A method for producing high-concentration sulfuric acid using a wet process

Abstract

This invention proposes a wet process for producing high-concentration sulfuric acid. Waste acid and hydrogen sulfide are decomposed into high-temperature flue gas by combustion of fuel gas, which is then precipitated by a high-temperature electrostatic precipitator. A two-stage conversion and two-stage condensation method is employed. A process gas mixer is added after the first condenser. The gas is pressurized by a process fan and heated by a heat exchanger before entering the combustion chamber. Fuel gas and excess air are introduced to further heat the process gas through combustion. This not only ensures the inlet temperature of the second reactor but also increases the O2 / SO2 ratio, promoting the reaction to the right and improving the conversion rate, resulting in a concentrated sulfuric acid concentration of over 99.5%. No drying is required; the wet catalytic sulfuric acid production ensures that SO3 and H2O are directly condensed to produce sulfuric acid during the process, and the exhaust gas directly meets emission standards.

Description

Technical Field

[0001] The present invention belongs to the field of waste acid treatment, and particularly relates to a method for producing high-concentration sulfuric acid by a wet process. Background Art

[0002] In recent years, with the development of China's economy and the improvement of people's living standards, the national standards for vehicle gasoline have become increasingly stringent. In 2019, the "National VI" standard was adopted for domestic vehicle gasoline, and the content indicators of olefins and aromatics in gasoline have been continuously reduced, resulting in a decrease in the octane number of gasoline. On the other hand, with the strengthening of people's environmental awareness, gasoline antiknock agents harmful to the environment such as MTBE have been increasingly resisted. In order to maintain the octane number of gasoline, alkylate has become a popular choice.

[0003] Most alkylation units in China adopt the sulfuric acid process, which will produce a large amount of alkylation waste acid. The waste acid regeneration unit is an environmental protection device supporting the alkylation unit. Its process mainly burns and cracks, oxidizes, and absorbs waste sulfuric acid with w(H2SO4) of 89% - 90.5% through a waste acid cracking furnace to become commercial sulfuric acid with w(H2SO4) of 98% - 99.2%. The regenerated product sulfuric acid is returned to the alkylation unit and recycled as a catalyst for sulfuric acid alkylation reaction. In order to meet the demand for gasoline, referring to the blending ratio of alkylated gasoline in the United States, the demand for domestic alkylated gasoline in 2019 was about 20 million tons. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for producing high-concentration sulfuric acid by a wet process, which adopts a double conversion and double absorption process in配合工艺气燃烧升温单元,提高O 2 / SO2 ratio, promotes the reaction to proceed to the right, improves the reaction conversion rate and produces high-concentration concentrated acid.

[0005] The main technical solution of the present invention, a method for producing high-concentration sulfuric acid by a wet process, is characterized in that in the regeneration process of treating alkylation waste sulfuric acid, fuel gas combustion is used to provide heat to crack alkylation waste acid and H2S into high-temperature flue gas at high temperature. The high-temperature flue gas is dust-removed by a high-temperature electrostatic dust removal device, and a two-stage wet conversion and two-stage condensation and acidification process is adopted; a process gas mixer is added after the first condenser, and after being pressurized by a process fan and heated by a heat exchanger, it enters the combustion chamber, and fuel gas and excess air are introduced to heat up the process gas by combustion.

[0006] Generally, the wet process method for producing high-concentration sulfuric acid of the present invention includes a process gas combustion unit H1, a waste heat recovery unit E1, E2, a process gas dust removal unit A1, a denitrification unit R1, an SO2 first converter R2, a first condenser E3, a process gas mixer X1, a process gas booster fan K1, a heat exchanger E4, E5, a process gas burner H2, an SO2 first converter R2, a second condenser E6, and a chimney X2 connected in sequence. After the first condenser E3, the process gas mixer X1 is added. After being pressurized by the process gas booster fan K1 and heated by the heat exchanger, the mixture enters the process gas burner H2. Fuel gas and excess air are introduced to burn and heat the process gas.

[0007] Furthermore, the raw materials are divided into two streams: alkylation waste acid and acidic gas H2S; the waste acid flow rate is 3600~4100 kg / h, and the H2S flow rate is 700~770 Nm³. 3 / h.

