A method and system for producing electronic grade sulfuric acid by absorption method

Abstract

The present application relates to the production of electronic-grade chemicals, and in particular to a method and system for producing electronic-grade sulfuric acid by absorption. A method for producing electronic-grade sulfuric acid by absorption includes: cooling the waste gas generated after the combustion of liquid sulfur to produce industrial sulfuric acid, and catalytically converting it with a modified metal organic framework catalyst; evaporating high-oleum sulfuric acid to obtain sulfur trioxide gas and low-concentration oleum sulfuric acid; the heat utilized in the evaporation of oleum sulfuric acid is the heat generated by the cooling of the converted flue gas; the produced low-concentration oleum sulfuric acid is contacted with the forwarded flue gas to obtain high-concentration oleum sulfuric acid; the obtained high-concentration oleum sulfuric acid is repeatedly evaporated and purified; the purified sulfur trioxide gas is absorbed by sulfuric acid to produce electronic-grade sulfuric acid. The present application utilizes the waste gas and heat generated when liquid sulfur is used to produce industrial sulfuric acid to produce G5-grade electronic-grade sulfuric acid, which greatly saves energy and reduces energy consumption.

Description

Technical Field

[0001] The present application relates to the field of electronic-grade chemical production industry, and in particular to a method and system for producing electronic-grade sulfuric acid by absorption method. Background Art

[0002] Electronic grade sulfuric acid, also known as high purity sulfuric acid or ultrapure sulfuric acid, is an ultra-clean and high purity reagent and an indispensable key basic chemical reagent in the development of microelectronics technology. Electronic grade sulfuric acid is widely used in the assembly and processing of semiconductors and ultra-large scale integrated circuits, mainly for cleaning and etching silicon wafers, and can effectively remove impurity particles, inorganic residues and carbon deposits on the wafers.

[0003] Chinese patent application number 202210380210.2 discloses a method and system for producing G1-G5 electronic-grade sulfuric acid, which discloses the use of a SO3 distillation system to distill and remove impurities from industrial-grade SO3 to obtain ultra-high purity SO3; the ultra-high purity SO3 enters a SO3 absorption device, and is countercurrently absorbed or statically mixed with an absorption liquid to obtain a crude electronic-grade sulfuric acid with a sulfuric acid concentration of 95-97%wt; the crude electronic-grade sulfuric acid passes through a G1-grade filter to obtain G1-grade electronic-grade sulfuric acid, or enters a distillation and light removal device for distillation and light removal treatment to obtain high-purity electronic-grade sulfuric acid; the high-purity electronic-grade sulfuric acid passes through a G2-grade or G3-grade filter to obtain G2-grade or G3-grade electronic-grade sulfuric acid, or enters a distillation and heavy removal device for distillation and heavy removal treatment to obtain ultra-high purity electronic-grade sulfuric acid, and a G4-grade or G5-grade filter is used to obtain G4-grade or G5-grade electronic-grade sulfuric acid.

[0004] Regarding the above-mentioned related technologies, the applicant believes that it uses a distillation tower to purify sulfur trioxide. The core of the distillation tower is to achieve the purpose of purification by continuously gasifying and condensing the material. In the purification and preparation process, it is also necessary to consider the temperature required to maintain the liquid or gas phase of sulfur trioxide. Especially in winter, the heating of equipment and pipelines requires a lot of heat, and this part of energy waste cannot be ignored. In addition, as a professional sulfuric acid production enterprise, the applicant has a rich product line. In the daily production process, a large amount of hot flue gas and steam are generated. How to utilize this heat and save energy is a problem that needs to be solved urgently. Summary of the invention

[0005] In order to improve the utilization rate of heat and reduce energy waste, the present application provides a method and system for producing electronic grade sulfuric acid by absorption method.

[0006] In a first aspect, the present application provides a method for producing electronic grade sulfuric acid by absorption, which adopts the following technical scheme.

[0007] A method for producing electronic grade sulfuric acid by absorption method comprises the following steps:

[0008] S1. When liquid sulfur is burned to produce industrial sulfuric acid, a large amount of 1000℃ waste gas is generated. The waste gas is cooled from 1000℃ to 400℃, and then converted into conversion flue gas through the action of a catalyst, and the conversion flue gas is cooled to 150℃;

[0009] The catalyst is a modified metal organic framework catalyst, and its preparation method is:

[0010] 1) Dissolve zinc nitrate and terephthalic acid in DMF solvent, then add triethylamine to react. After the reaction is completed, filter and retain the filtrate;

[0011] 2) Heat the filtrate at 90-110°C for 30-40h. After the reaction is complete, filter and wash to obtain crystals;

[0012] 3) Dissolve chitosan to obtain a chitosan solution, add the obtained crystals to the chitosan solution, add the malondialdehyde solution, mix, and condense and reflux at 60-70° C. for 1 h to obtain a colloid;

[0013] 4) After freeze-drying the colloid, washing and drying it, a catalyst is obtained;

