A plant and method for the production of acid from high concentration so2 flue gas

Abstract

The present application relates to the technical field of sulfuric acid production, and particularly relates to a device and method for producing sulfuric acid from high-concentration SO2 flue gas. The device and method improve the conversion rate by reforming the equipment in the purification section of the device for producing sulfuric acid from high-concentration SO2 flue gas, reducing the resistance of the device, improving the flue gas receiving capacity of the whole device, increasing the catalyst loading of the converter, improving the catalyst loading coefficient of the converter, timely screening, backfilling and supplementing new catalyst for each layer of the converter after the device is operated for a period of time, and increasing the loading amount. The device and method also increase the circulating water cooling system, improve the cooling effect of the circulating water, and meet the cooling requirements of the process for producing sulfuric acid from high-concentration SO2 flue gas.

Description

Technical Field

[0001] This invention relates to the field of sulfuric acid production technology, and in particular to an apparatus and method for producing sulfuric acid from high-concentration SO2 flue gas. Background Technology

[0002] Sulfuric acid, as a fundamental industrial raw material, plays a vital role in the industrial system. Currently, sulfuric acid production using smelting flue gas is a key process, but it still faces numerous challenges in actual industrial production, particularly when dealing with high concentrations of sulfur dioxide (SO2) flue gas. 1. The SO2 concentration in the flue gas treated by the existing process is usually maintained at about 12%, which requires a large amount of dilution air to adjust the concentration, resulting in a significant increase in the total air volume of the system and a corresponding increase in system resistance. The existing fan design capacity is difficult to meet the operating requirements under high resistance conditions, which restricts the continuous and stable production of the system.

[0003] 2. Insufficient catalyst loading in the converter and low loading coefficient lead to incomplete SO2 conversion reaction and a decrease in overall conversion rate. This not only affects the sulfuric acid yield but also increases SO2 emissions in the tail gas, resulting in raw material waste and environmental pressure.

[0004] 3. When processing high-concentration SO2 flue gas, especially after the production capacity is increased, the reaction heat in the system increases significantly. The existing circulating water cooling system cannot remove the excess heat in a timely and effective manner, causing the system temperature to rise. This not only affects the conversion efficiency but also poses a threat to the safe and stable operation of the equipment.

[0005] 4. As the SO2 concentration in flue gas increases, the load on the subsequent desulfurization system increases sharply, making it difficult for the system to achieve efficient desulfurization. This leads to an increase in SO2 concentration in the exhaust gas, making it difficult to meet increasingly stringent environmental emission standards.

[0006] In view of this, the present invention is hereby proposed. Summary of the Invention

[0007] The primary objective of this invention is to provide an apparatus for producing acid from high-concentration SO2 flue gas. This apparatus has low resistance, high flue gas receiving capacity, and high conversion rate, and can be used for the treatment of high-concentration SO2 flue gas.

[0008] The second objective of this invention is to provide a method for producing acid from high-concentration SO2 flue gas, which has a high conversion rate and low SO2 concentration in the tail gas.

[0009] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted: This invention provides an apparatus for producing acid from high-concentration SO2 flue gas, comprising: a primary dynamic wave scrubber, a gas cooling tower, a secondary dynamic wave scrubber, a primary electrostatic precipitator, a secondary electrostatic precipitator, a drying tower, a sulfur dioxide fan, a first heat exchanger, a second heat exchanger, a third heat exchanger, a fourth heat exchanger, a fifth heat exchanger, a converter, a first heating furnace, a second heating furnace, a waste heat boiler, a first absorption tower, and a second absorption tower. The primary dynamic wave scrubber, the gas cooling tower, the secondary dynamic wave scrubber, the primary electrostatic precipitator, the secondary electrostatic precipitator, the drying tower, the sulfur dioxide fan, the third heat exchanger, the first heat exchanger, and the first heating furnace are connected in sequence. The converter is connected to the first heat exchanger, the second heat exchanger, the third heat exchanger, the fourth heat exchanger, the fifth heat exchanger, and the first heating furnace, respectively. The third heat exchanger, the waste heat boiler, and the first absorption tower are connected in sequence. The first absorption tower is connected to the second heat exchanger, the fourth heat exchanger, and the fifth heat exchanger, respectively. The second heating furnace is connected to the second heat exchanger, the fourth heat exchanger, the fifth heat exchanger, and the converter, respectively. The fifth heat exchanger is connected to the second absorption tower; The inner diameter of the gas inlet pipe of the gas cooling tower is 1995~2005mm; The inner diameter of the reverse spray pipe of the secondary dynamic wave scrubber is 1695~1705mm; The converter is provided with five catalyst layers, and the catalyst filling coefficient of the converter is 210~230 liters per day / ton of acid.

[0010] Furthermore, the primary dynamic wave scrubber, the gas cooling tower, and the secondary dynamic wave scrubber are all equipped with a dilute acid circulation system.

[0011] Furthermore, the drying tower is equipped with an acid circulation system, and the acid circulation system is equipped with a cooler; a wire mesh demister is installed at the top of the drying tower.

[0012] Furthermore, both the first absorption tower and the second absorption tower are equipped with an acid circulation system, and the acid circulation system is equipped with a cooler; both the top of the first absorption tower and the top of the second absorption tower are equipped with fiber demisters.

[0013] Furthermore, an acid circulation line is provided between the acid circulation system of the first absorption tower and the acid circulation system of the drying tower; an acid circulation line is also provided between the acid circulation system of the second absorption tower and the acid circulation system of the drying tower.

[0014] Furthermore, the high-concentration SO2 flue gas acid production device also includes a desulfurization system, which is connected to the second absorption tower; The desulfurization system includes several desulfurization towers and a main flue. Each desulfurization tower is connected to the main flue, and a pneumatic butterfly valve is installed on the inlet flue and outlet flue of each desulfurization tower.

