Secondary incineration treatment system and process for sulfur-containing tail gas in sulfuric acid production process

Abstract

The invention discloses a secondary incineration treatment system and process for sulfur-containing tail gas in the sulfuric acid production process. The secondary incineration treatment system comprises a dry powder incineration and waste heat recovery section, a flue gas purification and drying section, a flue gas conversion and absorption section and a tail gas treatment section. The dry powder incineration and waste heat recovery section comprises a concentration filter, a drying machine, a dry powder bin, a sulfur burning furnace and a waste heat boiler which are connected in sequence, and the sulfur burning furnace is further connected with an air blower; the flue gas purifying and drying section comprises a dynamic wave washer, a cooling tower, an electric demister, a drying tower and a sulfur dioxide blower which are connected in sequence; the flue gas conversion and absorption section comprises a third heat exchanger, a first electric heating furnace, a first heat exchanger, a five-section conversion bed layer, a fifth heat exchanger and a second absorption tower which are connected in sequence; the tail gas treatment section comprises a tail gas desulfurization tower, a tail gas denitration tower and a tail gas chimney which are connected in sequence. The method has the advantages that the environment-friendly sudden emission accidents can be prevented and treated, the hidden danger of environment pollution is effectively solved, and the environment-friendly accidents are completely eradicated.

Description

Technical Field

[0001] This invention relates to the field of tail gas treatment technology, and in particular to a secondary incineration treatment system and process for sulfur-containing tail gas in sulfuric acid production. Background Technology

[0002] Currently, sulfuric acid production from coking plant flue gas is a process that utilizes sulfur dioxide-containing flue gas generated during the combustion of dry sulfur powder to produce and prepare sulfuric acid. The traditional treatment process is: tail gas desulfurization → tail gas denitrification → chimney discharge. In the traditional tail gas treatment process, it is impossible to prevent and deal with environmental pollution incidents, which can easily cause tail gas chimney emission indicators to exceed the standards. When production abnormalities or improper operation occur, a large amount of yellow smoke may even be emitted, which not only poses a hidden danger of environmental pollution, but also carries the risk of environmental accidents that will have an adverse impact on the company's reputation. Summary of the Invention

[0003] The purpose of this invention is to provide a secondary incineration treatment system and process for sulfur-containing tail gas in the sulfuric acid production process, which can prevent and treat environmental pollution incidents, effectively solve potential environmental pollution hazards, and prevent environmental accidents.

[0004] The above-mentioned technical objective of the present invention is achieved through the following technical solution: A secondary incineration treatment system for sulfur-containing tail gas in sulfuric acid production process is characterized by comprising a dry powder incineration and waste heat recovery section, a flue gas purification and drying section, a flue gas conversion and absorption section, and a tail gas treatment section. The dry powder incineration and waste heat recovery section includes a concentration filter, a dryer, a dry powder silo, a sulfur incineration furnace and a waste heat boiler connected in sequence. The sulfur incineration furnace is also connected to an air blower. The flue gas purification and drying section includes a dynamic wave scrubber, a cooling tower, an electrostatic precipitator, a drying tower, and a sulfur dioxide blower connected in sequence. The dynamic wave scrubber is connected to a waste heat boiler. The flue gas conversion and absorption section includes a third heat exchanger, a first electric heating furnace, a first heat exchanger, a five-stage conversion bed, a fifth heat exchanger, and a second absorption tower connected in sequence. The third heat exchanger is connected to a sulfur dioxide blower. The exhaust gas treatment section includes an exhaust gas desulfurization tower, an exhaust gas denitrification tower, and an exhaust gas chimney connected in sequence, wherein the exhaust gas desulfurization tower is connected to the second absorption tower.

[0005] Preferably, the acid outlet of the drying tower is further connected in sequence to a drying acid circulation tank, a drying acid circulation pump, and a drying acid cooler, and the outlet of the drying acid cooler is connected to the acid inlet of the drying tower.