[0014] S2. Evaporating fuming sulfuric acid with a concentration of 30-35%, evaporating sulfur trioxide-containing gas, and producing fuming sulfuric acid with a concentration of 20-22% and a temperature of 130-140 ° C; the heat used for evaporation of the fuming sulfuric acid is the heat generated by cooling the converted flue gas from 400 ° C to 150 ° C in the above S1;

[0015] S3. The oleum having a concentration of 20-22% and a temperature of 130-140°C produced in S2 is contacted with the forwarded flue gas in S1 to absorb sulfur trioxide in the forwarded flue gas to obtain oleum having a concentration of 30-35% and a temperature of 110-120°C;

[0016] S4. The fuming sulfuric acid having a concentration of 30-35% and a temperature of 110-120 ° C obtained in S3 is evaporated, and S2 is repeated;

[0017] S5. The sulfur trioxide evaporated from S2 is purified and absorbed by sulfuric acid to obtain electronic grade sulfuric acid.

[0018] By adopting the above technical scheme, the waste gas generated by the production of industrial sulfuric acid from liquid sulfur is utilized, the waste gas is cooled and catalyzed to generate forward flue gas, the fuming sulfuric acid evaporates to generate low-concentration fuming sulfuric acid, and the fuming sulfuric acid is contacted with the converted flue gas for heat exchange, the low-concentration fuming sulfuric acid absorbs sulfur trioxide in the converted flue gas and is converted into high-concentration fuming sulfuric acid, the temperature of the low-concentration fuming sulfuric acid is increased while the low-concentration fuming sulfuric acid is converted into high-concentration fuming sulfuric acid, the high-concentration fuming sulfuric acid after heating is evaporated again, and the fuming sulfuric acid evaporates at a higher initial temperature, which can accelerate the evaporation rate and reduce energy consumption. In addition, the heat released by the cooling of the waste gas is used for the evaporation of fuming sulfuric acid, the waste heat of the waste gas is fully utilized, the utilization rate of energy is greatly improved, the waste of resources is reduced, and it is in line with the concept of green energy-saving development.

[0019] The role of the catalyst is to oxidize sulfur dioxide in the exhaust gas into sulfur trioxide. The present application synthesizes an organic metal compound skeleton through zinc nitrate, terephthalic acid and triethylamine, and then modifies chitosan on the organic metal compound skeleton. The H2BDC ligand in the organic metal compound skeleton forms a covalent interaction with the free amino group in chitosan. Chitosan undergoes a self-crosslinking reaction under the action of glutaraldehyde, so that the organic metal compound skeleton and chitosan are combined to form a stable complex to obtain a bulk catalyst. The obtained catalyst has a large absorption capacity for exhaust gas, and the exhaust gas is adsorbed by the catalyst and fully contacts the active sites in the catalyst, so that the sulfur dioxide in the exhaust gas is oxidized into sulfur trioxide. In addition, the catalyst pore structure and chemical environment obtained in the present application can optimize the catalytic reaction path and improve the catalytic efficiency. Finally, the block catalyst of the present application is easier to recycle.

[0020] Furthermore, the weight ratio of the zinc nitrate, terephthalic acid and triethylamine is (1.6-3.0):(0.3-0.7):1.

[0021] Furthermore, the weight ratio of chitosan to crystal is 2:(3-5).

[0022] Furthermore, the exhaust gas in S1 contains 10% sulfur dioxide, 80% nitrogen, 10% oxygen and other gases; the catalyst converts sulfur dioxide into sulfur trioxide.

[0023] Furthermore, the fuming sulfuric acid with a concentration of 30-35% in S2 is evaporated to evaporate a gas containing sulfur trioxide, and to generate fuming sulfuric acid with a concentration of 21% and a temperature of 130°C.

[0024] Furthermore, the oleum with a concentration of 20-22% and a temperature of 130-140° C. in S3 contacts the forwarded flue gas in S1 to absorb sulfur trioxide in the forwarded flue gas, thereby obtaining oleum with a concentration of 30-35% and a temperature of 110° C.

[0025] Furthermore, the temperature of the fuming sulfuric acid with a concentration of 30-35% in S2 is 60-80°C.

[0026] Furthermore, the evaporation temperature in S7 is 60-100°C; the temperature of the evaporated further purified sulfur trioxide gas is 70-80°C.

[0027] In a second aspect, the present application provides a system for producing electronic grade sulfuric acid by absorption method, which adopts the following technical solution.

[0028] A system for producing electronic grade sulfuric acid by absorption method comprises an oleum absorption tower, an oleum evaporator, a sulfur trioxide gas cooler, a sulfur trioxide condenser, a sulfur trioxide liquid evaporator, a gas-liquid separator, a sulfuric acid absorption tower and a degassing tower which are connected in sequence.

