A flue gas recovery system in a process for roasting zinc sulphide

Abstract

The application discloses a flue gas recovery system in a calcination zinc sulfide process and relates to the technical field of zinc sulfide production. The flue gas recovery system comprises, which are connected by pipelines in sequence, a waste heat recovery boiler, a bag-type dust collector, an electrostatic precipitator, a mixed converter, a cyclone separator, an absorption tower and a spray tower. The mixed converter comprises an outer cavity, an inner cavity and a tail gas inlet pipe. The tail gas inlet pipe is connected with one end of the inner cavity. The outer cavity is provided with a medium inlet at the end far from the tail gas inlet pipe. The outer cavity is provided with a medium outlet at the end far from the medium inlet. The inner cavity is provided with a tail gas outlet pipe at the end far from the tail gas inlet pipe. An oxygen inlet and a powder inlet are installed on the side wall of the inner cavity. The inner cavity is internally provided with a turbulence column. Under the guidance of the turbulence column, the tail gas, oxygen and catalyst powder can be fully mixed, which can accelerate the reaction speed of sulfur dioxide and oxygen in the tail gas, thereby accelerating the generation speed and quality of sulfur trioxide.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of zinc sulfide production, and in particular to a flue gas recovery system in a roasting zinc sulfide process. BACKGROUND

[0002] Zinc sulfide roasting is a key process in the zinc smelting process, which converts zinc sulfide into zinc oxide through high-temperature oxidation. A large amount of tail gas is generated in the zinc sulfide roasting process, and the tail gas is composed of sulfur dioxide, dust particles and a small amount of sulfur trioxide, so the tail gas needs to be harmlessly treated and then discharged.

[0003] The traditional tail gas treatment method is generally as follows: the tail gas is sequentially conveyed to a heat recovery device, a dust removal device and an alkali liquid spraying device, heat energy is recovered through the heat recovery device, dust particles are recovered through the dust removal device, and sulfur dioxide and sulfur trioxide gases are removed through the alkali liquid spraying device to prepare sodium sulfate and sodium sulfite. However, this method needs to use a large amount of alkali liquid, has a high cost, and the product added value of sodium sulfate and sodium sulfite is low, which makes the enterprise invest a lot in tail gas treatment and increases the production cost.

[0004] In order to solve the above problems, the Chinese patent with the application number "202021974293.0" discloses "a flue gas recovery system in a roasting zinc sulfide process", the content of which is "it includes a zinc sulfide concentrate storage bin, an oxidation roasting furnace, a waste heat boiler, a cyclone dust collector, an electric dust collector, an intermediate bin and a sulfuric acid preparation system; the discharge port of the zinc sulfide concentrate storage bin is connected with the feeding port of the oxidation roasting furnace; the gas outlet of the oxidation roasting furnace is in communication with the gas inlet of the waste heat boiler; the gas outlet of the waste heat boiler is in communication with the gas inlet of the cyclone dust collector; the gas outlet of the cyclone dust collector is in communication with the gas inlet of the electric dust collector, and the gas outlet of the electric dust collector is in communication with the gas inlet of the sulfuric acid preparation system. The application has the advantages of simple connection structure, easy implementation, realization of heat energy recycling, saving of production cost, realization of effective recycling of sulfur dioxide resources, sale of the produced sulfuric acid product and increase of the economic benefit of the enterprise".

[0005] In actual application, how to improve the conversion rate of sulfur dioxide to the highest is a key challenge to be solved. SUMMARY

[0006] In view of the above defects, the purpose of the present application is to provide a flue gas recovery system in a roasting zinc sulfide process, which aims to solve the problem that sulfur dioxide is difficult to be fully converted into sulfur trioxide when the tail gas of the existing technology zinc sulfide production is recycled.

