affecting the stable long-term operation of the boiler; the existing wet flue gas purification technology cannot solve the corrosion problem occurring in the front-end flue. At the same time, the yellow phosphorus tail gas has not undergone pretreatment, and the SO 2 concentration is high, reaching up to 14,000 mg / Nm 3 or more. Simply relying on primary desulfurization, it is very difficult to meet the discharge standards; there are many pollutant components and high pollutant concentrations, including SO 2 , SO 3 , P 2 O 5 , HCl, HF, high arsenic content, etc. It is not easy to remove multiple pollutants; the water consumption of the desulfurization and dephosphorization device is relatively large; the post-furnace tail gas treatment device uses traditional wet desulfurization to treat the yellow phosphorus tail gas boiler flue gas, generating a large amount of wastewater that is not easy to dispose of. The existing flue gas purification technology has problems such as high cost, high operation and maintenance costs, frequent shutdowns for maintenance, high water consumption, and difficult wastewater disposal. Summary of the Invention

[0005] In view of this, the present invention provides a method for treating yellow phosphorus tail gas-fired boiler flue gas, which adopts a method of hierarchical desulfurization and dephosphorization to remove SO 2 , SO 3 , P 2 O 5 , HCl, HF, arsenic compounds and other multiple pollutants in the flue gas, solves the problem of removing ultra-high-concentration SO 2 , solves the corrosion problem of the boiler's tail flue, greatly reduces the concentration of acidic pollutants in the flue gas, reduces environmental pollution, enables the boiler to operate stably for a long time, and improves the efficiency of the boiler.

[0006] The present invention also provides a yellow phosphorus tail gas-fired boiler flue gas treatment system.

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] A method for treating yellow phosphorus tail gas-fired boiler flue gas includes the following steps:

[0009] S1. Perform primary acid removal treatment on the flue gas in the range of 300°C to 500°C of the flue gas temperature in the boiler, and the primary acid removal treatment is dry flue gas treatment;

[0010] S2. Perform secondary acid removal treatment on the flue gas discharged from the tail of the boiler's flue, and the tail gas after the secondary acid removal treatment is discharged through the chimney.

[0011] Optionally, in step S1, the flue gas in the temperature range of 300°C to 500°C in the flue is led out, and the primary acid removal treatment uses a primary desulfurization and dephosphorization system to treat the led-out flue gas, and the tail gas after being treated by the primary desulfurization and dephosphorization system is transported back to the position of the flue gas lead-out temperature area in the flue.

[0012] In step S2, the secondary acid removal treatment uses a secondary desulfurization and dephosphorization system to treat the flue gas discharged from the tail of the flue.

[0013] Optionally, in step S1, the primary acid removal treatment is to add an alkaline absorbent to the area where the flue gas temperature in the flue is 300°C to 500°C.

[0014] In step S2, the secondary acid removal treatment uses a secondary desulfurization and dephosphorization system to treat the flue gas discharged from the tail of the flue.

[0015] Optionally, the primary desulfurization and dephosphorization system includes a first desulfurization and dephosphorization tower and a first dust collector. The flue gas led out from the flue of the boiler undergoes acid removal treatment in the first desulfurization and dephosphorization tower and then flows into the first dust collector for dust removal treatment. The flue gas after being dust-removed by the first dust collector flows back into the flue of the boiler.

[0016] The air inlet of the first desulfurization and dephosphorization tower and the exhaust outlet of the first dust collector are both connected to the temperature range of 300°C to 500°C in the flue of the boiler.

[0017] Optionally, the flue gas reacts with the sprayed alkaline absorbent in the first desulfurization and dephosphorization tower.

[0018] An alkaline absorbent is sprayed in the pipeline connecting the first dust collector and the flue of the boiler.

[0019] Optionally, part of the dust in the first dust collector is recycled back to the first desulfurization and dephosphorization tower, and part flows into the pipeline behind the first dust collector.

[0020] Optionally, the secondary desulfurization and dephosphorization system includes a second desulfurization and dephosphorization tower and a second dust collector. The flue gas discharged from the tail of the flue of the boiler is treated in the second desulfurization and dephosphorization tower and then discharged to the second dust collector for dust removal treatment. The flue gas after being treated by the second dust collector is discharged through the chimney.

[0021] Optionally, the flue gas entering the second desulfurization and dephosphorization tower needs to undergo dust removal treatment by a third dust collector.

