System for preparing acid by using sulfur-containing waste liquid through wet method

Abstract

The utility model relates to the technical field of chemical environmental protection, and discloses a sulfur-containing waste liquid wet-process acid making system which comprises an incineration unit, a purification unit, a flue gas mixer, a heat exchanger and a converter which are sequentially arranged in the material flow direction. The flue gas mixer comprises a shell, the shell comprises a cylindrical barrel section and a cone section which are sequentially connected from top to bottom, the cone section is gradually reduced from top to bottom, a flue gas inlet is formed in the bottom of the cone section, a hot air inlet is formed in the side portion of the cylindrical barrel section, and a mixed flue gas outlet is formed in the top of the cylindrical barrel section. And the hot air inlet is configured to be capable of spirally feeding air or tangentially feeding air. According to the system disclosed by the utility model, the efficient flue gas mixer is additionally arranged between the purification process and the existing heat exchanger for heating and oxygenating the flue gas, so that the system is good in purification effect and high in heat exchange efficiency, the problem of dew point corrosion of the low-temperature flue gas is solved, and the service life of subsequent equipment and pipelines and the long-term running stability of the device are ensured.

Description

TECHNICAL FIELD

[0001] The utility model relates to a chemical industry environmental protection technical field, concretely relates to a system of sulfur-containing waste liquid wet method acid making. BACKGROUND

[0002] With the continuous improvement of environmental protection requirements, various waste sulfuric acid, propylene cyanide device by-product containing high concentration of ammonium sulfate waste liquid and other sulfur-containing waste liquid generated in industry are difficult to be completely treated by using conventional neutralization, oxidation, extraction, adsorption, biochemical process and other processes due to large emission amount and high concentration, and have become a problem restricting the development of the industry. The sulfur-containing waste liquid incineration regeneration acid making process is the most clean and complete sulfur-containing waste liquid treatment method at present, and is also the development trend of the sulfur-containing waste liquid treatment process.

[0003] The sulfur-containing waste liquid incineration acid making technology mainly includes dry method and wet method processes. The dry method process includes four units of cracking, purification, dry absorption and conversion, and the wet method process is composed of three units of incineration, conversion and acid condensation. The main difference between the two processes is that: the dry method regeneration process needs to carry out acid washing and purification on the cracking gas from the incinerator and dry the cracking gas, the SO2-containing flue gas after drying is converted into SO3 in the converter by catalyst oxidation, and then the concentrated sulfuric acid is produced after absorption; the wet method acid regeneration process removes dust and other solid impurities from the cracking gas from the incinerator by using an electrostatic precipitator and a high-temperature ceramic filter, the SO2-containing flue gas does not need to be dried, and under the condition of water vapor, the flue gas is directly catalytically oxidized into SO3 in the converter, and then the concentrated sulfuric acid is produced by condensation of SO3 and water vapor.

[0004] In order to solve the problems of poor purification effect, easy plugging of filter and converter bed in the traditional wet method process, a wet method process replacing the physical dust removal process with an acid washing and purification process is newly developed, but the low-temperature flue gas containing saturated water vapor after purification is easy to cause dew point corrosion on the subsequent equipment and pipelines, and the flue gas needs to be heated to about 420 DEG C before entering the converter for catalytic oxidation, if a conventional metal heat exchanger is used, the dew point corrosion is easy to occur in the low-temperature section of the heat exchange pipe, and the non-metal equipment cannot withstand the high temperature of the flue gas after heat exchange. UTILITY MODEL CONTENTS

[0005] The utility model aims at overcoming the problems of the prior art that the low-temperature flue gas containing saturated water vapor after purification in the wet method process is easy to cause dew point corrosion on the subsequent equipment and pipelines, and the flue gas needs to be heated to about 420 DEG C before entering the converter for catalytic oxidation, the dew point corrosion is easy to occur in the low-temperature section of the heat exchange pipe of the heat exchanger or the heat exchanger cannot withstand the high temperature of the flue gas after heat exchange, and provides a system of sulfur-containing waste liquid wet method acid making.

