Method and system for recovering sulfur element in sulfur-containing waste

Abstract

The invention relates to the field of sulfur-containing waste treatment, and discloses a method and a system for recovering sulfur element in sulfur-containing waste, and the method comprises the following steps: firstly, decomposing the sulfur-containing waste into first process gas containing sulfur dioxide; carrying out a first catalytic oxidation reaction on the first process gas, and condensing to obtain a second process gas; performing a second catalytic oxidation reaction on the second process gas, and condensing to discharge tail gas to be treated; according to the method, sulfur-containing waste is decomposed into gas containing sulfur dioxide through the reaction furnace, sulfur dioxide is catalytically oxidized into sulfur trioxide through the reaction tower, sulfur trioxide is condensed into concentrated sulfuric acid through the condensing tower, and the sulfur element recovery liquid is obtained. The sulfur-containing waste is decomposed into process gas containing sulfur dioxide in the reaction furnace, and the recovery rate of the sulfur element is not lower than 99% through two times of catalytic oxidation and two times of condensation.

Description

Technical Field

[0001] The invention relates to the field of sulfur-containing waste treatment, and in particular to a method and system for recovering sulfur from sulfur-containing waste. Background Art

[0002] For the treatment of sulfur-containing liquids and sulfur-containing gases, one of the processes is to recover sulfur elements to make concentrated sulfuric acid. The acid production process mainly includes dry acid production process and wet acid production process. The traditional dry process generally adopts a two-turn and two-absorption process, including cracking, purification, conversion, drying and absorption, etc., which can obtain concentrated sulfuric acid and fuming sulfuric acid products of any concentration, but the process has many equipment, long process, low heat recovery rate, large pressure drop, high energy consumption and other problems. In the process of wet sulfuric acid production, after the sulfur-containing waste liquid and waste gas are produced into a gas containing sulfur dioxide, there is no need to wash and dry it, and the sulfur dioxide is converted into sulfur trioxide, and the sulfur trioxide and water vapor are combined to form gaseous sulfuric acid, which is then condensed into liquid sulfuric acid. The process of wet acid production is relatively short, and the utilization rate of heat and sulfur is relatively high, but the wet acid production process also has disadvantages, and the recovery rate of sulfur elements is not high enough. Summary of the invention

[0003] The purpose of the present invention is to overcome the problem of low recovery rate of sulfur in the prior art and to provide a method and system for recovering sulfur from sulfur-containing waste. The method has a high recovery rate of sulfur.

[0004] In order to achieve the above-mentioned object, the first aspect of the present invention provides a system for recovering sulfur from sulfur-containing waste, wherein the system comprises a reaction furnace, a reaction tower, a primary condensation tower, a secondary condensation tower, and a post-processing device;

[0005] Wherein, the reaction tower is provided with a first oxidation reaction component and a second oxidation reaction component, and the reaction tower is provided with a first process gas inlet and a first process gas outlet, and a second process gas inlet and a second process gas outlet;

[0006] The exhaust port of the reaction furnace is connected to the first process gas inlet of the reaction tower. After the gas flows through the first oxidation reaction component, it flows out from the first process gas outlet and enters the first condensation tower. The process gas outlet of the first condensation tower is connected to the second process gas inlet of the reaction tower. After the gas flows through the second oxidation reaction component, it flows out from the second process gas outlet and enters the second condensation tower.

[0007] The primary condensation tower and the secondary condensation tower are connected to the post-processing device.

[0008] A second aspect of the present invention provides a method for recovering sulfur from sulfur-containing waste, comprising the following steps:

[0009] Step (1): decomposing the sulfur-containing waste into a first process gas containing sulfur dioxide;

[0010] Step (2): subjecting the first process gas to a first catalytic oxidation reaction and then condensing the first process gas to obtain a second process gas;

[0011] Step (3): subjecting the second process gas to a second catalytic oxidation reaction, and then condensing and discharging the tail gas to be treated;

[0012] The condensate obtained in step (2) and step (3) is post-treated to obtain sulfur recovery liquid.

[0013] Through the above technical scheme, the reactor is used to decompose sulfur-containing waste into gas containing sulfur dioxide, the reaction tower is used to catalytically oxidize sulfur dioxide into sulfur trioxide, and the condensation tower is used to condense sulfur trioxide into concentrated sulfuric acid. The sulfur-containing waste is decomposed into process gas containing sulfur dioxide in the reactor, and after two catalytic oxidations and two condensations, the recovery rate of sulfur element is not less than 99%. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a schematic diagram of the process of Example 1;

[0015] Figure 2 It is a schematic diagram of the process of Example 2;

[0016] Figure 3 is a schematic diagram of the structure of the reactor;

[0017] Figure 4 A top view of the reactor.

[0018] Description of Reference Numerals

[0019] 1-reaction furnace; 2-waste heat boiler; 3-electric precipitator; 4-denitrification reactor; 5-purification washing tower; 6-purification tower circulation pump; 7-purification tower heat exchanger; 8-drying and dehydration tower; 9-drying tower circulation pump; 10-drying tower heat exchanger; 11-electric heater; 12-concentration tower; 13-concentrated acid pump; 14-concentrated acid heat exchanger; 15-nicotinic acid tower heat exchanger; 16-reaction tower; 17-third-stage catalyst layer; 18-third-stage heat exchanger; 19-first-stage catalyst layer; 20-first-stage heat exchanger; 21-second-stage catalyst layer; 22-second-stage catalyst layer -stage heat exchanger; 23-SO2 main fan; 24-first stage condensation tower; 25-second stage condensation tower; 26-tail gas absorption and demisting tower; 27-tail suction liquid circulation pump; 28-air fan; 29-first product tank; 30-second product tank; 31-process gas heater; 32-economizer; la-feed port; 1b-air inlet; 1c-exhaust port; a-first process gas inlet; b-first process gas outlet; c-second process gas inlet; d-second process gas outlet; e-third process gas inlet; f-third process gas outlet. DETAILED DESCRIPTION

[0020] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0021] The catalyst layer refers to a bed containing a catalyst for catalytically oxidizing sulfur dioxide into sulfur trioxide. The catalyst in the catalyst layer is a vanadium-based mixed catalyst containing cesium and / or not containing cesium; N1, N2, N3, and N4 are all positive integers and can be the same or different.

[0022] In the oxidation reaction assembly, each catalyst layer is distributed vertically from top to bottom in the reaction tower. The "uppermost layer" is a relative concept, referring to the first layer in the vertical direction, and the "lowermost layer" is a relative concept, referring to the lowest layer in the vertical direction.

[0023] A first aspect of the present invention provides a system for recovering sulfur from sulfur-containing waste, wherein the system comprises a reaction furnace, a reaction tower, a primary condensation tower, a secondary condensation tower, and a post-processing device;

[0024] Wherein, the reaction tower is provided with a first oxidation reaction component and a second oxidation reaction component, and the reaction tower is provided with a first process gas inlet and a first process gas outlet, and a second process gas inlet and a second process gas outlet;

[0025] The exhaust port of the reaction furnace is connected to the first process gas inlet of the reaction tower. After the gas flows through the first oxidation reaction component, it flows out from the first process gas outlet and enters the first condensation tower. The process gas outlet of the first condensation tower is connected to the second process gas inlet of the reaction tower. After the gas flows through the second oxidation reaction component, it flows out from the second process gas outlet and enters the second condensation tower.

[0026] The primary condensation tower and the secondary condensation tower are connected to the post-processing device.

[0027] In some embodiments of the present invention, preferably, the first oxidation reaction assembly includes N1 stage primary catalyst layer and N2 primary heat exchangers;

[0028] The first-stage catalyst layer in section N1 is vertically distributed in the reaction tower, the first process gas inlet is located above the uppermost first-stage catalyst layer, and the first process gas outlet is located below the lowermost first-stage catalyst layer;

[0029] N2 said first-stage heat exchangers are arranged in series, the said first-stage heat exchanger at the front end is connected to the said exhaust port, and the said first-stage heat exchanger at the rear end is connected to the first process gas inlet. By arranging multiple catalyst layers and multiple heat exchangers, the sulfur dioxide is subjected to multiple heat exchanges and catalytic oxidation in the reaction tower, which is beneficial to improving the heat recovery rate of the system and the conversion rate of sulfur dioxide.

[0030] In some embodiments of the present invention, preferably, the second oxidation reaction assembly includes N2 secondary catalyst layers and N3 secondary heat exchangers;

[0031] The secondary catalyst layer in the N2 section is vertically distributed in the reaction tower, the second process gas inlet is located above the uppermost secondary catalyst layer, and the second process gas outlet is located below the lowermost secondary catalyst layer;

[0032] N3 secondary heat exchangers are arranged in series, the secondary heat exchanger at the front end is connected to the process gas outlet of the primary condensation tower, and the secondary heat exchanger at the rear end is connected to the second process gas inlet. The process gas after the first condensation enters the reaction tower again, and after multiple heat exchanges and catalytic oxidation, the heat of the process gas is greatly recovered, which is beneficial to reducing the fuel consumption of the entire system, and the recovery rate of sulfur in the process gas is greatly improved.

