Industrial sulfuric acid preparation process capable of recycling heat

Abstract

The invention relates to a sulfuric acid preparation device, in particular to an industrial sulfuric acid preparation process capable of recycling heat, which comprises the following steps: transporting liquid sulfur into a liquid sulfur storage tank, and atomizing and combusting refined sulfur through a sulfur burning furnace; air is sucked into the system through an air filter, is dried by a drying tower, enters a main fan and then enters a sulfur burning furnace, and the temperature in the sulfur burning furnace is further increased to burn sulfur into sulfur dioxide; high-temperature flue gas discharged by the sulfur burning furnace enters the waste heat boiler to be cooled and then is discharged into the converter; the flue gas is subjected to heat exchange in the first layer, the second layer and the third layer of the converter, is discharged into a cold intermediate heat exchanger and a first economizer for heat exchange, and then enters an HRS system; after being treated by the HRS system, the gas enters a fourth layer of the converter and then is discharged into a first superheater to be cooled; and then the flue gas enters an HRS low-pressure steam superheater, after the temperature of the flue gas is reduced, the flue gas is discharged into a second economizer to complete flue gas cooling, and finally, the flue gas enters a tail gas absorption device through a second absorption tower and is discharged to the atmosphere through a chimney.

Description

Technical Field

[0001] The present invention relates to a sulfuric acid production device, specifically an industrial sulfuric acid production process capable of heat recovery. Background Art

[0002] Sulfuric acid is the most active dibasic inorganic strong acid and can react with many metals. Concentrated sulfuric acid has strong water absorption and can be used as a dehydrating agent to carbonize carbohydrates-containing substances such as wood, paper, cotton and linen fabrics, and biological skin and flesh. When mixed with water, it also releases a large amount of heat energy. It has strong corrosiveness and oxidizing property, so it needs to be used with caution. It is an important industrial raw material and can be used to manufacture fertilizers, drugs, explosives, pigments, detergents, storage batteries, etc. It is also widely used in industries such as petroleum purification, metal smelting, and dyes. It is commonly used as a chemical reagent and can be used as a dehydrating agent and sulfonating agent in organic synthesis.

[0003] The production process of sulfuric acid is complex, requires long-term operation, and has low production efficiency. At present, when producing sulfuric acid, sulfur-based acid production or pyrite-based acid production can be adopted. The whole process generates sulfur dioxide by combustion, and then catalytically oxidizes sulfur dioxide to sulfur trioxide. Finally, sulfur trioxide reacts with concentrated sulfuric acid for absorption to generate sulfuric acid. In order to ensure the normal progress of each stage of the reaction, it is necessary to accurately control the temperature throughout the process by inputting external energy, which results in high energy consumption in the whole sulfuric acid production process. Moreover, in the above-mentioned exothermic reaction processes, the released heat cannot be utilized, which causes waste of resources. Summary of the Invention

[0004] The purpose of the present invention is to provide an industrial sulfuric acid production process capable of heat recovery to solve the problems raised in the above background art.

[0005] Glossary: The HRS system is a heat recovery system used to absorb sulfur trioxide and condense sulfuric acid from flue gas, and at the same time recover the heat in the absorption and condensation processes and convert it into low-pressure steam.

[0006] To achieve the above purpose, the present invention provides the following technical solutions:

[0007] An industrial sulfuric acid production process capable of heat recovery, comprising: Step 1: Use a tank truck to transport the required liquid sulfur to the liquid sulfur storage tank, and then send the refined sulfur to the sulfur gun of the sulfur burner for atomization combustion through the sulfur burner feed pump;

[0008] Step 2: Air is inhaled into the system through an air filter, and then enters the main fan after being dried by a drying tower circulating 93-95% sulfuric acid. Subsequently, the air enters the sulfur burner. The temperature of the air in the sulfur burner is further increased, and the sulfur is burned into sulfur dioxide;

[0009] Step 3: The high-temperature flue gas containing sulfur dioxide discharged from the sulfur-burning furnace enters the waste heat boiler for cooling, and the waste heat is recovered in the form of high-pressure saturated steam at 5.6 MPa. Then, it is discharged from the waste heat boiler and enters the converter.

[0010] Step 4: After the flue gas undergoes heat exchange in the first, second, and third layers of the converter in sequence, it is discharged into the cold intermediate heat exchanger and the first economizer for heat exchange, and then enters the HRS system.