[0007] To solve the above technical problems, the technical scheme of the present application is:

[0008] The application discloses a flue gas recovery system in a calcination process of zinc sulfide, which comprises a waste heat recovery boiler, a bag filter, an electrostatic precipitator, a mixed converter, a cyclone separator, an absorption tower and a spray tower which are sequentially connected by pipelines, a medium storage tank is arranged between the waste heat recovery boiler and the mixed converter, and the mixed converter is further connected with a catalyst storage tank and an oxygen storage tank by pipelines, the mixed converter comprises an outer cavity, an inner cavity and a tail gas inlet pipe, the outer cavity is arranged around the inner cavity, the tail gas inlet pipe is connected with one end of the inner cavity, a medium inlet is arranged at one end of the outer cavity away from the tail gas inlet pipe, a medium outlet is arranged at one end of the outer cavity away from the medium inlet, a medium inlet pipe is arranged between the medium inlet and the waste heat recovery boiler, and a medium outlet pipe is arranged between the medium outlet and the medium storage tank; a tail gas outlet pipe is arranged at one end of the inner cavity away from the tail gas inlet pipe, an oxygen inlet and a powder inlet are arranged on the side wall of the inner cavity, the oxygen inlet is connected with the oxygen storage tank by a pipeline, the powder inlet is connected with the catalyst storage tank by a pipeline, and a turbulence column is arranged in the inner cavity.

[0009] The turbulence column is composed of a plurality of curved blades, adjacent curved blades are cross-connected, and adjacent curved blades are located in different planes.

[0010] The turbulence column is located between the tail gas inlet pipe and the tail gas outlet pipe, and the oxygen inlet and the powder inlet are located between the tail gas inlet pipe and the turbulence column.

[0011] The inner cavity comprises a first cavity and a second cavity, the turbulence column is located in the first cavity, the tail gas inlet pipe is connected with one end of the first cavity away from the second cavity, the tail gas outlet pipe is connected with one end of the second cavity away from the tail gas inlet pipe, the oxygen inlet is located between the tail gas inlet pipe and the turbulence column, the powder inlet is connected with the side wall of the second cavity, a guide column is arranged in the second cavity, and the guide column has the same structure as the turbulence column.

[0012] One end of the guide column, which faces the turbulence column, is provided with an air induction hood, the air induction hood comprises a fixed ring and a cover body, the fixed ring is sealingly connected with the inner wall of the second cavity, the cover body is rotationally connected with the fixed ring, the cover body comprises an inner cavity, the inner cavity is circular, a plurality of air induction holes are formed in the side wall of the cover body, the plurality of air induction holes are uniformly arranged around the inner cavity, and one end of the air induction hole, which faces the inner cavity, is tangent to the inner cavity.

[0013] One end of the cover body, which is away from the fixed ring, and the guide column are provided with a connecting column, one end of the guide column, which is away from the connecting column, is provided with an adapter column, the adapter column is rotationally connected with one end of the second cavity, which is away from the first cavity, and the powder inlet is located between the air induction hood and the guide column.

[0014] The fixed ring comprises an inner ring body and an outer ring body, the outer ring body is arranged around the inner ring body, and the outer ring body is rotationally connected with the inner ring body, the outer ring body is sealingly connected with the inner wall of the second cavity, the inner ring body is arranged around the cover body, and a plurality of rolling balls are arranged between the inner ring body and the outer ring body.

[0015] The third cavity is arranged between the first cavity and the second cavity, the third cavity comprises a first section body, a second section body and a third section body, the first section body is located between the first cavity and the second section body, the third section body is located between the second section body and the second cavity, the inner diameter of the first section body is a, the inner diameter of the second section body is b, and the inner diameter of the third section body is c, along the direction from the first cavity to the second cavity, the inner diameter a gradually decreases until a=b, and along the direction from the first cavity to the second cavity, the inner diameter c gradually increases.

[0016] The side wall of the cyclone separator is provided with a receiving pipe connected with the tail gas outlet pipe, an air induction pipe is arranged in the inner cavity of the cyclone separator, the axis of the air induction pipe coincides with the axis of the cyclone separator, a catalytic pipe is connected to the top of the air induction pipe, and the catalytic pipe is filled with a catalyst.