[0006] In order to achieve the above object, the utility model provides a sulfur-containing waste liquid wet-process acid making system, the system includes successively arranged incineration unit, purification unit, flue gas mixer, heat exchanger and converter along the material flow direction,

[0007] Wherein, the flue gas mixer includes a shell, the shell includes a cylindrical barrel section and a conical section connected in turn from top to bottom, and the conical section is gradually reduced in diameter from top to bottom, the bottom of the conical section is provided as a flue gas inlet, the side of the cylindrical barrel section is provided with a hot air inlet, the top of the cylindrical barrel section is provided with a mixed flue gas outlet, and the hot air inlet is configured to be able to spiral into air or tangential air.

[0008] Preferably, the flue gas outlet of the incineration unit is connected with the heat source inlet of the heat exchanger, and the heat source outlet of the heat exchanger is connected with the inlet of the purification unit.

[0009] Preferably, the purification unit includes a humidifier, a scrubbing tower and a demister connected in turn along the flue gas flow direction.

[0010] Preferably, the material of the heat exchanger is 304 stainless steel or 304L stainless steel.

[0011] Preferably, the number of the flue gas mixers is 2, and the two flue gas mixers are connected in parallel.

[0012] Preferably, in the flue gas mixer, the number of the shells is 2, and the two shells are connected in parallel.

[0013] Preferably, in the flue gas mixer, the middle of the side wall of the cylindrical barrel section is provided with an ear seat.

[0014] Preferably, in the flue gas mixer, the ear seat is located below the hot air inlet.

[0015] Preferably, in the flue gas mixer, an oxygen and sulfur dioxide ratio analysis device is arranged on the pipeline of the mixed flue gas outlet; temperature measuring devices are arranged on the pipelines of the flue gas inlet, the hot air inlet and the mixed flue gas outlet.

[0016] Preferably, the flue gas mixer further includes an adjusting unit, which is used for collecting the detection data of the oxygen and sulfur dioxide ratio analysis device and the temperature measuring device, and adjusting the air inlet flow of the hot air inlet according to the detection data, so that the molar ratio of oxygen to sulfur dioxide in the mixed flue gas discharged from the mixed flue gas outlet is greater than or equal to 0.6, and the temperature is greater than or equal to 150 DEG C.

[0017] Preferably, the material of the shell of the flue gas mixer is carbon steel or stainless steel, and the inner lining of the conical section is graphite or acid-resistant ceramic tile.

[0018] The wet acid production system for sulfur-containing wastewater provided by this invention includes a flue gas mixer installed between the purification unit and the heat exchanger. The purified, low-temperature wet flue gas is first transported to the flue gas mixer and mixed with preheated, high-temperature air. This increases the flue gas temperature, preventing dew point corrosion of downstream equipment. It also replenishes oxygen in the flue gas, reducing the need for oxygen replenishment in subsequent units and ensuring the oxygen-to-sulfur ratio of the flue gas entering the converter. Therefore, by adding a high-efficiency flue gas mixer between the purification process and the existing heat exchanger to raise the temperature and replenish oxygen in the flue gas, this invention not only achieves excellent purification and high heat exchange efficiency but also features a small size, simple operation, and solves the problem of low-temperature flue gas dew point corrosion. It also ensures the service life of downstream equipment and pipelines and the long-term operational stability of the system. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of one embodiment of the wet acid production system for sulfur-containing waste liquid provided by this utility model;

[0020] Figure 2 yes Figure 1 A schematic diagram of the structure of the flue gas mixer in the diagram;

[0021] Figure 3 yes Figure 2 Top view of the flue gas mixer in the middle;

[0022] Figure 4 yes Figure 1 A schematic diagram of the working process of the flue gas mixer in the diagram;

[0023] Figure 5 yes Figure 1 The diagram shows the structure of the flue gas mixer when it has two housings.