[0011] Step 5: The flue gas treated by the HRS system enters the cold intermediate heat exchanger and the hot intermediate heat exchanger successively. Under the heating of the hot gas discharged from the second and third layers of the converter, it is further heated and then enters the fourth layer of the converter. After reaching the specified temperature, it is discharged into the first superheater for cooling.

[0012] Step 6: The cooled flue gas enters the HRS low-pressure steam superheater. When the flue gas drops to the specified temperature, it is discharged into the second economizer to complete the cooling of the flue gas. Then, after passing through the second absorption tower, the flue gas enters the tail gas absorption device.

[0013] Step 7: After the tail gas absorption device absorbs sulfur dioxide and acid mist in the tail gas, it is discharged into the atmosphere through the chimney.

[0014] The industrial sulfuric acid production process capable of heat recovery as described above: In the above-mentioned Step 4, when the flue gas enters the first layer of the converter, under the action of vanadium catalyst, part of the sulfur dioxide is converted into sulfur trioxide, and heat is generated during the reaction. Subsequently, the flue gas leaves the first layer of the converter and enters the second superheater, and is cooled by further heating the superheated high-pressure steam. The cooled flue gas enters the second layer of the converter from the superheater.

[0015] The industrial sulfuric acid production process capable of heat recovery as described above: The sulfur dioxide entering the second layer of the converter can continue to react in the second layer of the converter to produce sulfur trioxide and generate heat at the same time. After the flue gas leaves the second layer of the converter, it is cooled by the hot intermediate converter, and then enters the third layer of the converter for continuous reaction. After the flue gas is heated up, the hot flue gas leaves the third layer and enters the heat exchanger and the first economizer.

[0016] The industrial sulfuric acid production process capable of heat recovery as described above: In the above-mentioned Step 4, in order to utilize the extra heat generated when sulfuric acid steam is formed, when the flue gas leaves the first economizer, low-pressure steam is injected into the first economizer. The low-pressure steam can obtain the extra heat generated during the humidification of the flue gas and be converted into medium-pressure steam, thus increasing the total output.

[0017] The industrial sulfuric acid production process capable of heat recovery as described above: In the fifth step, the HRS system includes an HRS heat recovery tower, which can absorb sulfur trioxide and condense sulfuric acid from the flue gas, while recovering the heat during the absorption and condensation processes and converting it into low-pressure steam. After the flue gas passes through the HRS heat recovery tower, the flue gas enters a demister installed at the top of the HRS heat recovery tower, and the demister can remove the acid mist formed in the tower until it is the same as the traditional first absorption tower, so as to protect the downstream cold intermediate heat converter.

[0018] The industrial sulfuric acid production process capable of heat recovery as described above: In the sixth step, after the flue gas enters the second absorption tower, sulfur trioxide in the flue gas reacts with the water in the circulating acid with a concentration of 98.5% in the second absorption tower. Subsequently, the temperature of the circulating acid in the second absorption tower increases due to the heat of reaction and the heat brought into the tower by the combined gas. Then, it is removed by circulating cooling water so that the second absorption tower can continuously absorb the acid temperature.

[0019] The industrial sulfuric acid production process capable of heat recovery as described above: In the seventh step, the tail gas absorption device includes a tail gas absorption tower. The flue gas vertically enters the top of the reverse spray feed pipe of the tail gas absorption tower and makes reverse contact with the absorption liquid sprayed out by the tail gas absorption nozzle with large-diameter openings and no blockage to form a foam area, so as to quickly reduce the temperature of the flue gas and absorb SO2. Subsequently, the gas-liquid mixture enters the packing layer, the liquid falls into the liquid collection tank at the bottom of the tower, and the flue gas enters a double-layer baffle demister to remove the entrained liquid droplets and then enters the chimney for up-to-standard high-altitude emission.

[0020] The industrial sulfuric acid production process capable of heat recovery as described above: When the flue gas discharges outwards through the packing layer, the flue gas will carry away some moisture. To stabilize the liquid level of the liquid collection tank at the bottom of the tower, the make-up water automatic control valve installed in the tail gas absorption tower can appropriately add demineralized water to the tank according to the liquid level of the liquid collection tank of the tail gas absorption tower.