[0033] In some embodiments of the present invention, preferably, the post-processing device comprises a first product tank, and the condensate outlets of the primary condensation tower and the secondary condensation tower are connected to the first product tank.

[0034] In some embodiments of the present invention, preferably, the post-processing device further comprises a concentration tower and a second product tank;

[0035] The reaction tower also has a third oxidation reaction component, and the reaction tower is provided with a third process gas inlet and a third process gas outlet;

[0036] The third process gas inlet is connected to the exhaust port, and after the gas flows through the third oxidation reaction assembly, it flows out from the third process gas outlet and enters the concentration tower, the absorption acid inlet of the concentration tower is connected to the first product tank, and the product outlet of the concentration tower is connected to the second product tank;

[0037] The gas outlet of the concentration tower is connected to the first process gas inlet.

[0038] Fuming acid is obtained by bringing the sulfur trioxide produced by oxidation of a portion of the gas into reverse contact with concentrated sulfuric acid, and the unabsorbed gas enters the system again for circulation oxidation, which is beneficial to improving the recovery rate of sulfur element and the obtained fuming acid has a high concentration.

[0039] In some embodiments of the present invention, preferably, the system further comprises a washing and purification tower, the exhaust port is connected to the washing and purification tower, and the gas outlet of the washing and purification tower is connected to the third process gas inlet. The washing tower is used to wash and evolve the gas before entering the reaction tower, thereby reducing the dust content of the gas, and reducing the frequency of subsequent equipment blockage, heat exchanger corrosion, catalyst bed layer caking and other problems. The dust content of the gas at this stage is less than 30 mg / m 3 .

[0040] In some embodiments of the present invention, preferably, the system further comprises a drying and dehydration tower, the gas outlet of the washing and purification tower is connected to the air inlet of the drying and dehydration tower, and the gas outlet of the drying and dehydration tower is connected to the third process gas inlet;

[0041] The first product tank is connected to the drying liquid inlet of the drying and dehydration tower, and the drying liquid outlet of the drying and dehydration tower is connected to the first product tank.

[0042] The water content of the gas before entering the reaction tower is reduced by reflux of the obtained concentrated sulfuric acid, and the water content is controlled to ≤0.1g / m 3 , which is beneficial to increase the concentration of niacin, and the obtained niacin concentration is >100%.

[0043] In some embodiments of the present invention, preferably, the reaction furnace is in a "U" shape, a feed port is provided at the top of one arm of the "U" shape, an air inlet is provided on the side wall of the "U" shaped arm, and the exhaust port is provided on the side wall of the other arm of the "U" shape.

[0044] A "U"-shaped reactor is used. During the decomposition process, the gas undergoes two turns in the reactor, which increases the residence time of the gas and is beneficial to improving the decomposition rate of the material. 50-60% of the decomposition is completed in the first straight section at the feed point, and the rest is completed in other sections. The total time is about 6-8s.

[0045] A second aspect of the present invention provides a method for recovering sulfur from sulfur-containing waste, comprising the following steps:

[0046] Step (1): decomposing the sulfur-containing waste into a first process gas containing sulfur dioxide;

[0047] Step (2): subjecting the first process gas to a first catalytic oxidation reaction and then condensing the first process gas to obtain a second process gas;

[0048] Step (3): subjecting the second process gas to a second catalytic oxidation reaction, and then condensing and discharging the tail gas to be treated;

[0049] The condensate obtained in step (2) and step (3) is post-treated to obtain sulfur recovery liquid.

[0050] In some embodiments of the present invention, preferably, when the first catalytic oxidation reaction is performed, the molar ratio of oxygen to sulfur dioxide in the first process gas is not less than 1. By controlling the molar ratio of oxygen to sulfur dioxide, the conversion rate of sulfur dioxide can be controlled.

[0051] In some embodiments of the present invention, preferably, the post-treatment includes: combining the liquid condensed in step (2) and the liquid condensed in step (3) to obtain the sulfur recovery, i.e., the product concentrated sulfuric acid. The obtained product concentrated sulfuric acid has a concentration greater than 98 wt%.

[0052] In some embodiments of the present invention, preferably, the method further comprises subjecting a portion of the first process gas to a third catalytic oxidation reaction to obtain a third process gas;

[0053] The post-treatment further comprises: contacting the obtained third process gas with the condensate obtained after condensation in step (2) and step (3) in reverse order to obtain the sulfur recovery liquid, i.e., the product fuming acid or concentrated sulfuric acid. The concentration of the obtained product fuming acid is greater than 100wt%, and the concentration of the obtained concentrated sulfuric acid is greater than 98wt%.

[0054] In some embodiments of the present invention, preferably, the recovery rate of sulfur in the sulfur-containing waste is not less than 99%.

[0055] In some embodiments of the present invention, preferably, the first catalytic oxidation reaction comprises three stages of primary reactions carried out in sequence, wherein the inlet temperature of the primary reaction of the first stage is 390-430°C, the inlet temperature of the primary reaction of the second stage is 400-440°C, and the inlet temperature of the primary reaction of the third stage is 395-450°C.

[0056] In some embodiments of the present invention, preferably, the second catalytic oxidation reaction includes a secondary reaction, and the inlet temperature of the secondary reaction is 390-410°C.

[0057] The temperature of the process gas before entering each stage of the catalyst layer affects the oxidation efficiency of sulfur dioxide. The inlet temperature of the first stage primary reaction can be any value within the numerical range of any two of 390°C, 400°C, 410°C, 420°C, and 430°C; the inlet temperature of the second stage primary reaction can be any value within the numerical range of any two of 400°C, 410°C, 420°C, 430°C, and 440°C; the inlet temperature of the third stage primary reaction can be any value within the numerical range of any two of 395°C, 410°C, 420°C, 430°C, 440°C, and 450°C; the inlet temperature of the secondary reaction can be any value within the numerical range of any two of 390°C, 400°C, and 410°C.

[0058] In some embodiments of the present invention, preferably, the method further comprises washing and purifying the first process gas before subjecting the first process gas to the first catalytic oxidation reaction, and the particulate matter content of the first process gas after washing and purifying is ≤5 mg / m 3 Reducing the particulate matter content in the process gas through scrubbing and purification is beneficial to improving the stability of the device, extending the life of the catalyst, and making the heat exchanger less prone to corrosion.

[0059] In some embodiments of the present invention, preferably, the sulfur-containing waste includes waste sulfuric acid, and mixed waste of waste sulfuric acid and acid gas containing hydrogen sulfide, wherein the concentration of sulfuric acid in the waste sulfuric acid is not less than 60wt%; and the content of hydrogen sulfide in the acid gas is not less than 10Vol% calculated by volume concentration. The method is also applicable to waste sulfuric acid and acid gas with lower concentrations, and does not require additional equipment or processes, and the recovery rate of sulfur element is still guaranteed. The concentration of waste sulfuric acid can be not less than a concentration range formed by any one of 60%, 70%, 80%, and 90%, and the content of hydrogen sulfide in the acid gas can be not less than a concentration range formed by any one of 10Vol%, 20Vol%, and 30Vol%.

[0060] Combination Figure 1 First, the structure of the reaction tower 16 in the system of the present invention is described as follows:

[0061] The reaction tower 16 is provided with a third oxidation reaction assembly, a second oxidation reaction assembly and a first oxidation reaction assembly, and the reaction tower 16 is provided with a third process gas inlet e, a third process gas outlet f, a first process gas inlet a, a first process gas outlet b, a second process gas inlet c, and a second process gas outlet d.

[0062] The third oxidation reaction assembly includes a third-stage catalyst layer 17 and a third-stage heat exchanger 18, wherein the third-stage catalyst layer 17 is located above the third-stage heat exchanger 18, the third process gas inlet e is located above the third-stage catalyst layer 17, the third process gas outlet f is located below the third-stage heat exchanger 18, and a first baffle is provided in the reaction tower 16 below the third process gas outlet f;

[0063] The first oxidation reaction assembly is located below the first baffle, and the first oxidation reaction assembly includes three primary catalyst layers 19 and two primary heat exchangers 20. The three primary catalyst layers 19 are arranged in sequence from top to bottom. The first process gas inlet a is located above the uppermost primary catalyst layer 19. A primary heat exchanger 20 is arranged between the two primary catalyst layers 19 of the uppermost layer and the middle layer. A primary heat exchanger 20 is arranged below the lowermost primary catalyst layer 19. The two primary heat exchangers 20 are connected in series. The first process gas outlet b is located below the lowermost primary heat exchanger 20. A second baffle is arranged in the reaction tower 16 below the first process gas outlet b.

[0064] The second oxidation reaction component includes a secondary catalyst layer 21 and two secondary heat exchangers 22, wherein the secondary catalyst layer 21 is located below the second partition, the second process gas inlet c is located above the secondary catalyst layer 21 and between the second partition, a secondary heat exchanger 22 is arranged below the secondary catalyst layer 21, a secondary heat exchanger 22 is arranged between the primary catalyst layer 19 of the middle layer and the primary catalyst layer 19 of the lowest layer, the two secondary heat exchangers 22 are connected in series, and the second process gas outlet d is located at the bottom of the reaction tower 16.