[0024] Explanation of reference numerals in the attached figures

[0025] 100 - Incineration unit; 200 - Purification unit; 300 - Flue gas mixer; 400 - Heat exchanger; 500 - Converter;

[0026] 1-Cylindrical section; 2-Conical section; 3-Hot air inlet; 4-Flue gas inlet; 5-Mixed flue gas outlet; 6-Hear seat; 7-Inner lining; 8a-First temperature measuring device; 8b-Second temperature measuring device; 8c-Third temperature measuring device; 91-Oxygen analyzer; 92-Sulfur dioxide analyzer; 10-Regulating valve. Detailed Implementation

[0027] The specific embodiments described herein are intended to be illustrative only and are not intended to limit the scope of the present application. Numerous variations and modifications will be readily apparent to those skilled in the art, and the generic principles defined herein can be applied to other variations and modifications without departing from the scope of the application.

[0028] The endpoints of the ranges and any values disclosed herein are not limited to the precise values recited. The endpoints of the ranges and the values are approximations that are already adequately described. Any numerical value, however, can be expressed as a range by either adding to or subtracting from that value. In so doing, every intermediate value betweenthe recited ranges and the values is encompassed within the scope of the various aspects.

[0029] The utility model provides a kind of system for sulfur-containing waste liquid wet-process acid making, please refer to Figures 1-3 The system includes incineration unit 100, purification unit 200, flue gas mixer 300, heat exchanger 400 and converter 500 arranged in turn along the material flow direction;

[0030] The flue gas mixer 300 includes a shell, which includes a cylindrical barrel section 1 and a conical section 2 connected in turn from top to bottom, and the conical section 2 gradually reduces in diameter from top to bottom, the bottom of the conical section 2 is provided as a flue gas inlet 4, the side of the cylindrical barrel section 1 is provided with a hot air inlet 3, the top of the cylindrical barrel section 1 is provided with a mixed flue gas outlet 5, and the hot air inlet 3 is configured to be able to spiral into the air or tangential air.

[0031] In the utility model, the high-temperature air (≥350℃) after preheating enters the flue gas mixer 300 through the hot air inlet 3, and mixes with the low-temperature wet flue gas (≥38℃) from the purification unit 200, so as to realize the purpose of warming up and oxygen supplementing of the low-temperature wet flue gas, solve the dew point corrosion of low-temperature flue gas to subsequent equipment pipelines, and at the same time ensure the oxygen-sulfur ratio of flue gas into the converter 500.

[0032] In the utility model, the sulfur-containing waste liquid is combusted in the incineration unit 100 to obtain high-temperature flue gas (above 1000℃), in order to reduce energy consumption, the high-temperature flue gas can be used for waste heat utilization first, and then acid washing and purification. The utility model does not limit the specific waste heat utilization mode of the high-temperature flue gas, which can be used in the system, or can be used in other systems or devices. In the preferred embodiment, the flue gas outlet of the incineration unit 100 is connected with the heat source inlet of the heat exchanger 400, and the heat source outlet of the heat exchanger 400 is connected with the inlet of the purification unit 200, so that the waste heat of the incineration flue gas can be utilized in the heat exchanger 400, reducing energy consumption.

[0033] Since the incineration flue gas in the incineration unit 100 has a temperature as high as 1000℃ or above, the temperature is relatively high, and if the incineration flue gas is directly used for heat exchange with the mixed flue gas from the flue gas mixer 300, the temperature of the mixed flue gas is far higher than 420℃, which is not suitable for the subsequent catalytic oxidation reaction. Therefore, when the heat exchanger 400 is used as a heat source, the temperature needs to be reduced or the waste heat is utilized in other waste heat utilization equipment (not shown in the figure) so that the temperature is reduced to about 500℃.

[0034] In a specific embodiment, the flue gas outlet of the incineration unit 100 is first connected to a waste heat utilization equipment (such as a waste heat boiler) for waste heat utilization, and then connected to the heat source inlet of the heat exchanger 400. In this way, the high-temperature incineration flue gas (1000℃ or above) obtained by burning and cracking the sulfur-containing waste liquid in the incineration unit 100 can be reduced to about 500℃ through waste heat recovery, and then used as a heat source of the heat exchanger 400 to further heat the mixed flue gas from the flue gas mixer 300 to about 420℃, so that the mixed flue gas can enter the converter 500 for catalytic oxidation. Through the above arrangement, the waste heat of the incineration flue gas can be effectively utilized, thereby reducing the energy consumption of the sulfur-containing waste liquid wet-process acid production.

