High-efficiency resistance for the process of producing high-concentration sulfuric acid by wet process of waste acid cracking

Abstract

The present invention proposes a process for producing high-concentration sulfuric acid by using a high-efficiency resistance and wet-process technology for waste acid cracking. After the high-temperature flue gas produced by the combustion and cracking of waste acid is sent to a ten-stage dust collector to remove impurities such as particulate matter, the slag dust impurities in the process gas are further washed by a purification high-efficiency humidifier, and then passed into a first reactor to convert SO2 into SO3 and then passed into a first condenser for cooling. The water therein condenses into droplets attached to the cooler and reacts with SO3 to form concentrated sulfuric acid. Subsequently, the process gas passes through a second converter and a second condenser in sequence, and the tail gas is finally absorbed and discharged by an activated carbon device.

Description

Technical Field

[0001] The invention belongs to the field of waste acid treatment, and specifically relates to a process for producing high-concentration sulfuric acid by using a high-efficiency resistance-resistant waste acid cracking wet process. Background Art

[0002] In recent years, with the development of my country's economy and the improvement of people's living standards, the country has set higher and higher standards for automotive gasoline.

[0003] In 2019, domestic automotive gasoline adopted the "National VI" standard. The content of olefins and aromatics in gasoline continued to decrease, resulting in a decrease in the octane number of gasoline. On the other hand, with the strengthening of people's environmental awareness, environmentally harmful gasoline anti-knock agents such as MTBE are increasingly resisted. In order to maintain the octane number of gasoline, alkylate has become a popular choice.

[0004] Most of the alkylation units in my country 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 converts the waste sulfuric acid with w (H2SO4) of 89% to 90.5% into commercial sulfuric acid with w (H2SO4) of 98% to 99.2% through incineration, cracking, oxidation and absorption in the waste acid cracking furnace. The regenerated product sulfuric acid is returned to the alkylation unit for recycling as a catalyst for sulfuric acid alkylation reaction.

[0005] In order to meet the demand for gasoline, based on the blending ratio of alkylate gasoline in the United States, the domestic demand for alkylate gasoline in 2019 is expected to be around 20 million tons. Summary of the invention

[0006] The purpose of the present invention is to provide a process for producing high-concentration sulfuric acid by a waste acid cracking wet process, which can effectively remove dust in the process gas after the waste acid cracking and effectively prevent impurities from penetrating and causing bed blockage.

[0007] The main technical scheme of the present invention proposes a process for producing high-concentration sulfuric acid by wet technology of waste acid cracking. The technology of twice wet conversion and twice condensation into acid is adopted. The waste sulfuric acid from the alkylation unit is transported into the waste sulfuric acid spray gun through the acid pump, and is sprayed into the incineration cracking furnace after being fully contacted with compressed air and atomized. The fuel gas provides energy for the cracking of the waste acid, so that the waste acid is cracked into high-temperature flue gas at high temperature, and enters the dust removal equipment after heat exchange and cooling. The process gas after dust removal is further washed by the purification high-efficiency humidifier. The sulfur-containing process gas after purification is heated and enters the first reactor in turn to convert SO2 into SO3 and then enters the first condenser for cooling. The water therein is condensed into droplets attached to the cooler, and hydrated with SO3 to generate concentrated sulfuric acid. Then the process gas passes through the second converter and the second condenser in turn, and the tail gas is finally absorbed and discharged by the activated carbon device.

[0008] Generally, the dust removal equipment is a ten-stage dust removal parallel equipment.

[0009] The ten-stage dust removal parallel equipment, wherein the first five stages of dust removal devices are connected in parallel and then connected in parallel to the last five stages of dust removal devices.

[0010] The inlet temperature of the dust removal equipment is 380°C~400°C.

[0011] The process gas after dust removal passes through the purification high-efficiency humidifier. The furnace gas in the nozzle of the high-efficiency humidifier undergoes adiabatic humidification process to significantly reduce the temperature and remove slag and dust impurities. The high-efficiency humidifier is a tower and tank integrated structure, using adiabatic evaporation. The dust content of the process gas after dust removal is ≤1mg / m 3 .

[0012] The cracking temperature is controlled at 900°C to 1200°C.

[0013] The inlet temperature of the high-efficiency humidifier is 330°C to 350°C, and the outlet temperature is lower than 40°C.