[0008] Furthermore, the pyrolysis temperature is controlled at 900 ~ 1100℃.

[0009] Furthermore, the waste acid and H2S are decomposed into high-temperature flue gas at high temperature by providing heat through fuel gas combustion. After the heat is recovered by a two-stage waste heat boiler, the flue gas passes through a high-temperature electrostatic precipitator with a voltage of 50,000~60,000V and an outlet temperature of 390~400℃.

[0010] Furthermore, the catalyst bed in the converter is one or more layers, and the catalyst used is one or both of the platinum-based catalyst or vanadium-based catalyst used in wet acid production.

[0011] Furthermore, the inlet temperature of the process gas mixer X1 is 160~190℃, and the outlet temperature of the process gas burner H2 is 390~410℃.

[0012] Furthermore, the excess heat recovered by the waste heat recovery unit E2 is used to heat the process gas passing through the heat exchanger E5, and the temperature of the process gas after heating is 390~410℃.

[0013] Furthermore, a spray system is installed above the chimney X2, and the sprayed solution is NaOH alkaline solution to further absorb the exhaust gas. After absorption, the SO2 content is 5~30 mg / m³. 3 .

[0014] This invention relates to a wet process for producing high-concentration sulfuric acid, producing concentrated sulfuric acid with an average concentration of 98.6% to 99.9%.

[0015] The technical advantages of this invention are as follows: The process uses two raw materials. Alkylation waste acid and hydrogen sulfide are simultaneously cracked at high temperature into high-temperature flue gas, which is then precipitated by a high-temperature electrostatic precipitator. A two-stage conversion and two-stage condensation method is employed. A process gas mixer is added after the first condenser. The gas is pressurized by a process fan and heated by a heat exchanger before entering the combustion chamber. Fuel gas and excess air are introduced to burn and heat the process gas. This not only ensures the inlet temperature of the second reactor but also increases the O2 / SO2 ratio, promoting the reaction to the right and improving the conversion rate, resulting in a concentrated sulfuric acid concentration of over 99.5%. No drying is required; wet catalytic acid production ensures that SO3 and H2O are directly condensed to produce sulfuric acid during the process. The tail gas, after alkaline washing, directly meets emission standards. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the process flow for producing high-concentration sulfuric acid using a wet process according to an embodiment of the present invention.

[0017] In the diagram, H1—process gas combustion unit; E1, E2—waste heat recovery unit; R1—denitrification unit; R2—SO2 first converter; E3—first condenser; X1—process gas mixer; K1—process gas booster fan; E4, E5—heat exchangers; H2—process gas burner; R2—SO2 first converter; E6—second condenser; X2—chimney. Detailed Implementation

[0018] The present invention will be further described below with reference to the embodiments and accompanying drawings, but the scope of protection of the present invention is not limited thereto.

[0019] The following examples illustrate the process flow for producing high-concentration sulfuric acid using a wet process, please refer to the attached document. Figure 1 It includes, in sequence, a process gas combustion unit H1, a waste heat recovery unit E1, E2, a process gas dust removal unit A1, a denitrification unit R1, an SO2 first converter R2, a first condenser E3, a process gas mixer X1, a process gas booster fan K1, a heat exchanger E4, E5, a process gas burner H2, an SO2 first converter R2, a second condenser E6, and a chimney X2.

[0020] Example 1

[0021] The alkylation waste acid is atomized with compressed air and then fed into a waste acid incinerator for pyrolysis. The waste acid flow rate is 3800 kg / h, and the acidic gas (H2S) flow rate is 730 Nm³. 3 / h. Simultaneously, supplemental fuel gas is used for complete combustion, raising the pyrolysis furnace temperature to 950℃. Waste acid and H2S are pyrolyzed under the action of fuel to generate high-temperature furnace gas. After being cooled by waste heat recovery from two-stage waste heat boilers, it enters a high-temperature electrostatic precipitator for dust removal, with an outlet temperature of 385℃. Simultaneously, the process gas containing 6% sulfur enters the denitrification unit and the first SO2 converter. It sequentially passes through each section of wet-process platinum or vanadium catalyst beds within the converter, undergoing interlayer heat exchange. The converter outlet gas is cooled by a gas cooler and then enters the process gas mixer X1. The inlet temperature of X1 is 170℃. After being pressurized by process fan K1 and heated to 392℃ by heat exchangers E4 and E5, it enters the process gas burner H2. Fuel gas and excess air are introduced to combust the process gas, raising its temperature to 400℃ before it enters the second SO2 converter. Subsequently, it enters the second condenser and is condensed into 99.5% liquid sulfuric acid. The waste gas enters the chimney and is absorbed by alkaline solution, resulting in an SO2 content of 10mg / m³. 3 The back row is empty.