[0029] By adopting the above technical scheme, when liquid sulfur is burned to produce industrial sulfuric acid, a large amount of 1000°C waste gas is generated. The waste gas is cooled from 1000°C to 400°C, and then converted into conversion flue gas through the action of a catalyst. The conversion flue gas is cooled to 150°C and then enters the oleum absorption tower; oleum with a concentration of 30-35% is passed into the oleum evaporator for evaporation, evaporating a gas containing sulfur trioxide, and generating oleum with a concentration of 20-22% and a temperature of 130-140°C; the heat used by the oleum evaporator is the heat generated by the conversion flue gas being cooled from 400°C to 150°C. The oleum with a temperature of 130-140°C and a temperature of 20-22% returned from the oleum evaporator enters the oleum absorption tower to absorb sulfur trioxide in the conversion flue gas, and completes heat exchange to obtain oleum with a concentration of 30-35% and a temperature of 110-120°C, and then enters the oleum evaporator for evaporation. The sulfur trioxide gas evaporated in the oleum evaporator enters the sulfur trioxide gas cooler for gas-liquid separation, the liquid is discharged, and the gas continues to enter the sulfur trioxide condenser to condense to obtain pure sulfur trioxide liquid; the sulfur trioxide liquid enters the sulfur trioxide liquid evaporator for gasification, and then enters the gas-liquid separator for purification to obtain further purified sulfur trioxide gas; the further purified sulfur trioxide gas enters the sulfuric acid absorption tower to be absorbed by sulfuric acid, and then enters the degassing tower to remove sulfur dioxide gas to obtain G5 grade electronic sulfuric acid.

[0030] Furthermore, the oleum absorption tower includes an outer shell, which is connected to a liquid inlet pipe and an air inlet pipe, a plurality of fillers are arranged in the outer shell along the axis of the outer shell, and a driving component is also arranged in the outer shell, the driving component drives the fillers to rotate, the rotation axis of the fillers is parallel to the axis of the outer shell, and the rotation directions of two adjacent groups of fillers are opposite.

[0031] By adopting the above technical solution, oleum enters the oleum absorption tower from the top liquid inlet pipe, and the converted flue gas enters the oleum absorption tower from the bottom air inlet pipe, and the two are in countercurrent contact. The rotating filler allows the oleum to fully contact the forward flue gas, and the two adjacent fillers rotate in opposite directions, so that the oleum and the converted flue gas passing through the two fillers are in reverse contact, and each filler is in reverse contact, which greatly increases the contact area between the oleum and the converted flue gas, and better completes the absorption and heat exchange of sulfur trioxide in the converted flue gas.

[0032] Further, the driving assembly includes a parallel first rotating shaft and a second rotating shaft and a plurality of gears fixed coaxially with the second rotating shaft; the first rotating shaft is coaxial with the housing, and a connecting frame is arranged outside each filler, and the connecting frame is divided into a first connecting frame and a second connecting frame, and the first connecting frame and the second connecting frame are arranged in sequence; the first connecting frame is coaxial with the first rotating shaft and fixedly connected to the first rotating shaft; the second connecting frame is coaxial with the first rotating shaft and rotatably connected to the first rotating shaft; the second connecting frame is provided with meshing teeth meshing with the gears outside;

[0033] A conversion interval is arranged between a group of adjacent first connection frames and second connection frames, and two sides of the conversion interval are respectively provided with the first connection frame and the second connection frame.

[0034] By adopting the above technical solution, the first rotating shaft and the second rotating shaft rotate in the same direction, and the rotation direction is set to clockwise, and the first rotating shaft drives the first connecting frame to rotate clockwise. The second rotating shaft drives the second connecting frame to rotate through the gear, so that the second connecting frame rotates counterclockwise, realizing the reverse rotation of the first connecting frame and the second connecting frame.

[0035] The setting of the conversion interval provides more sufficient contact space for oleum and conversion flue gas, so that the two can fully contact and enter into chemical substance and heat conversion.

[0036] Furthermore, a power assembly is arranged in the outer shell, and the power assembly includes a bevel gear group, a transmission belt and two pulleys; the driven gear of the bevel gear group is coaxially arranged on the second rotating shaft, and the rotation axis of the driving gear of the bevel gear group is perpendicular to the axis of the second rotating shaft; the two pulleys are coaxially fixedly connected to the first rotating shaft and the second rotating shaft respectively, and the transmission belt is sleeved outside the two pulleys.

[0037] By adopting the above technical solution, the driving gear rotates to drive the driven gear to rotate, the driven gear drives the second rotating shaft to rotate, the second rotating shaft drives the first rotating shaft to rotate through the pulley and the transmission belt, and a group of power sources realizes the synchronous driving of the first rotating shaft and the second rotating shaft.