[0006] Preferably, the five-stage conversion bed includes a first conversion bed, a second conversion bed, a third conversion bed, a fourth conversion bed, and a fifth conversion bed. The fifth heat exchanger is also sequentially connected to a fourth heat exchanger, a second heating furnace, and a second heat exchanger. The first conversion bed and the first heat exchanger are connected end-to-end. The first heat exchanger is also connected to the second conversion bed. The second conversion bed is connected to the second heat exchanger. The second heat exchanger is connected to the third conversion bed and the fourth conversion bed. The third conversion bed is connected to the third heat exchanger. The fourth conversion bed is connected to the fourth heat exchanger. The fourth heat exchanger is also connected to the fifth conversion bed. The fifth conversion bed is connected to the fifth heat exchanger.

[0007] Preferably, the second absorption tower is also connected to an absorption circulation tank, the absorption circulation tank is connected to an absorption acid cooler via an absorption circulation pump, the absorption acid cooler is also connected to a first absorption tower, the first absorption tower is also connected to a third heat exchanger, a fifth heat exchanger, and the absorption circulation tank, the absorption circulation pump is also connected to a product acid tank, and the absorption acid cooler is also connected to a drying tower via a series acid pipeline.

[0008] Preferably, the outlet of the regenerated acid liquid of the tail gas desulfurization tower is connected to a regenerated acid circulation tank, and the regenerated acid circulation tank is sprayed back into the tail gas desulfurization tower by a regenerated circulation pump.

[0009] Preferably, the desulfurized tail gas outlet of the tail gas desulfurization tower is also directly connected to the tail gas chimney via a tail gas bypass pipe, bypassing the tail gas denitrification tower.

[0010] Preferably, the exhaust gas chimney is also equipped with an exhaust gas secondary combustion pipe connected to an air blower. The exhaust gas secondary combustion pipe has two U-shaped bends at the front end of the air blower and is connected to a drain valve group to drain the liquid to the process low-level tank. An adjustable flap valve is installed at the connection port between the exhaust gas secondary combustion pipe and the air blower. A quick-shut-off valve is installed one meter above the outlet point of the exhaust gas chimney and the exhaust gas secondary combustion pipe.