[0022] The flue gas discharged from the third dust collector enters the second desulfurization and dephosphorization tower for treatment after dephosphorization treatment;

[0023] When the flue gas is subjected to dephosphorization treatment and desulfurization and dephosphorization treatment, an alkaline absorbent is sprayed into it.

[0024] As can be seen from the above technical solution, in the method for treating flue gas of a yellow phosphorus tail gas-fired boiler provided by the present invention, primary acid removal treatment is carried out on the flue gas at a position where the temperature of the flue gas in the flue is 300-500 °C. The high-temperature flue gas is subjected to primary desulfurization and dephosphorization and the removal of other acidic gases. The treated flue gas continues to flow backward along the flue, thereby reducing the acidic gases in the flue, and thus reducing the acid condensation of the flue gas in the temperature range of 300 °C to 500 °C, and improving the corrosion of the downstream flue and equipment caused by acid condensation. The flue gas discharged from the tail of the flue enters further acid removal treatment, thereby removing sulfur, phosphorus and other acidic pollutants. In the method for treating flue gas of a yellow phosphorus tail gas-fired boiler of the present invention, by setting two-stage acid removal treatment, the flue gas is treated in the high-temperature acid gas condensation area and the low-temperature area of the flue gas respectively, greatly reducing the concentrations of sulfur and phosphorus in the flue gas, and synergistically removing other acidic pollutants, reducing the corrosion of the flue by flue gas condensation, enabling the boiler to operate stably for a long time, and improving the efficiency of the boiler.

[0025] The present invention also provides a flue gas treatment system for a yellow phosphorus tail gas-fired boiler, which uses the above-mentioned method for treating flue gas of a yellow phosphorus tail gas-fired boiler to treat flue gas, including a primary desulfurization and dephosphorization system and a secondary desulfurization and dephosphorization system. The primary desulfurization and dephosphorization system is used for primary acid removal treatment of the flue gas, and the primary desulfurization and dephosphorization system is connected to the position in the flue of the boiler where the flue gas temperature is 300 °C to 500 °C;

[0026] The secondary desulfurization and dephosphorization system is used for secondary acid removal treatment of the flue gas, and the secondary desulfurization and dephosphorization system is connected to the tail of the flue of the boiler.

[0027] Optionally, the primary desulfurization and dephosphorization system includes a first desulfurization and dephosphorization tower and a first dust collector connected in communication. The air inlet of the first desulfurization and dephosphorization tower is communicated with the flue of the boiler, and the exhaust port of the first dust collector is communicated with the flue of the boiler;

[0028] The secondary desulfurization and dephosphorization system includes a second desulfurization and dephosphorization tower and a second dust collector connected in communication. The air inlet of the second desulfurization and dephosphorization tower is communicated with the tail of the flue of the boiler, the exhaust port of the second dust collector is communicated with the chimney, and an induced draft fan is arranged on the connecting pipeline between the second dust collector and the chimney.

[0029] Optionally, a third dust collector is arranged on the pipeline connecting the second desulfurization and dephosphorization tower and the tail of the flue of the boiler.

[0030] Optionally, the primary desulfurization and dephosphorization system includes an absorbent injection pipe connected to the position of the flue gas with a temperature of 300°C to 500°C in the flue.

[0031] The flue gas treatment system of the yellow phosphorus tail gas-fired boiler of the present invention uses the above-mentioned flue gas treatment method for flue gas treatment, and thus has the advantages of the above-mentioned flue gas treatment method of the yellow phosphorus tail gas-fired boiler, which will not be elaborated here. Brief Description of the Drawings

[0032] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0033] Figure 1 It is a schematic structural diagram of the flue gas treatment system of the yellow phosphorus tail gas-fired boiler provided by an embodiment of the present invention;

[0034] Figure 2 It is a schematic structural diagram of the flue gas treatment system of the yellow phosphorus tail gas-fired boiler provided by another embodiment of the present invention;

[0035] Figure 3 It is a schematic structural diagram of the flue gas treatment system of the yellow phosphorus tail gas-fired boiler provided by yet another embodiment of the present invention;

[0036] Figure 4 It is a schematic structural diagram of the flue gas treatment system of the yellow phosphorus tail gas-fired boiler provided by the fourth embodiment of the present invention;

[0037] Figure 5 It is a device connection diagram of the flue gas treatment system of the yellow phosphorus tail gas-fired boiler provided by an embodiment of the present invention.