[0021] Compared with the prior art, the beneficial effects of the present invention are:

[0022] By recovering the waste heat of the high-temperature flue gas through a waste heat boiler to generate 5.6 MPa high-pressure saturated steam, it can be used for other production processes, thereby reducing the input of external energy and improving the energy utilization rate. When the steam generated by the waste heat boiler enters the HRS system for conversion through the first economizer, low-pressure steam is injected into the first economizer by the flue gas. The low-pressure steam can obtain the additional heat generated during the humidification of the flue gas and be converted into medium-pressure steam, increasing the total output;

[0023] During the process of sulfur dioxide entering the converter for the conversion into sulfur trioxide, as the flue gas flows through the converter, the cold intermediate heat exchanger, the hot intermediate heat exchanger, and the HRS heat recovery tower, heat can be recovered step by step. The recovered heat can be used to heat the steam and maintain the reaction temperature, thereby improving the overall conversion efficiency.

[0024] Meanwhile, during the process of the hot gas flowing, by combining the cooling regulation of the second superheater and the hot intermediate heat exchanger, the temperature of each layer of flue gas can be controlled at an appropriate temperature, thereby maximizing the activity of the vanadium catalyst and increasing the conversion rate of sulfur dioxide. Detailed implementation mode

[0025] The following will detail various exemplary embodiments, features, and aspects of the present application. The special term "exemplary" here means "serving as an example, embodiment, or illustrative". Any embodiment described as "exemplary" here does not necessarily have to be construed as superior to or better than other embodiments.

[0026] In addition, for a better illustration of the present application, numerous specific details are given in the following specific embodiments. Those skilled in the art should understand that the present application can also be implemented without certain specific details. In some instances, methods, means, and elements well-known to those skilled in the art are not described in detail in order to highlight the gist of the present application.

[0027] In an embodiment of the present invention, an industrialized sulfuric acid production process capable of heat recovery includes:

[0028] Step 1: Use a tank truck to transport the required liquid sulfur to the liquid sulfur storage tank, and then send the refined sulfur to the sulfur gun of the sulfur burner for atomized combustion through the sulfur burner feed pump.

[0029] Step 2: Air is inhaled into the system through an air filter, and then enters the main blower after being dried by the drying tower with 93 - 95% sulfuric acid circulation. Subsequently, the air enters the sulfur burner. The temperature of the air in the sulfur burner is further increased, and the sulfur is burned into sulfur dioxide.

[0030] Specifically, after the air enters the drying tower, the flowing air can take away part of the heat of the acid in the drying tower. Subsequently, this part of the heat plus the compression heat of the main blower adjusts the temperature of the air entering the horizontal sulfur burner (about 118°C). Subsequently, sulfur in the sulfur burner burns to form sulfur dioxide. The specific chemical reaction equation is as follows:

[0031] S + O2 → SO2, the heat generated during combustion, ΔH = -297.23 kJ / mol.

[0032] Subsequently, the temperature of the flue gas containing sulfur dioxide leaving the sulfur-burning furnace reaches 1000 - 1150 °C, which is higher than the required temperature of the catalyst. This high-temperature flue gas needs to be cooled by a waste heat boiler for subsequent conversion of sulfur dioxide.

[0033] Step 3: The high-temperature flue gas containing sulfur dioxide discharged from the sulfur-burning furnace enters the waste heat boiler for cooling, and the waste heat is recovered in the form of 5.6 MPa high-pressure saturated steam, and then discharged from the waste heat boiler and enters the converter.

[0034] In particular, the 5.6 MPa high-pressure saturated steam generated by the waste heat boiler can be used in other production processes, such as vinyl acetate plants and air separation plants.

[0035] Step 4: After the flue gas undergoes heat exchange in the first, second, and third layers of the converter in sequence, it is discharged into the cold intermediate heat exchanger and the first economizer for heat exchange, and then enters the HRS system.

[0036] In the above Step 4, the flue gas entering the first layer of the converter, under the action of vanadium catalyst, partially converts sulfur dioxide into sulfur trioxide (reaction exothermic). Subsequently, the flue gas leaves the first layer of the converter and enters the second superheater. Here, the second superheater uses a high-temperature superheater, and is cooled by further heating the superheated high-pressure steam. The cooled flue gas enters the second layer of the converter from the second superheater.

[0037] Specifically, after the above flue gas leaves the waste heat boiler, the flue gas temperature drops to 421 °C. Subsequently, the flue gas enters the first layer of the converter, and under the action of vanadium catalyst, partially converts sulfur dioxide into sulfur trioxide. The specific chemical reaction formula is as follows:

[0038] SO2 + 1 / 2O2 → SO3, during which heat is generated, ΔΗ = -98.32 kJ / mol.