[0022] Example 2

[0023] Alkylation waste acid is atomized with compressed air and then fed into a waste acid incinerator for pyrolysis. The waste acid flow rate is 3900 kg / h, and the acidic gas (H2S) flow rate is 750 Nm³. 3 / h. At the same time, supplemental fuel gas is added for complete combustion, so that the temperature of the pyrolysis furnace reaches 1050℃. Waste acid and H2S are pyrolyzed under the action of fuel to generate high-temperature furnace gas. After being cooled by waste heat recovery in two-stage waste heat boilers, it enters a high-temperature electrostatic precipitator for dust removal. The outlet temperature of the dust collector is 388℃. Simultaneously, the process gas containing 6.5% sulfur is purified and enters the denitrification unit and the first SO2 converter. It then passes through various wet-process platinum or vanadium catalyst beds within the converter, undergoing interlayer heat exchange. The converter outlet gas is cooled by a gas cooler and enters the process gas mixer X1. The inlet temperature of X1 is 188℃. After being pressurized by process fan K1 and heated to 390℃ by heat exchangers E4 and E5, it enters the process gas burner H2. Fuel gas and excess air are introduced to combust the process gas, raising its temperature to 410℃ before it enters the second SO2 converter. Subsequently, it passes through the second condenser and is condensed into 99.2% liquid sulfuric acid. The waste gas enters the chimney and is absorbed by alkaline solution, resulting in an SO2 content of 6.5 mg / m³. 3 The back row is empty.

[0024] Example 3

[0025] The alkylation waste acid is atomized with compressed air and then fed into a waste acid incinerator for pyrolysis. The waste acid flow rate is 4000 kg / h, and the acidic gas (H2S) flow rate is 755 Nm³. 3 / h. At the same time, supplemental fuel gas is added for complete combustion, so that the temperature of the pyrolysis furnace reaches 1080℃. Waste acid and H2S are pyrolyzed under the action of fuel to generate high-temperature furnace gas. After being cooled by waste heat recovery in two-stage waste heat boilers, it enters a high-temperature electrostatic precipitator for dust removal. The outlet temperature of the dust collector is 390℃. Simultaneously, the process gas containing 6.2% sulfur is purified and enters the denitrification unit and the first SO2 converter. It then passes through various wet-process platinum or vanadium catalyst beds within the converter, undergoing interlayer heat exchange. The converter outlet gas is cooled by a gas cooler and enters the process gas mixer X1. The inlet temperature of X1 is 185℃. After being pressurized by process fan K1 and heated to 395℃ by heat exchangers E4 and E5, it enters the process gas burner H2. Fuel gas and excess air are introduced to combust the process gas, raising its temperature to 405℃ before it enters the second SO2 converter. Subsequently, it passes through the second condenser and is condensed into 99.5% liquid sulfuric acid. The waste gas enters the chimney and is absorbed by alkaline solution, resulting in an SO2 content of 5.5 mg / m³. 3 The back row is empty.