[0038] In summary, this application has the following beneficial effects:

[0039] The waste gas generated by the production of industrial sulfuric acid from liquid sulfur is utilized. After the waste gas is cooled and catalyzed, a forward flue gas is generated. After the fuming sulfuric acid evaporates, a low-concentration fuming sulfuric acid is generated, which is contacted with the converted flue gas for heat exchange. The low-concentration fuming sulfuric acid absorbs sulfur trioxide in the converted flue gas and is converted into high-concentration fuming sulfuric acid. The temperature of the low-concentration fuming sulfuric acid increases while the low-concentration fuming sulfuric acid is converted into high-concentration fuming sulfuric acid. The high-concentration fuming sulfuric acid after heating is evaporated again. The fuming sulfuric acid evaporates at a higher initial temperature, which can accelerate the evaporation rate and reduce energy consumption. In addition, the heat released by the cooling of the waste gas is used for the evaporation of the fuming sulfuric acid, and the waste heat of the waste gas is fully utilized, which greatly improves the utilization rate of energy, reduces the waste of resources, and conforms to the concept of green energy-saving development. In addition, the catalyst of the present application has a high catalytic efficiency for sulfur dioxide in the waste gas, which is conducive to obtaining high-purity electronic-grade sulfuric acid. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 This is a schematic diagram of the overall structure of a system for producing electronic grade sulfuric acid by absorption method according to an embodiment of the present application;

[0041] Figure 2 This is a schematic diagram of the structure of the oleum absorption tower in the embodiment of the present application;

[0042] Figure 3 A cross-sectional view showing the interior of the oleum absorption tower of the embodiment of the present application;

[0043] Figure 4 A schematic diagram showing the mechanism of the drive assembly.

[0044] Description of reference numerals:

[0045] 1. Oleum absorption tower; 11. Shell; 12. Exhaust pipe; 13. Drain pipe; 14. Liquid inlet pipe; 15. Inlet pipe; 16. Drive assembly; 161. First rotating shaft; 1611. Connecting frame; 1612. Filler; 1613. Conversion interval; 162. Second rotating shaft; 163. Gear; 17. Power assembly; 171. Bevel gear set; 1711. Motor; 172. Drive belt; 173. Pulley; 2. Oleum evaporator; 3. Sulfur trioxide gas cooler; 31. Condensate collecting tank; 4. Sulfur trioxide condenser; 41. Liquid sulfur trioxide storage tank; 5. Sulfur trioxide liquid evaporator; 6. Gas-liquid separator; 7. Sulfuric acid absorption tower; 71. Mixing box; 8. Degassing tower. DETAILED DESCRIPTION

[0046] The present application is further described in detail below with reference to the accompanying drawings and embodiments.

[0047] The present application is further described in detail below in conjunction with embodiments.

[0048] Raw materials and intermediate preparation examples

[0049] raw material

[0050] Zinc nitrate, zinc nitrate hexahydrate, analytical grade;

[0051] Terephthalic acid, analytical grade;

[0052] Triethylamine, analytical grade;

[0053] Chitosan, degree of deacetylation ≥ 95%;

[0054] Malondialdehyde solution, concentration 5%.

[0055] Preparation Example

[0056] Preparation Example 1

[0057] A modified metal organic framework catalyst, the preparation method of which is:

[0058] 1) Dissolve 2.5 kg zinc nitrate and 0.5 kg terephthalic acid in DMF solvent, then add 1 kg triethylamine to react. After the reaction is completed, filter and retain the filtrate;

[0059] 2) The filtrate was heated at 100°C for 36 hours, filtered after the reaction was completed, and then the filtered solid was washed three times with deionized water and DMF in sequence to obtain crystals;

[0060] 3) Add 0.2 kg of chitosan to 20 mL of 2% acetic acid solution, stir thoroughly until all dissolved to obtain a chitosan solution, add 0.4 kg of the obtained crystals to the chitosan solution, and add 3.8 ml of malondialdehyde solution, mix, and heat under condensation reflux at 60 ° C for 1 h to obtain a colloid;

[0061] 4) Dry the colloid in a freeze dryer for 48 h, wash it with water and acetone three times in sequence, and finally dry it at room temperature to obtain the catalyst.

[0062] Preparation Example 2

[0063] A modified metal organic framework catalyst, the preparation method of which is:

[0064] 1) Dissolve 1.6 kg zinc nitrate and 0.7 kg terephthalic acid in DMF solvent, then add 1 kg triethylamine to react. After the reaction is completed, filter and retain the filtrate;

[0065] The other steps are the same as those in Preparation Example 1.

[0066] Preparation Example 3

[0067] A modified metal organic framework catalyst, the preparation method of which is:

[0068] 1) Dissolve 3.0 kg zinc nitrate and 0.3 kg terephthalic acid in DMF solvent, then add 1 kg triethylamine to react, filter after the reaction is completed, and retain the filtrate;

[0069] The other steps are the same as those in Preparation Example 1.

[0070] Preparation Example 4

[0071] A modified metal organic framework catalyst, the preparation method of which is:

[0072] 1) and 2) are the same as in Preparation Example 1;

[0073] 3) Add 0.2 kg of chitosan to 20 mL of 2% acetic acid solution, stir thoroughly until all dissolved to obtain a chitosan solution, add 0.3 kg of the obtained crystals to the chitosan solution, and add 3.8 ml of malondialdehyde solution, mix, and condense and reflux at 60 ° C for 1 h to obtain a colloid;

[0074] 4) Same as Preparation Example 1.