[0014] The catalyst used in the converter is a vanadium catalyst for wet acid production. The vanadium catalyst is divided into three beds in the first converter. The reaction temperature of the first bed is 490°C to 550°C, the reaction temperature of the second bed is 440°C to 480°C, and the reaction temperature of the third bed is 410°C to 420°C. The reaction temperature of the vanadium catalyst in the second converter is 400°C to 410°C.

[0015] The tail gas is absorbed by the activated carbon reactor, and the SO2 content in the tail gas is 0~8mg / m 3 .

[0016] The average concentration of concentrated sulfuric acid in the product is 98.6%~99.9%.

[0017] Technical effects of the present invention:

[0018] 1. The high-temperature filtration unit adopts a ten-stage dust removal parallel device, in which the first five stages of dust removal devices are connected in parallel and then connected in parallel to the last five stages of dust removal devices, which can effectively prevent the impurities from penetrating into the subsequent catalyst reaction bed layer and causing the catalyst bed layer to be blocked due to damage to one of the dust removal devices;

[0019] 2. The dust impurities in the process gas after dust removal are further washed by the purification high-efficiency humidifier. The high-efficiency humidifier is a tower and tank integrated structure, and adopts adiabatic evaporation. It ensures that the dust content of the process gas passing through the primary converter is ≤1mg / m 3 . BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1A schematic diagram of the process flow of using high-efficiency resistance to wet process production of high-concentration sulfuric acid by waste acid cracking according to an embodiment of the present invention. DETAILED DESCRIPTION

[0021] The present invention is further described below in conjunction with embodiments and drawings, but the protection scope of the present invention is not limited thereto.

[0022] The following embodiment process is referred to the attached Figure 1 .

[0023] Example 1

[0024] The alkylation waste acid is atomized by compressed air and sent to the waste acid incinerator for cracking. At the same time, fuel gas is added for full combustion, so that the temperature of the cracking furnace reaches 900℃. The alkylation waste acid is cracked by the fuel to generate high-temperature furnace gas. After the waste heat is recovered and cooled by the waste heat boiler, it enters the ten-stage high-temperature dust collector for dust removal. At the same time, the process gas temperature of 6% sulfur gas is reduced to 390℃. The process gas after dust removal is further washed by the purification high-efficiency humidifier. The inlet temperature of the high-efficiency humidifier is 350℃ and the outlet temperature is 35℃. After purification, the sulfur-containing process gas enters the first converter, passes through the wet process special vanadium catalyst bed layers in each section of the converter in turn and undergoes interlayer heat exchange. The outlet gas of the converter is cooled to 290°C by the gas cooler and then enters the first condenser tube from bottom to top. After condensation in the falling film condenser, it passes through the second converter in turn and controls the outlet temperature at 280°C; then enters the second condenser to condense into 98.5% liquid sulfuric acid. After the exhaust gas enters the activated carbon reactor for absorption, the SO2 content is 7.5mg / m 3 After emptying.

[0025] Example 2

[0026] The alkylation waste acid is atomized by compressed air and sent to the waste acid incinerator for cracking. At the same time, fuel gas is added for full combustion, so that the temperature of the cracking furnace reaches 1200℃. The alkylation waste acid is cracked by the fuel to generate high-temperature furnace gas. After the waste heat is recovered and cooled by the waste heat boiler, it enters the ten-stage high-temperature dust collector for dust removal. At the same time, the process gas temperature of 6.5% sulfur gas is reduced to 410℃. The process gas after dust removal is further washed by the purification high-efficiency humidifier. The inlet temperature of the high-efficiency humidifier is 355℃ and the outlet temperature is 40℃. After purification, the sulfur-containing process gas enters the first converter, passes through the wet process special vanadium catalyst bed layers in each section of the converter in turn and undergoes interlayer heat exchange. The outlet gas of the converter is cooled to 290°C by the gas cooler and then enters the first condenser tube from bottom to top. After condensation in the falling film condenser, it passes through the second converter in turn and controls the outlet temperature at 282°C; then enters the second condenser to condense into 99.0% liquid sulfuric acid. After the exhaust gas enters the activated carbon reactor for absorption, the SO2 content is 7mg / m 3 After emptying.

