Purification treatment system and method for sulfur melting flue gas in process of preparing acid from sulfur

Abstract

The invention relates to the technical field of waste gas purification treatment, in particular to a purification treatment system and method for sulfur melting flue gas in sulfur acid making, and the purification treatment system comprises a flue gas system and is characterized in that the flue gas system comprises a waste gas collecting pipeline, and one end of the waste gas collecting pipeline is connected with a reverse spraying pipe; the other end of the waste gas collection pipeline is connected with a reverse spraying dust removal tower, one end of the reverse spraying dust removal tower is connected with a secondary dust removal tower, one end of the secondary dust removal tower is connected with a heat exchanger, and one end of the heat exchanger is connected with a dry-process fine desulfurization device. The device has the advantages of integration of multiple functions, energy conservation and environmental protection. Firstly, a reverse spraying washing technology is adopted in the system, a foam area is formed in a reverse spraying pipe through reverse spraying, the contact area of flue gas and circulating liquid is increased, and multifunctional integrated treatment of flue gas quenching, acid gas (such as SO2) removal and solid dust removal is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of waste gas purification and treatment, and in particular to a purification and treatment system and method for molten sulfur flue gas in sulfuric acid production. Background Art

[0002] At present, in the sulfur acid industry, solid sulfur raw materials need to be heated, melted and filtered with steam before they can be used in subsequent processes. Because sulfur contains moisture, volatile organic matter, organic acid, etc., the waste gas formed by these impurities during the sulfur melting process contains steam, sulfur vapor, acidic gas, etc., which will cause many adverse effects on the surrounding environment, equipment corrosion, on-site maintenance and management, etc. The existing technology for treating sulfur melting waste gas is mostly to use an induced draft fan to introduce the waste gas into a water washing tower for washing and purification and alkaline washing liquid to strengthen the absorption and treatment of acidic gas. In order to enhance the spray density of the water washing tower and increase the washing effect, the washing tower often uses a packing layer for spray cooling and washing, but it is very easy to be condensed and blocked by sulfur vapor (sublimated sulfur), and it is not easy to clean. At the same time, the water washing absorption rate of insoluble or insoluble acidic gas in the waste gas is not high, and it cannot meet the tail discharge standard. For example, patent CN 105169892B discloses a sulfur melting waste gas washing and purification system, in which alkali liquid adjusts the pH value of the washing circulating liquid, and cools and absorbs the waste gas. From the perspective of sulfur resource recovery and recycling and environmental protection, it is crucial to purify and discharge the molten sulfur flue gas in sulfuric acid production in compliance with emission standards.

[0003] The present invention provides a method for purifying molten sulfur flue gas to meet emission standards by combining wet dust removal with heat exchange dry desulfurization. The flue gas is washed by large-caliber reverse spraying alkali solution, and absorbs and removes sulfur dioxide waste gas and particulate matter in the enhanced mass transfer contact between the reverse spray pipe and the foam zone of the washing liquid. The flue gas is then heated by heat exchange, and dry desulfurization is performed with a desulfurization catalyst to remove hydrogen sulfide in the flue gas, and the tail gas is discharged from a chimney. After purification, the molten sulfur flue gas can meet emission standards, and the tail exhaust flue gas has no smoke plume and no odor, thereby optimizing the working environment.

[0004] A Chinese patent discloses a molten sulfur waste gas cleaning device system and a cleaning process thereof: (CN 105169892B) comprising a molten sulfur tank, a washing tank, an induced draft fan, and a circulating cold water washing system. The exhaust port of the molten sulfur tank is connected to the air inlet of the washing tank, the exhaust port of the washing tank is connected to the inlet of the induced draft fan, the circulating cold water washing system is connected to the washing tank to form a loop, and an alkali adding device is also connected to the circulating cold water washing system; at the same time, a process for cleaning the molten sulfur waste gas using the device system is disclosed. However, when this waste gas cleaning device treats the molten sulfur waste gas, there are problems such as sulfur vapor condensation blocking the packing layer, low acid gas absorption rate, serious equipment corrosion, difficult maintenance, substandard tail gas emissions, and waste of resources. Therefore, a purification treatment system and method for molten sulfur flue gas in sulfur-based acid production is needed. Summary of the invention

[0005] The purpose of the present invention is to solve the problems of sulfur vapor condensation blocking the packing layer, low acid gas absorption rate, serious equipment corrosion, difficult maintenance, substandard tail gas emissions and waste of resources when the waste gas cleaning device treats molten sulfur waste gas, and to propose a purification treatment system and method for molten sulfur flue gas in sulfur-fired acid production.

[0006] The technical solution adopted by the present invention to solve its technical problem is: a purification and treatment system for molten sulfur flue gas in sulfuric acid production, including a flue gas system, characterized in that: the flue gas system includes a waste gas collection pipeline, one end of the waste gas collection pipeline is connected to a reverse spray pipe, the other end of the waste gas collection pipeline is connected to a reverse spray dust removal tower, one end of the reverse spray dust removal tower is connected to a secondary dust removal tower, one end of the secondary dust removal tower is connected to a heat exchanger, one end of the heat exchanger is connected to a dry fine desulfurization device, the dry desulfurization device includes a steel structure support, a desulfurization tower body is arranged inside the steel structure support, the desulfurization tower body is composed of an upper section of the tower body, a middle section of the tower body and a lower section of the tower body, a silo is arranged on one side of the desulfurization tower body, a foot is arranged on the top of the steel structure body, and pre-buried iron is arranged between the steel structure body and the foot. High-efficiency desulfurization: the desulfurization tower is filled with a desulfurizer (such as activated carbon or metal oxide), which can efficiently remove hydrogen sulfide and organic sulfur in the flue gas, and the desulfurization efficiency is ≥95%. Pre-buried iron and steel structure supports ensure the overall stability of the desulfurization tower and prevent vibration and tilting during equipment operation; the silo design is convenient for adding fresh desulfurizer, and the waste agent is discharged through the outlet of the lower section of the tower body, which is easy to operate. One end of the dry fine desulfurization device is connected to an induced draft fan, and one end of the induced draft fan is connected to an exhaust pipe. Multi-stage purification: Through the multi-stage treatment of the reverse spray dust removal tower, the secondary dust removal tower and the dry fine desulfurization device, particulate matter, droplets and harmful gases (such as sulfur dioxide, hydrogen sulfide, etc.) in the flue gas can be efficiently removed to ensure that the flue gas meets the emission standards; Systematic design: Each device is connected in sequence to form a complete flue gas treatment process with a compact structure and easy operation; Energy saving and emission reduction: The by-product steam is used to heat the flue gas through the heat exchanger to reduce energy consumption and increase the flue gas temperature, which is conducive to subsequent desulfurization treatment.