[0035] In the utility model, the incineration flue gas from the incineration unit 100 is subjected to pickling purification in the purification unit 200. The specific device included in the purification unit 200 is not particularly limited in the utility model, and can be a conventional device included in the crystallization unit 200 in the art. In some embodiments, the purification unit 200 includes a humidifier (not shown in the figure), a scrubber (not shown in the figure) and a mist eliminator (not shown in the figure) connected in sequence in the direction of flue gas flow. In a specific implementation, the incineration flue gas from the incineration unit 100 first enters the humidifier for humidification, cooling and dust removal, then enters the scrubber for further washing and cooling of the flue gas by spraying, and then enters the mist eliminator to remove acid mist.

[0036] In some embodiments, the mist eliminator is provided with two mist eliminators arranged in series, so that the low-temperature wet flue gas obtained after pickling purification is subjected to mist removal by two-stage mist elimination, and the mist removal effect is better.

[0037] The utility model does not limit the specific type of the mist eliminator, which can be a conventional mist eliminator in the art. In a specific embodiment, the mist eliminator is an electric mist eliminator.

[0038] In some embodiments, the material of the heat exchanger 400 is 304 stainless steel or 304L stainless steel.

[0039] In some embodiments, the incineration unit 100 can include an incinerator.

[0040] In a specific embodiment, the process flow of the sulfur-containing waste liquid wet-process acid-making system comprises: incineration and cracking of the sulfur-containing waste liquid at a high temperature of 1100°C in an incinerator to generate high-temperature flue gas containing SO2, SO3, CO2, H2O, N2, O2 and other components, and then cooling and / or waste heat utilization; after the incinerator flue gas is cooled to about 350°C, it is sent to the purification unit 200, and the flue gas is subjected to acid washing purification through high-efficiency humidifiers, spray scrubbing towers and other equipment, and then the acid mist is removed through two-stage electric precipitators; the low-temperature wet flue gas (38-55°C) obtained from the purification unit 200 is transported to the flue gas mixer 300 to be mixed and warmed with hot air, and mixed flue gas at 150-220°C is obtained; the mixed flue gas is subjected to heat exchange in the heat exchanger 400 (the heat exchanger 400 is made of 304 or 304L stainless steel), and the mixed flue gas is heated to about 420°C and then transported into the converter 500 for catalytic oxidation to generate SO3, and then concentrated sulfuric acid is obtained by condensation of SO3 and water vapor.

[0041] In a specific embodiment, the hot air inlet 3 of the flue gas mixer 300 is in the form of spiral air inlet or tangential air inlet, and the air inlet is square.

[0042] In some embodiments, the flue gas mixer 300 is provided with an ear seat 6 in the middle of the side wall of the cylindrical barrel section 1, so that the installation and fixation of the flue gas mixer 300 are facilitated.

[0043] In a preferred embodiment, the ear seat 6 of the flue gas mixer 300 is located below the hot air inlet 3.

[0044] In some embodiments, the mixed flue gas outlet 5 is provided with an oxygen-to-sulfur dioxide ratio analysis device, so that the molar ratio of oxygen to sulfur dioxide in the mixed flue gas can be monitored, and the flow rate at the hot air inlet 3 and / or the flue gas inlet 4 can be adjusted according to the actual working conditions to make the mixed flue gas meet the requirements of the subsequent working conditions.

[0045] In a specific implementation, the oxygen-to-sulfur dioxide ratio analysis device can include an oxygen analyzer 91 and a sulfur dioxide analyzer 92.

[0046] In some embodiments, temperature measuring devices are arranged on the pipes of the flue gas inlet 4, the hot air inlet 3 and the mixed flue gas outlet 5. Through the arrangement of the temperature measuring devices, the temperature of the medium entering and leaving the flue gas mixer 300 can be monitored, so that the temperature of the high-temperature air input, the flow rate at the hot air inlet 3 and / or the flue gas inlet 4 can be adjusted according to the actual working conditions. Specifically, a first temperature measuring device 8a is arranged on the pipe of the flue gas inlet 4, a second temperature measuring device 8b is arranged on the pipe of the hot air inlet 3, and a third temperature measuring device 8c is arranged on the pipe of the mixed flue gas outlet 5.