[0038] Wherein:

[0039] 1. Boiler,

[0040] 2. Evaporator,

[0041] 3. First desulfurization and dephosphorization tower,

[0042] 4. First dust collector,

[0043] 5. Economizer,

[0044] 6. Second desulfurization and dephosphorization tower,

[0045] 7. Second dust collector,

[0046] 8. Induced draft fan,

[0047] 9. Chimney

[0048] 10. Third dust collector

[0049] 11. Dephosphorization tower

[0050] 12. Flue Detailed implementation manners

[0051] The present invention discloses a method for treating flue gas of a yellow phosphorus tail gas-fired boiler, which adopts a method of hierarchical desulfurization and dephosphorization to remove SO 2 , SO 3 , P 2 O 5 , HCl, HF, arsenic compounds and other various pollutants, solves the problem of removing ultra-high concentration SO 2 , solves the problem of corrosion of the boiler tail flue, greatly reduces the concentration of acidic pollutants in the flue gas, reduces environmental pollution, enables the boiler to operate stably for a long time, and improves the efficiency of the boiler.

[0052] The present invention also discloses a flue gas treatment system for a yellow phosphorus tail gas-fired boiler.

[0053] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0054] Refer to Figures 1 to 5 , the method for treating flue gas of a yellow phosphorus tail gas-fired boiler of the present invention includes the following steps: S1. Perform primary acid removal treatment on the flue gas in the temperature range of 300°C to 500°C in the flue 12 of the boiler 1. The primary acid removal treatment is dry flue gas treatment to avoid increasing the humidity of the flue gas and reducing the generation of acid liquid. S2. Perform secondary acid removal treatment on the flue gas discharged from the tail of the flue 12 of the boiler 1, and the tail gas after the secondary acid removal treatment is discharged through the chimney 9.

[0055] The method for treating the flue gas of a yellow phosphorus tail gas-fired boiler according to the present invention performs primary acid removal treatment on the flue gas at a position where the flue gas temperature in the flue 12 is 300-500°C. The high-temperature flue gas undergoes primary desulfurization, dephosphorization, and removal of other acidic gases. The treated flue gas continues to flow backward along the flue 12, thereby reducing the acidic gases in the flue 12 and reducing the occurrence of acid condensation in the flue gas in the temperature range of 300°C to 500°C, improving the corrosion of the downstream flue and equipment caused by acid condensation. The flue gas discharged from the tail of the flue 12 enters further acid removal treatment, thereby removing sulfur, phosphorus, and other acidic pollutants. The method for treating the flue gas of a yellow phosphorus tail gas-fired boiler according to the present invention, by setting two-stage acid removal treatment, performs flue gas treatment in the high-temperature acidic gas condensation area and the low-temperature area of the flue gas respectively, greatly reducing the concentrations of sulfur and phosphorus in the flue gas, synergistically removing other acidic pollutants, reducing the corrosion of the flue 12 caused by flue gas condensation, enabling the boiler 1 to operate stably for a long time, and improving the efficiency of the boiler 1.

[0056] Among them, the flue gas generated after the combustion of the yellow phosphorus tail gas input into the boiler 1 has a very high temperature, exceeding 700°C. In order to reduce the temperature of the flue gas in the flue 12, an evaporator 2 for cooling the flue gas is provided in the flue 12 to reduce the temperature of the flue gas to a temperature that meets the requirements of primary acid removal treatment. In order to reduce the temperature of the flue gas discharged from the tail of the flue 12, an economizer 5 is also provided in the flue 12, and the economizer 5 is used to recover and utilize the waste heat of the flue gas.