[0007] Preferably, the exhaust gas collection pipe model is DN700mm, about 130m, and the resistance is about 3.1KPa. The exhaust gas collection pipe is a large-diameter heating sleeve, and the flue gas temperature is heated to 145-150°C. The flue gas temperature is maintained by the heating sleeve to prevent sulfur particles from condensing and blocking in the pipe, ensuring smooth flue gas transportation; the large-diameter design reduces pipeline resistance and system energy consumption; the heated flue gas is taken out in the form of sublimated sulfur, which is conducive to subsequent dust removal and desulfurization treatment.

[0008] Preferably, the heat exchanger includes a main frame, plates are arranged inside the main frame, the number of plates is 20 to 30 and they are arranged side by side in an array with equal spacing, an auxiliary support frame is arranged on one side of the main frame, a steam inlet pipe is arranged on one side of the main frame, and a steam outlet pipe is arranged on the other side. The plate structure increases the heat exchange area, improves the heat exchange efficiency, uses the by-product steam to heat the flue gas, and reduces energy consumption; the auxiliary support frame and the fixing rod ensure the stability of the plate assembly and prevent vibration deviation.

[0009] Preferably, a plurality of fixing rods are arranged evenly on both sides of the edge of the main frame, positioning bolts are arranged on the fixing rods, and L-shaped legs are arranged at the bottom of the main frame. The fixing rods and positioning bolts further strengthen the plate array to prevent vibration and deviation, ensuring the long-term stable operation of the heat exchanger; the L-shaped leg design facilitates the installation and fixation of the heat exchanger and reduces the difficulty of construction; the fixing structure reduces the mechanical stress during the operation of the equipment and prolongs the service life of the equipment.

[0010] Preferably, a steam inlet pipe is provided on one side of the main frame, and a steam outlet pipe is provided on the other side. Steam enters through the inlet pipe, and condensed water is discharged through the outlet pipe, thereby preventing scaling of the plates and extending the service life of the equipment.

[0011] Preferably, one end of the waste gas collection pipeline is connected to a filter gas collection hood, and the other end is provided with a melting sulfur tank gas collection hood, the top of the melting sulfur tank gas collection hood is provided with a liquid sulfur storage tank gas collection pipeline, the top of the liquid sulfur storage tank gas collection pipeline is provided with a square trough gas collection pipeline, and the filter gas collection hood, the melting sulfur tank gas collection hood, the liquid sulfur storage tank gas collection pipeline and the square trough gas collection pipeline are all interconnected and coordinated. Through the multi-stage gas collection hood and pipeline design, it is ensured that the flue gas generated during the sulfur melting process is fully collected to reduce the spillage of pollutants; each gas collection hood and pipeline cooperate with each other to optimize the flue gas collection path and improve the system processing efficiency; the flue gas is fully collected to reduce pollution to the environment, meeting environmental protection requirements.

[0012] Preferably, one side of the reverse-jet dust removal tower is connected to an alkali liquid dosing device, the top of the reverse-jet dust removal tower is provided with a top outlet, one side of the top of the secondary dust removal tower is provided with a variable diameter air duct, and the other side is provided with a secondary dust outlet, and the variable diameter air duct cooperates with the top outlet. The reverse-jet dust removal tower absorbs sulfur dioxide through the alkali liquid dosing device, and the secondary dust removal tower further removes the remaining particulate matter and droplets to improve the purification efficiency; the variable diameter air duct design ensures that the flue gas enters the secondary dust removal tower smoothly from the reverse-jet dust removal tower, reduces resistance, and improves the system operation efficiency; the two-stage dust removal tower is used in conjunction to reduce the load of subsequent equipment and reduce system energy consumption.

[0013] Preferably, a reverse spray pipe is provided on one side of the reverse spray dust removal tower, one end of the reverse spray pipe cooperates with the reverse spray dust removal tower, a delivery pipe is provided on one side of the secondary dust removal tower, the delivery pipe cooperates with the reverse spray dust removal tower and the secondary dust removal tower, one end of the reverse spray dust removal tower is connected to a liquid adding pipe, and the other end of the liquid adding pipe is connected to a liquid sulfur storage tank. The washing liquid is recycled in the reverse spray dust removal tower, and the washing liquid is pumped into the secondary dust removal tower through the delivery pipe to reduce water consumption; the liquid adding pipe is connected to the liquid sulfur storage tank to replenish the washing liquid lost due to evaporation in time to ensure the stable operation of the system; the liquid circulation and replenishment design improves the system operation efficiency and reduces resource waste.

[0014] Preferably, the resistance of the secondary dust removal tower is about 2.5KPa, the resistance of the heat exchanger is about 1.0KPa, the resistance of the dry desulfurization device is about 1.0KPa, the total resistance of the flue gas system is about 7.6KPa, the margin coefficient is 1.1-1.3, 1.2 is taken, and the flue gas system resistance is rounded to 9.2KPa. By calculating the system resistance and setting the margin coefficient, the system can be ensured to operate stably and avoid equipment failure due to excessive resistance; the resistance is reasonably designed to reduce the energy consumption of the induced draft fan and improve the economy of the system; the margin coefficient design ensures that the system can still operate stably under fluctuating conditions and improves equipment reliability.