[0027] Example 3

[0028] The alkylation waste acid is atomized by compressed air and sent to the waste acid incinerator for cracking. At the same time, fuel gas is added for full combustion, so that the temperature of the cracking furnace reaches 1100℃. The alkylation waste acid is cracked by the fuel to generate high-temperature furnace gas. After the waste heat of the waste heat boiler is recovered and cooled, it enters the ten-stage high-temperature dust collector for dust removal. At the same time, the temperature of the process gas containing 5% sulfur gas is reduced to 380℃. The process gas after dust removal is further washed by the purification high-efficiency humidifier. The inlet temperature of the high-efficiency humidifier is 360℃ and the outlet temperature is 38℃. After purification, the sulfur-containing process gas enters the first converter, passes through the wet process special vanadium catalyst bed layers in each section of the converter in turn and undergoes interlayer heat exchange. The outlet gas of the converter is cooled to 288°C by the gas cooler and then enters the first condenser tube from bottom to top. After condensation in the falling film condenser, it passes through the second converter in turn and controls the outlet temperature at 288°C; then enters the second condenser to condense into 99.5% liquid sulfuric acid. After the exhaust gas enters the activated carbon reactor for absorption, the SO2 content is 6mg / m 3 After emptying.

[0029] Example 4

[0030] The alkylation waste acid is atomized by compressed air and sent to the waste acid incinerator for cracking. At the same time, fuel gas is added for full combustion, so that the temperature of the cracking furnace reaches 1000℃. The alkylation waste acid is cracked by the fuel to generate high-temperature furnace gas. After the waste heat is recovered and cooled by the waste heat boiler, it enters the ten-stage high-temperature dust collector for dust removal. At the same time, the process gas temperature of 5.5% sulfur gas is reduced to 395℃. The process gas after dust removal is further washed by the purification high-efficiency humidifier. The inlet temperature of the high-efficiency humidifier is 345℃ and the outlet temperature is 35℃. After purification, the sulfur-containing process gas enters the first converter, passes through the wet process special vanadium catalyst bed layers in each section of the converter in turn and undergoes interlayer heat exchange. The outlet gas of the converter is cooled to 275°C by the gas cooler and then enters the first condenser tube from bottom to top. After condensation in the falling film condenser, it passes through the second converter in turn and controls the outlet temperature at 289°C; then enters the second condenser to condense into 99.2% liquid sulfuric acid. After the exhaust gas enters the activated carbon reactor for absorption, the SO2 content is 6.5mg / m 3 After emptying.

[0031] Example 5

[0032] The alkylation waste acid is atomized by compressed air and sent to the waste acid incinerator for cracking. At the same time, fuel gas is added for full combustion, so that the temperature of the cracking furnace reaches 950℃. The alkylation waste acid is cracked by the fuel to generate high-temperature furnace gas. After the waste heat is recovered and cooled by the waste heat boiler, it enters the ten-stage high-temperature dust collector for dust removal. At the same time, the process gas temperature of 4.5% sulfur gas is reduced to 395℃. The process gas after dust removal is further washed by the purification high-efficiency humidifier. The inlet temperature of the high-efficiency humidifier is 340℃ and the outlet temperature is 30℃. After purification, the sulfur-containing process gas enters the first converter, passes through the wet process special vanadium catalyst bed in each section of the converter in turn and undergoes interlayer heat exchange. The gas at the converter outlet is cooled to 275°C by the gas cooler and then enters the first condenser tube from bottom to top. After condensation in the falling film condenser, it passes through the second converter in turn and controls the outlet temperature to 285°C; the second acid mist control system controls the outlet temperature of the acid control system to 290°C; and then enters the second condenser to condense into 99.9% liquid sulfuric acid. The exhaust gas enters the activated carbon reactor for absorption and the SO2 content is 6.5mg / m 3 After emptying.

[0033] Example 6

[0034] The alkylation waste acid is atomized by compressed air and sent to the waste acid incinerator for cracking. At the same time, fuel gas is added for full combustion, so that the temperature of the cracking furnace reaches 1200℃. The alkylation waste acid is cracked by the fuel to generate high-temperature furnace gas. After the waste heat is recovered and cooled by the waste heat boiler, it enters the ten-stage high-temperature dust collector for dust removal. At the same time, the temperature of the process gas containing 7% sulfur gas is reduced to 410℃. The process gas after dust removal is further washed by the purification high-efficiency humidifier. The inlet temperature of the high-efficiency humidifier is 360℃ and the outlet temperature is 35℃. After purification, the sulfur-containing process gas enters the first converter, passes through the wet process special vanadium catalyst bed layers in each section of the converter in turn and undergoes interlayer heat exchange. The outlet gas of the converter is cooled to 275°C by the gas cooler and then enters the first condenser tube from bottom to top. After condensation in the falling film condenser, it passes through the second converter in turn and controls the outlet temperature at 290°C; then enters the second condenser to condense into 99.8% liquid sulfuric acid. After the exhaust gas enters the activated carbon reactor for absorption, the SO2 content is 7mg / m 3 After emptying.