[0039] The heat generated by the reaction will cause the temperature of the flue gas to rise. At this time, the flue gas must be cooled before the conversion rate of sulfur dioxide in the next catalyst layer can be increased.

[0040] The temperature of the flue gas when it leaves the first layer of the converter reaches 621 °C. Subsequently, the flue gas enters the second superheater and is cooled by further heating the superheated high-pressure steam. The temperature of the steam and the inlet temperature of the flue gas in the second layer (435 °C) are controlled by a steam bypass around the superheater. Subsequently, the cooled flue gas enters the second layer of the converter.

[0041] The sulfur dioxide entering the second layer of the converter can continue to react in the second layer of the converter to produce sulfur trioxide while generating heat. After the flue gas leaves the second layer of the converter, the temperature of the flue gas drops to 517 °C and is cooled by the hot intermediate converter, thereby increasing the conversion rate of sulfur dioxide in the next layer. In particular, after heat exchange in the hot intermediate heat exchanger, the temperature of the flue gas drops to 435 °C, and then the flue gas leaves the hot intermediate heat exchanger and enters the third layer of the converter for continuous reaction. During this process, after the temperature of the flue gas rises to 458 °C, the hot flue gas leaves the third layer and enters the heat exchanger and the first economizer for further cooling, thereby increasing the conversion rate of sulfur dioxide in the fourth layer of the converter.

[0042] In particular, during the above process, to utilize the additional heat generated when sulfuric acid vapor is formed, when the flue gas leaves the first economizer, low-pressure steam is injected into the first economizer. The low-pressure steam can obtain the additional heat generated during the humidification of the flue gas and be converted into medium-pressure steam, increasing the total output.

[0043] Step Five: The flue gas treated by the HRS system enters the cold intermediate heat exchanger and the hot intermediate heat exchanger successively, and is further heated by the hot gas discharged from the second and third layers of the converter, and then enters the fourth layer of the converter. After reaching the specified temperature, it is discharged into the first superheater for cooling;

[0044] Specifically, in Step Five, the HRS system includes an HRS heat recovery tower. The HRS heat recovery tower can absorb sulfur trioxide and condensed sulfuric acid from the flue gas, and at the same time recover the heat during the absorption and condensation processes and convert it into low-pressure steam. After the flue gas passes through the HRS heat recovery tower, the flue gas enters a demister installed at the top of the HRS heat recovery tower, and the demister can remove the acid mist formed in the tower until it is the same as the traditional first absorption tower to protect the downstream cold intermediate heat converter.

[0045] Specifically, a Monsanto ES type demister is installed at the top of the above HRS heat recovery tower. The demister can remove the acid mist formed in the tower. After passing through the HRS heat recovery tower, the temperature of the flue gas drops to 71 °C. At this time, the flue gas discharged from the HRS heat recovery tower still contains unreacted sulfur dioxide. After these sulfur dioxides enter the cold intermediate heat exchanger, they are heated by the hot gas leaving the third layer of the converter, and then enter the hot intermediate heat exchanger again and are further heated by the hot gas leaving the second layer of the converter. Finally, the temperature of the flue gas discharged from the hot intermediate heat exchanger rises to 425 °C, and then the flue gas will enter the fourth layer of the converter. The temperature of the fourth layer of the converter is controlled by the gas bypass around the hot intermediate heat exchanger. When the flue gas passes through the fourth layer of the converter, part of the sulfur dioxide is converted into sulfur trioxide, and during the reaction, the heat released further raises the temperature of the flue gas to 443 °C.

[0046] Subsequently, the flue gas enters the first superheater and is cooled by further heating the superheated high-pressure steam. The flue gas (361°C) leaving the first superheater enters the HRS low-pressure steam superheater.

[0047] Step 6: The cooled flue gas enters the HRS low-pressure steam superheater. When the flue gas drops to the specified temperature, it is discharged into the second economizer to complete the flue gas cooling. Subsequently, after passing through the second absorption tower, the flue gas enters the tail gas absorption device.

[0048] In Step 6 described above, after the flue gas enters the second absorption tower, sulfur trioxide in the flue gas reacts with the water in the circulating acid with a concentration of 98.5% in the second absorption tower.

[0049] Specifically, the temperature of the circulating acid in the second absorption tower is 75°C. After entering the second absorption tower, sulfur trioxide reacts with water to form sulfuric acid. The chemical reaction formula is as follows:

[0050] SO3 + H2O → H2SO4, and heat is generated during this process, ΔΗ = -130 kJ / mol.