[0015] This invention provides a method for producing acid from high-concentration SO2 flue gas, using the apparatus for producing acid from high-concentration SO2 flue gas as described above, and includes the following steps: After dust removal, high-concentration SO2 flue gas enters the first-stage dynamic wave scrubber for circulating acid washing and cooling; then it enters the gas cooling tower for adiabatic cooling with circulating acid; then it enters the second-stage dynamic wave scrubber for circulating acid washing and cooling; and then it passes through the first-stage electrostatic precipitator and the second-stage electrostatic precipitator in sequence before entering the drying tower for drying. After being dried in the drying tower, the flue gas is sent to the third heat exchanger by a sulfur dioxide blower for heat exchange and temperature increase, then enters the first heat exchanger for heat exchange and temperature increase, and then enters the first catalyst layer of the converter for oxidation reaction after being heated by the first heating furnace. The generated gas is cooled by the first heat exchanger, and then enters the second catalyst layer of the converter for oxidation reaction. The generated gas is cooled by the second heat exchanger, and then enters the third catalyst layer of the converter for oxidation reaction. The generated gas is cooled by the third heat exchanger and then enters the waste heat boiler. The flue gas from the waste heat boiler passes through the first absorption tower. Part of the flue gas enters the fifth heat exchanger for heat exchange and temperature increase before entering the second heating furnace. Another part of the flue gas enters the fourth heat exchanger for heat exchange and temperature increase before entering the second heating furnace. After being heated in the second heating furnace, the flue gas enters the fourth catalyst layer of the converter for oxidation reaction. The generated gas is cooled by the fourth heat exchanger and then enters the fifth catalyst layer of the converter for oxidation reaction. The generated gas is cooled by the fifth heat exchanger and then enters the second absorption tower.

[0016] Furthermore, the volume concentration of SO2 in the high-concentration SO2 flue gas is 13%~15%.

[0017] Furthermore, the method for backfilling the catalyst in the converter includes: screening the catalyst in the converter and then backfilling it, with the filling amount increasing by 18-25 mg / L compared to the original filling amount. 3 .

[0018] Furthermore, the flue gas exiting the second absorption tower is purified by the desulfurization system before being discharged.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows: The apparatus and method for producing sulfuric acid from high-concentration SO2 flue gas provided by this invention can process high-concentration SO2 flue gas, converting SO2 in the high-concentration SO2 flue gas into sulfuric acid. It has a high conversion rate, low SO2 concentration in the tail gas, stable operation, low energy consumption, and low operating cost.

[0020] This invention improves the conversion rate by modifying the equipment in the purification section, reducing resistance and increasing flue gas receiving capacity; increasing the catalyst loading amount in the converter, improving the catalyst loading coefficient, and timely screening, backfilling, and replenishing the catalyst in each layer of the converter after a period of operation to increase the loading amount; and improving the cooling effect of the circulating water cooling system by adding a circulating water cooling system to meet the cooling requirements of the high-concentration SO2 flue gas acid production process. Attached Figure Description

[0021] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of the purification section of the high-concentration SO2 flue gas acid production process of the present invention. Detailed Implementation

[0023] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings and specific embodiments. However, those skilled in the art will understand that the embodiments described below are some embodiments of the present invention, but not all embodiments, and are only used to illustrate the present invention, and should not be regarded as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall be followed. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0024] See Figure 1 In some embodiments of the present invention, an apparatus for producing acid from high-concentration SO2 flue gas is provided, comprising: a primary dynamic wave scrubber, a gas cooling tower, a secondary dynamic wave scrubber, a primary electrostatic precipitator, a secondary electrostatic precipitator, a drying tower, a sulfur dioxide fan, a first heat exchanger, a second heat exchanger, a third heat exchanger, a fourth heat exchanger, a fifth heat exchanger, a converter, a first heating furnace, a second heating furnace, a waste heat boiler, a first absorption tower, and a second absorption tower; The first-stage dynamic wave scrubber, gas cooling tower, second-stage dynamic wave scrubber, first-stage electrostatic precipitator, second-stage electrostatic precipitator, drying tower, sulfur dioxide fan, third heat exchanger, first heat exchanger and first heating furnace are connected in sequence. The converter is connected to the first heat exchanger, the second heat exchanger, the third heat exchanger, the fourth heat exchanger, the fifth heat exchanger, and the first heating furnace, respectively. The third heat exchanger, the waste heat boiler and the first absorption tower are connected in sequence; The first absorption tower is connected to the second, fourth, and fifth heat exchangers, respectively. The second heating furnace is connected to the second heat exchanger, the fourth heat exchanger, the fifth heat exchanger, and the converter, respectively. The fifth heat exchanger is connected to the second absorption tower; The inner diameter of the gas inlet pipe of the gas cooling tower is 1995~2005mm; The inner diameter of the reverse spray pipe of the two-stage dynamic wave scrubber is 1695~1705mm; The converter has five catalyst layers, and the catalyst filling coefficient of the converter is 210~230 liters per day / ton of acid (210~230 liters of catalyst are required to produce 1 ton of sulfuric acid per day).

[0025] The apparatus for producing sulfuric acid from high-concentration SO2 flue gas of the present invention can process high-concentration SO2 flue gas and convert SO2 in the high-concentration SO2 flue gas into sulfuric acid. It has a high conversion rate, low SO2 concentration in the tail gas, stable operation, low energy consumption, and low operating cost.

[0026] This invention modifies the gas cooling tower, the secondary dynamic wave scrubber, and the electrostatic precipitator; increases the inner diameter of the gas inlet pipe of the gas cooling tower; and increases the inner diameter of the reverse spray pipe of the secondary dynamic wave scrubber. This reduces the total resistance of the purification section in the high-concentration SO2 flue gas acid production process under the same load, thereby helping to reduce the overall resistance of the device and improve the flue gas receiving capacity of the entire device.

[0027] The converter of the present invention is provided with five catalyst layers, which increases the amount of catalyst loaded in the converter and improves the catalyst loading coefficient, thereby improving the conversion rate.

[0028] For high-concentration SO2 flue gas to acid production processes, the increased production capacity leads to increased heat energy. This invention adds a circulating water cooling system to improve the cooling effect of the circulating water, thereby meeting the cooling requirements of high-concentration SO2 flue gas to acid production processes.