[0035] Example 7

[0036] The alkylation waste acid is atomized by compressed air and sent to the waste acid incinerator for cracking. At the same time, fuel gas is added for full combustion, so that the temperature of the cracking furnace reaches 1150℃. The alkylation waste acid is cracked by the fuel to generate high-temperature furnace gas. After the waste heat of the waste heat boiler is recovered and cooled, it enters the ten-stage high-temperature dust collector for dust removal. At the same time, the temperature of the process gas containing 6.8% sulfur gas is reduced to 400℃. The process gas after dust removal is further washed by the purification high-efficiency humidifier. The inlet temperature of the high-efficiency humidifier is 360℃ and the outlet temperature is 29℃. After purification, the sulfur-containing process gas enters the first converter, passes through the wet process special vanadium catalyst bed in each section of the converter in turn and undergoes interlayer heat exchange. The outlet gas of the converter is cooled to 290°C by the gas cooler and then enters the first condenser tube from bottom to top. After condensation in the falling film condenser, it passes through the second converter in turn and controls the outlet temperature at 289°C; then enters the second condenser to condense into 99.5% liquid sulfuric acid. After the exhaust gas enters the activated carbon reactor for absorption, the SO2 content is 8mg / m 3 After emptying.

Claims

1. A process for producing high-concentration sulfuric acid by wet process of waste acid cracking with high efficiency resistance, characterized in that The process of two wet conversions and two condensations into acid is adopted: the waste sulfuric acid from the alkylation unit is fully contacted with compressed air and atomized, and then sprayed into the incineration cracking furnace. The fuel gas provides energy for the cracking of the waste acid. The waste acid is cracked into high-temperature flue gas at high temperature, and enters the dust removal equipment after heat exchange and cooling. The process gas after dust removal is further washed by the purification high-efficiency humidifier to further wash the slag dust impurities in the process gas. The purified sulfur-containing process gas is heated and then enters the first converter in turn to convert SO2 into SO3 and then pass into the first condenser for cooling. The water in it is condensed into droplets attached to the cooler and undergoes hydration reaction with SO3 to generate concentrated sulfuric acid. Then the process gas passes through the second converter and the second condenser in turn, and the tail gas is absorbed and discharged through the activated carbon device; The dust removal equipment is a ten-stage parallel dust removal equipment, wherein the first five stages of dust removal devices are connected in parallel and then connected in parallel to the last five stages of dust removal devices; The process gas after dust removal is then passed through a purified high-efficiency humidifier. The furnace gas in the nozzle of the high-efficiency humidifier is greatly cooled and the slag and dust impurities are removed through an adiabatic humidification process. The high-efficiency humidifier is a tower and trough integrated structure, and adopts adiabatic evaporation. The dust content of the process gas after dust removal is ≤1mg / m 3 .

2. The process of using a high-efficiency resistor for the wet production of high-concentration sulfuric acid by waste acid cracking according to claim 1 is characterized in that The inlet temperature of the dust removal equipment is 380℃~400℃.

3. The process of using a high-efficiency resistor for the wet production of high-concentration sulfuric acid by waste acid cracking according to claim 1 is characterized in that The cracking temperature is controlled at 900℃ ~ 1200℃.

4. The process of using a high-efficiency resistor for the wet production of high-concentration sulfuric acid by waste acid cracking according to claim 1 is characterized in that The inlet temperature of the high-efficiency humidifier is 330℃~350℃, and the outlet temperature is lower than 40℃.

5. The process of using a high-efficiency resistor for the wet production of high-concentration sulfuric acid by waste acid cracking according to claim 1 is characterized in that The catalyst used in the converter is a vanadium catalyst for wet acid production. The vanadium catalyst is divided into three beds in the first converter. The reaction temperature of the first bed is 490℃~550℃, the reaction temperature of the second bed is 440℃~480℃, and the reaction temperature of the third bed is 410℃~420℃. The reaction temperature of the vanadium catalyst in the second converter is 400℃~410℃.

6. The process of using a high-efficiency resistor for the wet production of high-concentration sulfuric acid by waste acid cracking according to claim 1 is characterized in that The tail gas is absorbed by the activated carbon reactor, and the SO2 content in the tail gas is 0~8mg / m 3 .

7. The process of using a high-efficiency resistor for the wet production of high-concentration sulfuric acid by waste acid cracking according to claim 1 is characterized in that The average concentration of concentrated sulfuric acid produced is 98.6%~99.9%.

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