[0015] Preferred:

[0016] (1) Waste gas collection and pretreatment:

[0017] Start the sulfur melting tank gas collection hood (2×6000m 3 / h), filter hood (12000m 3 / h), square trough gas collection pipeline (4000m 3 / h), liquid sulfur storage tank gas collection pipeline (4000m 3 / h), total air volume 26000m 3 / h; turn on the electric heating system of the DN700mm heating sleeve to maintain the flue gas temperature at 145-150℃, ensure that the sulfur particles are carried out with the flue gas in the form of sublimated sulfur, and prevent the sublimated sulfur from condensing and clogging the pipeline;

[0018] (2) Reverse spray dust removal tower treatment:

[0019] The molten sulfur flue gas enters the reverse spray pipe through the flue gas pipeline. The large-diameter nozzle in the reverse spray pipe sprays in reverse, impacts with the flue gas to produce a foam area, and strengthens mass transfer. Through the continuous contact of the flue gas foam liquid film, particulate matter and related harmful gases are absorbed and removed; the reverse spray flushes the foam area produced by the flue gas, which has the effect of rapid cooling and reduces the flue gas temperature from 145-150℃ to 60-65℃; the washing liquid is recycled in the reverse spray tower. When the density reaches the set requirement of 1.15-1.25g / ml, the circulating liquid is pumped into the filter press through the reverse spray pump bypass to filter the particulate matter (The particulate matter is mainly solid sulfur powder, which is recycled as solid sulfur raw material for melting sulfur after cleaning); the reverse spray tower is equipped with an alkali dosing device, and the sulfur dioxide waste gas in the flue gas is absorbed by adding an appropriate amount of alkali in the circulating liquid. The amount of alkali is 1.05-1.1 times the molar amount of sulfur dioxide in the flue gas. After the sulfur dioxide waste gas is absorbed by the alkali, the flue gas is neutral or slightly acidic, which can ensure the normal operation of the back-end equipment; the liquid sulfur storage tank is connected through a liquid adding pipe to replenish the washing liquid lost due to evaporation; the purified flue gas is discharged through the top outlet of the reverse spray dust removal tower and enters the secondary dust removal tower;

[0020] (3) Secondary dust removal tower deep purification variable diameter air duct transportation:

[0021] The flue gas passes through the variable diameter air duct from the top outlet of the reverse spray dust removal tower and enters the secondary dust removal tower in reverse. The secondary dust removal tower is equipped with fillers to further remove the remaining particulate matter in the flue gas. It can process more than 85% of the remaining particulate matter and remove more than 90% of the droplets and fine particles at the same time, greatly reducing the water content in the flue gas; the secondary dust removal tower is equipped with water spray, which runs for 48-60 hours and regularly flushes the filler layer for 15-30 minutes, and uses a delivery pump to pump the flushing liquid into the reverse spray dust removal tower for reuse, reducing water consumption; the purified flue gas is discharged through the secondary dust outlet of the secondary dust removal tower and enters the heat exchanger;

[0022] (4) Heat exchanger temperature control:

[0023] After secondary dust removal, the flue gas enters the heat exchanger, adopts gas-steam heat exchange mode (steam produced by sulfuric acid plant), and uses 0.3-0.6MPa low-pressure steam of 130-150℃ to heat the flue gas through the plate heat exchanger; the flue gas contacts with the plates (20-30 plates, arranged side by side in an array with equal spacing) inside the main frame of the heat exchanger, and the heat is transferred from the steam side to the flue gas side, heating the flue gas from 60-65℃ to 80-120℃, preferably 90-110℃, and the steam enters the heat exchanger through the steam inlet pipe, and the condensed water is discharged through the steam outlet pipe to prevent the scaling of the plates. An auxiliary support frame is provided on one side of the main frame of the heat exchanger to ensure the stability of the plate assembly; the fixing rods (including positioning bolts) on both sides of the edge of the main frame further reinforce the plate array to prevent vibration deviation;

[0024] (5) Dry fine desulfurization treatment:

[0025] The flue gas enters the dry fine desulfurization device. The main body of the desulfurization tower is composed of the upper section, the middle section and the lower section of the tower. The tower is filled with desulfurizer (such as activated carbon or metal oxide). The flue gas passes through the desulfurizer bed at 90-110°C to effectively remove hydrogen sulfide and organic sulfur in the flue gas (desulfurization efficiency ≥ 95%). A silo is provided on one side of the main body of the desulfurization tower to replenish fresh desulfurizer; pre-buried iron is provided between the steel structure support and the bottom foot to ensure the overall stability of the desulfurization tower. When the outlet H2S concentration exceeds the standard, fresh desulfurizer is added from the silo, and the waste agent is discharged through the outlet of the lower section of the tower;

[0026] (6) Tail exhaust system emissions

[0027] Starting air volume 32000m 3 / h, induced draft fan with wind pressure of 9.2kPa, overcomes the total resistance of the system (9.2kPa), and the purified flue gas passes through the DN1000-1200mm exhaust pipe (height ≥20m) to meet the discharge standards;

[0028] (7) Real-time monitoring of key parameters

[0029] Flue gas temperature: reverse spray pipe inlet (145-150℃), secondary tower outlet (60-65℃), heat exchanger outlet (90-110℃); circulating liquid density: the density in the reverse spray tower is 1.15-1.25g / ml, and the filter press is started when the limit is exceeded; real-time monitoring of pipeline resistance (3.1kPa), dust removal tower resistance (2.5kPa), heat exchanger resistance (1.0kPa), check for blockage when the total resistance exceeds 9.2kPa;

[0030] Exhaust gas pipe: Clean the sulfur residue on the inner wall of DN700mm pipe every week.

[0031] Reverse spray nozzle: Check nozzle wear every month and replace damaged nozzles.

[0032] Packing layer: Clean the scale on the packing layer of the secondary tower every quarter.

[0033] Desulfurizer: According to the H2S concentration monitoring, the desulfurizer should be replaced every 3-6 months.