[0047] In a preferred embodiment, the flue gas mixer 300 further comprises an adjusting unit (not shown in the figure), which is used to collect the detection data of the oxygen-to-sulfur ratio analysis device and the temperature measuring device, and adjust the inlet flow rate of the hot air inlet 3 according to the detection data, so that the molar ratio of oxygen to sulfur in the mixed flue gas discharged from the mixed flue gas outlet 5 is greater than or equal to 0.6, thereby meeting the oxygen-to-sulfur ratio requirement of the subsequent converter 500 flue gas without the need for additional oxygen supplementing links; at the same time, the temperature of the mixed flue gas is greater than or equal to 150℃, thereby avoiding dew point corrosion of the flue gas on the subsequent equipment and pipelines and improving the service life of the equipment and pipelines.

[0048] In a specific embodiment, an adjusting valve 10 is arranged on the pipe of the hot air inlet 3, and the adjusting valve 10 is electrically connected with the adjusting unit. When the molar ratio of oxygen to sulfur in the mixed flue gas is less than 0.6 or the temperature is less than 150℃, the adjusting unit controls the adjusting valve 10 to self-adjust, thereby controlling the flow rate of the high-temperature air input into the flue gas mixer 300.

[0049] Obviously, the design of the present application is not limited to this. In another specific embodiment, adjusting valves 10 are arranged on the pipes of the flue gas inlet 4 and the hot air inlet 3, and the adjusting valves 10 are electrically connected with the adjusting unit. When the molar ratio of oxygen to sulfur in the mixed flue gas is less than 0.6 or the temperature is less than 150℃, the adjusting unit controls the adjusting valves 10 on the pipes of the flue gas inlet 4 and the hot air inlet 3 to self-adjust, thereby controlling the flow rates of the high-temperature air and the low-temperature wet flue gas input into the flue gas mixer 300.

[0050] In a preferred embodiment, the adjusting unit adjusts the inlet flow rate of the hot air inlet 3 according to the detection data, so that the molar ratio of oxygen to sulfur in the mixed flue gas discharged from the mixed flue gas outlet 5 is 1-1.3; and the temperature is 170-220℃.

[0051] In a preferred embodiment, the shell of the flue gas mixer 300 is made of carbon steel or stainless steel, which is resistant to high temperature, so that the service life of the flue gas mixer 300 is longer.

[0052] In a preferred embodiment, the inner lining 7 of the conical section 2 is made of graphite or acid-resistant ceramic tile, which is resistant to corrosion and high temperature, so that the conical section 2 can avoid corrosion of low-temperature wet flue gas or resist high-temperature mixed flue gas.

[0053] The thickness of the inner lining 7 of the conical section 2 is not limited in the present application and can be designed according to actual working conditions. In a specific embodiment, the thickness of the inner lining 7 of the conical section 2 is 10-40 mm, preferably 20-30 mm.

[0054] The specific setting mode of the mixed flue gas outlet 5 is not limited in the present application and can be a conventional setting mode in the art. In a specific embodiment, the high-temperature flue gas outlet is cylindrical and is inserted into the cylindrical section 1.

[0055] In the present application, the low-temperature wet flue gas entering the flue gas mixer 300 is ≥38℃, specifically 38-55℃.

[0056] In the present application, the water vapor in the wet flue gas reaches a saturated state.

[0057] In some embodiments, the preheated high-temperature air delivered to the flue gas mixer 300 through the hot air inlet 3 has a temperature ≥350℃, preferably 350-500℃.