[0011] A process for a secondary incineration treatment system for sulfur-containing tail gas during sulfuric acid production is described below: The dilute sulfur foam sent from the coking desulfurization unit is filtered to form concentrated sulfur foam with a total solids content of about 35% to 45%. The concentrated sulfur foam is then pumped to a dryer for evaporation and drying to produce sulfur powder. Sulfur powder is transported to the furnace hopper via a tubular chain conveyor, and then conveyed to the sulfur incinerator via a belt conveyor. An air blower is connected to the outside of the sulfur incinerator to blow a large amount of air into the furnace, so that the sulfur powder can undergo a complete combustion reaction in the sulfur incinerator, generating flue gas containing SO2. The high-temperature flue gas exiting the sulfur incinerator reaches 800~1150℃, and is cooled to 230℃~350℃ by heat exchange in a waste heat boiler. The boiler water in the waste heat boiler exchanges heat with the high-temperature flue gas and vaporizes to generate steam to recover the high-temperature waste heat. The flue gas from the waste heat boiler is humidified, cooled, and pre-washed by a dynamic wave scrubber. Then the flue gas enters the cooling tower and comes into countercurrent contact with the cooling circulating dilute acid sprayed at the top of the tower. The flue gas is cooled, condensed, and washed again to remove water vapor and impurities. Then it enters the electrostatic precipitator to remove acid mist. The flue gas from the electrostatic precipitator enters the drying tower, where it comes into contact with 93% concentrated sulfuric acid to remove moisture. The gas is then pressurized by a sulfur dioxide blower and sent to the flue gas conversion and absorption section. After being dried, the cold SO2 flue gas is pressurized by a sulfur dioxide blower and then passes sequentially through the third heat exchanger, the first electric heating furnace, and the shell side of the first heat exchanger. It undergoes indirect heat exchange with the corresponding high-temperature converted gas, gradually being heated to 420°C before entering the converter. After conversion in the first conversion bed, the flue gas temperature rises to 585°C and enters the tube side of the first heat exchanger, where it undergoes indirect heat exchange with the hot SO2 flue gas from the third heat exchanger. The temperature drops to 460°C before entering the second conversion bed for further catalytic reaction. The temperature rises to 510°C before exiting the second conversion bed and entering the tube side of the second heat exchanger, where it undergoes indirect heat exchange with the hot SO2 flue gas from the fourth and fifth heat exchangers. After cooling to 440°C, it enters the third conversion bed of the converter for further reaction. The gas exiting the third conversion bed enters the tube side of the third heat exchanger, where it undergoes heat exchange and cooling with the cold flue gas from the sulfur dioxide blower. After cooling to 175°C, it enters the first absorption tower for primary absorption. The gas absorbed in the first absorption tower passes through the shell side of the fifth, fourth, and second heat exchangers in sequence, where it undergoes indirect heat exchange with the corresponding high-temperature converted gas. After being heated to 420°C, it enters the fourth conversion bed for a second conversion. The gas exiting the fourth conversion bed enters the tube side of the fourth heat exchanger, where it exchanges heat with the cold flue gas from the first absorption tower. After being cooled to 415°C, it enters the fifth conversion bed of the converter to continue the reaction. The gas in the fifth conversion bed passes through the tube side of the fifth heat exchanger, where it exchanges heat with the cold flue gas from the first absorption tower and is cooled to 165°C. It then enters the second absorption tower for a second absorption to obtain sulfur-containing tail gas. The sulfur-containing tail gas is first sent to the tail gas desulfurization tower, which is equipped with four independent parallel activated carbon adsorption reaction chambers. The tail gas is adsorbed by the activated carbon filter layer in the adsorption reaction chamber, reducing the sulfur dioxide content to below 30 mg / Nm³. It is then sent to the tail gas denitrification tower to remove nitrogen oxides from the tail gas before being discharged into the atmosphere through the tail gas chimney. If the emission indicators of the discharged tail gas exceed the standards, it is led to the sulfur incinerator for secondary combustion through the tail gas secondary combustion pipeline and air blower.

[0012] Preferably, one of the four independently connected parallel activated carbon adsorption reaction chambers in the desulfurization tower needs to be regenerated daily. The specific steps are as follows: S1, close the air inlet valve of the activated carbon adsorption reaction chamber; S2, open the regeneration circulation pump and the valves of the spray and return liquid pipeline, and rinse the activated carbon for 2 hours; S3, stop the regeneration circulation pump and close the spray valve; S4, let stand for 20 hours to allow the residual spray liquid to fully dissipate, then close the return liquid pipeline valve; S5, open the air inlet valve of the activated carbon adsorption reaction chamber and prepare for regeneration of the next reaction chamber the next day.

[0013] Preferably, the flap valve at the connection between the exhaust gas secondary combustion pipeline and the air blower controls the exhaust gas chimney outlet suction force to be -10Pa to -50Pa by adjusting the opening degree.

[0014] In summary, the beneficial effects of this invention are as follows: This invention can fully absorb sulfur dioxide in the exhaust gas and convert it into acid, with a sulfur dioxide conversion rate of 99.7% and a sulfur trioxide absorption efficiency of 99.99%. Subsequently, the exhaust gas passes through the activated carbon filter layer in the exhaust gas desulfurization tower, reducing the sulfur dioxide content to below 30 mg / Nm3, and is then sent to the exhaust gas denitrification tower to remove nitrogen oxides. After that, the exhaust gas is discharged into the atmosphere through the exhaust gas chimney. At the same time, the exhaust gas secondary combustion pipeline can be used to re-incinerate unqualified exhaust gas caused by sudden situations, which can prevent and deal with environmental pollution incidents, effectively solve the hidden dangers of environmental pollution, and prevent the occurrence of environmental accidents. Attached Figure Description

[0015] Figure 1 This is a process flow diagram of the present invention. Detailed Implementation

[0016] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings. These embodiments do not constitute a limitation on the present invention.