[0026] Example 4

[0027] The alkylation waste acid is atomized with compressed air and then fed into a waste acid incinerator for pyrolysis. The waste acid flow rate is 4100 kg / h, and the acidic gas (H2S) flow rate is 766 Nm³. 3 / h. Simultaneously, supplemental fuel gas is used for complete combustion, raising the pyrolysis furnace temperature to 1100℃. Waste acid and H2S are pyrolyzed under the action of fuel to generate high-temperature furnace gas. After being cooled by waste heat recovery from two-stage waste heat boilers, it enters a high-temperature electrostatic precipitator for dust removal, with an outlet temperature of 395℃. Simultaneously, the process gas containing 6.3% sulfur enters the denitrification unit and the first SO2 converter. It sequentially passes through each section of wet-process platinum or vanadium catalyst beds within the converter, undergoing interlayer heat exchange. The converter outlet gas is cooled by a gas cooler and then enters the process gas mixer X1, with an inlet temperature of 185℃. It is then pressurized by process fan K1 and heated to 398℃ by heat exchangers E4 and E5 before entering the process gas burner H2. Fuel gas and excess air are introduced to combust the process gas, raising its temperature to 415℃ before it enters the second SO2 converter. Subsequently, it enters the second condenser and is condensed into 98.9% liquid sulfuric acid. The waste gas enters the chimney and is absorbed by alkaline solution, resulting in an SO2 content of 15mg / m³. 3 The back row is empty.

[0028] Example 5

[0029] Alkylation waste acid is atomized with compressed air and then fed into a waste acid incinerator for pyrolysis. The waste acid flow rate is 3850 kg / h, and the acidic gas (H2S) flow rate is 740 Nm³. 3 / h. Simultaneously, supplemental fuel gas is used for complete combustion, raising the pyrolysis furnace temperature to 1030℃. Waste acid and H2S are pyrolyzed under the action of fuel to generate high-temperature furnace gas. After being cooled by waste heat recovery from two-stage waste heat boilers, it enters a high-temperature electrostatic precipitator for dust removal, with an outlet temperature of 388℃. Simultaneously, the process gas containing 6.1% sulfur enters the denitrification unit and the first SO2 converter. It sequentially passes through each section of wet-process platinum or vanadium catalyst beds within the converter, undergoing interlayer heat exchange. The converter outlet gas is cooled by a gas cooler and then enters the process gas mixer X1, with an inlet temperature of 188℃. It is pressurized by process fan K1 and heated to 395℃ by heat exchangers E4 and E5 before entering the process gas burner H2. Fuel gas and excess air are introduced to combust the process gas, raising its temperature to 410℃ before it enters the second SO2 converter. Subsequently, it enters the second condenser and is condensed into 99.2% liquid sulfuric acid. The waste gas enters the chimney and is absorbed by alkaline solution, resulting in an SO2 content of 20 mg / m³. 3 The back row is empty.

[0030] Example 6

[0031] Alkylation waste acid is atomized with compressed air and then fed into a waste acid incinerator for pyrolysis. The waste acid flow rate is 3950 kg / h, and the acidic gas (H2S) flow rate is 745 Nm³. 3 / h. Simultaneously, supplemental fuel gas is used for complete combustion, raising the pyrolysis furnace temperature to 980℃. Waste acid and H2S are pyrolyzed under the action of fuel to generate high-temperature furnace gas. After being cooled by waste heat recovery from two-stage waste heat boilers, it enters a high-temperature electrostatic precipitator for dust removal, with an outlet temperature of 380℃. Simultaneously, the process gas containing 6.8% sulfur enters the denitrification unit and the first SO2 converter. It sequentially passes through each section of wet-process platinum or vanadium catalyst beds within the converter, undergoing interlayer heat exchange. The converter outlet gas is cooled by a gas cooler and then enters the process gas mixer X1. The inlet temperature of X1 is 160℃. It is pressurized by process fan K1 and heated to 395℃ by heat exchangers E4 and E5 before entering the process gas burner H2. Fuel gas and excess air are introduced to combust the process gas, raising its temperature to 410℃ before it enters the second SO2 converter. Subsequently, it enters the second condenser and is condensed into 99.6% liquid sulfuric acid. The waste gas enters the chimney and is absorbed by alkaline solution, resulting in an SO2 content of 8.5 mg / m³. 3 The back row is empty.