[0017] The top of the cyclone separator is provided with a dust separation bin, a filter disc and an adapter pipe are arranged in the dust separation bin, one end of the adapter pipe is connected with the catalytic pipe, and the filter disc is located between the adapter pipe and the air induction pipe; the filter disc comprises a limiting ring and a support shaft, the limiting ring comprises a first ring body and a second ring body, the first ring body is arranged around the second ring body, and the first ring body is rotationally connected with the second ring body, the side wall of the first ring body is sealingly connected with the inner wall of the dust separation bin, a plurality of support balls are arranged between the first ring body and the second ring body, the second ring body is arranged around the support shaft, a circular filter screen is arranged between the second ring body and the support shaft, the circular filter screen is connected with the support shaft, one end of the support shaft is rotationally connected with the bottom of the dust separation bin, the other end of the support shaft is rotationally connected with the top of the dust separation bin, a power motor is arranged on the top of the dust separation bin, and the power end of the power motor is power-connected with the support shaft.

[0018] After the above technical scheme is adopted, the application has the following beneficial effects:

[0019] Under the guidance of the spoiler column, the tail gas, oxygen and catalyst powder are fully mixed. The catalyst powder has a large specific surface area, which can accelerate the reaction process of sulfur dioxide and oxygen in the tail gas, thereby improving the generation efficiency and purity of sulfur trioxide. This process not only increases the yield of concentrated sulfuric acid, but also reduces the consumption of alkali liquor, avoids the pollution of tail gas to the environment, improves the industrial added value, and effectively reduces the production cost. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 Structure diagram of the flue gas recovery system in the process of roasting zinc sulfide;

[0021] Figure 2 Connection diagram of the mixed converter and the cyclone separator;

[0022] Figure 3 Structure diagram of the mixed converter in Example 1;

[0023] Figure 4 Structure diagram of the mixed converter in Example 2;

[0024] Figure 5 Structure diagram of the induced draft hood;

[0025] Figure 6 Sectional view of the induced draft hood;

[0026] Figure 7 Structure diagram of the cyclone separator;

[0027] Figure 8 Top view of the filter disc;

[0028] Figure 9 Structure diagram of the catalytic pipeline.

[0029] In the drawings: 1 - waste heat recovery boiler, 2 - bag dust collector, 3 - electrostatic precipitator, 4 - mixed converter, 5 - cyclone separator, 6 - absorption tower, 7 - spray tower, 8 - medium storage tank, 9 - catalyst storage tank, 10 - oxygen storage tank, 11 - sulfuric acid storage tank, 12 - lye storage tank, 13 - recovery tank, 14 - outer cavity, 15 - inner cavity, 16 - tail gas inlet pipe, 17 - medium inlet, 18 - medium outlet, 19 - medium inlet pipe, 20 - medium outlet pipe, 21 - tail gas outlet pipe, 22 - oxygen inlet, 23 - powder inlet, 24 - turbulence column, 25 - curved blade, 26 - first cavity, 27 - second cavity, 28 - third cavity, 29 - guide column, 30 - induced draft hood, 31 - fixed ring, 32 - cover body, 33 - induced draft hole, 34 - connecting column, 35 - adapter column, 36 - inner ring body, 37 - outer ring body, 38 - rolling ball, 39 - first segment body, 40 - second segment body, 41 - third segment body, 42 - receiving pipe, 43 - induced draft pipeline, 44 - catalytic pipeline, 45 - dust separation bin, 46 - filter disc, 47 - adapter pipe, 48 - limiting ring, 49 - support shaft, 50 - first ring body, 51 - second ring body, 52 - support ball, 53 - filter screen, 54 - power motor, 55 - generation tower, 56 - water storage tank. DETAILED DESCRIPTION

[0030] It should be understood that the specific embodiments described herein are merely exemplary for the purpose of explanation and are not intended to limit the present application.

[0031] Embodiment 1:

[0032] As Figures 1-3 shown in the figure, a flue gas recovery system in a calcined zinc sulfide process comprises, in sequence, a waste heat recovery boiler 1, a bag filter 2, an electrostatic precipitator 3, a mixed converter 4, a cyclone separator 5, an absorption tower 6, and a spray tower 7, and a medium storage tank 8 is arranged between the waste heat recovery boiler 1 and the mixed converter 4.