[0057] In an embodiment, the flue gas in the temperature range of 300°C to 500°C in the flue 12 is led out, and the primary acid removal treatment uses a primary desulfurization and dephosphorization system to treat the led-out flue gas. The tail gas after being treated by the primary desulfurization and dephosphorization system is transported back to the position of the flue gas extraction temperature area in the flue 12. The flue gas in the temperature range of 300°C to 500°C is led out from the flue 12 and sent to the primary desulfurization and dephosphorization system for treatment without spraying water, avoiding increasing the humidity of the flue gas. The secondary acid removal treatment uses a secondary desulfurization and dephosphorization system to treat the flue gas discharged from the tail of the flue 12. The high-temperature flue gas undergoes primary desulfurization, dephosphorization, and removal of other acidic gases by the primary desulfurization and dephosphorization system. The treated flue gas flows back to the gas extraction temperature area in the flue 12, thereby reducing the occurrence of acid condensation in the flue gas in the temperature range of 300°C to 500°C in the flue 12, improving the corrosion of the downstream flue and equipment caused by acid condensation. The flue gas discharged from the tail of the flue 12 enters the secondary desulfurization and dephosphorization system for further desulfurization and dephosphorization treatment, thereby removing sulfur, phosphorus, and other acidic pollutants.

[0058] In another embodiment, the primary acid removal treatment is to add an alkaline absorbent to the area in the flue 12 where the flue gas temperature is 300°C to 500°C, and the secondary acid removal treatment uses a secondary desulfurization and dephosphorization system to treat the flue gas discharged from the tail of the flue 12. An alkaline absorbent is added to the flue 12, and the alkaline absorbent is fully contacted and mixed with the flue gas for desulfurization and dephosphorization to avoid acid condensation and corrosion of the inner wall of the flue 12. In this embodiment, the acid removal treatment is directly performed on the high-temperature flue gas at 300°C to 500°C in the flue.

[0059] Further, the primary desulfurization and dephosphorization system includes a first desulfurization and dephosphorization tower 3 and a first dust collector 4. The flue gas led out from the flue 12 of the boiler 1 is first subjected to acid removal treatment in the first desulfurization and dephosphorization tower 3. The flue gas discharged from the first desulfurization and dephosphorization tower 3 flows into the first dust collector 4 for dust removal treatment, and the flue gas after dust removal by the first dust collector 4 flows back into the flue 12 of the boiler 1. Specifically, the air inlet of the first desulfurization and dephosphorization tower 3 and the exhaust port of the first dust collector 4 are both connected to the temperature region of 300°C to 500°C of the flue 12 of the boiler 1. It can be understood that for acid removal treatment, the flue gas reacts with the sprayed alkaline absorbent in the first desulfurization and dephosphorization tower 3. Specifically, the alkaline absorbent is sprayed into the pipeline through port A provided on the pipeline connecting the first dust collector 4 and the flue 12. The alkaline absorbent is calcium oxide, calcium hydroxide, a material containing calcium oxide, or a material containing calcium hydroxide. In other embodiments, the first dust collector 4 may not be provided after the first desulfurization and dephosphorization tower 3, and the materials coming out of the tower can be directly discharged into the flue 12.

[0060] To reduce the consumption of the alkaline absorbent, most of the dust in the first dust collector 4 is recycled back into the first desulfurization and dephosphorization tower 3 for recycling. Since a lot of unutilized alkaline absorbent powder is mixed in the dust in the first dust collector 4, the dust is alkaline and can be recycled for acid removal. Part of the dust in the first dust collector 4 is conveyed into the pipeline at the rear end of the first dust collector 4, so that the alkaline dust can neutralize the SO 2 and P 2 O 5 condensed in the pipeline at the rear end of the first dust collector 4, avoiding the corrosion of the pipeline by acidic liquid. Fresh alkaline absorbent can also be directly added through port B into the pipeline at the rear end of the first dust collector 4 to be mixed with the condensed liquid in the pipeline. Here, the rear end of the first dust collector 4 refers to the exhaust port end of the first dust collector 4. Part of the dust in the first dust collector 4 can also be directly discharged through port C, and the discharged dust can be placed in a storage device.

[0061] In one embodiment, the secondary desulfurization and dephosphorization system includes a second desulfurization and dephosphorization tower 6 and a second dust collector 7. The flue gas discharged from the tail of the flue 12 of the boiler 1 is treated by the second desulfurization and dephosphorization tower 6 and then discharged to the second dust collector 7 for dust removal. The flue gas treated by the second dust collector 7 is discharged from the chimney 9. The dust in the second dust collector 7 is partially recycled back to the second desulfurization and dephosphorization tower 6 for recycling. Since the dust is alkaline, it can be recycled for deacidification. Among them, alkaline absorbent and water are sprayed into the pipeline for conveying flue gas to the second desulfurization and dephosphorization tower 6. In this position, the alkaline absorbent is input through the D port and the water enters through the E port.