[0032] Example 7

[0033] Alkylation waste acid is atomized with compressed air and then fed into a waste acid incinerator for pyrolysis. The waste acid flow rate is 4050 kg / h, and the acidic gas (H2S) flow rate is 760 Nm³. 3 / h. Simultaneously, supplemental fuel gas is used for complete combustion, raising the pyrolysis furnace temperature to 1070℃. Waste acid and H2S are pyrolyzed under the action of fuel to generate high-temperature furnace gas. After being cooled by waste heat recovery from two-stage waste heat boilers, it enters a high-temperature electrostatic precipitator for dust removal, with an outlet temperature of 394℃. Simultaneously, the process gas containing 6.6% sulfur enters the denitrification unit and the first SO2 converter. It sequentially passes through each section of wet-process platinum or vanadium catalyst beds within the converter, undergoing interlayer heat exchange. The converter outlet gas is cooled by a gas cooler and then enters the process gas mixer X1. The inlet temperature of X1 is 189℃. It is pressurized by process fan K1 and heated to 399℃ by heat exchangers E4 and E5 before entering the process gas burner H2. Fuel gas and excess air are introduced to combust the process gas, raising its temperature to 409℃ before it enters the second SO2 converter. Subsequently, it enters the second condenser and is condensed into 99.4% liquid sulfuric acid. The waste gas enters the chimney and is absorbed by alkaline solution, resulting in an SO2 content of 19 mg / m³. 3 The back row is empty.

Claims

1. A method for producing high-concentration sulfuric acid using a wet process, characterized in that... In the regeneration process for treating alkylation waste sulfuric acid, heat is provided by fuel gas combustion to decompose the alkylation waste acid and H2S into high-temperature flue gas at high temperatures. The high-temperature flue gas is then dedusted by a high-temperature electrostatic precipitator. The process employs a two-stage wet conversion and a two-stage condensation process to produce acid. Specifically, it includes, in sequence, a process gas combustion unit H1, waste heat recovery units E1 and E2, a process gas dust removal unit A1, a denitrification unit R1, a first SO2 converter R2, a first condenser E3, a process gas mixer X1, a process gas booster fan K1, heat exchangers E4 and E5, a process gas burner H2, and a second SO2 converter. The system includes a converter R3, a second condenser E6, and a chimney X2. A process gas mixer X1 is added after the first condenser E3. The process gas is pressurized by a process gas booster fan K1 and heated by a heat exchanger before entering the process gas burner H2. Fuel gas and excess air are introduced to burn and heat the process gas. The inlet temperature of the process gas mixer X1 is 160~190℃, and the outlet temperature of the process gas burner H2 is 390~410℃. Excess heat recovered by the waste heat recovery unit E2 is used to heat the process gas passing through the heat exchanger E5, resulting in a heated process gas temperature of 390~410℃.

2. The method for producing high-concentration sulfuric acid using a wet process according to claim 1, characterized in that... The raw materials are divided into two streams: alkylation waste acid and acidic gas H2S; the waste acid flow rate is 3600~4100 kg / h, and the H2S flow rate is 700~770 Nm³. 3 / h.

3. A method for producing high-concentration sulfuric acid using a wet process according to claim 1, characterized in that... The pyrolysis temperature is controlled at 900 ~ 1100℃.

4. A method for producing high-concentration sulfuric acid using a wet process according to claim 1, characterized in that... Waste acid and H2S are decomposed into high-temperature flue gas by providing heat through fuel gas combustion. After heat recovery by a two-stage waste heat boiler, the flue gas passes through a high-temperature electrostatic precipitator with a voltage of 50,000~60,000V and an outlet temperature of 390~400℃.

5. The method for producing high-concentration sulfuric acid using a wet process according to claim 1, characterized in that, The catalyst bed inside the converter consists of one or more layers, and the catalyst used is one or both of the platinum-based catalyst or vanadium-based catalyst used in wet acid production.

6. The method for producing high-concentration sulfuric acid using a wet process according to claim 1, characterized in that, A spray system is installed above the chimney X2, spraying a NaOH alkaline solution to further absorb the exhaust gas. After absorption, the SO2 content is 5~30 mg / m³. 3 .

7. The method for producing high-concentration sulfuric acid using a wet process according to claim 1, characterized in that, The average concentration of concentrated sulfuric acid in the product is 98.6%~99.9%.

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