[0065] One of the working processes of the system of the present invention is as follows:

[0066] Sulfur-containing liquid and / or sulfur-containing gas enters the reactor 1, and is decomposed into the first process gas containing sulfur dioxide at 1000-1300°C under the combustion of fuel gas and / or sulfur-containing gas. The first process gas enters the waste heat boiler 2 after leaving the reactor 1 from the exhaust port 1c, and recovers the heat in the high-temperature flue gas through the waste heat boiler 2, and produces high-quality superheated steam as a by-product. The first process gas leaves the waste heat boiler 2 and enters the electrostatic precipitator 3 for dust removal and the denitrification reactor 4 for denitrification. At this time, the dust content in the first process gas is less than 30mg / m 3 , NO x <50mg / m 3 ;

[0067] A portion of the first process gas after leaving the denitration reactor 4 enters the purification scrubber 5 for purification and scrubbing. The particulate matter content SS in the gas after scrubbing is ≤5mg / m 3 The washing liquid of the washing tower 5 is drawn out from the tower kettle by the purification tower circulation pump 6, and returns to the washing tower 5 for recycling after heat exchange in the purification tower heat exchanger 7;

[0068] The first process gas from the washing tower 5 enters the drying and dehydration tower 8, which uses concentrated sulfuric acid for dehydration. The concentrated sulfuric acid comes from the first product tank 33, is pumped out by the concentrated acid pump 13, and then heat-exchanged with the concentrated acid heat exchanger 14, and then enters the drying and dehydration tower 8. The water content of the first process gas after dehydration in the drying and dehydration tower 8 is ≤0.1g / m 3 , the first process gas from the drying and dehydration tower 8 is supplemented with air, enters the third heat exchanger 18, and then enters the third catalyst layer 17 in the reaction tower 16 from the third process gas inlet e, comes out from the third process gas outlet f after catalytic oxidation, enters the concentration tower 12, and is reversely contacted with the concentrated sulfuric acid from the first product tank 33 pumped by the concentrated acid pump 13 to obtain nicotinic acid, and the nicotinic acid enters the nicotinic acid product tank 34 after heat exchange in the nicotinic acid tower heat exchanger 15. The concentrated sulfuric acid in the bottom of the drying and dehydration tower 8 is re-sent to the drying and dehydration tower 8 for recycling by the drying tower circulation pump 9 after heat exchange in the drying tower heat exchanger 10. This part of concentrated sulfuric acid can also enter the first product tank 29;

[0069] Another part of the first process gas after leaving the denitration reactor 4 is combined with the gas discharged from the concentration tower 12, and after being supplemented with air and heat exchanged in the drying tower heat exchanger 11, it enters the first oxidation reaction component, passes through N2 primary heat exchangers 20, enters the primary catalyst layer 19 from the first process gas inlet a, and after catalytic oxidation in the N1 section primary catalyst layer 19, it exits the first process gas outlet b, enters the primary condensation tower 24, and condenses to obtain concentrated sulfuric acid, which enters the first product tank 29. The second process gas leaving the primary condensation tower 24 is sent to N4 series-connected secondary heat exchangers 22 by the SO2 main fan 23. After heat exchange, it is sent into the reaction tower 16 through the second process gas inlet c, and after catalytic oxidation by the N3 stage secondary catalyst layer 21, it is sent out of the second process gas outlet d and enters the secondary condensation tower 25, and the concentrated sulfuric acid product is obtained by condensation and enters the first product tank 29. The tail gas to be treated from the secondary condensation tower 25 enters the tail gas absorption and demisting tower 26. The tail gas absorption and demisting tower 26 is an empty tower, and a spray coil is arranged in the middle of the tower. A glass fiber demister is arranged on the top of the spray layer, and a honeycomb electric demister is arranged on the top of the demister. The exhaust gas discharged from the tail gas absorption and demisting tower 26 reaches sulfur dioxide ≤ 10mg / m 3 , acid mist ≤5mg / m 3 , NO x ≤50mg / m 3 , particulate matter ≤10mg / m 3 The tail washing liquid of the tail gas absorption and demisting tower 26 is drawn out through the tail suction liquid circulation pump 27, a part of which is returned to the tail gas absorption and demisting tower 26 for recycling, and the other part is sent to the reactor 1 for further decomposition;

[0070] During the entire catalytic oxidation process, the air fan 28 provides air to the reactor 1, the primary condensation tower 24, and the secondary condensation tower 25. Part of the air from the secondary condensation tower 25 is discharged after recovering heat through the economizer 32, and part of the air discharged from the primary condensation tower 24 and the secondary condensation tower 25 is combined with the first process gas from the drying and dehydration tower 8 to supplement oxygen. The remaining air discharged from the primary condensation tower 24 and the secondary condensation tower 25 is mixed with the first process gas from the denitration reactor 4 to undergo the first catalytic oxidation reaction.

[0071] The fuming acid produced in the process is the final sulfur recovery liquid, with a concentration of >100% and a sulfur recovery rate of >99%. The process gas undergoes multiple heat exchanges with the process gas in the external reaction tower in the primary heat exchanger and the secondary heat exchanger, thereby improving the heat recovery rate.

[0072] Combination Figure 2 , another structure of the reaction tower 16 in the system of the present invention is described as follows:

[0073] The reaction tower 16 is provided with a third oxidation reaction assembly, a second oxidation reaction assembly and a first oxidation reaction assembly, and the reaction tower 16 is provided with a third process gas inlet e, a third process gas outlet f, a first process gas inlet a, a first process gas outlet b, a second process gas inlet c, and a second process gas outlet d.

[0074] The first oxidation reaction assembly includes three primary catalyst layers 19 and two primary heat exchangers 20. The three primary catalyst layers 19 are arranged in sequence from top to bottom. The first process gas inlet a is located above the uppermost primary catalyst layer 19. A primary heat exchanger 20 is arranged between the two primary catalyst layers 19 of the uppermost layer and the middle layer. A primary heat exchanger 20 is arranged at the bottom of the reaction tower 16. The two primary heat exchangers 20 are connected in series. The first process gas outlet b is located below the lowermost primary catalyst layer 19. A second baffle is arranged in the reaction tower 16 below the first process gas outlet b.

[0075] The second oxidation reaction component includes a secondary catalyst layer 21 and two secondary heat exchangers 22, wherein the secondary catalyst layer 21 is located below the second partition and above the bottom primary heat exchanger 20, and the second process gas inlet c is located between the secondary catalyst layer 21 and the second partition, wherein one secondary heat exchanger 22 is located between the first partition and the bottom primary catalyst layer 19, and the other secondary heat exchanger 22 is located between the middle primary catalyst layer 19 and the bottom primary catalyst layer 19, the two secondary heat exchangers 22 are connected in series, and the second process gas outlet d is provided below the primary heat exchanger 20 at the bottom of the reaction tower 16.

[0076] Another working process of the system of the present invention is as follows:

[0077] Sulfur-containing liquid and / or sulfur-containing gas enters the reactor 1, and is decomposed into the first process gas containing sulfur dioxide at 1000-1300°C under the combustion of fuel gas and / or sulfur-containing gas. The first process gas enters the waste heat boiler 2 after leaving the reactor 1 from the exhaust port 1c, and recovers the heat in the high-temperature flue gas through the waste heat boiler 2, and produces high-quality superheated steam as a by-product. The first process gas leaves the waste heat boiler 2 and enters the electrostatic precipitator 3 for dust removal and the denitrification reactor 4 for denitrification. At this time, the dust content in the first process gas is less than 30mg / m 3 , NO x <50mg / m 3 After leaving the denitration reactor 4, it enters the purification washing tower 5 for purification and washing. The particulate matter content in the gas is SS≤5mg / m 3 The washing liquid in the tower kettle of the washing tower 5 is drawn out from the tower kettle by the purification tower circulation pump 6, and returns to the washing tower 5 for recycling after heat exchange in the purification tower heat exchanger 7;

[0078] The first process gas from the washing tower 5 is heated by the process gas heater 31 and supplemented with air, and then enters the N2 primary heat exchangers 20 of the first oxidation reaction assembly in sequence, and then enters the drying tower heat exchanger 11, and then enters the N1 primary catalyst layer 19 in sequence through the first process gas inlet a, and enters the primary condensation tower 24 after catalytic oxidation, and the concentrated sulfuric acid product is condensed and enters the first product tank 29. The second process gas from the primary condensation tower 24 is sent to the N4 secondary heat exchangers 22 in series by the SO2 main fan 23, and after heat exchange, it passes through the second The process gas inlet c enters the N3 stage secondary catalyst layer 21 for catalytic oxidation in turn, and enters the secondary condensation tower 25 through the second process gas outlet d, and the concentrated sulfuric acid product is condensed and enters the first product tank 29. The tail gas to be treated from the secondary condensation tower 25 enters the tail gas absorption and demisting tower 26. The tail gas absorption and demisting tower 26 is an empty tower, and a spray coil is arranged in the middle of the tower. A glass fiber demister is arranged on the top of the spray layer, and a honeycomb electric demister is arranged on the top of the demister. The exhaust gas from the tail gas absorption and demisting tower 26 reaches sulfur dioxide ≤ 10mg / m 3 , acid mist ≤5mg / m 3 , NO x ≤50mg / m 3 , particulate matter ≤10mg / m 3 The tail liquid in the tail gas absorption and demisting tower 26 is drawn out through the tail liquid circulation pump 27, a part of which is returned to the tail gas absorption and demisting tower 26 for recycling, and the other part is sent to the reactor 1 for further decomposition;

[0079] During the entire catalytic oxidation process, the air fan 28 provides air to the primary condensation tower 24 and the secondary condensation tower 25. Part of the air leaving the secondary condensation tower 25 is discharged after recovering heat through the economizer 32, part of the air enters the reactor 1, and the other part is combined with the air leaving the secondary condensation tower 25 and the first process gas leaving the washing tower 5 before entering the reaction tower 16 for the first catalytic oxidation reaction.