[0017] like Figure 1The sulfuric acid production process includes a secondary incineration treatment system for sulfur-containing tail gas, comprising a dry powder incineration and waste heat recovery section, a flue gas purification and drying section, a flue gas conversion and absorption section, and a tail gas treatment section. The dry powder incineration and waste heat recovery section includes a thickening filter, a dryer, a dry powder silo, a sulfur incinerator, and a waste heat boiler connected in sequence. The sulfur incinerator is also connected to an air blower. The flue gas purification and drying section includes a dynamic wave scrubber, a cooling tower, an electrostatic precipitator, a drying tower, and a sulfur dioxide blower connected in sequence. The dynamic wave scrubber is connected to the waste heat boiler. The flue gas conversion and absorption section includes a third heat exchanger, a first electric heating furnace, a first heat exchanger, a five-stage conversion bed, a fifth heat exchanger and a second absorption tower connected in sequence, and the third heat exchanger is connected to a sulfur dioxide blower. The exhaust gas treatment section includes an exhaust gas desulfurization tower, an exhaust gas denitrification tower, and an exhaust gas chimney connected in sequence. The exhaust gas desulfurization tower is connected to the second absorption tower.

[0018] The acid outlet of the drying tower is also connected in sequence to a drying acid circulation tank, a drying acid circulation pump, and a drying acid cooler. The outlet of the drying acid cooler is connected to the acid inlet of the drying tower.

[0019] The five-stage conversion bed includes a first conversion bed, a second conversion bed, a third conversion bed, a fourth conversion bed, and a fifth conversion bed. The fifth heat exchanger is also connected in sequence to a fourth heat exchanger, a second heating furnace, and a second heat exchanger. The first conversion bed and the first heat exchanger are connected end to end. The first heat exchanger is also connected to the second conversion bed. The second conversion bed is connected to the second heat exchanger. The second heat exchanger is connected to the third conversion bed and the fourth conversion bed respectively. The third conversion bed is connected to the third heat exchanger. The fourth conversion bed is connected to the fourth heat exchanger. The fourth heat exchanger is also connected to the fifth conversion bed. The fifth conversion bed is connected to the fifth heat exchanger.

[0020] The second absorption tower is also connected to an absorption circulation tank, which is connected to an absorption acid cooler via an absorption circulation pump. The absorption acid cooler is also connected to the first absorption tower. The first absorption tower is also connected to the third heat exchanger, the fifth heat exchanger, and the absorption circulation tank. The absorption circulation pump is also connected to a product acid tank, and the absorption acid cooler is also connected to a drying tower via a series acid pipeline.

[0021] The outlet of the exhaust gas desulfurization tower is connected to a regeneration acid circulation tank, and the regeneration acid circulation tank is sprayed back into the exhaust gas desulfurization tower by a regeneration circulation pump.

[0022] The desulfurized tail gas outlet of the tail gas desulfurization tower is also directly connected to the tail gas chimney via a tail gas bypass pipe, bypassing the tail gas denitrification tower.

[0023] The exhaust gas chimney is also equipped with an exhaust gas secondary combustion pipe connected to an air blower. The exhaust gas secondary combustion pipe has two U-shaped bends at the front end of the air blower to collect and discharge liquid droplets entrained in the exhaust gas, and is connected to a drain valve group to drain the liquid to the process low-level tank. An adjustable flap valve is installed at the connection between the exhaust gas secondary combustion pipe and the air blower. A quick-shut-off valve is installed one meter above the outlet point of the exhaust gas chimney and the exhaust gas secondary combustion pipe to ensure that the exhaust gas can be smoothly discharged from the original chimney during the initial start-up or in case of production abnormalities.

[0024] A process for a secondary incineration treatment system for sulfur-containing tail gas during sulfuric acid production is described below: The dilute sulfur foam sent from the coking desulfurization unit is filtered to form concentrated sulfur foam with a total solids content of about 35% to 45%. The concentrated sulfur foam is pumped to a dryer for evaporation and drying. The water in the sulfur foam evaporates rapidly, while the elemental sulfur and salts are simultaneously solidified into granular sulfur-containing mixed salts, which is sulfur dry powder.