[0034] The present invention is beneficial in that:

[0035] This application uses a series of innovative technologies to achieve efficient purification of molten sulfur flue gas in sulfuric acid production, and has the advantages of multifunctional integration and energy saving and environmental protection. First, the system adopts reverse spray washing technology to form a foam area in the reverse spray pipe through reverse spraying, increase the contact area between the flue gas and the circulating liquid, and achieve multifunctional integrated treatment of flue gas rapid cooling, removal of acidic gases (such as SO2) and solid dust. The reverse spray washing system has a removal efficiency of more than 95% for particulate matter. At the same time, it is equipped with a non-clogging large-diameter nozzle, which can adapt to fluctuations in the system load within the range of 50-120%, ensuring that the system can still operate stably when the flue gas flow changes. Secondly, combined with gas-solid catalytic oxidation dry desulfurization technology, hydrogen sulfide (H2S) and low-concentration organic sulfur can be efficiently removed without the use of hydrolysis or hydrogenation catalysts. The desulfurization reaction speed is fast, and the air velocity can reach 500-3000h -1 , the total sulfur at the outlet is stable <10mg / m 3 , meeting the ultra-low emission requirements. In addition, the system uses copper salt modified activated carbon as a desulfurization catalyst, which is prepared by copper salt impregnation, drying and roasting modification, significantly improving the adsorption and purification capacity of activated carbon for H2S and organic sulfur. Its adsorption capacity is 5-10 times that of unmodified activated carbon, and the working sulfur capacity is more than 30%, which prolongs the catalyst replacement cycle and reduces the operating cost. In terms of flue gas dehumidification, through the design of variable diameter duct and secondary dust removal tower, the principle of reducing the diameter of the duct, accelerating the flow rate and reducing the pressure is used to promote the condensation of water vapor. At the same time, the temperature in the secondary dust removal tower is normal, which further removes the droplets and dissolved salts in the flue gas, ensuring that the flue gas outlet meets the ultra-low emission standards. Finally, the system uses flue gas reheating technology to heat the saturated wet flue gas treated by the two-stage dust removal tower, reduce the relative humidity of the exhaust gas, and avoid the condensation of water vapor to form small droplets during the diffusion process, visually eliminating the "wet smoke plume" (commonly known as "big white smoke"), improving the visual effect and enhancing the environmental protection image of the enterprise. The overall system has significant advantages such as multifunctional integration, high efficiency and stability, energy saving and environmental protection. It can adapt to flue gas flow fluctuations and ensure ultra-low emission requirements, while reducing operating costs and maintenance frequency, and has significant economic and environmental benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0037] See also Figure 1-5 As shown:

[0038] Figure 1 It is a schematic diagram of the working process of the present invention;

[0039] Figure 2 It is a schematic diagram of the structure of the heat exchanger of the present invention.

[0040] Figure 3 It is a schematic diagram of the main structure of the heat exchanger of the present invention.

[0041] Figure 4 This is a schematic diagram of the desulfurization tower structure of the present invention.

[0042] Figure 5 For the present invention Figure 4 A is an enlarged view of the middle image.

[0043] In the figure: 1. Square trough gas collection pipeline; 2. Liquid sulfur storage tank gas collection pipeline; 3. Molten sulfur tank gas collection hood; 4. Filter gas collection hood; 5. Waste gas collection pipeline; 6. Top outlet; 7. Backward spray pipe; 8. Backward spray dust removal tower; 9. Alkali liquid dosing device; 10. Delivery pipe; 11. Variable diameter air duct; 12. Secondary dust outlet; 13. Secondary dust removal tower; 15. Heat exchanger; 16. Dry fine desulfurization device; 17. Induced draft fan; 18. Exhaust Cylinder; 19. Liquid sulfur storage tank; 20. Liquid adding pipe; 21. Steam inlet pipe; 22. Positioning bolts; 23. Auxiliary support frame; 24. Steam outlet pipe; 25. Fixing rod; 26. Plate; 27. Main frame; 28. L-shaped support leg; 29. ​​Desulfurization tower; 30. Upper section of tower body; 31. Middle section of tower body; 32. Steel structure support; 33. Silo; 34. Lower section of tower body; 35. Embedded iron; 36. Foot. DETAILED DESCRIPTION

[0044] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0045] Example

[0046] See also Figure 1-5 As shown:

[0047] Embodiment: A purification and treatment system for molten sulfur flue gas in sulfuric acid production includes a flue gas system, characterized in that: the flue gas system includes a waste gas collecting pipe 5, one end of the waste gas collecting pipe 5 is connected to a reverse spray pipe 7, the other end of the waste gas collecting pipe 5 is connected to a reverse spray dust removal tower 8, one end of the reverse spray dust removal tower 8 is connected to a secondary dust removal tower 13, one end of the secondary dust removal tower 13 is connected to a heat exchanger 15, one end of the heat exchanger 15 is connected to a dry fine desulfurization device 16, the dry desulfurization device includes a steel structure support 32, a desulfurization tower 29 body is arranged inside the steel structure support 32, the desulfurization tower 29 body is composed of an upper tower body 30, a middle tower body 31 and a lower tower body 34, a silo 33 is arranged on one side of the desulfurization tower 29 body, a base 36 is arranged on the top of the steel structure body, and embedded iron 35 is arranged between the steel structure body and the base 36. High-efficiency desulfurization: The desulfurization tower 29 is filled with a desulfurizer (such as activated carbon or metal oxide), which can efficiently remove hydrogen sulfide and organic sulfur in the flue gas, and the desulfurization efficiency is ≥95%. The embedded iron 35 and the steel structure support 32 ensure the overall stability of the desulfurization tower 29 to prevent vibration and tilting during equipment operation; the silo 33 is designed to facilitate the replenishment of fresh desulfurizer, and the waste agent is discharged through the outlet of the lower section 34 of the tower body, which is easy to operate. The dry fine desulfurization device 16 is connected to an induced draft fan 17 at one end, and the induced draft fan 17 is connected to an exhaust pipe 18 at one end. Multi-stage purification: Through the multi-stage treatment of the reverse-jet dust removal tower 8, the secondary dust removal tower 13 and the dry fine desulfurization device 16, the particulate matter, droplets and harmful gases (such as sulfur dioxide, hydrogen sulfide, etc.) in the flue gas can be efficiently removed to ensure that the flue gas meets the emission standards; Systematic design: The various devices are connected in sequence to form a complete flue gas treatment process with a compact structure and easy operation; Energy saving and emission reduction: The by-product steam is used to heat the flue gas through the heat exchanger 15 to reduce energy consumption and increase the flue gas temperature, which is beneficial to the subsequent desulfurization treatment.