[0033] The tail gas will reach the waste heat recovery boiler 1, the bag filter 2, the electrostatic precipitator 3, the mixed converter 4, the cyclone separator 5, the absorption tower 6, and the spray tower 7 in sequence, wherein the waste heat recovery boiler 1 is used to recover the heat of the tail gas; the bag filter 2 and the electrostatic precipitator 3 are both used to recover the dust particles in the tail gas, wherein the bag filter 2 is used to recover larger dust particles, and the electrostatic precipitator 3 is used to recover smaller dust particles, which ensures that the dust particles in the tail gas can be removed to the greatest extent. Because larger dust particles are intercepted by the bag filter 2, the amount of dust collected by the electrostatic precipitator 3 is reduced, thereby reducing the maintenance frequency.

[0034] The mixed converter 4 is used to convert sulfur dioxide in the tail gas into sulfur trioxide through high-temperature oxidation and oxidation catalyst. For this purpose, the mixed converter 4 is also connected in pipeline with a catalyst storage tank 9 and an oxygen storage tank 10, and the mixed converter 4 comprises an outer cavity 14, an inner cavity 15, and a tail gas inlet pipe 16, the outer cavity 14 is arranged around the inner cavity 15, the tail gas inlet pipe 16 is connected to one end of the inner cavity 15, the outer cavity 14 is provided with a medium inlet 17 at the end away from the tail gas inlet pipe 16, the outer cavity 14 is provided with a medium outlet 18 at the end away from the medium inlet 17, a medium inlet pipe 19 is arranged between the medium inlet 17 and the waste heat recovery boiler 1, and a medium outlet pipe 20 is arranged between the medium outlet 18 and the medium storage tank 8; the inner cavity 15 is provided with a tail gas outlet pipe 21 at the end away from the tail gas inlet pipe 16, the oxygen inlet 22 and the powder inlet 23 are installed on the side wall of the inner cavity 15, the oxygen inlet 22 is connected in pipeline with the oxygen storage tank 10, the powder inlet 23 is connected in pipeline with the catalyst storage tank 9, and the inner cavity 15 is provided with a turbulence column 24 inside.

[0035] The medium inlet 17 is connected with the waste heat recovery boiler 1 through the medium inlet pipe 19, which is used to send the high-temperature medium (such as water vapor) in the waste heat recovery boiler 1 into the outer cavity 14, so as to realize the function of heating the inner cavity 15. The medium outlet 18 is connected with the medium storage tank 8 through the medium outlet pipe 20, which is used to send the high-temperature medium in the outer cavity 14 back to the medium storage tank 8. In order to facilitate the full heating of the inner cavity 15, the medium inlet 17 and the medium outlet 18 are respectively located at the two ends of the outer cavity 14, which prolongs the flow path of the high-temperature medium in the outer cavity 14, and ensures that the high-temperature medium and the inner cavity 15 can fully realize heat exchange.

[0036] In order to facilitate temperature adjustment, the medium inlet pipe 19 can also be connected with a temperature adjustment mechanism, which is used to assist in further heating the medium, or to cool the medium, so as to ensure that the sulfur dioxide in the inner cavity 15 can be in the best temperature range during the reaction.

[0037] After the temperature in the inner cavity 15 reaches a certain value, the tail gas enters the inner cavity 15 through the tail gas inlet pipe 16, the oxygen in the oxygen storage tank 10 enters the inner cavity 15 along the oxygen inlet 22, and the catalyst in the catalyst storage tank 9 enters the inner cavity 15 along the powder inlet 23. It is worth noting that the catalyst used in this scheme is a powder catalyst with extremely small particle size (such as vanadium pentoxide powder). Because the catalyst powder has small particle size and light weight, after entering the inner cavity 15, the catalyst powder will move along the inner cavity 15 under the driving of the tail gas and oxygen. Under the interference of the turbulence column 24, the tail gas, oxygen and catalyst powder are continuously sheared and mixed, which ensures that the tail gas, oxygen and catalyst are fully mixed. At the same time, the powder catalyst has a larger surface area, which enables the tail gas and oxygen to fully contact with it, thereby ensuring that the sulfur dioxide in the tail gas can be converted into sulfur trioxide to the greatest extent, and thereby improving the yield of the final product concentrated sulfuric acid.