[0025] Sulfur powder is transported to the furnace hopper via a tubular chain conveyor, and then conveyed to the sulfur incinerator via a belt conveyor. An air blower connected to the outside of the sulfur incinerator blows a large amount of air into the furnace, allowing the sulfur powder to undergo a complete combustion reaction and generate flue gas containing SO2. The high-temperature flue gas exiting the sulfur incinerator reaches 800~1150℃, and is cooled to 230℃~350℃ by heat exchange in a waste heat boiler. The boiler water in the waste heat boiler exchanges heat with the high-temperature flue gas and vaporizes to generate steam to recover the high-temperature waste heat.

[0026] The flue gas from the waste heat boiler is humidified, cooled, and pre-washed by a dynamic wave scrubber. After that, the flue gas enters the cooling tower and comes into countercurrent contact with the cooling circulating dilute acid sprayed at the top of the tower. The flue gas is cooled, condensed, and washed again to remove water vapor and impurities. Then it enters the electrostatic precipitator to remove acid mist.

[0027] The SO2 flue gas exiting the electrostatic precipitator contains a certain amount of water vapor. The flue gas from the electrostatic precipitator enters the drying tower, where it comes into contact with 93% concentrated sulfuric acid to remove the moisture. Then, it is pressurized by a sulfur dioxide blower and sent to the flue gas conversion and absorption section.

[0028] The flue gas conversion and absorption section adopts a "3+2" five-stage conversion and two-stage absorption process. The dried SO2 cold flue gas is pressurized by a sulfur dioxide blower and then sequentially passes through the third heat exchanger, the first electric heating furnace, and the shell side of the first heat exchanger, where it undergoes indirect heat exchange with the corresponding high-temperature conversion gas, gradually being heated to 420°C before entering the converter. After conversion in the first conversion bed, the flue gas temperature rises to 585°C before entering the tube side of the first heat exchanger, where it undergoes indirect heat exchange with the hot SO2 flue gas from the third heat exchanger, causing its temperature to decrease. The gas enters the second conversion bed at 460°C to continue the catalytic reaction. After the temperature rises to 510°C, it exits the second conversion bed and enters the tube side of the second heat exchanger, where it indirectly exchanges heat with the hot SO2 flue gas from the fourth and fifth heat exchangers. After cooling down to 440°C, it enters the third conversion bed of the converter for further reaction. The gas exiting the third conversion bed enters the tube side of the third heat exchanger, where it exchanges heat with the cold flue gas from the sulfur dioxide blower. After cooling down to 175°C, it enters the first absorption tower for primary absorption.

[0029] The gas absorbed in the first absorption tower passes through the shell side of the fifth, fourth, and second heat exchangers in sequence, where it undergoes indirect heat exchange with the corresponding high-temperature converted gas. After being heated to 420°C, it enters the fourth conversion bed for a second conversion. The gas exiting the fourth conversion bed enters the tube side of the fourth heat exchanger, where it exchanges heat with the cold flue gas from the first absorption tower. After being cooled to 415°C, it enters the fifth conversion bed of the converter to continue the reaction. The gas in the fifth conversion bed passes through the tube side of the fifth heat exchanger, where it exchanges heat with the cold flue gas from the first absorption tower and is cooled to 165°C. It then enters the second absorption tower for a second absorption to obtain sulfur-containing tail gas.

[0030] The conversion process mainly involves converting sulfur dioxide flue gas into sulfur trioxide flue gas through a reaction with a catalyst (vanadium pentoxide), allowing the sulfur in the flue gas to be directly absorbed and converted into sulfuric acid.

[0031] After conversion and two absorption processes, the sulfur content in the flue gas decreased significantly, with a sulfur dioxide conversion rate of 99.7% and a sulfur trioxide absorption efficiency of 99.99%. The flue gas then formed sulfur-containing tail gas.