[0080] The concentrated sulfuric acid produced in the process is the final sulfur recovery liquid, with a concentration of >98.5% and a sulfur recovery rate of >99%. The process gas undergoes multiple heat exchanges with the process gas in the external reaction tower in the primary heat exchanger and the secondary heat exchanger, thereby improving the heat recovery rate.

[0081] Example 1

[0082] like Figure 1 , 3 As shown in FIG. 4 , it includes a reaction furnace 1, a reaction tower 16, a primary condensation tower 24, a secondary condensation tower 25, and a post-processing device.

[0083] The reaction furnace 1 is in a "U" shape, with a feed port 1a disposed on the top of one arm of the "U" shape, an air inlet 1b disposed on the side wall of the arm, and an exhaust port 1c disposed on the side wall of the other arm of the "U" shape.

[0084] The exhaust port 1c is connected to the waste heat boiler 2, the electrostatic precipitator 3, the denitrification reactor 4, the purification and washing tower 5, and the drying and dehydration tower 8 in sequence. The kettle of the purification and washing tower 5 is connected to the purification tower circulation pump 6 and the purification tower heat exchanger 7, and the kettle of the drying and dehydration tower 8 is connected to the drying tower circulation pump 9 and the drying tower heat exchanger 10.

[0085] The structure of the reaction tower 16 is as follows:

[0086] The reaction tower 16 is provided with a third oxidation reaction assembly, a second oxidation reaction assembly and a first oxidation reaction assembly, and the reaction tower 16 is provided with a third process gas inlet e, a third process gas outlet f, a first process gas inlet a, a first process gas outlet b, a second process gas inlet c, and a second process gas outlet d.

[0087] The third oxidation reaction assembly includes a third-stage catalyst layer 17 and a third-stage heat exchanger 18, wherein the third-stage catalyst layer 17 is located above the third-stage heat exchanger 18, the third process gas inlet e is located above the third-stage catalyst layer 17, the third process gas outlet f is located below the third-stage heat exchanger 18, and a first baffle is provided in the reaction tower 16 below the third process gas outlet f;

[0088] The first oxidation reaction assembly includes three primary catalyst layers 19 and two primary heat exchangers 20. The three primary catalyst layers 19 are arranged in sequence from top to bottom. The first process gas inlet a is located above the uppermost primary catalyst layer 19. A primary heat exchanger 20 is arranged between the uppermost and middle primary catalyst layers 19. Another primary heat exchanger 20 is arranged below the lowermost primary catalyst layer 19. The two primary heat exchangers 20 are connected in series. The first process gas outlet b is located below the lowermost primary heat exchanger 20. A second baffle is arranged in the reaction tower 16 below the first process gas outlet b.

[0089] The second oxidation reaction component includes a secondary catalyst layer 21 and two secondary heat exchangers 22, wherein the secondary catalyst layer 21 is located below the second partition, the second process gas inlet c is located between the secondary catalyst layer 21 and the second partition, a secondary heat exchanger 22 is arranged below the secondary catalyst layer 2, another secondary heat exchanger 22 is arranged between the primary catalyst layer 19 of the middle layer and the primary catalyst layer 19 of the lowest layer, the two secondary heat exchangers 22 are connected in series, and the second process gas outlet d is located below the secondary heat exchanger 22 of the lowest layer.

[0090] The post-processing device includes a first product tank 29, a concentration tower 12, and a second product tank 30;

[0091] The gas outlet of the drying and dehydration tower 8 is connected to the three-stage heat exchanger 18, the outlet of the three-stage heat exchanger 18 is connected to the third process gas inlet e, the third process gas outlet f is connected to the concentration tower 12, the first product tank 29 is connected to the concentrated acid pump 13 and the concentrated acid heat exchanger 14 in sequence, the concentrated acid heat exchanger 14 is connected to the absorption acid inlet of the concentration tower 12 and the drying liquid inlet of the drying and dehydration tower 8, and the product outlet of the concentration tower 12 is connected to the second product tank 30.

[0092] The gas outlet of the denitration reactor 4 and the gas outlet of the concentration tower 12 are connected to the primary heat exchanger 20 located at the front end, the primary heat exchanger 20 located at the rear end is connected to the first process gas inlet a, the first process gas outlet b is connected to the process gas inlet of the primary condensation tower 24, the process gas outlet of the primary condensation tower 24 is connected to the SO3 main fan 23 and the secondary heat exchanger 22 located at the front end in sequence, the secondary heat exchanger 20 located at the rear end is connected to the second process gas inlet c, the second process gas outlet d is connected to the process gas inlet of the secondary condensation tower 25, and the condensate outlet of the primary condensation tower 24 and the condensate outlet of the secondary condensation tower 25 are connected to the first product tank 29.

[0093] The tail gas outlet of the secondary condensation tower 25 is connected to an absorption and demisting tower 26 , and the bottom of the absorption and demisting tower 26 is connected to a tail suction liquid circulation pump 27 . The tail suction liquid circulation pump 27 is connected to the feed inlet 1a and the absorption and demisting tower 26 .

[0094] The air blower 28 is connected to the air inlet 1a of the reaction furnace 1, the air inlets of the primary condensation tower 24 and the secondary condensation tower 25, the air outlet of the secondary condensation tower 25 is connected to the coal awakener 32, and the air outlets of the primary condensation tower 24 and the secondary condensation tower 25 are connected to the three-stage heat exchanger 18;

[0095] Taking 80wt% waste sulfuric acid as an example, the waste sulfuric acid with a concentration of 80wt% is atomized and enters from the feed port 1a at the top of the U-shaped reactor 1, and the fuel hydrogen sulfide gas and air enter from the air inlet 1b of the reactor 1. The concentration of hydrogen sulfide gas is 85Vol% by volume, and the combustion generates heat for the decomposition of the waste sulfuric acid. The temperature in the reactor is controlled at 1000-1100°C, and 50-60% of the decomposition of the waste sulfuric acid is completed in the first straight section of the "U"-shaped arm at the feed, and the rest is completed in other sections. The total time is about 6-8s, and the total decomposition rate is greater than 99%;

[0096] The first process gas from the reactor 1 enters the waste heat boiler 2 to cool down to 350°C, and then passes through the electrostatic precipitator 3 for dust removal and the denitrification reactor 4 for denitrification to remove NO x The last 50% of the process gas enters the purification scrubber 5 and is cooled to 40°C. After deep purification, the water content of the process gas is ≤8.5wt% and the dust content is <5mg / m 3 , NO x<50mg / m 3 ;

[0097] The first process gas after exiting the purification and washing tower 5 enters the drying and dehydration tower 8, and the first process gas is nearly completely dry after dehydration. The 55°C first process gas exiting the drying and dehydration tower 8 is supplemented with 200°C hot air to make the molar ratio of oxygen and sulfur dioxide reach 1.15:1, and the sulfur dioxide concentration is 9Vol%. After mixing, the third process gas is obtained, and the third process gas enters the third-stage heat exchanger 18 to be heated to 390-400°C, and then enters the third-stage catalyst layer 17 of the reaction tower 16 from the third process gas inlet e for reaction, during which the conversion rate of sulfur dioxide to sulfur trioxide reaches 74%. The temperature of the third process gas exiting the reaction tower 16 is 180-185°C, and it exits from the third process gas outlet f and enters the concentration tower 12, where it is in reverse contact with the concentrated sulfuric acid from the first product tank 29, and the concentrated sulfuric acid absorbs the sulfur trioxide therein, producing 105wt% fuming acid and entering the second product tank 30;

[0098] The process gas from the concentration tower 12 is mixed with the remaining 50wt% of the first process gas that does not enter the purification and washing tower 5 after exiting the denitration reactor 4, and 200°C hot air is added to make the molar ratio of oxygen and sulfur dioxide reach 1.1:1. The sulfur dioxide concentration in the first process gas after mixing is 6.5Vol% and the temperature is 190°C. The process gas enters the first oxidation reaction component and performs three-stage primary reactions in sequence, as follows:

[0099] The first process gas enters two first-stage heat exchangers 20 connected in series and is heated to 390-400°C. It enters the top first-stage catalyst layer 19 from the first process gas inlet a. After the first stage first-stage reaction in the top first-stage catalyst layer 19, the temperature of the first-stage catalyst layer 19 after heat exchange with one of the first-stage heat exchangers 20 is 400-410°C. The first process gas continues to descend and enters the middle first-stage catalyst layer 19. After the second stage first-stage reaction in the middle first-stage catalyst layer 19, the temperature of the first-stage catalyst layer 19 after heat exchange with one of the second-stage heat exchangers 22 is 400-410°C. The first process gas continues to descend and enters the bottom first-stage catalyst layer 19. After the third stage first-stage reaction in the bottom first-stage catalyst layer 19, the first process gas continues to descend and exchanges heat with another first-stage heat exchanger 20, and the temperature drops to 265°C. It enters the first condensation tower 24.