[0048] In this embodiment, the exhaust gas collection pipe 5 is DN700mm, about 130m, and has a resistance of about 3.1KPa. The exhaust gas collection pipe 5 is a large-diameter heating sleeve, and the flue gas temperature is heated to 145-150°C. The flue gas temperature is maintained by the heating sleeve to prevent sulfur particles from condensing and blocking in the pipe, thereby ensuring smooth flue gas transportation; the large-diameter design reduces pipe resistance and system energy consumption; the heated flue gas is taken out in the form of sublimated sulfur, which is conducive to subsequent dust removal and desulfurization treatment.

[0049] In this embodiment, the heat exchanger 15 includes a main frame 27, and plates 26 are arranged inside the main frame 27. The number of the plates 26 is 20 to 30 and they are arranged side by side in an array with equal spacing. An auxiliary support frame 23 is provided on one side of the main frame 27. The plate 26 structure increases the heat exchange area, improves the heat exchange efficiency, utilizes by-product steam to heat the flue gas, and reduces energy consumption; the auxiliary support frame 23 and the fixing rod 25 ensure the stability of the plate 26 assembly to prevent vibration deviation.

[0050] In this embodiment, a plurality of fixing rods 25 are provided on both sides of the edge of the main frame 27 and are evenly arranged, and positioning bolts 22 are provided on the fixing rods 25, and L-shaped legs 28 are provided at the bottom of the main frame 27. The fixing rods 25 and the positioning bolts 22 further reinforce the array of plates 26 to prevent vibration and deviation, and ensure the long-term stable operation of the heat exchanger 15; the L-shaped legs 28 are designed to facilitate the installation and fixation of the heat exchanger 15, reducing the difficulty of construction; the fixed structure reduces the mechanical stress during the operation of the equipment and prolongs the service life of the equipment.

[0051] In this embodiment, a steam inlet pipe 21 is provided on one side of the main frame 27, and a steam outlet pipe 24 is provided on the other side. Steam enters through the inlet pipe and condensed water is discharged through the outlet pipe, thereby preventing scaling of the plate 26 and extending the service life of the equipment.

[0052] In this embodiment, one end of the top of the waste gas collection pipeline 5 is connected to a filter gas collection hood 4, and the other end is provided with a sulfur melting tank gas collection hood 3, the top of the sulfur melting tank gas collection hood 3 is provided with a liquid sulfur storage tank gas collection pipeline 2, and the top of the liquid sulfur storage tank gas collection pipeline 2 is provided with a square trough gas collection pipeline 1, and the filter gas collection hood 4, the sulfur melting tank gas collection hood 3, the liquid sulfur storage tank gas collection pipeline 2 and the square trough gas collection pipeline 1 are all related and coordinated with each other. Through the multi-stage gas collection hood and pipeline design, it is ensured that the flue gas generated during the sulfur melting process is fully collected to reduce the spillage of pollutants; each gas collection hood and pipeline cooperate with each other to optimize the flue gas collection path and improve the system processing efficiency; the flue gas is fully collected to reduce pollution to the environment, meeting environmental protection requirements.

[0053] In this embodiment, the reverse-jet dust removal tower 8 is connected to an alkali liquid dosing device 9 on one side, and a top outlet 6 is provided on the top of the reverse-jet dust removal tower 8. A variable-diameter air duct 11 is provided on one side of the top of the secondary dust removal tower 13, and a secondary dust outlet 12 is provided on the other side. The variable-diameter air duct 11 cooperates with the top outlet 6. The reverse-jet dust removal tower 8 absorbs sulfur dioxide through the alkali liquid dosing device 9, and the secondary dust removal tower 13 further removes the remaining particulate matter and droplets to improve the purification efficiency; the variable-diameter air duct 11 is designed to ensure that the flue gas smoothly enters the secondary dust removal tower 13 from the reverse-jet dust removal tower 8, reduces resistance, and improves the system operation efficiency; the two-stage dust removal tower is used in conjunction to reduce the load of subsequent equipment and reduce system energy consumption.

[0054] In this embodiment, a reverse spray pipe 7 is provided on one side of the reverse spray dust removal tower 8, one end of the reverse spray pipe 7 cooperates with the reverse spray dust removal tower 8, a delivery pipe 10 is provided on one side of the secondary dust removal tower 13, the delivery pipe 10 cooperates with the reverse spray dust removal tower 8 and the secondary dust removal tower 13, one end of the reverse spray dust removal tower 8 is connected to a liquid adding pipe 20, and the other end of the liquid adding pipe 20 is connected to a liquid sulfur storage tank 19. The washing liquid is recycled in the reverse spray dust removal tower 8, and the washing liquid is pumped into the secondary dust removal tower 13 through the delivery pipe 10 to reduce water consumption; the liquid adding pipe 20 is connected to the liquid sulfur storage tank 19 to replenish the washing liquid lost due to evaporation in time to ensure the stable operation of the system; the liquid circulation and replenishment design improves the system operation efficiency and reduces resource waste.

[0055] In this embodiment, the resistance of the secondary dust removal tower 13 is about 2.5KPa, the resistance of the heat exchanger 15 is about 1.0KPa, the resistance of the dry desulfurization device is about 1.0KPa, the total resistance of the flue gas system is about 7.6KPa, the margin coefficient is 1.1-1.3, 1.2 is taken, and the flue gas system resistance is rounded to 9.2KPa. By calculating the system resistance and setting the margin coefficient, the system can be ensured to operate stably and avoid equipment failure due to excessive resistance; the resistance is reasonably designed to reduce the energy consumption of the induced draft fan 17 and improve the economy of the system; the margin coefficient design ensures that the system can still operate stably under fluctuating conditions and improves equipment reliability.