[0075] Preparation Example 5

[0076] A modified metal organic framework catalyst, the preparation method of which is:

[0077] 1) and 2) are the same as in Preparation Example 1;

[0078] 3) Add 0.2 kg of chitosan to 20 mL of 2% acetic acid solution, stir thoroughly until all dissolved to obtain a chitosan solution, add 0.5 kg of the obtained crystals to the chitosan solution, and add 3.8 ml of malondialdehyde solution, mix, and heat under condensation reflux at 60 ° C for 1 h to obtain a colloid;

[0079] 4) Same as Preparation Example 1.

[0080] Preparation Example 6

[0081] A metal organic framework catalyst, the preparation method of which is:

[0082] 1) Dissolve 2.5 kg zinc nitrate and 0.5 kg terephthalic acid in DMF solvent, then add 1 kg triethylamine to react. After the reaction is completed, filter and retain the filtrate;

[0083] 2) The filtrate was heated at 100°C for 36 hours, filtered after the reaction was completed, and then the filtered solid was washed three times with deionized water and DMF in sequence to obtain crystals;

[0084] 3) Drying the crystals in a vacuum drying oven at 60° C. for 72 hours to obtain a catalyst. Example

[0085] Example 1

[0086] Reference Figure 1 A system for producing electronic grade sulfuric acid by absorption method comprises an oleum absorption tower 1, an oleum evaporator 2, a sulfur trioxide gas cooler 3, a sulfur trioxide condenser 4, a sulfur trioxide liquid evaporator 5, a gas-liquid separator 6, a sulfuric acid absorption tower 7 and a degassing tower 8 which are connected in sequence.

[0087] Reference Figure 1 The top of the housing 11 is connected to an exhaust pipe 12, and the bottom of the housing 11 is connected to a drain pipe 13. The housing 11 is connected to a liquid inlet pipe 14 and an air inlet pipe 15. The liquid inlet pipe 14 is located near the exhaust pipe 12, and the air inlet pipe 15 is located near the drain pipe 13. The end of the liquid inlet pipe 14 away from the oleum absorption tower 1 is connected to the liquid outlet of the oleum evaporator 2, and the end of the drain pipe 13 away from the oleum absorption tower 1 is connected to the liquid inlet of the oleum evaporator 2.

[0088] Reference Figure 1 The gas outlet of the oleum evaporator 2 is connected to the gas inlet of the sulfur trioxide gas cooler 3, the liquid outlet of the sulfur trioxide cooler is connected to the condensate collecting tank 31, and the gas outlet of the sulfur trioxide cooler is connected to the gas inlet of the sulfur trioxide condenser 4. The liquid outlet of the sulfur trioxide condenser 4 is connected to the liquid inlet of the sulfur trioxide liquid evaporator 5, and a liquid sulfur trioxide storage tank 41 is connected between the sulfur trioxide condenser 4 and the sulfur trioxide liquid evaporator 5. A heat converter is also provided on the oleum evaporator 2.

[0089] Reference Figure 1 The discharge port of the sulfur trioxide liquid evaporator 5 is connected to the feed port of the gas-liquid separator 6, the discharge port of the gas-liquid separator 6 is connected to the feed port of the sulfuric acid absorption tower 7, the discharge port of the sulfuric acid absorption tower 7 is connected to a mixing box 71, and the discharge port of the mixing box 71 is connected to the degassing tower 8.

[0090] Reference Figure 2-Figure 4The oleum absorption tower 1 includes a shell 11, and a driving assembly 16 is arranged in the shell 11. The driving assembly 16 includes a first rotating shaft 161 and a second rotating shaft 162 in parallel and a plurality of gears 163 coaxially fixed with the second rotating shaft 162. The first rotating shaft 161 is coaxial with the shell 11 and is rotatably connected to the shell 11, and a connecting frame for connecting the first rotating shaft 161 is arranged in the shell 11. The second rotating shaft 162 is rotatably connected in the shell 11 and is located near the side wall of the shell 11, and a connecting frame for connecting the second rotating shaft 162 is arranged in the shell 11. A plurality of connecting frames 1611 are sleeved on the first rotating shaft 161, and the connecting frames 1611 are filled with fillers 1612. The connecting frames 1611 include a first connecting frame 1611 and a second connecting frame 1611, and the first connecting frame 1611 and the second connecting frame 1611 are arranged in sequence along the first rotating shaft 161. The first connection frame 1611 is coaxial with the first rotating shaft 161 and fixedly connected to the first rotating shaft 161. The second connection frame 1611 is coaxial with the first rotating shaft 161 and rotatably connected to the first rotating shaft 161; the second connection frame 1611 is provided with meshing teeth meshing with the gear 163. The housing 11 is also provided with a power assembly 17 that drives the first rotating shaft 161 and the second rotating shaft 162 to rotate in the same direction.