[0058] Please refer to Figure 4In some embodiments, the working process of the flue gas mixer 300 includes: the preheated high-temperature air enters the flue gas mixer 300 from the air inlet of the flue gas mixer 300 in a spiral high speed, spirally moves downward along the inner wall of the cylindrical barrel section 1, after high-speed rotational mixing with the low-temperature wet flue gas entering from the flue gas inlet 4 at the lower part of the conical barrel section 2, turns upward, and rotates out of the mixed flue gas outlet 5 to form high-temperature flue gas entering the subsequent pipeline and equipment; wherein, the pipeline of the hot air inlet 3, the flue gas inlet 4 and the mixed flue gas outlet 5 is provided with a temperature measuring device to monitor the temperature of the medium entering and leaving the flue gas mixer 300; the pipeline of the mixed flue gas outlet 5 is provided with an oxygen and sulfur dioxide ratio analysis device to monitor the molar ratio of oxygen and sulfur dioxide in the mixed flue gas, and the adjusting unit is used to collect the detection data of the oxygen and sulfur dioxide ratio analysis device and the temperature measuring device, and adjust the air inlet flow of the hot air inlet 3 through the adjusting valve 10 according to the detection data to control the input high-temperature air flow, so that the molar ratio of oxygen and sulfur dioxide in the mixed flue gas discharged from the mixed flue gas outlet 5 is greater than or equal to 0.6, and the temperature is greater than or equal to 150 DEG C. Therefore, through the design of the flue gas mixer 300, the purpose of heating and oxygen supplementing of the low-temperature wet flue gas can be achieved, so that the dew point corrosion of the low-temperature flue gas to the subsequent equipment pipeline is solved, and the oxygen-sulfur ratio of the flue gas entering the converter 500 is ensured.

[0059] In order to improve the flue gas treatment capacity, please refer to Figure 5 In a preferred embodiment, the number of the shell in the flue gas mixer 300 is 2, and the two shells are arranged in parallel.

[0060] Obviously, the design of the utility model is not limited to this, but also can improve the flue gas treatment capacity by setting multiple flue gas mixers 300. In a preferred embodiment, the number of the flue gas mixer 300 in the system is 2, and the two flue gas mixers 300 are arranged in parallel. By setting two flue gas mixers 300, the treatment capacity of low-temperature wet flue gas can be improved, and the treatment time is short and the cost is low.

[0061] The utility model will be described in detail through examples below, but the protection scope of the utility model is not limited to this. The experimental method in the following examples is the conventional method in the field without special instructions. The experimental materials used in the following examples are commercially available products without special instructions.

[0062] Example 1

[0063] The method in this embodiment is implemented in the system for wet-process sulfuric acid production from sulfur-containing waste liquid according to the utility model, and the structure of the system is shown in Figure 1 .

[0064] The process flow for wet acid production from sulfur-containing wastewater includes: incinerating and pyrolyzing sulfur-containing wastewater (alkylated waste acid, composed of 90 wt% sulfuric acid, 6 wt% organic matter, and 4 wt% water) in an incinerator at a high temperature of 1100℃ to generate high-temperature flue gas containing components such as SO2, SO3, CO2, H2O, N2, and O2. After utilizing waste heat, the high-temperature flue gas is cooled to ~500℃, then cooled to ~350℃ in heat exchanger 400, and finally transported to purification unit 200 for acid washing and purification. After acid mist is removed by two-stage electrostatic precipitators, the resulting ~50°C wet flue gas is sent to flue gas mixer 300 to be mixed and heated with high-temperature air to obtain mixed flue gas with an oxygen-to-sulfur ratio of 1 and a temperature of ~170°C. The mixed flue gas is heated to ~420°C in heat exchanger 400 (heat exchanger 400 is made of 304L stainless steel, using ~500°C flue gas from the incinerator as a heat source) and then sent to converter 500 for catalytic oxidation to generate SO3. Then SO3 and water vapor are condensed to produce concentrated sulfuric acid.

[0065] Among them, the flue gas mixer 300 is referenced Figures 2-3 As shown, the flue gas mixer 300 has a vertical structure, including a shell, an upper cylindrical section 1, a lower conical section 2, a hot air inlet 3 on the side of the cylindrical section 1, a flue gas inlet 4 at the bottom of the conical section 2, a cylindrical mixed flue gas outlet 5 at the top of the cylindrical section 1, and four lugs 6 in the middle of the cylindrical section 1; the shell is made of 304L stainless steel; the inner lining 7 of the conical section 2 is a 20mm thick graphite lining.