[0056] In this embodiment:

[0057] (1) Waste gas collection and pretreatment:

[0058] Start the sulfur melting tank gas collection hood 3 (2×6000m 3 / h), filter hood 4 (12000m 3 / h), square trough gas collection pipeline 1 (4000m 3 / h), liquid sulfur storage tank gas collection pipeline 2 (4000m 3 / h), total air volume 26000m 3 / h; turn on the electric heating system of the DN700mm heating sleeve to maintain the flue gas temperature at 145-150℃, ensure that the sulfur particles are carried out with the flue gas in the form of sublimated sulfur, and prevent the sublimated sulfur from condensing and clogging the pipeline;

[0059] (2) Reverse spray dust removal tower 8 treatment:

[0060] The molten sulfur flue gas enters the reverse spray pipe 7 through the flue gas pipeline. The large-caliber nozzle in the reverse spray pipe 7 sprays in reverse, impacts with the flue gas to produce a foam area, and strengthens mass transfer. Through the continuous contact of the flue gas foam liquid film, particulate matter and related harmful gases are absorbed and removed; the reverse spray flushes the foam area produced by the flue gas, which has the effect of rapid cooling and cooling the flue gas temperature from 145-150℃ to 60-65℃; the washing liquid is recycled in the reverse spray tower. When the density reaches the set requirement of 1.15-1.25g / ml, the circulating liquid is pumped into the filter press through the reverse spray pump bypass to filter the particulate matter (particulate matter The solid sulfur powder is mainly solid sulfur powder, which is reused as solid sulfur raw material for melting sulfur after cleaning); the reverse spray tower is provided with an alkali liquid dosing device 9, and the sulfur dioxide waste gas in the flue gas is absorbed by adding an appropriate amount of alkali liquid in the circulating liquid. The amount of alkali liquid is 1.05-1.1 times the molar amount of sulfur dioxide in the flue gas. After the sulfur dioxide waste gas is absorbed by the alkali liquid, the flue gas is neutral or slightly acidic, which can ensure the normal operation of the back-end equipment; the liquid sulfur storage tank 19 is connected through the liquid adding pipe 20 to supplement the washing liquid lost due to evaporation; the purified flue gas is discharged through the top outlet 6 of the reverse spray dust removal tower 8 and enters the secondary dust removal tower 13;

[0061] (3) The secondary dust removal tower 13 deeply purifies the variable diameter air duct 11 for transportation:

[0062] The flue gas is discharged from the top outlet of the reverse-jet dust removal tower 8 through the variable diameter air duct 11 and enters the secondary dust removal tower 13 in reverse direction. The secondary dust removal tower 13 is provided with fillers to further remove the remaining particulate matter in the flue gas, and can process more than 85% of the remaining particulate matter, while removing more than 90% of the droplets and fine particles, so that the water content in the flue gas is greatly reduced; the secondary dust removal tower 13 is equipped with water spray, and the packing layer is regularly flushed for 15-30 minutes after running for 48-60 hours, and the flushing liquid is pumped into the reverse-jet dust removal tower 8 for reuse by a delivery pump, so as to reduce water consumption; the purified flue gas is discharged through the secondary dust outlet 12 of the secondary dust removal tower 13 and enters the heat exchanger 15;

[0063] (4) Heat exchanger 15 temperature control:

[0064] After secondary dust removal, the flue gas enters the heat exchanger 15, and adopts a gas-steam heat exchange method (steam produced as a byproduct of a sulfuric acid plant). The flue gas is heated by a plate 26 heat exchanger 15 using low-pressure steam of 0.3-0.6MPa and 130-150°C. The flue gas contacts the plates 26 (20-30 plates, arranged side by side in an array with equal spacing) inside the main frame 27 of the heat exchanger 15, and the heat is transferred from the steam side to the flue gas side, heating the flue gas from 60-65°C to 80-120°C, preferably 90-110°C. The steam enters the heat exchanger 15 through the steam inlet pipe 21, and the condensed water is discharged through the steam outlet pipe 24 to prevent the plates 26 from scaling. An auxiliary support frame 23 is provided on one side of the main frame 27 of the heat exchanger 15 to ensure the stability of the plate 26 assembly. The fixing rods 25 (including positioning bolts 22) on both sides of the edge of the main frame 27 further reinforce the plate 26 array to prevent vibration deviation.

[0065] (5) Dry fine desulfurization treatment:

[0066] The flue gas enters the dry fine desulfurization device 16. The main body of the desulfurization tower 29 is composed of an upper tower section 30, a middle tower section 31 and a lower tower section 34. The tower is filled with a desulfurizer (such as activated carbon or metal oxide). The flue gas passes through the desulfurizer bed at 90-110°C to effectively remove hydrogen sulfide and organic sulfur in the flue gas (desulfurization efficiency ≥ 95%). A silo 33 is provided on one side of the main body of the desulfurization tower 29 for replenishing fresh desulfurizer; a pre-buried iron 35 is provided between the steel structure support 32 and the foot 36 to ensure the overall stability of the desulfurization tower 29. When the outlet H2S concentration exceeds the standard, fresh desulfurizer is replenished from the silo 33, and the waste agent is discharged through the outlet of the lower tower section 34;

[0067] (6) Tail exhaust system emissions

[0068] Starting air volume 32000m 3 / h, induced draft fan 17 with wind pressure of 9.2kPa, overcomes the total resistance of the system (9.2kPa), and the purified flue gas passes through DN1000-1200mm exhaust pipe 18 (height ≥20m) to meet the discharge standards;

[0069] (7) Real-time monitoring of key parameters

[0070] Flue gas temperature: reverse spray pipe 7 inlet (145-150℃), secondary tower outlet (60-65℃), heat exchanger 15 outlet (90-110℃); circulating liquid density: the density in the reverse spray tower is 1.15-1.25g / ml, and the filter press is started when it exceeds the limit; real-time monitoring of pipeline resistance (3.1kPa), dust removal tower resistance (2.5kPa), heat exchanger 15 resistance (1.0kPa), check for blockage when the total resistance exceeds 9.2kPa;

[0071] Exhaust gas pipe: Clean the sulfur residue on the inner wall of DN700mm pipe every week.