[0091] The power assembly 17 drives the first rotating shaft 161 and the second rotating shaft 162 to rotate, and the first rotating shaft 161 drives the first connecting frame 1611 to rotate clockwise. The second rotating shaft 162 drives the second connecting frame 1611 to rotate through the gear 163, so that the second connecting frame 1611 rotates counterclockwise. The first connecting frame 1611 and the second connecting frame 1611 rotate in the opposite direction, driving the two adjacent groups of fillers 1612 to rotate in the opposite direction. Oleum enters the oleum absorption tower 1 from the top liquid inlet pipe 14, and the converted flue gas enters the oleum absorption tower 1 from the bottom air inlet pipe 15 and moves in the filler 1612. The two fillers 1612 rotating in the opposite direction make the oleum and the converted flue gas passing through the two fillers 1612 contact in reverse, and each filler 1612 performs a reverse contact, which greatly increases the contact area between the oleum and the converted flue gas, and better completes the absorption and heat exchange of sulfur trioxide in the converted flue gas.

[0092] Reference Figure 3 and Figure 4The power assembly 17 includes a group of bevel gears 163, a transmission belt 172 and two pulleys 173. The driving gear 163 of the bevel gear 163 group is rotatably arranged in the housing 11, and its rotation axis is perpendicular to the axis of the second rotating shaft 162. A motor 1711 is fixedly arranged outside the housing 11 to drive the driving gear 163 of the bevel gear 163 group to rotate. The driven gear 163 of the bevel gear 163 group is coaxially fixed on the second rotating shaft 162; the two pulleys 173 are coaxially fixedly connected to the first rotating shaft 161 and the second rotating shaft 162, respectively, and the transmission belt 172 is sleeved outside the two pulleys 173. The motor 1711 drives the gear 163 to rotate and drives the driven gear 163 to rotate, and the driven gear 163 drives the second rotating shaft 162 to rotate. The second rotating shaft 162 drives the first rotating shaft 161 to rotate through the pulley 173 and the transmission belt 172, and a group of power sources realizes the synchronous drive of the first rotating shaft 161 and the second second rotating shaft 162.

[0093] Reference Figure 3 A conversion interval 1613 is provided between a set of adjacent first connection frames 1611 and second connection frames 1611, and the two sides of the conversion interval 1613 are respectively the first connection frame 1611 and the second connection frame 1611. The setting of the conversion interval 1613 provides more sufficient contact space for oleum and conversion flue gas, so that the two can fully contact and enter the conversion of chemical substances and heat.

[0094] A plurality of positioning plates are fixedly arranged on the first rotating shaft 161, and the positioning plates abut against the bottom of the second connecting frame 1611. The positioning plates support and fix the second connecting frame 1611 in the vertical direction, thereby ensuring the stability of the second connecting frame 1611 in rotation.

[0095] A method for producing electronic grade sulfuric acid by absorption method comprises the following steps:

[0096] S1. When liquid sulfur is burned to produce industrial sulfuric acid, a large amount of waste gas at 1000°C is generated. The waste gas is composed of 10% sulfur dioxide, 80% nitrogen, 10% oxygen and other gases. The waste gas is cooled from 1000°C to 400°C under the action of boiler cooling water, and then oxidized by the catalyst from Preparation Example 1 in the converter to convert sulfur dioxide into sulfur trioxide to form converted flue gas. The converted flue gas is heat exchanged by the heat converter on the oleum evaporator 2, cooled to 150°C, and then connected to the air inlet pipe 15 of the oleum absorption tower 1.

[0097] S2. Oleum with a concentration of 30% and a temperature of 70° C. is passed into the oleum evaporator 2 for evaporation, evaporating a gas containing sulfur trioxide and producing oleum with a concentration of 20% and a temperature of 130° C. The heat used for evaporation of oleum is the heat supplied by the heat converter in S1 above.

[0098] S3. The oleum with a concentration of 20% and a temperature of 130°C produced in the above S2 enters the oleum absorption tower 1 through the liquid inlet pipe 14, absorbs sulfur trioxide in the forwarded flue gas, and obtains oleum with a concentration of 30% and a temperature of 110°C.

[0099] S4. The oleum with a concentration of 30% and a temperature of 110° C. obtained in the above S3 enters the oleum evaporator 2 through the drain pipe 13, and S2 is repeated.

[0100] S5. The sulfur trioxide-containing gas evaporated from S2 enters the sulfur trioxide gas cooler 3 for gas-liquid separation and cooling to obtain liquid impurities and purified sulfur trioxide gas. The liquid impurities enter the condensate collection tank 31; the temperature of the sulfur trioxide cooler is maintained at 45°C.

[0101] S6. The purified sulfur trioxide gas obtained in the above S5 enters the sulfur trioxide condenser 4 and is condensed to obtain sulfur trioxide liquid; the temperature of the sulfur trioxide condenser 4 is maintained at 35°C.

[0102] S7. The sulfur trioxide liquid obtained in S6 enters the sulfur trioxide liquid evaporator 5 for evaporation to obtain further purified sulfur trioxide gas. The sulfur trioxide liquid evaporator 5 is heated by hot water at a temperature of 95°C; the evaporated sulfur trioxide gas has a temperature of 75°C.