[0051] Subsequently, the temperature of the circulating acid in the second absorption tower increases due to the heat of reaction and the heat brought into the tower by the combined gas. Then, the heat is removed by the circulating cooling water to enable the second absorption tower to continuously absorb the acid temperature.

[0052] Particularly, the circulating acid at the bottom of the second absorption tower enters the area of the second absorption tower in the pump sump. Part of the circulating acid that has desorbed sulfur dioxide and returns from the drying tower is mixed with the hot circulating acid from the second absorption tower to control the concentration of the circulating acid in the second absorption tower. If the acid concentration exceeds 98.5%, process water is added to maintain the acid concentration. After being cooled by the acid cooler of the second absorption tower, the required amount of circulating acid is pumped back to the second absorption tower (part enters the second stage of the HRS tower), which helps to reduce the sulfur dioxide emissions from the chimney. 93% of the circulating acid in the common pump sump drying tower area is pumped into the drying acid cooler (part of the acid enters the HRS diluter before the drying acid cooler in high humidity), and after being cooled by the drying acid cooler, it enters the drying tower.

[0053] 98.5% of the product acid in the second absorption tower area is pumped into the product acid cooler, cooled to 40°C Celsius, and then sent to the finished acid storage tank.

[0054] Step 7: After the tail gas absorption device absorbs sulfur dioxide and acid mist in the tail gas, it is discharged into the atmosphere through the chimney.

[0055] Specifically, in the seventh step, the tail gas absorption device includes a tail gas absorption tower. The flue gas vertically enters the top of the reverse spray feed pipe of the tail gas absorption tower and makes reverse contact with the absorption liquid sprayed out by the non-clogging tail gas absorption nozzle with a large-diameter opening to form a foam area, so as to rapidly reduce the temperature of the flue gas and absorb SO2. Subsequently, the gas-liquid mixture enters the packing layer, the liquid falls into the liquid collection tank at the bottom of the tower, and the flue gas enters the double-layer baffle demister to remove the entrained liquid droplets and then enters the chimney for up-to-standard emission at high altitude.

[0056] The absorption liquid in the liquid collection tank at the bottom of the tower is transported to the packing layer for spraying through a circulation pump. First, hydrogen peroxide, the oxidant, is pumped from the hydrogen peroxide tank in the finished product tank area to the hydrogen peroxide intermediate tank through a hydrogen peroxide pump, and then, according to the density of the circulating absorption liquid, it is fed into the circulating absorption liquid at the outlet of the circulation pump through a hydrogen peroxide metering pump, so that sulfurous acid in the circulating absorption liquid is oxidized to sulfuric acid. When the density of the circulating absorption liquid reaches the specified value, the dilute sulfuric acid is sent to the dilute sulfuric acid tank through a drain self-control valve, and then sent to the second absorption acid circulation tank through a dilute sulfuric acid pump as the absorption acid for sulfuric acid production.

[0057] Particularly, when the flue gas is discharged outwards through the packing layer, the flue gas will carry away some moisture. To stabilize the liquid level of the liquid collection tank at the bottom of the tower, the make-up water self-control valve installed in the tail gas absorption tower can appropriately add demineralized water into the tank according to the liquid level of the liquid collection tank of the tail gas absorption tower.

[0058] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and without departing from the spirit or basic characteristics of the present invention, the present invention can be implemented in other specific forms. Therefore, in any regard, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be encompassed by the present invention.

[0059] In addition, it should be understood that although this specification is described according to the embodiments, not every embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. An industrial sulfuric acid production process capable of heat recovery, characterized in that, Including: Step 1: Use a tank truck to transport the required liquid sulfur into the liquid sulfur storage tank, and then send the refined sulfur to the sulfur gun of the sulfur burning furnace for atomization and combustion through the sulfur burning furnace feed pump; Step 2: Air is inhaled into the system through an air filter, and then enters the main blower after being dried by a drying tower circulated with 93-95% sulfuric acid. Subsequently, the air enters the sulfur burning furnace, and the air temperature in the sulfur burning furnace is further increased to burn sulfur into sulfur dioxide; Step 3: The high-temperature flue gas containing sulfur dioxide discharged from the sulfur burning furnace enters the waste heat boiler for cooling, and the waste heat is recovered in the form of 5.6 MPa high-pressure saturated steam, and then discharged from the waste heat boiler and enters the converter; Step 4: After the flue gas undergoes heat exchange in the first layer, second layer, and third layer of the converter in sequence, it is discharged into the cold intermediate heat exchanger and the first economizer for heat exchange, and then enters the HRS system; Step 5: The flue gas processed by the HRS system enters the cold intermediate heat exchanger and the hot intermediate heat exchanger successively, and is further heated by the hot gas discharged from the second layer and the third layer of the converter, and then enters the fourth layer of the converter. After reaching the specified temperature, it is discharged into the first superheater for cooling; Step 6: The cooled flue gas enters the HRS low-pressure steam superheater. When the flue gas drops to the specified temperature, it is discharged into the second economizer to complete the flue gas cooling. Subsequently, the flue gas enters the tail gas absorption device after passing through the second absorption tower; Step 7: After the tail gas absorption device absorbs sulfur dioxide and acid mist in the tail gas, it is discharged into the atmosphere through a chimney.