[0062] In one embodiment, the flue gas entering the second desulfurization and dephosphorization tower 6 needs to be dusted by the third dust collector 10. In order to better remove P in the flue gas 2 O 5 The flue gas discharged from the third dust collector 10 is dephosphorized by the dephosphorization tower 11 and then enters the second desulfurization and dephosphorization tower 6 for treatment. The alkaline absorbent is sprayed into the flue gas during the dephosphorization and desulfurization and dephosphorization treatments. Figure 4 As shown, alkaline absorbent is added to the flue gas entering the dephosphorization tower 11 through the F port. The dust collected by the third dust collector 10 is partially circulated back to the first desulfurization and dephosphorization tower 3 or the pipeline at the rear end of the first dust collector 4 to mix and react with the acid liquid condensed on the inner wall of the pipeline, and part of the dust is directly discharged. In order to facilitate the discharge of flue gas, an induced draft fan 8 is provided on the pipeline connecting the second dust collector 7 and the chimney 9 to facilitate the flow of flue gas in the above-mentioned various treatment devices.

[0063] like Figure 1 and Figure 2 In the illustrated embodiment, the secondary desulfurization and dephosphorization system includes a second desulfurization and dephosphorization tower 6 and a second dust collector 7. Figure 3 In the embodiment shown, the secondary desulfurization and dephosphorization system includes a second desulfurization and dephosphorization tower 6, a second dust collector 7 and a third dust collector 10. Figure 4 In the illustrated embodiment, the secondary desulfurization and dephosphorization system includes a second desulfurization and dephosphorization tower 6 , a second dust collector 7 , a third dust collector 10 and a dephosphorization tower 11 .

[0064] The method for treating the flue gas of a yellow phosphorus tail gas-fired boiler according to the present invention sets up a primary desulfurization and dephosphorization system in the range of 300°C to 500°C of the flue gas temperature in the flue 12 of the boiler 1. The flue gas in the range of 300°C to 500°C is led out from the flue 12 and sent into the first desulfurization and dephosphorization tower 3. Without spraying water, primary desulfurization, dephosphorization and removal of other acidic gases are carried out. After desulfurization and dephosphorization, it is connected to the first dust collector 4 for dust collection. Most of the collected dust returns to the first desulfurization and dephosphorization tower 3 to continue to participate in the reaction, reducing the consumption of the alkaline absorbent. Part of the externally discharged dust is sent into the outlet flue of the first dust collector 4 for continuous desulfurization and dephosphorization, avoiding the corrosion of the equipment and flue downstream of the dust collector caused by acid condensation. It is also possible to directly add an alkaline absorbent into the flue in the range of 300°C to 500°C of the flue gas temperature in the flue of the boiler 1, making it fully contact and mix with the flue gas for desulfurization and dephosphorization, avoiding the acid condensation and causing the tail flue. After the flue gas undergoes primary acid removal treatment, the flue gas is discharged through the flue 12. The flue gas discharged from the flue 12 enters the secondary desulfurization and dephosphorization system to continue the secondary removal of sulfur, phosphorus and other acidic gases in the flue gas.

[0065] The method for treating the flue gas of a yellow phosphorus tail gas-fired boiler according to the present invention can efficiently remove acidic pollutants such as P2O5, SO2, SO3, HCl, and HF through two-stage acid removal treatment. At the same time, it can condense and adsorb and remove other pollutants such as arsenides. The synergistic removal of various pollutants enables the flue gas to meet the emission standards, solves the corrosion problem of the flue 12, reduces the boiler outlet temperature, and improves the boiler efficiency.

[0066] The present invention also provides a flue gas treatment system for a yellow phosphorus tail gas-fired boiler, which uses the above-mentioned method for treating the flue gas of a yellow phosphorus tail gas-fired boiler for flue gas treatment, including a primary desulfurization and dephosphorization system and a secondary desulfurization and dephosphorization system. The primary desulfurization and dephosphorization system is used for primary acid removal treatment of the flue gas. The inlet and outlet of the primary desulfurization and dephosphorization system are both connected to the position in the range of 300°C to 500°C of the flue gas temperature in the flue of the boiler. The secondary desulfurization and dephosphorization system is used for secondary acid removal treatment of the flue gas, and the secondary desulfurization and dephosphorization system is connected to the tail of the flue of the boiler.