[0032] The sulfur-containing tail gas is first sent to the tail gas desulfurization tower, which is equipped with four independent parallel activated carbon adsorption reaction chambers. The tail gas is adsorbed by the activated carbon filter layer in the adsorption reaction chamber, reducing the sulfur dioxide content to below 30 mg / Nm3. It is then sent to the tail gas denitrification tower to remove nitrogen oxides from the tail gas before being discharged into the atmosphere through the tail gas chimney. If the emission indicators of the discharged tail gas exceed the standards, it is led to the sulfur incinerator for secondary combustion through the tail gas secondary combustion pipeline and the air blower. The flap valve at the connection between the tail gas secondary combustion pipeline and the air blower controls the suction force at the tail gas chimney outlet to be -10 Pa to -50 Pa by adjusting the opening degree, ensuring that all tail gas is introduced into the sulfur incinerator.

[0033] Activated carbon adsorbs SO2 through both physical and chemical adsorption. When there is no oxygen or water vapor in the flue gas, activated carbon adsorbs SO2 only physically, resulting in a small adsorption capacity. However, when oxygen and water vapor are present, chemical adsorption also occurs during the physical adsorption process. When SO2 reaches the surface of the activated carbon through physical adsorption, the activated carbon surface catalyzes the oxidation of SO2 to SO3. In the presence of water vapor, it transforms into H2SO4, thus facilitating the continuous removal of SO2 through this adsorption reaction.

[0034] The four independent parallel activated carbon adsorption reaction chambers in the desulfurization tower require daily regeneration of one of them. The specific steps are as follows: S1, close the air inlet valve of the activated carbon adsorption reaction chamber; S2, open the regeneration circulation pump and the valves of the spray and return liquid pipeline, and rinse the activated carbon for 2 hours; S3, stop the regeneration circulation pump and close the spray valve; S4, let stand for 20 hours to allow the residual spray liquid to fully dissipate, then close the return liquid pipeline valve; S5, open the air inlet valve of the activated carbon adsorption reaction chamber and prepare for regeneration of the next reaction chamber the next day.

[0035] This invention can fully absorb sulfur dioxide in exhaust gas and convert it into acid, with a sulfur dioxide conversion rate of 99.7% and a sulfur trioxide absorption efficiency of 99.99%. Subsequently, the exhaust gas passes through an activated carbon filter layer in the exhaust gas desulfurization tower, reducing the sulfur dioxide content to below 30 mg / Nm3, and is then sent to the exhaust gas denitrification tower to remove nitrogen oxides before being discharged into the atmosphere through the exhaust gas chimney. At the same time, the exhaust gas secondary incineration pipeline can be used to re-incinerate unqualified exhaust gas caused by emergencies, which can prevent and deal with environmental pollution incidents, effectively solve the hidden dangers of environmental pollution, and prevent the occurrence of environmental accidents.

[0036] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art can make various modifications or equivalent substitutions to the present invention within the scope of its essence and protection. Such modifications or equivalent substitutions should also be considered to fall within the protection scope of the present invention.

Claims

1. A system for the secondary incineration of sulfur-containing off-gas in a sulfuric acid production process, characterized in that, The dry powder incineration and waste heat recovery section, the flue gas purification and drying section, the flue gas conversion and absorption section and the tail gas treatment section are connected in sequence. The dry powder incineration and waste heat recovery section comprises a concentration filter, a dryer, a dry powder bin, a sulfur incinerator and a waste heat boiler connected in sequence, and the sulfur incinerator is further connected with an air blower. The flue gas purification and drying section comprises a dynamic wave scrubber, a cooling tower, an electric demister, a drying tower and a sulfur dioxide blower connected in sequence, and the dynamic wave scrubber is connected with the waste heat boiler. The flue gas conversion and absorption section comprises a third heat exchanger, a first electric heating furnace, a first heat exchanger, a five-stage conversion bed, a fifth heat exchanger and a second absorption tower connected in sequence, and the third heat exchanger is connected with the sulfur dioxide blower. The tail gas treatment section comprises a tail gas desulfurization tower, a tail gas denitration tower and a tail gas chimney connected in sequence, and the tail gas desulfurization tower is connected with the second absorption tower.