[0072] Reverse spray nozzle: Check nozzle wear every month and replace damaged nozzles.

[0073] Packing layer: Clean the scale on the packing layer of the secondary tower every quarter.

[0074] Desulfurizer: According to the H2S concentration monitoring, the desulfurizer should be replaced every 3-6 months.

[0075] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a combined manner.

[0076] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of the present invention to be protected.

Claims

1. A system for purifying molten sulfur flue gas in sulfuric acid production, comprising a flue gas system, characterized in that: The flue gas system comprises an exhaust gas collection pipe (5), one end of the exhaust gas collection pipe (5) is connected to a reverse spray pipe (7), the other end of the exhaust gas collection pipe (5) is connected to a reverse spray dust removal tower (8), one end of the reverse spray dust removal tower (8) is connected to a secondary dust removal tower (13), one end of the secondary dust removal tower (13) is connected to a heat exchanger (15), one end of the heat exchanger (15) is connected to a dry fine desulfurization device (16), the dry desulfurization device comprises a steel structure support (32), the steel structure support (32) A desulfurization tower (29) body is provided inside, and the desulfurization tower (29) body is composed of an upper tower section (30), a middle tower section (31) and a lower tower section (34). A silo (33) is provided on one side of the desulfurization tower (29) body. A foot (36) is provided on the top of the steel structure body. Pre-buried iron (35) is provided between the steel structure body and the foot (36). One end of the dry fine desulfurization device (16) is connected to an induced draft fan (17), and one end of the induced draft fan (17) is connected to an exhaust pipe (18).

2. The system for purifying molten sulfur flue gas in sulfuric acid production according to claim 1, characterized in that: The exhaust gas collecting pipe (5) has a model of DN700mm and a length of about 130m, and a resistance of about 3.1KPa. The exhaust gas collecting pipe (5) is a large-diameter heating sleeve, and the temperature of the heated flue gas is 145-150°C.

3. The purification system for molten sulfur flue gas in sulfuric acid production according to claim 1, characterized in that: The heat exchanger (15) comprises a main frame (27), wherein plates (26) are arranged inside the main frame (27), wherein the number of the plates (26) is 20 to 30 and the plates (26) are arranged side by side in an array with equal spacing, and an auxiliary support frame (23) is provided on one side of the main frame (27).

4. The system for purifying molten sulfur flue gas in sulfuric acid production according to claim 3, characterized in that: A plurality of fixing rods (25) are arranged evenly on both sides of the edge of the main frame (27), positioning bolts (22) are arranged on the fixing rods (25), and an L-shaped support leg (28) is arranged at the bottom of the main frame (27).

5. The system for purifying molten sulfur flue gas in sulfuric acid production according to claim 3, characterized in that: A steam inlet pipe (21) is provided on one side of the main frame (27), and a steam outlet pipe (24) is provided on the other side.

6. The system for purifying molten sulfur flue gas in sulfuric acid production according to claim 2, characterized in that: One end of the top of the waste gas collection pipeline (5) is connected to a filter gas collecting hood (4), and the other end is provided with a molten sulfur tank gas collecting hood (3). The top of the molten sulfur tank gas collecting hood (3) is provided with a liquid sulfur storage tank gas collecting pipeline (2), and the top of the liquid sulfur storage tank gas collecting pipeline (2) is provided with a square trough gas collecting pipeline (1). The filter gas collecting hood (4), the molten sulfur tank gas collecting hood (3), the liquid sulfur storage tank gas collecting pipeline (2) and the square trough gas collecting pipeline (1) are all interconnected and coordinated.

7. The system for purifying molten sulfur flue gas in sulfuric acid production according to claim 1, characterized in that: One side of the reverse jet dust removal tower (8) is connected to an alkali solution dosing device (9), and a top outlet (6) is provided at the top of the reverse jet dust removal tower (8). One side of the top of the secondary dust removal tower (13) is provided with a variable diameter air duct (11), and the other side is provided with a secondary dust outlet (12), and the variable diameter air duct (11) cooperates with the top outlet (6).

8. The system for purifying molten sulfur flue gas in sulfuric acid production according to claim 1, characterized in that: A reverse spray pipe (7) is provided on one side of the reverse spray dust removal tower (8), and one end of the reverse spray pipe (7) is matched with the reverse spray dust removal tower (8). A delivery pipe (10) is provided on one side of the secondary dust removal tower (13), and the delivery pipe (10) is matched with the reverse spray dust removal tower (8) and the secondary dust removal tower (13). One end of the reverse spray dust removal tower (8) is connected to a liquid adding pipe (20), and the other end of the liquid adding pipe (20) is connected to a liquid sulfur storage tank (19).

9. The system for purifying molten sulfur flue gas in sulfuric acid production according to claim 1, characterized in that: The resistance of the secondary dust removal tower (13) is about 2.5 KPa, the resistance of the heat exchanger (15) is about 1.0 KPa, the resistance of the dry desulfurization device is about 1.0 KPa, the total resistance of the flue gas system is about 7.6 KPa, the margin coefficient is 1.1-1.3, and 1.2 is taken. The resistance of the flue gas system is rounded to 9.2 KPa.