[0029] In some embodiments of the present invention, the outlet of the primary dynamic wave scrubber is connected to the inlet of the gas cooling tower; the outlet of the gas cooling tower is connected to the inlet of the secondary dynamic wave scrubber; the outlet of the secondary dynamic wave scrubber is connected to the inlet of the primary electrostatic precipitator; the outlet of the primary electrostatic precipitator is connected to the inlet of the secondary electrostatic precipitator; and the outlet of the secondary electrostatic precipitator is connected to the inlet of the drying tower.

[0030] In some embodiments of the present invention, the primary dynamic wave scrubber, the gas cooling tower, and the secondary dynamic wave scrubber are all equipped with a dilute acid circulation system.

[0031] The primary dynamic wave scrubber is equipped with a dilute acid circulation system, where the flue gas is purified, cooled, and deheated by the circulating acid. The gas cooling tower is also equipped with a dilute acid circulation system, where the flue gas and circulating dilute acid meet for adiabatic cooling. The secondary dynamic wave scrubber is equipped with a dilute acid circulation system, where the flue gas is purified, cooled, and deheated by the circulating acid.

[0032] In some embodiments of the present invention, the primary dynamic wave scrubber is sequentially connected to the inclined plate sedimentation tank, the clear liquid tank, the clear liquid pump, and the high-level tank. The high-level tank is connected to the primary dynamic wave scrubber, and the clear liquid tank is connected to the sewage pump.

[0033] In some embodiments of the present invention, the circulating acid in the gas cooling tower is heat exchanged via a plate heat exchanger.

[0034] In some embodiments of the present invention, both the primary electrostatic precipitator and the secondary electrostatic precipitator are conductive fiberglass electrostatic precipitators.

[0035] In some embodiments of the present invention, the drying tower is provided with an acid circulation system, and the acid circulation system is provided with a cooler; a wire mesh demister is provided at the top of the drying tower.

[0036] Inside the drying tower, the flue gas is dried by the circulating spray of concentrated sulfuric acid, and the heat released is removed by the cooling water in the cooler. The installation of the wire mesh demister reduces the corrosion of the equipment caused by sulfuric acid mist entrained in the gas.

[0037] In some embodiments of the present invention, the first heat exchanger, the second heat exchanger, the third heat exchanger, the fourth heat exchanger and the fifth heat exchanger are all shell-and-tube heat exchangers.

[0038] In some embodiments of the present invention, a first catalyst layer, a second catalyst layer, a third catalyst layer, a fourth catalyst layer, and a fifth catalyst layer are sequentially disposed within the converter; preferably, the total amount of catalyst loaded in the converter is 310~340 mg / L. 3 (For example, 310m) 3 318m 3 328m 3 338m 3340m 3 wait).

[0039] By optimizing the internal structure of the converter, increasing the catalyst loading amount, and improving the catalyst loading coefficient, the SO2 conversion rate is significantly improved, the sulfuric acid production is increased, the SO2 concentration in the tail gas is reduced, and the raw material utilization rate is improved.

[0040] In some embodiments of the present invention, the shell-side gas outlet of the third heat exchanger is connected to the shell-side gas inlet of the first heat exchanger; the shell-side gas outlet of the first heat exchanger is connected to the gas inlet of the first furnace; the gas outlet of the first catalyst layer of the converter is connected to the tube-side gas inlet of the first heat exchanger; the gas outlet of the first furnace is connected to the gas inlet of the first catalyst layer of the converter; the tube-side gas outlet of the first heat exchanger is connected to the gas inlet of the second catalyst layer of the converter; the gas outlet of the second catalyst layer of the converter is connected to the tube-side gas inlet of the second heat exchanger; the tube-side gas outlet of the second heat exchanger is connected to the gas inlet of the third catalyst layer of the converter; the gas outlet of the third catalyst layer of the converter is connected to the tube-side gas inlet of the third heat exchanger; and the tube-side gas outlet of the third heat exchanger is connected to the gas inlet of the waste heat boiler. The gas outlet of the waste heat boiler is connected to the gas inlet of the first absorption tower; the gas outlet of the first absorption tower is connected to the shell-side inlet of the fifth heat exchanger; the shell-side outlet of the fifth heat exchanger is connected to the gas inlet of the second heater; the gas outlet of the first absorption tower is connected to the shell-side inlet of the fourth heat exchanger; the shell-side outlet of the fourth heat exchanger is connected to the gas inlet of the second heater; the gas outlet of the first absorption tower is connected to the shell-side inlet of the second heat exchanger; the shell-side outlet of the second heat exchanger is connected to the gas inlet of the second heater; the gas outlet of the second heater is connected to the gas inlet of the fourth catalyst layer of the converter; the gas outlet of the fourth catalyst layer of the converter is connected to the tube-side gas inlet of the fourth heat exchanger; the tube-side gas outlet of the fourth heat exchanger is connected to the gas inlet of the fifth catalyst layer of the converter; the gas outlet of the fifth catalyst layer of the converter is connected to the tube-side gas inlet of the fifth heat exchanger; the tube-side gas outlet of the fifth heat exchanger is connected to the gas inlet of the second absorption tower.

[0041] In some embodiments of the present invention, both the first absorption tower and the second absorption tower are equipped with an acid circulation system, and the acid circulation system is equipped with a cooler; both the top of the first absorption tower and the top of the second absorption tower are equipped with fiber demisters. Preferably, the cooler is connected to a cooling water tower; by adding two cooling water towers connected to the original cooling water tower, adding two sets of cooling tower fans, modifying the circulating water pump, replacing the energy-saving motor and the pump outlet check valve, the cooling effect of the circulating water is improved, ensuring that the circulating water inlet temperature is ≤42℃ and the outlet temperature is ≤32℃.

[0042] Both the first and second absorption towers are equipped with an acid circulation system, which uses 98% concentrated sulfuric acid to absorb SO3. The acid circulation system is equipped with a cooler to remove heat and prevent the equipment from overheating.

[0043] In some embodiments of the present invention, an acid circulation line is provided between the acid circulation system of the first absorption tower and the acid circulation system of the drying tower; an acid circulation line is also provided between the acid circulation system of the second absorption tower and the acid circulation system of the drying tower.