[0103] S8. The further purified sulfur trioxide gas obtained in S7 above enters the sulfuric acid absorption tower 7. The sulfuric acid absorption tower 7 uses 96.5% sulfuric acid to absorb sulfur trioxide. The outlet temperature of the mixed absorption tower in the mixing tank is 88°C. An appropriate amount of ultrapure water is added to adjust the concentration. A circulating cooler is set in the absorption tower. The water flow of the cooler is 45m3 / h. The reaction heat is continuously removed by the cooling water circulation to ensure the normal reaction; the outlet temperature of the sulfuric acid cooler is 75°C. While the absorption tower continuously absorbs sulfur trioxide, a certain amount of sulfuric acid is continuously drawn out as a product. Part of the sulfuric acid drawn out from the absorption tower passes through a secondary regulator and is adjusted again by ultrapure water to ensure the sulfuric acid concentration. The temperature of the sulfuric acid after the secondary adjustment is 130°C. The obtained sulfuric acid enters the degassing tower 8, and dry air is introduced into the degassing tower 8 to remove SO2 in the sulfuric acid to ensure that the SO2 content in the obtained sulfuric acid is less than 1ppm. The outer ends of the absorption tower and the degassing tower 8 are connected to the tail gas recovery device, and pure hydrogen peroxide reagent is added to oxidize SO2 to SO3, which is convenient for sulfuric acid absorption. The absorption liquid uses 25-27% dilute sulfuric acid to convert SO2 in the exhaust gas into dilute sulfuric acid, and this part of dilute sulfuric acid is recovered to the analytical pure sulfuric acid reaction tower. After cooling in the cooler, it enters the tank and removes particles through the filter element to ensure that the 0.01um particles are 5pcs / ml, and finally filled and shipped.

[0104] The electronic grade sulfuric acid obtained is G5 grade.

[0105] Example 2

[0106] Different from Example 1, in Example 2, fuming sulfuric acid with a concentration of 30-35% in S2 is evaporated to evaporate a gas containing sulfur trioxide, and to produce fuming sulfuric acid with a concentration of 21% and a temperature of 130° C.;

[0107] The oleum with a concentration of 20% and a temperature of 130° C. in S3 enters the oleum absorption tower 1 through the liquid inlet pipe 14, absorbs sulfur trioxide in the flue gas, and obtains oleum with a concentration of 33% and a temperature of 120° C.

[0108] The electronic grade sulfuric acid obtained is G5 grade.

[0109] Example 3

[0110] Different from Example 1, in Example 3, the oleum with a concentration of 30-35% in S2 is evaporated to evaporate a gas containing sulfur trioxide, and to produce oleum with a concentration of 22% and a temperature of 140° C.;

[0111] Oleum with a concentration of 20% and a temperature of 130° C. enters the oleum absorption tower 1 through the liquid inlet pipe 14, absorbs sulfur trioxide in the flue gas, and obtains oleum with a concentration of 35% and a temperature of 120° C.

[0112] The electronic grade sulfuric acid obtained is G5 grade.

[0113] Embodiment 4-7

[0114] Different from Example 1, the catalysts in Examples 4-7 are from Preparation Examples 2-5, respectively.

[0115] The electronic grade sulfuric acid obtained is G5 grade.

[0116] Comparative Example

[0117] Comparative Example 1

[0118] The difference from Example 1 is that the catalyst in Comparative Example 1 comes from Preparation Example 6.

[0119] Performance Testing

[0120] The sulfur dioxide content in the converted flue gas formed after catalytic oxidation was tested, and then the sulfur dioxide conversion rate was calculated. The conversion rate = (10% - chlorine dioxide content in the converted flue gas) / 10% * 100%. The results are shown in Table 1.

[0121] Table 1 Sulfur dioxide conversion rate

[0122]

[0123] Combining the embodiment with the comparative example and Table 1, it can be seen that the efficiency of catalytic oxidation of sulfur dioxide in the embodiment is higher than that in the comparative example, which indicates that the catalyst prepared in the present application has a better catalytic effect on sulfur dioxide in the exhaust gas, which is beneficial to improving the purity of electronic grade sulfuric acid. This may be because the obtained catalyst has a large absorption capacity for exhaust gas, the exhaust gas is adsorbed by the catalyst, and is fully in contact with the active sites in the catalyst, so that the sulfur dioxide in the exhaust gas is oxidized to sulfur trioxide.