[0100] The cold air is pressurized by the air blower 28 and enters the primary condensation tower 24, cooling the process gas at 265°C in the condensation tube. The 97-98% concentrated sulfuric acid condensed in the tube enters the first product tank 29. The process gas is cooled to 110°C and exits the primary condensation tower 28 to obtain the second process gas. After being pressurized by the SO2 main blower 23, it enters the two secondary heat exchangers 22 in series in sequence, and is heated to 400-410°C and enters the secondary catalyst layer 21 through the second process gas inlet c for secondary reaction. After being cooled to 250°C by one of the secondary heat exchangers 22, it flows out from the second process gas outlet d and enters the secondary condensation tower 25. The final total conversion rate of sulfur dioxide to sulfur trioxide reaches 99.9%.

[0101] The cold air is pressurized by the air blower 28 and enters the secondary condensation tower 25 to cool the process gas at 250°C in the condensation tube. The concentrated sulfuric acid condensed in the tube enters the first product tank 29. The concentrated sulfuric acid in the first product tank 29 is sent to the concentration tower 12 through the concentrated acid pump 13 to produce fuming acid. The fuming acid is cooled by the heat exchanger 15 and enters the second product tank 30.

[0102] The washing liquid from the bottom of the purification and washing tower 5 is drawn out by the purification tower circulation pump 6, and returns to the purification and washing tower 5 for recycling after heat exchange with the purification tower heat exchanger 7. The concentrated sulfuric acid from the bottom of the drying and dehydration tower 8 is drawn out by the drying tower circulation pump 9, and returns to the drying and dehydration tower 8 for recycling after heat exchange with the drying tower heat exchanger. The heat in the concentration tower 12 is removed by the circulating water heat exchanger, which is beneficial to improving the heat recovery rate.

[0103] A portion of the hot air exiting the secondary condensation tower 25 is exchanged with boiler feed water in the economizer 32 to recover waste heat and increase steam production by 5-6%. Another portion of the hot air is combined with the hot air exiting the primary condensation tower 24, and then mixed with the first process gas exiting the drying and dehydration tower 8 and enters the reaction tower 16 for a third catalytic oxidation reaction to obtain dry sulfur trioxide.

[0104] The tail gas to be treated from the secondary condensation tower 25 enters the tail gas absorption and demisting tower 26, which uses hydrogen peroxide as an absorbent to oxidize the sulfur dioxide in the tail gas into sulfur trioxide, which is then discharged into the reactor 1 to continue decomposition after forming dilute sulfuric acid, thereby improving the recovery rate of sulfur in the system. The tail gas absorption and demisting tower 26 removes the acid mist in the process gas through a fiber filter and electrostatic demisting, and the discharged tail gas SO2≤10mg / m 3 , acid mist ≤5mg / m 3 , NO x ≤50mg / m 3 , particulate matter ≤10mg / m 3 .

[0105] The total recovery rate of sulfur element in the waste sulfuric acid reaches 99.9%, and the concentration of fuming acid obtained is 105%.

[0106] Example 2

[0107] like Figure 2-4 As shown, it includes a reaction furnace 1, a reaction tower 16, a primary condensation tower 24, a secondary condensation tower 25, and a post-processing device.

[0108] The reaction furnace 1 is in a "U" shape, with a feed port 1a disposed on the top of one arm of the "U" shape, an air inlet 1b disposed on the side wall of the arm, and an exhaust port 1c disposed on the side wall of the other arm of the "U" shape.

[0109] The exhaust port 1c is connected to the waste heat boiler 2, the electrostatic precipitator 3, the denitrification reactor 4, the purification washing tower 5, and the process gas heater 31 in sequence. The kettle of the purification washing tower 5 is connected to the purification tower circulation pump 6 and the purification tower heat exchanger 7. The gas outlet of the process gas heater 31 is connected to the first oxidation reaction component of the reaction tower 16.

[0110] The structure of reaction tower 6 is as follows:

[0111] The reaction tower 16 is provided with a third oxidation reaction assembly, a second oxidation reaction assembly and a first oxidation reaction assembly, and the reaction tower 16 is provided with a third process gas inlet e, a third process gas outlet f, a first process gas inlet a, a first process gas outlet b, a second process gas inlet c, and a second process gas outlet d.

[0112] The first oxidation reaction assembly includes three sections of primary catalyst layers 19 and two primary heat exchangers 20. The three primary catalyst layers 19 are arranged in sequence from top to bottom. The first process gas inlet a is located above the uppermost primary catalyst layer 19. A primary heat exchanger 20 is arranged between the uppermost and middle primary catalyst layers 19. Another primary heat exchanger 20 is arranged at the bottom of the reaction tower 16. The two primary heat exchangers 20 are connected in series. The first process gas outlet b is located below the lowermost primary catalyst layer 19. A second baffle is arranged in the reaction tower 16 below the first process gas outlet b.

[0113] The second oxidation reaction assembly includes a secondary catalyst layer 21 and two secondary heat exchangers 22, wherein the secondary catalyst layer 21 is located below the second baffle and above the first heat exchanger 20 at the bottom, the second process gas inlet c is located between the secondary catalyst layer 21 and the second baffle, one of the secondary heat exchangers 22 is located between the second baffle and the first catalyst layer 19 at the bottom, the other secondary heat exchanger 22 is located between the first catalyst layer 19 at the middle layer and the first catalyst layer 19 at the bottom, the two secondary heat exchangers 22 are connected in series, and the second process gas outlet d is located below the first heat exchanger 20 at the bottom of the reaction tower 16;

[0114] The gas outlet of the process gas heater 31 is connected to the primary heat exchanger 20 located at the front end, the primary heat exchanger 20 located at the rear end is connected to the first process gas inlet a, the first process gas outlet b is connected to the process gas inlet of the primary condenser 24, the process gas outlet of the primary condensation tower 24 is connected to the SO3 main fan 23 and the secondary heat exchanger 22 located at the front end in sequence, the secondary heat exchanger 22 located at the rear end is connected to the second process gas inlet c, the second process gas outlet d is connected to the process gas inlet of the secondary condensation tower 25, the tail gas outlet of the secondary condensation tower 25 is connected to the absorption and demisting tower 26, the tower kettle of the absorption and demisting tower 26 is connected to the tail suction liquid circulation pump 27, and the tail suction liquid circulation pump 27 is connected to the feed port 1a and the absorption and demisting tower 26.

[0115] The air blower 28 is connected to the air inlet of the primary condensation tower 24 and the secondary condensation tower 25, the air outlet of the secondary condensation tower 25 is connected to the coal awakener 32 and the air inlet 1b of the reaction furnace 1, and the air outlet of the primary condensation tower 24 and the secondary condensation tower 25 is connected to the primary heat exchanger 20 located at the front end;

[0116] The condensate outlet of the primary condensation tower 24 and the condensate outlet of the secondary condensation tower 25 are connected to the first product tank 29 , and the first product tank 29 is connected to the concentrated acid pump 13 and the concentrated acid heat exchange pump 14 in sequence.

[0117] Taking 85wt% waste sulfuric acid as an example, the waste sulfuric acid with a concentration of 85wt% is atomized and enters from the feed port 1a at the top of the reactor 1, and natural gas is used as fuel and enters from the air inlet 1b of the reactor 1. The combustion generates heat for the decomposition of the waste sulfuric acid. The temperature in the reactor is controlled at 1000-1100°C, and 50-60% of the decomposition of the waste sulfuric acid is completed in the first straight section at the feed, and the rest is completed in other sections. The total time is about 6-8s, and the total decomposition rate is greater than 99%;

[0118] The first process gas from the reactor 1 enters the waste heat boiler 2 to cool down to 350°C, and then passes through the electrostatic precipitator 3 for dust removal and the denitrification reactor 4 for denitrification to remove NO x After entering the purification scrubber 5, the temperature is cooled to 42°C. After deep purification, the molar ratio of sulfur dioxide to water is 1:1, and the dust content is less than 5mg / m 3 , NO x <50mg / m 3The waste heat boiler 2 uses the heat of the process gas to produce 4MPa saturated steam as a by-product. The first process gas from the purification and washing tower 5 is heated to 200°C by the process gas heater 31, mixed with the 200°C air from the first condensation tower 24 and the second condensation tower 25, and then enters the first heat exchanger 20 at the front end. After exiting the first heat exchanger 20 at the rear end, it is further heated to 390°C by the electric heater 11. The molar ratio of oxygen to sulfur dioxide in the first process gas mixed with air is 1:1. The sulfur dioxide concentration in the first process gas after complete mixing is 7Vol%. It enters the first oxidation reaction component from the first process gas inlet a and performs three-stage primary reactions in sequence, as follows:

[0119] The first process gas enters the topmost first-stage catalyst layer 19, undergoes the first-stage first-stage reaction in the topmost first-stage catalyst layer 19, then continues to descend and exchanges heat with one of the first-stage heat exchangers 20 at a temperature of 405-410°C, enters the middle first-stage catalyst layer 19, undergoes the second-stage first-stage reaction in the middle first-stage catalyst layer 19, then continues to descend and exchanges heat with the second-stage heat exchanger 22 at a temperature of 395-405°C, enters the bottom first-stage catalyst layer 19, undergoes the third-stage first-stage reaction in the bottom first-stage catalyst layer 19, then continues to descend and exchanges heat with another second-stage heat exchanger 22 at a temperature of 265°C, and enters the first-stage condensation tower 24.