[0044] By using a series acid pipeline, concentrated sulfuric acid from the acid circulation system of the absorption tower can be continuously replenished to the acid circulation system of the drying tower, so that the acid in the drying tower can be maintained at a specified concentration.

[0045] In some embodiments of the present invention, the high-concentration SO2 flue gas acid production device further includes a desulfurization system, which is connected to a second absorption tower; preferably, the gas outlet of the second absorption tower is connected to the desulfurization system. The desulfurization system includes several desulfurization towers and a main flue. Each desulfurization tower is connected to the main flue, and a pneumatic butterfly valve is installed on the inlet and outlet flues of each desulfurization tower.

[0046] The desulfurization system consists of inlet and outlet flue gas pipes, bypass flue, valves, expansion joints and related pipelines; flue gas enters a single desulfurization tower through the pneumatic butterfly valve at the inlet, and the desulfurized and qualified flue gas enters the main flue through the top of the desulfurization tower outlet chamber and is finally discharged through the chimney.

[0047] In some embodiments of the present invention, a method for producing acid from high-concentration SO2 flue gas is also provided, employing the aforementioned apparatus for producing acid from high-concentration SO2 flue gas, comprising the following steps: Purification section: After dust removal, high-concentration SO2 flue gas enters the first-stage dynamic wave scrubber for circulating acid washing and cooling; then it enters the gas cooling tower for adiabatic cooling with circulating acid; then it enters the second-stage dynamic wave scrubber for circulating acid washing and cooling; subsequently, it passes through the first-stage electrostatic precipitator and the second-stage electrostatic precipitator in sequence before entering the drying tower for drying. Conversion and dry absorption section: The flue gas dried in the drying tower is sent to the third heat exchanger by the sulfur dioxide blower for heat exchange and temperature increase, then enters the first heat exchanger for heat exchange and temperature increase, and then enters the first catalyst layer of the converter for oxidation reaction after being heated by the first heating furnace. The generated gas is cooled by the first heat exchanger, and then enters the second catalyst layer of the converter for oxidation reaction. The generated gas is cooled by the second heat exchanger, and then enters the third catalyst layer of the converter for oxidation reaction. The generated gas is cooled by the third heat exchanger and then enters the waste heat boiler. The flue gas from the waste heat boiler passes through the first absorption tower. Part of the flue gas enters the fifth heat exchanger for heat exchange and temperature increase before entering the second heating furnace. Another part of the flue gas enters the fourth heat exchanger for heat exchange and temperature increase before entering the second heating furnace. After being heated in the second heating furnace, the flue gas enters the fourth catalyst layer of the converter for oxidation reaction. The generated gas is cooled by the fourth heat exchanger and then enters the fifth catalyst layer of the converter for oxidation reaction. The generated gas is cooled by the fifth heat exchanger and then enters the second absorption tower.

[0048] The method for producing acid from high-concentration SO2 flue gas of the present invention includes a purification section as well as a conversion and dry absorption section; Cleanroom Section: The high-concentration SO2 flue gas generated during smelting is treated with dust removal and then sequentially passes through a primary dynamic wave scrubber, a gas cooling tower, a secondary dynamic wave scrubber, a primary electrostatic precipitator, and a secondary electrostatic precipitator before entering the drying tower.

[0049] The flue gas is washed, purified, cooled, and deheated by circulating acid in the first-stage dynamic wave scrubber. Then, it meets the circulating dilute acid in the gas cooling tower for adiabatic cooling. Finally, it enters the second-stage dynamic wave scrubber for further washing, purification, cooling, and deheating by circulating acid.

[0050] In the primary dynamic wave scrubber, gas cooling tower, and secondary dynamic wave scrubber, trace amounts of SO3 in the flue gas are transformed from sulfuric acid vapor into acid mist; oxides of arsenic, selenium, and some other metals become solid particles and are separated from the gas phase; some of them are washed away along with trace amounts of mineral dust remaining in the flue gas, while the other part enters the electrostatic precipitator with the flue gas and is cleaned under the action of high voltage electrostatics.

[0051] Excess dilute sulfuric acid in the acid circulation system of the secondary dynamic wave scrubber is transferred to the acid circulation system of the gas cooling tower; excess dilute sulfuric acid in the acid circulation system of the gas cooling tower is transferred to the acid circulation system of the primary dynamic wave scrubber, and after solid impurities are removed by the inclined plate settling device, it is either recycled or neutralized and discharged.

[0052] The flue gas from the secondary electrostatic precipitator is dried by concentrated sulfuric acid that is circulated and sprayed in the drying tower. A large amount of heat is released during the drying process of the flue gas by concentrated sulfuric acid, and the heat is removed by cooling water in the cooler. In order to reduce the corrosion of the equipment caused by sulfuric acid mist entrained in the gas, a wire mesh demister is installed at the top of the drying tower.

[0053] Conversion and dry absorption section: After drying in the drying tower, the flue gas is sent to the third heat exchanger by a sulfur dioxide blower for heat exchange and temperature increase. Then, it enters the first heat exchanger to exchange heat with the gas exiting the first catalyst layer of the converter for further temperature increase. After being heated by the first heating furnace, it enters the first catalyst layer of the converter for oxidation reaction. The generated SO3 gas is cooled by the first heat exchanger and then enters the second catalyst layer of the converter for oxidation reaction. The generated SO3 gas is cooled by the second heat exchanger and then enters the third catalyst layer of the converter for oxidation reaction, producing SO3 gas. At this point, more than 95% of the SO2 is converted into SO3 gas. After being cooled by the third heat exchanger, it enters the waste heat boiler to recover heat. After the flue gas from the waste heat boiler enters the first absorption tower to absorb SO3, part of it enters the fifth heat exchanger to exchange heat with the gas from the fifth catalyst layer of the converter and is heated; part of it enters the fourth heat exchanger to exchange heat with the gas from the fourth catalyst layer of the converter and is heated; and the remaining part enters the second heat exchanger to exchange heat with the gas from the second catalyst layer of the converter and is heated. Then, the flue gas from the fifth, fourth, and second heat exchangers is heated by the second heater and enters the fourth catalyst layer of the converter for oxidation. The SO3 gas produced is cooled by the fourth heat exchanger and then enters the fifth catalyst layer of the converter for oxidation. After being cooled by the fifth heat exchanger again, it is sent to the second absorption tower to absorb the SO3.