[0124] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. A method for producing electronic grade sulfuric acid by absorption method, characterized in that: The following steps are involved: S1. When liquid sulfur is burned to produce industrial sulfuric acid, a large amount of 1000℃ waste gas is generated. The waste gas is cooled from 1000℃ to 400℃, and then converted into conversion flue gas through the action of a catalyst, and the conversion flue gas is cooled to 150℃; The catalyst is a modified metal organic framework catalyst, and its preparation method is: 1) Dissolve zinc nitrate and terephthalic acid in DMF solvent, then add triethylamine to react, filter after the reaction is completed, and retain the filtrate; 2) Heat the filtrate at 90-110°C for 30-40h, filter and wash to obtain crystals after the reaction is completed; 3) dissolving chitosan to obtain a chitosan solution, adding the obtained crystals to the chitosan solution, and adding a malondialdehyde solution, mixing, and condensing and reflux heating at 60-70° C. for 1 h to obtain a colloid; 4) After freeze-drying the colloid, washing and drying it, a catalyst is obtained; S2. Evaporating fuming sulfuric acid with a concentration of 30-35%, evaporating sulfur trioxide-containing gas, and producing fuming sulfuric acid with a concentration of 20-22% and a temperature of 130-140 ° C; the heat used for evaporation of the fuming sulfuric acid is the heat generated by cooling the converted flue gas from 400 ° C to 150 ° C in the above S1; S3. The oleum having a concentration of 20-22% and a temperature of 130-140°C produced in S2 is contacted with the forwarded flue gas in S1 to absorb sulfur trioxide in the forwarded flue gas to obtain oleum having a concentration of 30-35% and a temperature of 110-120°C; S4. The fuming sulfuric acid having a concentration of 30-35% and a temperature of 110-120 ° C obtained in S3 is evaporated, and S2 is repeated; S5. The sulfur trioxide evaporated from S2 is purified and absorbed by sulfuric acid to obtain electronic grade sulfuric acid; The weight ratio of zinc nitrate, terephthalic acid and triethylamine is (1.6-3.0): (0.3-0.7): 1; The weight ratio of chitosan to crystal is 2:(3-5); The exhaust gas in S1 is composed of 10% sulfur dioxide, 80% nitrogen, 10% oxygen and other gases; the catalyst converts sulfur dioxide into sulfur trioxide; The temperature of the oleum with a concentration of 30-35% in S2 is 60-80°C; the oleum with a concentration of 30-35% in S2 is evaporated to evaporate a gas containing sulfur trioxide, and produce oleum with a concentration of 21% and a temperature of 130°C.

2. The method for producing electronic grade sulfuric acid by absorption method according to claim 1, characterized in that: The oleum with a concentration of 20-22% and a temperature of 130-140° C. in S3 contacts the forwarded flue gas in S1, absorbs sulfur trioxide in the forwarded flue gas, and obtains oleum with a concentration of 30-35% and a temperature of 110° C.

3. A system for producing electronic grade sulfuric acid by absorption method, characterized in that: A method for producing electronic grade sulfuric acid by the absorption method as described in any one of claims 1 to 2, comprising a oleum absorption tower (1), a oleum evaporator (2), a sulfur trioxide gas cooler (3), a sulfur trioxide condenser (4), a sulfur trioxide liquid evaporator (5), a gas-liquid separator (6), a sulfuric acid absorption tower (7) and a degassing tower (8) connected in sequence.

4. The system for producing electronic grade sulfuric acid by absorption method according to claim 3, characterized in that: The oleum absorption tower (1) comprises a shell (11), the shell (11) is connected with a liquid inlet pipe (14) and an air inlet pipe (15), a plurality of fillers (1612) are arranged in the shell (11) along the axis of the shell (11), and a driving component (16) is also arranged in the shell (11), the driving component (16) drives the fillers (1612) to rotate, the rotation axis of the fillers (1612) is parallel to the axis of the shell (11), and the rotation directions of two adjacent groups of fillers (1612) are opposite.

5. The system for producing electronic grade sulfuric acid by absorption method according to claim 4, characterized in that: The driving assembly (16) comprises a first rotating shaft (161) and a second rotating shaft (162) which are parallel to each other, and a plurality of gears (163) which are coaxially fixed to the second rotating shaft (162); the first rotating shaft (161) is coaxial with the housing (11); a connecting frame (1611) is arranged outside each filler (1612); the connecting frame (1611) is divided into a first connecting frame (1611) and a second connecting frame (1611); the first connecting frame (1611) and the second connecting frame (1611) are arranged in sequence; the first connecting frame (1611) is coaxial with the first rotating shaft (161) and is fixedly connected to the first rotating shaft (161); the second connecting frame (1611) is coaxial with the first rotating shaft (161) and is rotatably connected to the first rotating shaft (161); and meshing teeth which mesh with the gears (163) are arranged outside the second connecting frame (1611); A conversion gap (1613) is provided between a group of adjacent first connection frames (1611) and second connection frames (1611), and the first connection frame (1611) and the second connection frame (1611) are located on both sides of the conversion gap (1613).

6. The system for producing electronic grade sulfuric acid by absorption method according to claim 5, characterized in that: A power assembly (17) is arranged in the housing (11), and the power assembly (17) comprises a group of bevel gears (163), a transmission belt (172) and two pulleys (173); the driven gear (163) of the bevel gear (163) group is coaxially arranged on the second rotating shaft (162), and the rotation axis of the driving gear (163) of the bevel gear (163) group is perpendicular to the axis of the second rotating shaft (162); the two pulleys (173) are coaxially fixedly connected to the first rotating shaft (161) and the second rotating shaft (162), respectively, and the transmission belt (172) is sleeved outside the two pulleys (173).

Images