[0120] The cold air is pressurized by the air blower 28 and enters the primary condensation tower 24 to cool the process gas at 265°C in the condensation tube. The 99wt% concentrated sulfuric acid condensed in the tube enters the first product tank 29. The process gas is cooled to 110°C and exits the primary condensation tower 24 to obtain the second process gas. After being pressurized by the SO2 main blower 23, it enters the secondary heat exchanger 22 at the front end and comes out from the secondary heat exchanger 22 at the rear end. During this process, the temperature is increased to 395-405°C, and then enters the secondary catalyst layer 21 through the second process gas inlet c for secondary reaction. After the reaction, the temperature is reduced to 250°C after heat exchange with the primary heat exchanger 20, and enters the secondary condensation tower 25 from the second process gas outlet d. The final total conversion rate of sulfur dioxide in the first process gas into sulfur trioxide reaches 99.9%.

[0121] The cold air is pressurized by the air blower 28 and enters the secondary condensation tower 25 to cool the process gas at 250°C in the condensation tube. The 99wt% concentrated sulfuric acid condensed in the tube enters the first product tank 29. After the excess 200°C hot air from the primary condensation tower 24 and the secondary condensation tower 25 are combined, 90% of it enters the reaction furnace 1 to assist combustion, a part of it is heat exchanged with the boiler feed water in the economizer 32 to recover the waste heat and increase the steam production by 5-6%, and another part of it is combined with the first process gas from the purification and washing tower 5 and enters the reaction tower 16 for the first catalytic oxidation reaction.

[0122] The untreated tail gas from the secondary condensation tower 25 enters the tail gas absorption and demisting tower 26, where hydrogen peroxide is used as an absorbent to oxidize the sulfur dioxide in the process gas into sulfur trioxide, forming dilute sulfuric acid, and then a part of it is discharged back to the tail gas absorption and demisting tower 26 for recycling, and a part of it enters the reactor 1 for decomposition, thereby improving the sulfur recovery rate of the system. The tail gas absorption and demisting tower 26 removes the acid mist in the process gas through a fiber filter and electrostatic demisting, and the discharged tail gas SO2≤10mg / m 3 , acid mist ≤5mg / m 3 , NO x ≤50mg / m 3 , particulate matter ≤10mg / m 3 .

[0123] The recovery rate of sulfur in waste sulfuric acid reaches 99.9%, and the concentration of the obtained concentrated sulfuric acid product is 99wt%.

[0124] Example 3

[0125] Taking 60wt% waste sulfuric acid as an example, the waste sulfuric acid with a concentration of 60wt% is atomized and enters from the feed port 1a at the top of the reactor 1, and natural gas is used as fuel and enters from the air inlet 1b of the reactor 1. The combustion generates heat for the decomposition of the waste sulfuric acid. The temperature in the reactor is controlled at 1000-1100°C. 50-60% of the decomposition of the waste sulfuric acid is completed in the first straight section at the feed, and the rest is completed in other sections. The total time is about 6-8s, and the total decomposition rate is greater than 99%;

[0126] The first process gas from the reactor 1 enters the waste heat boiler 2 to cool down to 320°C, then passes through the electrostatic precipitator 3 for dust removal, the denitrification reactor 4 for denitrification, and after removing NOx, enters the purification scrubber 5 to cool down to 38°C. After deep purification, the molar ratio of sulfur dioxide to water is 1:1, and the dust content is less than 5mg / m 3 , NOx<50mg / m 3 The waste heat boiler 2 uses the heat of the process gas to produce 4MPa saturated steam as a by-product. The first process gas from the purification and washing tower 5 is heated to 195°C by the process gas heater 31, and is mixed with the 195°C air from the first condensation tower 24 and the second condensation tower 25, and then enters the first heat exchanger 20 at the front end. After exiting the first heat exchanger 20 at the rear end, it is further heated to 410°C by the electric heater 11. The molar ratio of oxygen to sulfur dioxide in the first process gas mixed with air is 1:1. The sulfur dioxide concentration in the first process gas after complete mixing is 6Vol%. It enters the first oxidation reaction component from the first process gas inlet a and performs three-stage primary reactions in sequence, as follows:

[0127] The first process gas enters the topmost first-stage catalyst layer 19, undergoes the first-stage first-stage reaction in the topmost first-stage catalyst layer 19, then continues to descend and exchanges heat with one of the first-stage heat exchangers 20 at a temperature of 415-425°C, enters the middle first-stage catalyst layer 19, undergoes the second-stage first-stage reaction in the middle first-stage catalyst layer 19, then continues to descend and exchanges heat with the second-stage heat exchanger 22 at a temperature of 425-435°C, enters the bottom first-stage catalyst layer 19, undergoes the third-stage first-stage reaction in the bottom first-stage catalyst layer 19, then continues to descend and exchanges heat with another second-stage heat exchanger 22 at a temperature of 255°C, and enters the first-stage condensation tower 24.

[0128] The cold air is pressurized by the air blower 28 and enters the primary condensation tower 24 to cool the process gas at 255°C in the condensation tube. The 99% concentrated sulfuric acid condensed in the tube enters the first product tank 29. The process gas is cooled to 90°C and exits the primary condensation tower 24 to obtain the second process gas. After being pressurized by the SO2 main blower 23, it enters the secondary heat exchanger 22 at the front end and comes out from the secondary heat exchanger 22 at the rear end. During this process, the temperature is increased to 390-400°C, and then enters the secondary catalyst layer 21 through the second process gas inlet c for secondary reaction. After the reaction, the temperature is reduced to 240°C after heat exchange with the primary heat exchanger 20, and enters the secondary condensation tower 25 from the second process gas outlet d. The final total conversion rate of sulfur dioxide in the first process gas into sulfur trioxide reaches 99.9%.

[0129] The cold air is pressurized by the air blower 28 and enters the secondary condensation tower 25 to cool the process gas at 240°C in the condensation tube. The 99% concentrated sulfuric acid condensed in the tube enters the first product tank 29. After the excess 195°C hot air from the primary condensation tower 24 and the secondary condensation tower 25 are combined, 85% of it enters the reaction furnace 1 to assist combustion, a part of it is heat exchanged with the boiler feed water in the economizer 32 to recover the waste heat and increase the steam production by 2-4%, and another part of it is combined with the first process gas from the purification and washing tower 5 and enters the reaction tower 16 for the first catalytic oxidation reaction.

[0130] The untreated tail gas from the secondary condensation tower 25 enters the tail gas absorption and demisting tower 26, where hydrogen peroxide is used as an absorbent to oxidize the sulfur dioxide in the process gas into sulfur trioxide, forming dilute sulfuric acid, and then a part of it is discharged back to the tail gas absorption and demisting tower 26 for recycling, and a part of it enters the reactor 1 for decomposition, thereby improving the sulfur recovery rate of the system. The tail gas absorption and demisting tower 26 removes the acid mist in the process gas through a fiber filter and electrostatic demisting, and the discharged tail gas SO2≤10mg / m 3 , acid mist ≤5mg / m 3 , NOx≤50mg / m 3 , particulate matter ≤10mg / m 3 .

[0131] The recovery rate of sulfur in waste sulfuric acid reaches 99.9%, and the concentration of the obtained concentrated sulfuric acid product is 99wt%.