[0066] The process flow of ~50°C humid flue gas from purification unit 200 and high-temperature air in flue gas mixer 300 (refer to...) Figure 4) includes: preheated 400℃ high temperature air from the air inlet of the flue gas mixer 300 at a flow rate of 20m / s, spirally high speed into the flue gas mixer 300, spirally downward along the inner wall of the cylindrical barrel section 1, after high speed rotation mixing with ~50℃ wet flue gas from the flue gas inlet 4, turn upward, and rotate out from the flue gas outlet, to obtain mixed flue gas, which enters the subsequent equipment; wherein the pipeline of the flue gas inlet 4 is provided with a first temperature measuring device 8a, the pipeline of the hot air inlet 3 is provided with a second temperature measuring device 8b, and the pipeline of the mixed flue gas outlet 5 is provided with a third temperature measuring device 8c, to monitor the temperature of the medium entering and leaving the flue gas mixer 300; the pipeline of the mixed flue gas outlet 5 is provided with an oxygen and sulfur dioxide ratio analysis device to monitor the molar concentration of oxygen and sulfur dioxide in the mixed flue gas, and the adjusting unit controls the adjusting valve 10 on the pipeline of the hot air inlet 3 according to the detection data of the oxygen and sulfur dioxide ratio analysis device to perform self-adjustment, so as to control the flow of the supplemented high temperature air, so that the oxygen-sulfur ratio in the mixed flue gas reaches 1, and the detection result of the third temperature measuring device 8c shows that the temperature of the mixed flue gas reaches ~170℃. The purpose of heating and supplementing oxygen for low-temperature wet flue gas is finally achieved, thereby solving the problem of dew point corrosion of low-temperature flue gas on the pipeline of the subsequent equipment, while ensuring the oxygen-sulfur ratio of the flue gas entering the converter 500.

[0067] The results show that the corrosion rate of the mixed flue gas on the equipment (heat exchanger 400) and the pipeline is about 0.1mm / a; after replacing the original ceramic membrane dust removal process with an acid pickling purification process, the content of dust in the flue gas can be greatly reduced, and the process can be continuously and stably operated for more than 4 years.

[0068] Comparative Example 1

[0069] This comparative example is used to illustrate the traditional method of wet-process sulfuric acid production from sulfur-containing waste liquid.

[0070] The sulfur-containing waste liquid (alkylated waste acid, composition including 90wt% sulfuric acid, 6wt% organic matter, and 4wt% water) is incinerated and cracked at a high temperature of 1100℃ in an incinerator to generate high-temperature flue gas containing SO2, SO3, CO2, H2O, N2, O2, etc., then after waste heat recovery and ceramic membrane dust removal, a certain amount of air is supplemented to adjust the oxygen-sulfur ratio to 1, and the flue gas is cooled to ~420℃ before being transported into the converter 500 for catalytic oxidation to generate SO3, and then SO3 and water vapor are condensed to produce concentrated sulfuric acid.

[0071] The results show that during operation, the ceramic membrane filter is prone to damage and blockage, resulting in a significant increase in the dust content of the flue gas, the catalyst bed of the converter 500 is prone to blockage, causing the bed pressure drop to rise, the heat exchange effect in the converter 500 is poor, dew point corrosion of the heat exchange tubes occurs, and the device needs to be shut down for maintenance every 3 months to half a year.

[0072] Comparative Example 2

[0073] The method is carried out according to the method described in Example 1, except that the purified low-temperature wet flue gas is not treated by the flue gas mixer 300, but is directly introduced into the heat exchanger 400 for temperature rising.

[0074] The results show that the purified low-temperature flue gas is easy to combine with water to condense sulfuric acid due to being below the dew point temperature, which causes corrosion to the equipment (heat exchanger 400) and pipeline, and the corrosion rate can reach more than 10 mm / a, which can cause corrosion perforation of the equipment (heat exchanger 400) and pipeline in no more than one month.