2. A system for the secondary incineration of sulphurous off-gases in a sulphuric acid production process according to claim 1, characterised in that: The acid liquid outlet of the drying tower is further connected with a drying acid circulating tank, a drying acid circulating pump and a drying acid cooler in sequence, and the outlet of the drying acid cooler is connected with the acid liquid inlet of the drying tower.

3. A system for the secondary incineration of sulphurous off-gases in a sulphuric acid production process according to claim 1, characterised in that: The five-stage conversion bed comprises a first conversion bed, a second conversion bed, a third conversion bed, a fourth conversion bed and a fifth conversion bed, the fifth heat exchanger is further connected with a fourth heat exchanger, a second heating furnace and a second heat exchanger in sequence, the first conversion bed and the first heat exchanger are connected at opposite ends, the first heat exchanger is further connected with the second conversion bed, the second conversion bed is connected with the second heat exchanger, the second heat exchanger is connected with the third conversion bed and the fourth conversion bed respectively, the third conversion bed is connected with the third heat exchanger, the fourth conversion bed is connected with the fourth heat exchanger, the fourth heat exchanger is further connected with the fifth conversion bed, and the fifth conversion bed is connected with the fifth heat exchanger.

4. The system for secondary incineration treatment of sulfur-containing tail gas in a sulfuric acid production process according to claim 1, characterized in that: The second absorption tower is further connected with an absorption circulating tank, the absorption circulating tank is connected with an absorption acid cooler through an absorption circulating pump, the absorption acid cooler is further connected with a first absorption tower, the first absorption tower is further connected with the third heat exchanger, the fifth heat exchanger and the absorption circulating tank respectively, the absorption circulating pump is further connected with a product acid tank, and the absorption acid cooler is further connected with the drying tower through a serial acid pipeline.

5. A system for the secondary incineration of sulphurous off-gases in a sulphuric acid production process according to claim 1, characterised in that: The regenerated acid liquid outlet of the tail gas desulfurization tower is connected with a regenerated acid circulating pool, and the regenerated acid circulating pool reenters the tail gas desulfurization tower through a regenerated circulating pump.

6. A system for the secondary incineration of sulphurous off-gases in a sulphuric acid production process according to claim 1, characterised in that: The desulfurized tail gas outlet of the tail gas desulfurization tower is further connected with a tail gas chimney through a tail gas bypass pipeline.

7. A system for the secondary incineration of sulphurous off-gases in a sulphuric acid production process according to claim 1, characterised in that: The tail gas chimney is further provided with a tail gas secondary incineration pipeline in communication with the air blower, two U-shaped bends are arranged at the front end of the air blower, and a sewage discharge valve group is connected with a process low tank.