[0132] Example 4

[0133] Taking 70% waste sulfuric acid and hydrogen sulfide gas with a volume concentration of 25Vol% as an example, the waste sulfuric acid with a concentration of 70wt% enters from the feed port 1a at the top of the U-shaped reactor 1 after being atomized, and the hydrogen sulfide gas and air enter from the air inlet 1b of the reactor 1. In terms of volume concentration, the concentration of the hydrogen sulfide gas is 25Vol%. The combustion generates heat for the decomposition of the waste sulfuric acid. The temperature in the reactor is controlled at 1050-1130°C. 50-60% of the decomposition of the waste sulfuric acid is completed in the first straight section of the "U"-shaped arm at the feed, and the rest is completed in other sections. The total time is about 6-8s, and the total decomposition rate is greater than 99%;

[0134] The first process gas from the reactor 1 enters the waste heat boiler 2 to cool down to 320℃, and then passes through the electrostatic precipitator 3 for dust removal and the denitrification reactor 4 for denitrification to remove NO x The last 10% of the process gas enters the purification scrubber 5 and is cooled to 38°C. After deep purification, the water content of the process gas is ≤7.5% and the dust content is <5mg / m 3 , NO x <50mg / m 3 ;

[0135] The first process gas after exiting the purification and washing tower 5 enters the drying and dehydration tower 8, and the first process gas is nearly completely dry after dehydration. The 55°C first process gas exiting the drying and dehydration tower 8 is supplemented with 200°C hot air to make the molar ratio of oxygen and sulfur dioxide reach 1:1, and the sulfur dioxide concentration is 8.5Vol%. After mixing, the third process gas is obtained, and the third process gas enters the third-stage heat exchanger 18 to be heated to 395-405°C, and then enters the third-stage catalyst layer 17 of the reaction tower 16 from the third process gas inlet e for reaction, during which the conversion rate of sulfur dioxide to sulfur trioxide reaches 75%. The temperature of the third process gas exiting the reaction tower 16 is 170-175°C, and it exits from the third process gas outlet f and enters the concentration tower 12, where it is in reverse contact with the concentrated sulfuric acid from the concentrated sulfuric acid tank 29, and the concentrated sulfuric acid absorbs the sulfur trioxide therein, and the 99% concentrated acid is produced and enters the product tank 30;

[0136] The process gas from the concentration tower 12 is mixed with the remaining first process gas that does not enter the purification and washing tower 5 after exiting the denitration reactor 4, and 200°C hot air is added to make the molar ratio of oxygen and sulfur dioxide reach 1:1. The sulfur dioxide concentration in the first process gas after mixing is 5.5 Vol%, and the temperature is 190°C. The process gas enters the first oxidation reaction component and performs three-stage primary reactions in sequence, as follows:

[0137] The first process gas enters two first-stage heat exchangers 20 connected in series and is heated to 415-420°C. It enters the first-stage catalyst layer 19 at the top through the first process gas inlet a. After the first stage of the first stage reaction in the first-stage catalyst layer 19, the temperature of the first-stage catalyst layer 19 after heat exchange with one of the first-stage heat exchangers 20 is 420-430°C. The first process gas continues to descend and enters the first-stage catalyst layer 19 at the middle layer. After the second stage of the first stage reaction in the first-stage catalyst layer 19 at the middle layer, the temperature of the first-stage catalyst layer 19 after heat exchange with one of the second-stage heat exchangers 22 is 430-440°C. The first process gas continues to descend and enters the first-stage catalyst layer 19 at the bottom layer. After the third stage of the first stage reaction in the first-stage catalyst layer 19 at the bottom layer, the first process gas continues to descend and exchanges heat with another first-stage heat exchanger 20, and the temperature drops to 255°C. It enters the first-stage condensation tower 24.

[0138] The cold air is pressurized by the air blower 28 and enters the primary condensation tower 24, cooling the process gas at 255°C in the condensation tube. The 97-98% concentrated sulfuric acid condensed in the tube enters the first product tank 29. The process gas is cooled to 90°C and exits the primary condensation tower 28 to obtain the second process gas. After being pressurized by the SO2 main blower 23, it enters the two secondary heat exchangers 22 in series in turn, and is heated to 415-420°C and enters the secondary catalyst layer 21 through the second process gas inlet c for secondary reaction. After being cooled to 250°C by one of the secondary heat exchangers 22, it flows out from the second process gas outlet d and enters the secondary condensation tower 25. The final total conversion rate of sulfur dioxide to sulfur trioxide reaches 99.9%.

[0139] The cold air is pressurized by the air blower 28 and enters the secondary condensation tower 25 to cool the process gas at 250°C in the condensation tube. The concentrated sulfuric acid condensed in the tube enters the first product tank 29. The concentrated sulfuric acid in the first product tank 29 is sent to the concentration tower 12 for concentration through the concentrated acid pump 13. The acid with increased concentration is cooled by the heat exchanger 15 and enters the product tank 30.

[0140] The washing liquid from the bottom of the purification and washing tower 5 is drawn out by the purification tower circulation pump 6, and returns to the purification and washing tower 5 for recycling after heat exchange with the purification tower heat exchanger 7. The concentrated sulfuric acid from the bottom of the drying and dehydration tower 8 is drawn out by the drying tower circulation pump 9, and returns to the drying and dehydration tower 8 for recycling after heat exchange with the drying tower heat exchanger. The heat in the concentration tower 12 is removed by the circulating water heat exchanger, which is beneficial to improving the heat recovery rate.

[0141] A portion of the hot air exiting the secondary condensation tower 25 is exchanged with boiler feed water in the economizer 32 to recover waste heat and increase steam production by 1-3%. Another portion of the hot air is combined with the hot air exiting the primary condensation tower 24, and then mixed with the first process gas exiting the drying and dehydration tower 8 and enters the reaction tower 16 for a third catalytic oxidation reaction to obtain dry sulfur trioxide gas.

[0142] The tail gas to be treated from the secondary condensation tower 25 enters the tail gas absorption and demisting tower 26, which uses hydrogen peroxide as an absorbent to oxidize the sulfur dioxide in the tail gas into sulfur trioxide, which is then discharged into the reactor 1 to continue decomposition after forming dilute sulfuric acid, thereby improving the recovery rate of sulfur in the system. The tail gas absorption and demisting tower 26 removes the acid mist in the process gas through a fiber filter and electrostatic demisting, and the discharged tail gas SO2≤10mg / m 3 , acid mist ≤5mg / m 3 , NO x ≤50mg / m 3 , particulate matter ≤10mg / m 3 .

[0143] The total recovery rate of sulfur element in the waste sulfuric acid reaches 99.9%, and the concentration of the obtained sulfuric acid is 99wt%.

[0144] Example 5

[0145] Taking 70% waste sulfuric acid and hydrogen sulfide gas with a volume concentration of 10Vol% as an example, the waste sulfuric acid with a concentration of 70wt% enters from the feed port 1a at the top of the U-shaped reactor 1 after being atomized, and the hydrogen sulfide gas and air enter from the air inlet 1b of the reactor 1. The combustion generates heat for the decomposition of the waste sulfuric acid. The temperature in the reactor is controlled at 1100-1150°C. 50-60% of the decomposition of the waste sulfuric acid is completed in the first straight section of the "U"-shaped arm at the feed, and the rest is completed in other sections. The total time is about 6-8s, and the total decomposition rate is greater than 99%;

[0146] The first process gas from the reactor 1 enters the waste heat boiler 2 to cool down to 320℃, and then passes through the electrostatic precipitator 3 for dust removal and the denitrification reactor 4 for denitrification to remove NO x The last 9.7% of the process gas enters the purification scrubber 5 and is cooled to 36°C. After deep purification, the water content of the process gas is ≤6.7% and the dust content is <5mg / m 3 , NO x <50mg / m 3 ;

[0147] The first process gas after exiting the purification and washing tower 5 enters the drying and dehydration tower 8, and the first process gas is nearly completely dry after dehydration. The 55°C first process gas exiting the drying and dehydration tower 8 is supplemented with 190°C hot air to make the molar ratio of oxygen and sulfur dioxide reach 1:1, and the sulfur dioxide concentration is 5.9Vol%. After mixing, the third process gas is obtained, and the third process gas enters the third-stage heat exchanger 18 to be heated to 400-410°C, and then enters the third-stage catalyst layer 17 of the reaction tower 16 from the third process gas inlet e for reaction, during which the conversion rate of sulfur dioxide to sulfur trioxide reaches 75%. The temperature of the third process gas exiting the reaction tower 16 is 160-165°C, and it exits from the third process gas outlet f and enters the concentration tower 12, where it is in reverse contact with the concentrated sulfuric acid from the concentrated sulfuric acid tank 29, and the concentrated sulfuric acid absorbs the sulfur trioxide therein, and the 99% concentrated acid is produced and enters the second product tank 30;

[0148] The process gas from the concentration tower 12 is mixed with the remaining first process gas that does not enter the purification and washing tower 5 after exiting the denitration reactor 4, and 190°C hot air is added to make the molar ratio of oxygen and sulfur dioxide reach 1:1. The sulfur dioxide concentration in the first process gas after mixing is 4.7 Vol%, and the temperature is 190°C. The process gas enters the first oxidation reaction component and performs three-stage primary reactions in sequence, as follows:

[0149] The first process gas enters two first-stage heat exchangers 20 connected in series and is heated to 425-430°C. It enters the top first-stage catalyst layer 19 from the first process gas inlet a. After the first stage first-stage reaction in the top first-stage catalyst layer 19, the temperature of the first-stage catalyst layer 19 after heat exchange with one of the first-stage heat exchangers 20 is 430-440°C. The first process gas continues to descend and enters the middle first-stage catalyst layer 19. After the second stage first-stage reaction in the middle first-stage catalyst layer 19, the temperature of the first-stage catalyst layer 19 after heat exchange with one of the second-stage heat exchangers 22 is 440-450°C. The first process gas continues to descend and enters the bottom first-stage catalyst layer 19. After the third stage first-stage reaction in the bottom first-stage catalyst layer 19, the first process gas continues to descend and exchanges heat with another first-stage heat exchanger 20, and the temperature drops to 255°C and enters the first-stage condensation tower 24.