[0054] Since the conversion of SO2 to SO3 is a reversible exothermic reaction, lowering the temperature will reduce the reaction rate, which will not achieve the goal of economic operation in actual production. Therefore, when selecting the conversion temperature index, it is necessary to consider not only a high conversion rate but also a high reaction rate.

[0055] During the conversion process, the conversion temperature should not be controlled within the same range from the beginning to the end. In the initial stage of the reaction, the SO2 concentration is high and the SO3 concentration is low, and the reaction is far from the endpoint. At high temperatures, the reaction shifts towards the forward reaction direction, so it is advisable to convert the gas at a higher temperature to achieve a larger reaction rate. In the later stage of the reaction, the gas composition concentration relationship within the converter is exactly the opposite, and the reaction is closer to the equilibrium state. Therefore, it is advisable to convert the gas at a lower temperature to obtain a higher conversion rate. The five-layer catalyst design allows for precise temperature control to prevent catalyst overheating and deactivation, adapts to fluctuations in flue gas volume and SO2 concentration, and has strong operational adaptability. Layered control of the reaction depth not only improves the overall conversion efficiency but also reduces system resistance, decreases fan power consumption, and extends catalyst lifespan.

[0056] In the first and second absorption towers, concentrated sulfuric acid with a concentration of 98% is used to absorb SO3 in the flue gas; the heat of reaction generated is absorbed and removed by the cooler; in order to remove sulfuric acid mist entrained in the gas, fiber demisters are installed at the top of both the first and second absorption towers.

[0057] A series acid pipeline is installed between the acid circulation systems of the first and second absorption towers and the acid circulation system of the drying tower. Concentrated sulfuric acid from the absorption tower's acid circulation system is continuously supplied to the drying tower's acid circulation system, maintaining the acid concentration in the drying tower at a specified level. Excess drying acid is transferred to the absorption tower's acid circulation system. Inside the absorption tower, sulfur trioxide is continuously absorbed to form sulfuric acid, thus the amount of sulfuric acid in the absorption tower's acid circulation system continuously increases. The excess sulfuric acid is withdrawn from the circulation system as the finished product.

[0058] In some embodiments of the present invention, the volume concentration of SO2 in the high-concentration SO2 flue gas is 13% to 15% (e.g., 13%, 13.5%, 14%, 14.5%, 15%, etc.); preferably, the oxygen-sulfur ratio is 1:(1.2 to 1.3); the oxygen-sulfur ratio is the volume fraction ratio of O2 to SO2; preferably, the volume concentration of SO2 in the high-concentration SO2 flue gas is 13% to 15%, the sum of the volume concentrations of nitrogen and carbon dioxide is 70% to 74%, and the volume concentration of oxygen is 10% to 12%.

[0059] In some embodiments of the present invention, the outlet flue gas temperature of the first heat exchanger is 400~410°C; The temperature of the flue gas entering the first catalyst layer of the converter is 400~410℃, and the volume concentration of SO2 is 13%~15%; The gas enters the first catalyst layer of the converter for oxidation reaction, producing gas at a temperature of 610~620℃. This gas is then cooled to 445~455℃ by the first heat exchanger. It then enters the second catalyst layer of the converter for oxidation reaction, producing gas at a temperature of 520~530℃. This gas is then cooled to 440~450℃ by the second heat exchanger. Finally, it enters the third catalyst layer of the converter for oxidation reaction, producing gas at a temperature of 455~465℃. This gas is then cooled to 300~310℃ by the third heat exchanger before entering the waste heat boiler. The flue gas temperature at the outlet of the waste heat boiler is 190~210℃; The flue gas from the second absorption is heated to 420~430℃ by heat exchange and then enters the fourth catalyst layer of the converter for oxidation reaction. The resulting gas at 440~450℃ is cooled to 410~425℃ by the fourth heat exchanger and then enters the fifth catalyst layer of the converter for oxidation reaction. The resulting gas at 420~430℃ is cooled to 170~200℃ by the fifth heat exchanger and then enters the second absorption tower.

[0060] In some embodiments of the present invention, the concentration of SO2 in the flue gas exiting the second absorption tower is <700 mg / Nm³. 3 .

[0061] In some embodiments of the present invention, the total SO2 conversion rate of the method for producing acid from high-concentration SO2 flue gas is ≥99.9%.

[0062] In some embodiments of the present invention, the catalyst loading coefficient in the converter is 210-230 L / day / ton of acid, and the total catalyst loading is 310-340 m³. 3 The catalyst includes vanadium catalyst and / or cesium catalyst, preferably 305~337m. 3 Vanadium catalyst and 3~5m 3 Cesium catalyst.

[0063] During normal production, the temperature inside the equipment can reach as low as 400℃. Long-term scouring by flue gas, control of process parameters, and acid mist and moisture in the equipment can cause the catalyst in the converter to scale and pulverize, resulting in increased internal resistance of the converter. It is necessary to screen the catalyst in time to reduce the resistance of the conversion system.

[0064] In some embodiments of the present invention, the catalyst backfilling method in the converter includes: screening the catalyst in the converter and then backfilling it, wherein the filling amount is increased by 18-25 mg / L compared with the original filling amount. 3 (For example, 20m) 3 Preferably, according to the original catalyst filling method, the catalyst located at the bottom of the original low bed layer is added to the upper middle part of the high bed layer, and the catalyst located in the upper middle part of the original low bed layer is added to the bottom. The new catalyst is placed in the low temperature bed layer (or the low temperature part of the bed layer), and the original catalyst at the bottom of the low temperature bed layer is moved and backfilled according to the principle of moving from low temperature to high temperature.