[0075] From the above Example 1 and Comparative Examples 1-2, it can be seen that the low-temperature flue gas is easy to combine with water to condense sulfuric acid due to being below the dew point temperature, which causes corrosion to the equipment and pipeline, and the corrosion rate can reach more than 10 mm / a, which can cause corrosion perforation of the equipment and pipeline in no more than one month; while the present application can reduce the flue gas corrosion rate to 0.1 mm / a by increasing the temperature of the low-temperature flue gas to above the dew point temperature by the flue gas mixer 300 and then introducing it into the heat exchanger 400 for heat exchange; the traditional sulfur-containing waste liquid wet acid-making process uses a ceramic membrane dust removal process, which results in high dust content in the flue gas after dust removal, causing the bed resistance of the first stage of the converter 500 to increase, and the converter 500 needs to be stopped for cleaning in about 3 months to 6 months; while the use of the pickling purification process instead of the original ceramic membrane dust removal process can greatly reduce the dust content in the flue gas, and the acid-making process can be continuously and stably operated for more than 4 years after the use of the pickling purification process.

[0076] The preferred embodiments of the present application are described in detail above, but the present application is not limited thereto. Within the technical concept of the present application, various simple modifications can be made to the technical solution of the present application, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be considered as disclosed by the present application, and all fall within the protection scope of the present application.

Claims

1. A system for wet acid production from sulfur-containing wastewater, characterized in that, The system includes an incineration unit (100), a purification unit (200), a flue gas mixer (300), a heat exchanger (400), and a converter (500) arranged sequentially along the material flow direction; The flue gas mixer includes a housing, which includes a cylindrical section (1) and a conical section (2) connected sequentially from top to bottom. The conical section (2) gradually narrows from top to bottom. The bottom of the conical section (2) is configured as a flue gas inlet (4). The side of the cylindrical section (1) is configured with a hot air inlet (3). The top of the cylindrical section (1) is configured with a mixed flue gas outlet (5). The hot air inlet (3) is configured to allow spiral or tangential air intake.

2. The system according to claim 1, characterized in that, The flue gas outlet of the incineration unit (100) is connected to the heat source inlet of the heat exchanger (400), and the heat source outlet of the heat exchanger (400) is connected to the inlet of the purification unit (200).

3. The system according to claim 1, characterized in that, The purification unit (200) includes a humidifier, a scrubbing tower, and a demister connected in sequence along the flue gas flow direction.

4. The system according to claim 1, characterized in that, The heat exchanger (400) is made of 304 stainless steel or 304L stainless steel.

5. The system according to claim 1, characterized in that, The number of flue gas mixers (300) is two, and the two flue gas mixers (300) are arranged in parallel; and / or The flue gas mixer (300) has two housings connected in parallel.

6. The system according to any one of claims 1-5, characterized in that, In the flue gas mixer (300), an ear seat (6) is provided in the middle of the side wall of the cylindrical section (1).

7. The system according to claim 6, characterized in that, In the flue gas mixer (300), the ear seat (6) is located below the hot air inlet (3).

8. The system according to any one of claims 1-5, characterized in that, In the flue gas mixer, an oxygen to sulfur dioxide ratio analyzer is installed on the pipe of the mixed flue gas outlet (5); a temperature measuring device is installed on the pipes of the flue gas inlet (4), the hot air inlet (3) and the mixed flue gas outlet (5).

9. The system according to claim 8, characterized in that, The flue gas mixer also includes an adjustment unit, which is used to collect the detection data of the oxygen to sulfur dioxide ratio analysis device and the temperature measuring device, and adjust the air flow rate of the hot air inlet (3) according to the detection data, so that the molar ratio of oxygen to sulfur dioxide in the mixed flue gas discharged from the mixed flue gas outlet (5) is greater than or equal to 0.6 and the temperature is greater than or equal to 150°C.

10. The system according to any one of claims 1-5, characterized in that, The casing of the flue gas mixer is made of carbon steel or stainless steel, and the inner lining (7) of the conical section (2) is made of graphite or acid-resistant ceramic tile.

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