[0038] In order to facilitate the flow of the catalyst powder in the inner cavity 15, the powder catalyst can be driven into the inner cavity 15 by high-speed airflow, which avoids the accumulation of the catalyst powder in the inner cavity 15, and also speeds up the mixing speed of the catalyst powder with the sulfur dioxide and oxygen.

[0039] In order to speed up the mixing speed of the tail gas, oxygen and catalyst powder, the turbulence column 24 is composed of a plurality of curved blades 25, adjacent curved blades 25 are cross-connected, and adjacent curved blades 25 are located in different planes. This design enables the various materials in the inner cavity 15 to be continuously sheared by the curved blades 25 when flowing, which enables the various materials to rotate and mix at multiple angles, and ensures the mixing efficiency.

[0040] In order to ensure the mixing quality, the length direction of the turbulence column 24 is the same as the length direction of the inner cavity 15.

[0041] In this embodiment, in order to facilitate the rapid mixing of exhaust gas, oxygen and catalyst powder, the turbulence column 24 is located between the exhaust gas inlet pipe 16 and the exhaust gas outlet pipe 21, and the oxygen inlet 22 and the powder inlet 23 are both located between the exhaust gas inlet pipe 16 and the turbulence column 24.

[0042] Example 2:

[0043] like Figures 4-6 As shown, to improve conversion efficiency, we can first mix the exhaust gas with oxygen, and then mix the mixed gas with catalyst powder. For this purpose, the inner cavity 15 includes a first cavity 26 and a second cavity 27. The turbulence column 24 is located inside the first cavity 26. The exhaust gas inlet pipe 16 is connected to the end of the first cavity 26 away from the second cavity 27. The exhaust gas outlet pipe 21 is connected to the end of the second cavity 27 away from the exhaust gas inlet pipe 16. The oxygen inlet 22 is located between the exhaust gas inlet pipe 16 and the turbulence column 24. The powder inlet 23 is connected to the side wall of the second cavity 27. A guide column 29 is provided inside the second cavity 27, and the structure of the guide column 29 is the same as that of the turbulence column 24. During use, the exhaust gas and oxygen are fully mixed with the assistance of the turbulence column 24 in the first chamber 26. At the same time as the exhaust gas and oxygen are input into the mixing converter 4, the powder inlet 23 releases catalyst powder into the second chamber 27. After entering the first chamber 26, the exhaust gas and oxygen will push the original air towards the second chamber 27. This part of the air will cause the catalyst powder to fill the second chamber 27 in advance. This allows the mixed gas from the first chamber 26 to fully contact the catalyst powder after entering the second chamber 27. At the same time, with the assistance of the guide column 29, the mixed gas and catalyst powder are mixed evenly.

[0044] This design avoids the problem of insufficient sulfur dioxide conversion caused by uneven mixing of exhaust gas, oxygen and catalyst powder in the early stage of operation of the mixed converter 4.

[0045] In order to further improve the mixing quality, the flow guide column 29 is provided with an air guide hood 30 at one end of the spoiler column 24, the air guide hood 30 comprises a fixed ring 31 and a cover body 32, the fixed ring 31 is sealingly connected with the inner wall of the second cavity 27, the cover body 32 is rotationally connected with the fixed ring 31, the cover body 32 comprises an inner cavity, the inner cavity is circular, a plurality of air guide holes 33 are arranged on the side wall of the cover body 32, the plurality of air guide holes 33 are uniformly arranged around the inner cavity, and one end of the air guide hole 33 towards the inner cavity is tangent to the inner cavity. The air guide hood 30 in the scheme has the following effects: first, the mixed gas in the first cavity 26 will drive the air guide hood 30 to rotate under the action of the air guide hole 33 when flowing through the air guide hood 30, which makes the mixed gas form a spiral flow, which makes the mixed gas released by different air guide holes drive the catalyst powder to spiral forward after contacting the catalyst powder, which causes the catalyst powder to collide with the inner wall of the second cavity 27 constantly, forcing it to expand the distribution range in the mixed gas. Second, the air guide hood 30 will slow down the flow speed of the mixed gas, which prolongs the existence time of the mixed gas in the second cavity 27, ensuring that the catalyst powder and the mixed gas are fully mixed under the action of the flow guide column 29.