[0065] Due to long-term scouring by flue gas, control of process parameters, and acid mist and moisture in the equipment, the catalyst in the converter has become scaled and powdered, resulting in an increase in pressure drop in layers 2 to 5 inside the converter. It is necessary to screen, backfill, and add new catalyst to each layer of the converter, while screening and backfilling ceramic balls in each layer of the converter.

[0066] During the overhaul, a dedicated catalyst screening machine is used to extract and screen the catalyst from each layer. After removing the pulverized catalyst, it is backfilled, and new catalyst is added according to the screening loss. By screening the catalyst in the converter and adjusting the position of the old catalyst in the converter, the pressure drop of each bed layer in the converter is reduced. By increasing the catalyst and improving the catalyst loading coefficient, the conversion rate is improved, and the goal of high conversion rate and low tail discharge is achieved.

[0067] In some embodiments of the present invention, the method for producing acid from high-concentration SO2 flue gas further includes: the flue gas from the outlet of the second absorption tower is purified by a desulfurization system before being discharged.

[0068] The function of the desulfurization system is to send the flue gas to be treated into the SO2 adsorption and removal system when the desulfurization device is operating normally, and at the same time send the purified flue gas into the chimney for discharge.

[0069] Inspect and clean the desulfurization inlet and outlet flues, the desulfurization tower inlet and outlet chambers and grids, and the desulfurization tower unloader to ensure normal material circulation, uniform tail gas distribution, and reduced resistance of the desulfurization tower in the activated coke desulfurization system.

[0070] Example 1 The apparatus for producing sulfuric acid from high-concentration SO2 flue gas provided in this embodiment includes: a primary dynamic wave scrubber, a gas cooling tower, a secondary dynamic wave scrubber, a primary electrostatic precipitator, a secondary electrostatic precipitator, a drying tower, a sulfur dioxide fan, a first heat exchanger, a second heat exchanger, a third heat exchanger, a fourth heat exchanger, a fifth heat exchanger, a converter, a first heating furnace, a second heating furnace, a waste heat boiler, a first absorption tower, a second absorption tower, and a desulfurization system; The primary dynamic wave scrubber, gas cooling tower, and secondary dynamic wave scrubber are all equipped with a dilute acid circulation system; the gas inlet pipe of the gas cooling tower has an inner diameter of 2000mm, and the reverse spray pipe of the secondary dynamic wave scrubber has an inner diameter of 1700mm. The drying tower is equipped with an acid circulation system, and the acid circulation system is equipped with a cooler; a wire mesh demister is installed at the top of the drying tower. The first, second, third, fourth, and fifth heat exchangers are all shell-and-tube heat exchangers. The converter contains a first catalyst layer, a second catalyst layer, a third catalyst layer, a fourth catalyst layer, and a fifth catalyst layer arranged sequentially; the total catalyst loading in the converter is 318m³. 3 The catalyst filling coefficient is 220 liters per day / ton of acid, and the total filling volume of ceramic balls is 40m³. 3 The catalyst is a vanadium catalyst; The outlet of the primary dynamic wave scrubber is connected to the inlet of the gas cooling tower; the outlet of the gas cooling tower is connected to the inlet of the secondary dynamic wave scrubber; the outlet of the secondary dynamic wave scrubber is connected to the inlet of the primary electrostatic precipitator; the outlet of the primary electrostatic precipitator is connected to the inlet of the secondary electrostatic precipitator; and the outlet of the secondary electrostatic precipitator is connected to the inlet of the drying tower. The shell-side gas outlet of the third heat exchanger is connected to the shell-side gas inlet of the first heat exchanger; the shell-side gas outlet of the first heat exchanger is connected to the gas inlet of the first heating furnace; the gas outlet of the first catalyst layer of the converter is connected to the tube-side gas inlet of the first heat exchanger; the gas outlet of the first heating furnace is connected to the gas inlet of the first catalyst layer of the converter; the tube-side gas outlet of the first heat exchanger is connected to the gas inlet of the second catalyst layer of the converter; the gas outlet of the second catalyst layer of the converter is connected to the tube-side gas inlet of the second heat exchanger; the tube-side gas outlet of the second heat exchanger is connected to the gas inlet of the third catalyst layer of the converter; the gas outlet of the third catalyst layer of the converter is connected to the tube-side gas inlet of the third heat exchanger; the tube-side gas outlet of the third heat exchanger is connected to the gas inlet of the waste heat boiler. The gas outlet of the waste heat boiler is connected to the gas inlet of the first absorption tower; the gas outlet of the first absorption tower is connected to the shell-side inlet of the fifth heat exchanger; the shell-side outlet of the fifth heat exchanger is connected to the gas inlet of the second heater; the gas outlet of the first absorption tower is connected to the shell-side inlet of the fourth heat exchanger; the shell-side outlet of the fourth heat exchanger is connected to the gas inlet of the second heater; the gas outlet of the first absorption tower is connected to the shell-side inlet of the second heat exchanger; the shell-side outlet of the second heat exchanger is connected to the gas inlet of the second heater; the gas outlet of the second heater is connected to the gas inlet of the fourth catalyst layer of the converter; the gas outlet of the fourth catalyst layer of the converter is connected to the tube-side gas inlet of the fourth heat exchanger; the tube-side gas outlet of the fourth heat exchanger is connected to the gas inlet of the fifth catalyst layer of the converter; the gas outlet of the fifth catalyst layer of the converter is connected to the tube-side gas inlet of the fifth heat exchanger; the tube-side gas outlet of the fifth heat exchanger is connected to the gas inlet of the second absorption tower. Both the first and second absorption towers are equipped with acid circulation systems, and the acid circulation systems are equipped with coolers; both the top of the first and second absorption towers are equipped with fiber demisters; the coolers are connected to cooling water towers. The gas outlet of the second absorption tower is connected to the desulfurization system; The desulfurization system consists of several desulfurization towers and a main flue. Each desulfurization tower is connected to the main flue, and a pneumatic butterfly valve is installed on the inlet and outlet flues of each desulfurization tower.