[0067] Specifically, the primary desulfurization and dephosphorization system includes a first desulfurization and dephosphorization tower 3 and a first dust collector 4 connected in communication. The air inlet of the first desulfurization and dephosphorization tower 3 is communicated with the flue 12 of the boiler 1, and the exhaust port of the first dust collector 4 is communicated with the flue 12 of the boiler 1. The secondary desulfurization and dephosphorization system includes a second desulfurization and dephosphorization tower 6 and a second dust collector 7 connected in communication. The air inlet of the second desulfurization and dephosphorization tower 6 is communicated with the tail of the flue of the boiler 1, and the exhaust port of the second dust collector 7 is communicated with the chimney 9. An induced draft fan 8 is provided on the connecting pipeline between the second dust collector 7 and the chimney 9.

[0068] In one embodiment, a third dust collector 10 is provided on the pipeline connecting the second desulfurization and dephosphorization tower 6 to the tail of the flue of the boiler 1. The third dust collector 10 is a pre-dust collector. The ash collected by the third dust collector 10 can be recycled back to the flue in the temperature range of 300°C to 500°C of the flue gas as an alkaline material for continuous desulfurization and dephosphorization, reducing the consumption of absorbent, or can be directly discharged to the ash bunker. A dephosphorization tower 11 is provided between the third dust collector 10 and the second desulfurization and dephosphorization tower 6. The flue gas after dephosphorization by the dephosphorization tower 11 enters the second desulfurization and dephosphorization tower 6 for deacidification treatment, improving the deacidification efficiency.

[0069] The flue gas treatment system for yellow phosphorus tail gas-fired boiler of the present invention includes a primary desulfurization and dephosphorization system and a secondary desulfurization and dephosphorization system. The primary desulfurization and dephosphorization system performs desulfurization and dephosphorization in the temperature range of 300 - 500°C of the flue gas in the flue 12 of the boiler 1 without spraying water.

[0070] In one embodiment, the primary desulfurization and dephosphorization system includes a first desulfurization and dephosphorization tower 3 and a first dust collector 4. Part of the desulfurized ash collected by the first dust collector 4 returns to the first desulfurization and dephosphorization tower 3 to continue participating in the reaction, part of the desulfurized ash returns to the outlet pipeline of the first dust collector 4 to continue participating in the reaction, and part of the collected desulfurized ash is directly discharged to the ash bunker. In another embodiment, the primary desulfurization and dephosphorization system includes an absorbent feeding pipe connected to the position of the flue gas at 300°C - 500°C in the flue 12. Through the absorbent feeding pipe, an alkaline absorbent is directly input into the position of the flue gas at 300°C - 500°C in the flue 12. The added alkaline material reacts directly with the flue gas for removal, and there is no need to set up a desulfurization and dephosphorization tower and a dust collector. The alkaline absorbent can be an alkaline material mixed with Ca(OH) 2 , CaO.

[0071] In the description of this solution, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "vertical", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, so it cannot be understood as a limitation to this solution.

[0072] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of this solution, "a plurality" means two or more unless otherwise specifically defined.

[0073] The various embodiments in this specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. For the same or similar parts among the various embodiments, reference can be made to each other.

[0074] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art. The general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown herein, but rather will be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for treating flue gas from a yellow phosphorus tail gas gas boiler, characterized in that: The following steps are involved: S1. Performing a primary deacidification treatment on the flue gas with a flue gas temperature of 300° C. to 500° C. in the flue of the boiler, wherein the primary deacidification treatment is a dry flue gas treatment; S2. Performing secondary acid removal treatment on the flue gas discharged from the tail of the flue of the boiler, and the tail gas after the secondary acid removal treatment is discharged from the chimney.

2. The method for treating flue gas from a yellow phosphorus tail gas gas boiler according to claim 1, characterized in that: In step S1, the flue gas with a flue gas temperature of 300°C to 500°C in the flue is led out, and the primary deacidification treatment uses a primary desulfurization and dephosphorization system to treat the led out flue gas, and the tail gas treated by the primary desulfurization and dephosphorization system is transported back to the flue gas lead-out temperature area; In step S2, the secondary deacidification treatment uses a secondary desulfurization and dephosphorization system to treat the flue gas discharged from the tail of the flue.