8. The process of a sulfur-containing tail gas secondary incineration treatment system in a sulfuric acid production process according to any one of claims 1 to 7, characterized in that: The specific implementation is as follows. The dilute sulfur foam from the coking desulfurization unit is sent to the concentration filter to form concentrated sulfur foam with a total solid content of about 35% to 45%, and the concentrated sulfur foam is sent to the dryer by a screw pump for evaporation drying to form sulfur dry powder; The sulfur dry powder is transported to the furnace hopper by a pipe chain conveyor, and is sent to the sulfur incinerator by a belt conveyor. The sulfur incinerator is connected to an air blower, which blows a large amount of air into the furnace to make the sulfur dry powder fully burn in the sulfur incinerator to generate flue gas containing SO2. The high-temperature flue gas from the sulfur incinerator reaches 800-1150℃, and is cooled to 230-350℃ by the waste heat boiler. The boiler water in the waste heat boiler is vaporized by heat exchange with the high-temperature flue gas to generate steam to recover high-temperature waste heat. The flue gas from the waste heat boiler is sent to the power wave scrubber to increase the humidity, cooling, temperature reduction and preliminary washing and purification of the flue gas. Then the flue gas is sent to the cooling tower to contact with the cooling circulating dilute acid sprayed from the top of the tower. The flue gas is cooled and condensed, washed and purified again to remove water vapor and impurities, and then enters the electric precipitator to remove acid mist. The flue gas from the electric precipitator enters the drying tower to contact with 93% concentrated sulfuric acid to remove water in the flue gas. The SO2 flue gas is pressurized by the SO2 blower and sent to the flue gas conversion and absorption section. The dried SO2 flue gas is pressurized by the SO2 blower and sequentially passes through the third heat exchanger, the first electric heater, and the shell side of the first heat exchanger to indirectly exchange heat with the corresponding high-temperature conversion gas, and is gradually heated to 420℃ and enters the converter. The flue gas after the first conversion bed layer conversion reaction is heated to 585℃ and enters the tube side of the first heat exchanger to indirectly exchange heat with the hot SO2 flue gas from the third heat exchanger, and the temperature is reduced to 460℃ and enters the second conversion bed layer for further catalytic reaction. The temperature is increased to 510℃ and then enters the tube side of the second heat exchanger to indirectly exchange heat with the hot SO2 flue gas from the fourth and fifth heat exchangers, and the temperature is reduced to 440℃ after cooling and enters the third conversion bed layer of the converter for further reaction. The gas from the third conversion bed layer outlet enters the tube side of the third heat exchanger to exchange heat with the cold flue gas from the SO2 blower, and is cooled to 175℃ and enters the first absorption tower for primary absorption. The gas after the primary absorption of the first absorption tower sequentially passes through the shell sides of the fifth, fourth and second heat exchangers to indirectly exchange heat with the corresponding high-temperature conversion gas, and is heated to 420℃ and enters the fourth conversion bed layer for secondary conversion. The gas from the fourth conversion bed layer enters the tube side of the fourth heat exchanger to exchange heat with the cold flue gas from the first absorption tower, and is cooled to 415℃ and enters the fifth conversion bed layer of the converter for further reaction. The gas from the fifth conversion bed layer enters the tube side of the fifth heat exchanger to exchange heat with the cold flue gas from the first absorption tower, and the temperature is reduced to 165℃ and enters the second absorption tower for secondary absorption to obtain sulfur-containing tail gas. The sulfur-containing tail gas is first sent into a tail gas desulfurization tower, four sets of independent and parallel activated carbon adsorption reaction chambers are arranged in the desulfurization tower, the tail gas is adsorbed by the activated carbon filter layer in the adsorption reaction chamber, the content of sulfur dioxide is reduced to below 30 mg / Nm3, the tail gas is sent to a tail gas denitration tower, after the nitrogen oxides in the tail gas are removed, the tail gas is discharged into the atmosphere through a tail gas chimney, if the emission index of the discharged tail gas exceeds the standard, the tail gas is introduced into a sulfur incinerator through a tail gas secondary incineration pipeline and an air blower for secondary incineration.

9. The process according to claim 8, characterized in that, The four sets of independent and parallel activated carbon adsorption reaction chambers in the desulfurization tower need to regenerate one set of activated carbon adsorption reaction chamber every day, and the specific steps are as follows: S1, close the air inlet valve of the activated carbon adsorption reaction chamber; S2, open the regeneration circulating pump and the spray and liquid return pipeline valves, and flush the activated carbon for 2 hours; S3, stop the regeneration circulating pump and close the spray valve; S4, stand for 20 hours to allow the spray residual liquid to be discharged, and close the liquid return pipeline valve; S5, open the air inlet valve of the activated carbon adsorption reaction chamber, and prepare for the regeneration of the next reaction chamber the next day.

10. The process as claimed in claim 8, wherein the process is characterized by, The flap valve at the connecting port of the tail gas secondary incineration pipeline and the air blower controls the suction force of the tail gas chimney outlet to be-10 Pa to-50 Pa by adjusting the opening degree.

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