[0071] Example 2 The method for producing acid from high-concentration SO2 flue gas provided in this embodiment uses the apparatus for producing acid from high-concentration SO2 flue gas in Example 1, and includes the following steps: S1, Cleanroom Section High-concentration SO2 flue gas (SO2 concentration of 13%~15%) enters the first-stage dynamic wave scrubber after dust removal, where it is purified by circulating acid washing and cooled. Then it enters the gas cooling tower for adiabatic cooling with circulating acid. Next, it enters the second-stage dynamic wave scrubber for purification by circulating acid washing and cooling. Finally, it passes through the first-stage electrostatic precipitator and the second-stage electrostatic precipitator in sequence before entering the drying tower for drying. S2, Conversion and Dry Absorption Section After drying in the drying tower, the flue gas enters the third heat exchanger via a sulfur dioxide blower for heat exchange and temperature increase. It then enters the first heat exchanger and exchanges heat with the gas exiting the first catalyst layer of the converter, reaching a temperature of 400-410°C. After being heated by the first heating furnace, it enters the first catalyst layer of the converter for an oxidation reaction, producing SO3 flue gas at 615°C. The 615°C SO3 flue gas is cooled to 450°C by the first heat exchanger and then enters the second catalyst layer of the converter for an oxidation reaction, producing SO3 flue gas at 528°C. The 528°C SO3 flue gas is cooled to 445°C by the second heat exchanger and then enters the third catalyst layer of the converter for an oxidation reaction, producing SO3 gas at 460°C. At this point, 95.1% of the SO2 has been converted into SO3 gas. SO3 gas at 460℃ enters the third heat exchanger and is cooled to 305℃ before entering the waste heat boiler to recover heat. The flue gas temperature at the outlet of the waste heat boiler is 200℃. After the flue gas from the waste heat boiler enters the first absorption tower to absorb SO3, a portion enters the fifth heat exchanger to exchange heat with the gas from the fifth catalyst layer of the converter, another portion enters the fourth heat exchanger to exchange heat with the gas from the fourth catalyst layer of the converter, and the remaining portion enters the second heat exchanger to exchange heat with the gas from the second catalyst layer of the converter. Then, the flue gas from the fifth, fourth, and second heat exchangers is heated to 425°C in the second heating furnace and enters the fourth catalyst layer of the converter for oxidation, producing SO3 gas at a temperature of 445°C. The 445°C SO3 gas is cooled to 410~425°C in the fourth heat exchanger and then enters the fifth catalyst layer of the converter for oxidation, producing SO3 gas at a temperature of 420~430°C. After being cooled to 180°C in the fifth heat exchanger, it is sent to the second absorption tower to absorb SO3. Finally, it enters the desulfurization system for purification before being discharged.

[0072] The SO2 concentration in the flue gas exiting the second absorption tower is 200~700 mg / m³. 3 The total SO2 conversion rate was 99.92%; the sulfuric acid concentration was 98.5%; and the flue gas receiving volume was 100,000~120,000 m³. 3 / h.

[0073] Example 3 After two years of operation, the high-concentration SO2 flue gas acid production device in Example 1 showed increased internal resistance in the converter, with pressure drops in layers 2-5 increasing by 1 kPa, 0.4 kPa, 0.3 kPa, and 0.2 kPa, respectively; a major overhaul was required.

[0074] During the overhaul, a dedicated catalyst screening machine was used to extract and screen the catalyst from each layer. Powdered catalyst was removed and then backfilled. New catalyst was added based on the screening loss. Simultaneously, 40m³ of ceramic balls from each layer of the converter were screened and backfilled. 3Place the new catalyst in the low-temperature bed (or the low-temperature section of the bed). The existing catalyst at the bottom of the low-temperature bed should be moved and backfilled according to the principle of moving from low temperature to high temperature. Specifically, backfill the bottom of the second layer to the lower middle part of the first layer, the bottom of the fourth layer to the upper middle part of the second layer, and the bottom of the fifth layer to the upper middle part of the third layer. Add a portion of new catalyst to the top of each layer to reach the original filling volume, increasing the volume by 20m³ per layer. 3 Catalyst, the filling volume was increased from the original 318m³ 3 Increased to 338m 3 .

[0075] The method for producing acid from high-concentration SO2 flue gas provided in this embodiment uses a renovated high-concentration SO2 flue gas acid production device and includes the following steps: S1, Cleanroom Section High-concentration SO2 flue gas (SO2 concentration of 13%~15%) passes through a primary dynamic wave scrubber, a gas cooling tower, a secondary dynamic wave scrubber, a primary electrostatic precipitator, and a secondary electrostatic precipitator before entering the drying tower. S2, Conversion and Dry Absorption Section After being dried in the drying tower, the flue gas enters the third heat exchanger via a sulfur dioxide blower for heat exchange and temperature increase. It then enters the first heat exchanger for further heat exchange and temperature increase to 400-410℃. Next, it enters the first catalyst layer of the converter for an oxidation reaction, producing SO3 flue gas at a temperature of 610-620℃. This SO3 flue gas is then cooled to 445-455℃ by the first heat exchanger and enters the second catalyst layer of the converter for another oxidation reaction, producing SO3 flue gas at a temperature of 520-530℃. Finally, this SO3 flue gas is cooled to 440-450℃ by the second heat exchanger and enters the third catalyst layer of the converter for yet another oxidation reaction, producing SO3 gas at a temperature of 455-465℃. SO3 gas at 455~465℃ enters the third heat exchanger and is cooled to 300~310℃ before entering the waste heat boiler to recover heat. The flue gas temperature at the outlet of the waste heat boiler is 190~210℃. After the flue gas from the waste heat boiler enters the first absorption tower to absorb SO3, part of it enters the fifth heat exchanger, part enters the fourth heat exchanger, and the rest enters the second heat exchanger. Then, the flue gas from the fifth, fourth, and second heat exchangers is heated to 420-430℃ through heat exchange and enters the fourth catalyst layer of the converter for oxidation reaction, producing SO3 gas at a temperature of 440-450℃. The SO3 gas at 440-450℃ is cooled to 410-425℃ by the fourth heat exchanger and then enters the fifth catalyst layer of the converter for oxidation reaction, producing SO3 gas at a temperature of 420-430℃. It is then cooled to 190-200℃ by the fifth heat exchanger and sent to the second absorption tower. Finally, it enters the desulfurization system for purification before being discharged.