2. The industrial sulfuric acid production process capable of heat recovery according to claim 1, wherein, In the above Step 4, when the flue gas enters the first layer of the converter, under the action of vanadium catalyst, part of the sulfur dioxide is converted into sulfur trioxide, and heat is generated during the reaction. Subsequently, the flue gas leaves the first layer of the converter and enters the second superheater, and is cooled by further heating the superheated high-pressure steam. The cooled flue gas enters the second layer of the converter from the superheater.

3. The industrial sulfuric acid production process capable of heat recovery according to claim 2, characterized in that, The sulfur dioxide entering the second layer of the converter can continue to react in the second layer of the converter to produce sulfur trioxide and generate heat at the same time. After the flue gas leaves the second layer of the converter, it is cooled by the hot intermediate converter, and then enters the third layer of the converter for continuous reaction. After the flue gas is heated up, the hot flue gas leaves the third layer and enters the heat exchanger and the first economizer.

4. The industrial sulfuric acid production process capable of heat recovery according to claim 1, characterized in that, In the above Step 4, in order to utilize the extra heat generated when sulfuric acid vapor is formed, when the flue gas leaves the first economizer, low-pressure steam is injected into the first economizer. The low-pressure steam can obtain the extra heat generated during the humidification of the flue gas and be converted into medium-pressure steam, thereby increasing the total output.

5. A process for the industrial production of sulfuric acid capable of heat recovery according to claim 1, characterized in that, In the above Step 5, the HRS system includes an HRS heat recovery tower. The HRS heat recovery tower can absorb sulfur trioxide and condensed sulfuric acid from the flue gas, and at the same time recover the heat during the absorption and condensation processes and convert it into low-pressure steam. And after the flue gas passes through the HRS heat recovery tower, the flue gas enters a demister installed at the top of the HRS heat recovery tower, and the demister can remove the acid mist formed in the tower until it is the same as the traditional first absorption tower, so as to protect the downstream cold intermediate heat converter.

6. The industrial sulfuric acid production process capable of heat recovery according to claim 1, characterized in that, In Step 6, after the flue gas enters the second absorption tower, sulfur trioxide in the flue gas reacts with the water in the circulating acid with a concentration of 98.5% in the second absorption tower. Subsequently, the temperature of the circulating acid in the second absorption tower increases due to the heat of reaction and the heat brought into the tower by the combined gas. Then, it is removed by the circulating cooling water so that the second absorption tower can continuously absorb the acid temperature.

7. A process for industrially producing sulfuric acid capable of heat recovery according to claim 1, characterized in that, In Step 7, the tail gas absorption device includes a tail gas absorption tower. The flue gas vertically enters the top of the reverse spray feed pipe of the tail gas absorption tower and makes reverse contact with the absorption liquid sprayed out by the tail gas absorption nozzle with large-diameter open holes without blockage to form a foam zone, so as to rapidly reduce the temperature of the flue gas and absorb SO2. Subsequently, the gas-liquid mixture enters the packing layer, the liquid falls into the liquid collecting tank at the bottom of the tower, and the flue gas enters the double-layer baffle demister to remove the entrained liquid droplets and then enters the chimney for up-to-standard emission at high altitude.

8. An industrial sulfuric acid production process capable of heat recovery according to claim 7, characterized in that, When the flue gas is discharged outwards through the packing layer, the flue gas will carry away some moisture. To stabilize the liquid level of the liquid collecting tank at the bottom of the tower, the make-up water automatic control valve installed in the tail gas absorption tower can appropriately add demineralized water into the tank according to the liquid level of the liquid collecting tank in the tail gas absorption tower.