[0150] The cold air is pressurized by the air blower 28 and enters the primary condensation tower 24, cooling the process gas at 255°C in the condensation tube. The 97-98% concentrated sulfuric acid condensed in the tube enters the first product tank 29. The process gas is cooled to 90°C and exits the primary condensation tower 28 to obtain the second process gas. After being pressurized by the SO2 main blower 23, it enters the two secondary heat exchangers 22 in series in turn, and is heated to 415-420°C and enters the secondary catalyst layer 21 through the second process gas inlet c for secondary reaction. After being cooled to 250°C by one of the secondary heat exchangers 22, it flows out from the second process gas outlet d and enters the secondary condensation tower 25. The final total conversion rate of sulfur dioxide to sulfur trioxide reaches 99.9%.

[0151] The cold air is pressurized by the air blower 28 and enters the secondary condensation tower 25 to cool the process gas at 250°C in the condensation tube. The concentrated sulfuric acid condensed in the tube enters the first product tank 29. The concentrated sulfuric acid in the first product tank 29 is sent to the concentration tower 12 for concentration through the concentrated acid pump 13. The acid with increased concentration is cooled by the heat exchanger 15 and enters the second product tank 30.

[0152] The washing liquid from the bottom of the purification and washing tower 5 is drawn out by the purification tower circulation pump 6, and returns to the purification and washing tower 5 for recycling after heat exchange with the purification tower heat exchanger 7. The concentrated sulfuric acid from the bottom of the drying and dehydration tower 8 is drawn out by the drying tower circulation pump 9, and returns to the drying and dehydration tower 8 for recycling after heat exchange with the drying tower heat exchanger. The heat in the concentration tower 12 is removed by the circulating water heat exchanger, which is beneficial to improving the heat recovery rate.

[0153] A portion of the hot air exiting the secondary condensation tower 25 is exchanged with boiler feed water in the economizer 32 to recover waste heat and increase steam production by 1-3%. Another portion of the hot air is combined with the hot air exiting the primary condensation tower 24, and then mixed with the first process gas exiting the drying and dehydration tower 8 and enters the reaction tower 16 for a third catalytic oxidation reaction to obtain dry sulfur trioxide gas.

[0154] The tail gas to be treated from the secondary condensation tower 25 enters the tail gas absorption and demisting tower 26, which uses hydrogen peroxide as an absorbent to oxidize the sulfur dioxide in the tail gas into sulfur trioxide, which is then discharged into the reactor 1 to continue decomposition after forming dilute sulfuric acid, thereby improving the recovery rate of sulfur in the system. The tail gas absorption and demisting tower 26 removes the acid mist in the process gas through a fiber filter and electrostatic demisting, and the discharged tail gas SO2≤10mg / m 3 , acid mist ≤5mg / m 3 , NO x ≤50mg / m 3 , particulate matter ≤10mg / m 3 .

[0155] The total recovery rate of sulfur element in the waste sulfuric acid reaches 99.9%, and the concentration of sulfuric acid obtained is 99wt%.

[0156] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A system for recovering sulfur from sulfur-containing waste, characterized in that: The system includes a reaction furnace, a reaction tower, a primary condensation tower, a secondary condensation tower, and a post-processing device; Wherein, the reaction tower is provided with a first oxidation reaction component and a second oxidation reaction component, and the reaction tower is provided with a first process gas inlet and a first process gas outlet, and a second process gas inlet and a second process gas outlet; The exhaust port of the reaction furnace is connected to the first process gas inlet of the reaction tower. After the gas flows through the first oxidation reaction component, it flows out from the first process gas outlet and enters the first condensation tower. The process gas outlet of the first condensation tower is connected to the second process gas inlet of the reaction tower. After the gas flows through the second oxidation reaction component, it flows out from the second process gas outlet and enters the second condensation tower. The primary condensation tower and the secondary condensation tower are connected to the post-processing device.

2. The system according to claim 1, characterized in that The first oxidation reaction assembly includes N1 first-stage catalyst layer and N2 first-stage heat exchangers; The first-stage catalyst layer in section N1 is vertically distributed in the reaction tower, the first process gas inlet is located above the uppermost first-stage catalyst layer, and the first process gas outlet is located below the lowermost first-stage catalyst layer; N2 primary heat exchangers are arranged in series, the primary heat exchanger located at the front end is connected to the exhaust port, and the primary heat exchanger located at the rear end is connected to the first process gas inlet.

3. The system according to claim 1 or 2, characterized in that: The second oxidation reaction assembly includes N3 sections of secondary catalyst layer and N4 secondary heat exchangers; The secondary catalyst layer in the N3 section is vertically distributed in the reaction tower, the second process gas inlet is located above the uppermost secondary catalyst layer, and the second process gas outlet is located below the lowermost secondary catalyst layer; N4 secondary heat exchangers are arranged in series, the secondary heat exchanger located at the front end is connected to the process gas outlet of the first condensation tower, and the secondary heat exchanger located at the rear end is connected to the second process gas inlet.

4. The system according to any one of claims 1 to 3, characterized in that: The post-processing device comprises a first product tank, and the condensate outlets of the first condensation tower and the second condensation tower are connected to the first product tank; Preferably, the post-processing device further comprises a concentration tower and a second product tank; The reaction tower also has a third oxidation reaction assembly, and the reaction tower is provided with a third process gas inlet and a third process gas outlet; The third process gas inlet is connected to the exhaust port, and after the gas flows through the third oxidation reaction assembly, it flows out from the third process gas outlet and enters the concentration tower, the absorption acid inlet of the concentration tower is connected to the first product tank, and the product outlet of the concentration tower is connected to the second product tank; The gas outlet of the concentration tower is connected to the first process gas inlet.

5. The system according to claim 4, characterized in that The system further comprises a washing and purification tower, the exhaust port is connected to the washing and purification tower, and the gas outlet of the washing and purification tower is connected to the third process gas inlet.

6. The system according to claim 5, characterized in that The system further comprises a drying and dehydration tower, the gas outlet of the washing and purification tower is connected to the air inlet of the drying and dehydration tower, and the gas outlet of the drying and dehydration tower is connected to the third process gas inlet; The first product tank is connected to the drying liquid inlet of the drying and dehydration tower, and the drying liquid outlet of the drying and dehydration tower is connected to the first product tank.

7. The system according to any one of claims 1 to 6, characterized in that: The reactor is in a "U" shape, a feed port is arranged at the top of one arm of the "U" shape, an air inlet is arranged on the side wall of the arm, and the exhaust port is arranged on the side wall of the other arm of the "U" shape.

8. A method for recovering sulfur from sulfur-containing waste, characterized in that: The following steps are involved: Step (1): decomposing the sulfur-containing waste into a first process gas containing sulfur dioxide; Step (2): subjecting the first process gas to a first catalytic oxidation reaction and then condensing the first process gas to obtain a second process gas; Step (3): subjecting the second process gas to a second catalytic oxidation reaction, and then condensing and discharging the tail gas to be treated; The condensate obtained in step (2) and step (3) is post-treated to obtain sulfur recovery liquid.

9. The method according to claim 8, characterized in that The post-treatment comprises: combining the liquid condensed in step (2) and the liquid condensed in step (3) to obtain the sulfur recovery liquid, i.e., the product concentrated sulfuric acid; Preferably, the method further comprises subjecting a portion of the first process gas to a third catalytic oxidation reaction to obtain a third process gas; The post-treatment further comprises: contacting the obtained third process gas with the condensate obtained after condensation in step (2) and step (3) in reverse order to obtain the sulfur recovery liquid, i.e., the product fuming acid or concentrated sulfuric acid; Preferably, the recovery rate of sulfur in the sulfur-containing waste is not less than 99%.

10. The method according to claim 8 or 9, characterized in that: The first catalytic oxidation reaction includes three stages of primary reactions performed sequentially, wherein the inlet temperature of the first stage of the primary reaction is 390-430°C, the inlet temperature of the second stage of the primary reaction is 400-440°C, and the inlet temperature of the third stage of the primary reaction is 395-450°C; Preferably, the second catalytic oxidation reaction includes a secondary reaction, and the inlet temperature of the secondary reaction is 390-410°C.

11. The method according to any one of claims 8 to 10, characterized in that: The sulfur-containing waste includes waste sulfuric acid and mixed waste of waste sulfuric acid and acid gas containing hydrogen sulfide, wherein the concentration of sulfuric acid in the waste sulfuric acid is not less than 60wt%; and the content of hydrogen sulfide in the acid gas is not less than 10Vol% calculated by volume concentration.

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