[0076] The SO2 concentration in the flue gas exiting the second absorption tower is 200~700 mg / m³. 3 The total SO2 conversion rate was 99.92%.

[0077] Although the present invention has been illustrated and described with specific embodiments, it should be understood that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; those skilled in the art should understand that modifications can be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein, without departing from the spirit and scope of the present invention; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention; therefore, this means that all such substitutions and modifications that fall within the scope of the present invention are included in the appended claims.

Claims

1. A device for producing acid from high-concentration SO2 flue gas, characterized in that, include: Primary dynamic wave scrubber, gas cooling tower, secondary dynamic wave scrubber, primary electrostatic precipitator, secondary electrostatic precipitator, drying tower, sulfur dioxide fan, first heat exchanger, second heat exchanger, third heat exchanger, fourth heat exchanger, fifth heat exchanger, converter, first heating furnace, second heating furnace, waste heat boiler, first absorption tower and second absorption tower. The primary dynamic wave scrubber, the gas cooling tower, the secondary dynamic wave scrubber, the primary electrostatic precipitator, the secondary electrostatic precipitator, the drying tower, the sulfur dioxide fan, the third heat exchanger, the first heat exchanger, and the first heating furnace are connected in sequence. The converter is connected to the first heat exchanger, the second heat exchanger, the third heat exchanger, the fourth heat exchanger, the fifth heat exchanger, and the first heating furnace, respectively. The third heat exchanger, the waste heat boiler, and the first absorption tower are connected in sequence. The first absorption tower is connected to the second heat exchanger, the fourth heat exchanger, and the fifth heat exchanger, respectively. The second heating furnace is connected to the second heat exchanger, the fourth heat exchanger, the fifth heat exchanger, and the converter, respectively. The fifth heat exchanger is connected to the second absorption tower; The inner diameter of the gas inlet pipe of the gas cooling tower is 1995~2005mm; The inner diameter of the reverse spray pipe of the secondary dynamic wave scrubber is 1695~1705mm; The converter is provided with five catalyst layers, and the catalyst filling coefficient of the converter is 210~230 liters per day / ton of acid.

2. The apparatus for producing acid from high-concentration SO2 flue gas according to claim 1, characterized in that, The primary dynamic wave scrubber, the gas cooling tower, and the secondary dynamic wave scrubber are all equipped with a dilute acid circulation system.

3. The apparatus for producing acid from high-concentration SO2 flue gas according to claim 1, characterized in that, The drying tower is equipped with an acid circulation system, and the acid circulation system is equipped with a cooler; a wire mesh demister is installed at the top of the drying tower.

4. The apparatus for producing acid from high-concentration SO2 flue gas according to claim 1, characterized in that, Both the first absorption tower and the second absorption tower are equipped with an acid circulation system, and the acid circulation system is equipped with a cooler; both the top of the first absorption tower and the top of the second absorption tower are equipped with fiber demisters.

5. The apparatus for producing acid from high-concentration SO2 flue gas according to claim 4, characterized in that, An acid circulation line is provided between the acid circulation system of the first absorption tower and the acid circulation system of the drying tower; an acid circulation line is also provided between the acid circulation system of the second absorption tower and the acid circulation system of the drying tower.

6. The apparatus for producing acid from high-concentration SO2 flue gas according to claim 1, characterized in that, The high-concentration SO2 flue gas acid production device also includes a desulfurization system, which is connected to the second absorption tower; The desulfurization system includes several desulfurization towers and a main flue. Each desulfurization tower is connected to the main flue, and a pneumatic butterfly valve is installed on the inlet flue and outlet flue of each desulfurization tower.

7. A method for producing acid from high-concentration SO2 flue gas, using the apparatus for producing acid from high-concentration SO2 flue gas as described in any one of claims 1 to 6, characterized in that, Includes the following steps: After dust removal, high-concentration SO2 flue gas enters the first-stage dynamic wave scrubber where it is washed and cooled by circulating acid; then it enters the gas cooling tower for adiabatic cooling with circulating acid. It then enters the secondary dynamic wave scrubber for circulating acid washing and cooling; subsequently, it passes through the primary electrostatic precipitator and the secondary electrostatic precipitator before entering the drying tower for drying. After being dried in the drying tower, the flue gas is sent to the third heat exchanger by a sulfur dioxide blower for heat exchange and temperature increase, then enters the first heat exchanger for heat exchange and temperature increase, and then enters the first catalyst layer of the converter for oxidation reaction after being heated by the first heating furnace. The generated gas is cooled by the first heat exchanger, and then enters the second catalyst layer of the converter for oxidation reaction. The generated gas is cooled by the second heat exchanger, and then enters the third catalyst layer of the converter for oxidation reaction. The generated gas is cooled by the third heat exchanger and then enters the waste heat boiler. The flue gas from the waste heat boiler passes through the first absorption tower. Part of the flue gas enters the fifth heat exchanger for heat exchange and temperature increase before entering the second heating furnace. Another part of the flue gas enters the fourth heat exchanger for heat exchange and temperature increase before entering the second heating furnace. After being heated in the second heating furnace, the flue gas enters the fourth catalyst layer of the converter for oxidation reaction. The generated gas is cooled by the fourth heat exchanger and then enters the fifth catalyst layer of the converter for oxidation reaction. The generated gas is cooled by the fifth heat exchanger and then enters the second absorption tower.

8. The method for producing acid from high-concentration SO2 flue gas according to claim 7, characterized in that, The volume concentration of SO2 in the high-concentration SO2 flue gas is 13%~15%.

9. The method for producing acid from high-concentration SO2 flue gas according to claim 7, characterized in that, The method for backfilling the catalyst in the converter includes: screening the catalyst in the converter and then backfilling it, with the filling amount increasing by 18-25 mg / L compared to the original filling amount. 3 .

10. The method for producing acid from high-concentration SO2 flue gas according to claim 7, characterized in that, The flue gas from the outlet of the second absorption tower is discharged after being purified by the desulfurization system.

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