10. A method for using the system for purifying molten sulfur flue gas in sulfuric acid production according to claim 1: (1) Waste gas collection and pretreatment: Start the sulfur melting tank gas collection hood (3) (2×6000m 3 / h), filter hood (4) (12000m 3 / h), square trough gas collection pipeline (1) (4000m 3 / h), liquid sulfur storage tank gas collection pipeline (2) (4000m 3 / h), total air volume 26000m 3 / h; turn on the electric heating system of the DN700mm heating sleeve to maintain the flue gas temperature at 145-150℃, ensure that the sulfur particles are carried out with the flue gas in the form of sublimated sulfur, and prevent the sublimated sulfur from condensing and clogging the pipeline; (2) Reverse spray dust removal tower (8) treatment: The molten sulfur flue gas enters the reverse spray pipe (7) through the flue gas pipeline. The large-diameter nozzle in the reverse spray pipe (7) sprays in reverse direction, impacts with the flue gas to generate a foam zone, and performs enhanced mass transfer. Through the continuous contact of the flue gas foam liquid film, particulate matter and related harmful gases are absorbed and removed; the reverse spray flushes the foam zone generated by the flue gas, and has the effect of rapid cooling, so that the flue gas temperature drops from 145-150°C to 60-65°C; the washing liquid is circulated in the reverse spray tower, and when the density reaches the set requirement of 1.15-1.25g / ml, the circulating liquid is pumped into the filter press through the reverse spray pump bypass to filter the particulate matter (the particulate matter is mainly Solid sulfur powder is washed and reused as solid sulfur raw material for melting sulfur); the reverse spray tower is provided with an alkali liquid dosing device (9); sulfur dioxide waste gas in the flue gas is absorbed by adding an appropriate amount of alkali liquid in the circulating liquid, and the amount of alkali liquid is 1.05-1.1 times the molar amount of sulfur dioxide in the flue gas. After the sulfur dioxide waste gas is absorbed by the alkali liquid, the flue gas is neutral or slightly acidic, which can ensure the normal operation of the back-end equipment; the liquid sulfur storage tank (19) is connected through a liquid adding pipe (20) to replenish the washing liquid lost due to evaporation; the purified flue gas is discharged through the top outlet (6) of the reverse spray dust removal tower (8) and enters the secondary dust removal tower (13); (3) Secondary dust removal tower (13) deep purification variable diameter air duct (11) transportation: The flue gas is discharged from the top outlet of the reverse-jet dust removal tower (8) through the variable-diameter air duct (11) and enters the secondary dust removal tower (13) in reverse direction. The secondary dust removal tower (13) is provided with fillers to further remove the remaining particulate matter in the flue gas, and can process more than 85% of the remaining particulate matter, while removing more than 90% of the droplets and fine particulate matter, thereby greatly reducing the water content in the flue gas. The secondary dust removal tower (13) is equipped with a water sprayer, and the filler layer is regularly flushed for 15-30 minutes after running for 48-60 hours, and the flushing liquid is pumped into the reverse-jet dust removal tower (8) for reuse by a delivery pump, thereby reducing water consumption. The purified flue gas is discharged through the secondary dust outlet (12) of the secondary dust removal tower (13) and enters the heat exchanger (15). (4) Heat exchanger (15) temperature rise control: After secondary dust removal, the flue gas enters the heat exchanger (15) and adopts a gas-steam heat exchange method (steam produced as a byproduct of a sulfuric acid plant). The flue gas is heated by using 0.3-0.6 MPa low-pressure steam at 130-150°C through the plate (26) heat exchanger (15). The flue gas contacts the plates (26) (20-30 plates, arranged side by side in an array with equal spacing) inside the main frame (27) of the heat exchanger (15). Heat is transferred from the steam side to the flue gas side, heating the flue gas from 60-65°C to 80 -120°C, preferably 90-110°C, steam enters the heat exchanger (15) through the steam inlet pipe (21), and condensed water is discharged through the steam outlet pipe (24) to prevent scaling of the plate (26). An auxiliary support frame (23) is provided on one side of the main frame (27) of the heat exchanger (15) to ensure the stability of the plate (26) assembly; fixing rods (25) (including positioning bolts (22)) on both sides of the edge of the main frame (27) further reinforce the plate (26) array to prevent vibration deviation; (5) Dry fine desulfurization treatment: The flue gas enters the dry fine desulfurization device (16). The main body of the desulfurization tower (29) is composed of an upper tower section (30), a middle tower section (31) and a lower tower section (34). The tower is filled with a desulfurizer (such as activated carbon or metal oxide). The flue gas passes through the desulfurizer bed at 90-110° C. to effectively remove hydrogen sulfide and organic sulfur in the flue gas (desulfurization efficiency ≥ 95%). A silo (33) is provided on one side of the main body of the desulfurization tower (29) for replenishing fresh desulfurizer. Pre-buried iron (35) is provided between the steel structure support (32) and the foot (36) to ensure the overall stability of the desulfurization tower (29). When the outlet H2S concentration exceeds the standard, fresh desulfurizer is replenished from the silo (33), and the waste agent is discharged through the outlet of the lower tower section (34). (6) Tail exhaust system emissions Starting air volume 32000m 3 / h, and an induced draft fan (17) with a wind pressure of 9.2 kPa, overcomes the total system resistance (9.2 kPa), and the purified flue gas passes through a DN1000-1200 mm exhaust pipe (18) (height ≥ 20 m) to meet the discharge standards; (7) Real-time monitoring of key parameters Flue gas temperature: reverse spray pipe (7) inlet (145-150°C), secondary tower outlet (60-65°C), heat exchanger (15) outlet (90-110°C); circulating liquid density: density in reverse spray tower 1.15-1.25g / ml, start filter press when exceeding the limit; real-time monitoring of pipeline resistance (3.1kPa), dust removal tower resistance (2.5kPa), heat exchanger (15) resistance (1.0kPa), check for blockage when total resistance exceeds 9.2kPa; Exhaust gas pipe: Clean the sulfur residue on the inner wall of DN700mm pipe every week. Reverse spray nozzle: Check nozzle wear every month and replace damaged nozzles. Packing layer: Clean the scale on the packing layer of the secondary tower every quarter. Desulfurizer: According to the H2S concentration monitoring, the desulfurizer should be replaced every 3-6 months.

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