3. The method for treating flue gas from a yellow phosphorus tail gas gas boiler according to claim 1, characterized in that: In step S1, the primary acid removal treatment is to add an alkaline absorbent into the area of ​​the flue gas with a temperature of 300°C to 500°C; In step S2, the secondary deacidification treatment uses a secondary desulfurization and dephosphorization system to treat the flue gas discharged from the tail of the flue.

4. The method for treating flue gas from a yellow phosphorus tail gas gas boiler according to claim 2, characterized in that: The primary desulfurization and dephosphorization system comprises a first desulfurization and dephosphorization tower and a first dust collector. The flue gas drawn out of the flue of the boiler is deacidified by the first desulfurization and dephosphorization tower and then flows into the first dust collector for dust removal. The flue gas after dust removal by the first dust collector flows back into the flue of the boiler. The air inlet of the first desulfurization and dephosphorization tower and the exhaust port of the first dust collector are both connected to the temperature region of 300° C. to 500° C. of the flue of the boiler.

5. The method for treating flue gas from a yellow phosphorus tail gas gas boiler according to claim 4, characterized in that: The flue gas reacts with the sprayed alkaline absorbent in the first desulfurization and dephosphorization tower; Alkaline absorbent is sprayed in the pipeline connecting the first dust collector and the flue of the boiler.

6. The method for treating flue gas from a yellow phosphorus tail gas gas boiler according to claim 4, characterized in that: Part of the dust in the first dust collector is circulated back to the first desulfurization and dephosphorization tower, and part of it flows into the pipeline at the rear end of the first dust collector.

7. The method for treating flue gas from a yellow phosphorus tail gas gas boiler according to claim 2, characterized in that: The secondary desulfurization and dephosphorization system includes a second desulfurization and dephosphorization tower and a second dust collector. The flue gas discharged from the tail of the flue of the boiler is treated by the second desulfurization and dephosphorization tower and then discharged to the second dust collector for dust removal. The flue gas treated by the second dust collector is discharged from the chimney.

8. The method for treating flue gas from a yellow phosphorus tail gas gas boiler according to claim 7, characterized in that: The flue gas entering the second desulfurization and dephosphorization tower needs to be dusted by the third dust collector; The flue gas discharged from the third dust collector enters the second desulfurization and dephosphorization tower for treatment after being dephosphorized; The alkaline absorbent is sprayed into the flue gas during the dephosphorization treatment and the desulfurization and dephosphorization treatment.

9. A yellow phosphorus tail gas gas boiler flue gas treatment system, characterized in that: The flue gas treatment method for a yellow phosphorus tail gas gas-fired boiler according to any one of claims 1 to 8 is used for flue gas treatment, comprising a primary desulfurization and dephosphorization system and a secondary desulfurization and dephosphorization system, wherein the primary desulfurization and dephosphorization system is used for primary deacidification of the flue gas, and the primary desulfurization and dephosphorization system is connected to a flue of the boiler at a flue gas temperature interval of 300°C to 500°C; The secondary desulfurization and dephosphorization system is used for performing secondary acid removal on the flue gas, and the secondary desulfurization and dephosphorization system is connected to the tail of the flue of the boiler.

10. The yellow phosphorus tail gas gas boiler flue gas treatment system according to claim 9, characterized in that: The primary desulfurization and dephosphorization system comprises a first desulfurization and dephosphorization tower and a first dust collector which are connected to each other, the air inlet of the first desulfurization and dephosphorization tower is connected to the flue of the boiler, and the exhaust port of the first dust collector is connected to the flue of the boiler; The secondary desulfurization and dephosphorization system comprises a second desulfurization and dephosphorization tower and a second dust collector which are connected to each other. The air inlet of the second desulfurization and dephosphorization tower is connected to the tail end of the flue of the boiler. The exhaust port of the second dust collector is connected to the chimney. An induced draft fan is arranged on the connecting pipeline between the second dust collector and the chimney.

11. The yellow phosphorus tail gas gas boiler flue gas treatment system according to claim 10, characterized in that: A third dust collector is arranged on the pipeline connecting the second desulfurization and dephosphorization tower with the tail end of the flue of the boiler.

12. The yellow phosphorus tail gas gas boiler flue gas treatment system according to claim 9, characterized in that: The primary desulfurization and dephosphorization system comprises an absorbent delivery pipe connected to the flue at a position where the flue gas temperature is 300°C to 500°C.

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