[0046] Preferably, a connecting column 34 is arranged between the end of the cover body 32 away from the fixed ring 31 and the flow guide column 29, the flow guide column 29 is provided with an adapter column 35 at the end away from the connecting column 34, the adapter column 35 is rotationally connected with the end of the second cavity 27 away from the first cavity 26, and the powder inlet 23 is located between the air guide hood 30 and the flow guide column 29. This design makes the air guide hood 30 rotate together with the flow guide column 29 when rotating, which makes the flow guide column 29 play a stirring effect. At the same time, since the flow guide column 29 rotates, the curved blades 25 on the flow guide column 29 can constantly change the contact angle with the mixed gas and the catalyst powder, forcing the mixed gas and the catalyst powder to mix faster.

[0047] In order to reduce the friction force when the air guide hood 30 rotates, the fixed ring 31 comprises an inner ring body 36 and an outer ring body 37, the outer ring body 37 is arranged around the inner ring body 36, and the outer ring body 37 is rotationally connected with the inner ring body 36, the outer ring body 37 is sealingly connected with the inner wall of the second cavity 27, the inner ring body 36 is arranged around the cover body 32, and a plurality of rolling balls 38 are arranged between the inner ring body 36 and the outer ring body 37.

[0048] Because the guide column 29 is relatively heavy, the mixed gas can drive the draft hood 30 and the guide column 29 to rotate, but the rotation speed of the draft hood 30 and the guide column 29 is relatively slow. In order to increase the rotation speed, a third cavity 28 is provided between the first cavity 26 and the second cavity 27. The third cavity 28 includes a first segment 39, a second segment 40 and a third segment 41. The first segment 39 is located between the first cavity 26 and the second segment 40, and the third segment 41 is located between the second segment 40 and the second cavity 27. The inner diameter of the first segment 39 is a, the inner diameter of the second segment 40 is b, and the inner diameter of the third segment 41 is c. Along the direction from the first cavity 26 to the second cavity 27, the inner diameter a gradually decreases until a=b; along the direction from the first cavity 26 to the second cavity 27, the inner diameter c gradually increases. This design creates a Laval nozzle structure within the third chamber 28, which accelerates the flow velocity of the mixed gas as it passes through the third chamber 28. This increases the impact force of the mixed gas on the draft hood 30, thereby accelerating the rotation speed of the draft hood 30 and the guide column 29.

[0049] Example 3:

[0050] like Figures 7-9 As shown, after sulfur dioxide is converted into sulfur trioxide in the mixing converter 4, it still carries catalyst powder. To reduce costs, we need to recycle this catalyst powder. Therefore, this solution introduces a cyclone separator 5. A receiving pipe 42 is installed on the side wall of the cyclone separator 5, and the receiving pipe 42 is connected to the exhaust gas outlet pipe 21. An induced draft pipe 43 is installed inside the cyclone separator 5, and the axis of the induced draft pipe 43 coincides with the axis of the cyclone separator 5. A catalyst pipe 44 is connected to the top of the induced draft pipe 43, and the catalyst pipe 44 is filled with catalyst. Sulfur trioxide, a small amount of unreacted oxygen, and catalyst powder enter the cyclone separator 5 along the exhaust gas outlet pipe 21 and the receiving pipe 42. Subsequently, the reaction gas composed of sulfur trioxide and the upper portion of oxygen is transported to the absorption tower 6 along the induced draft pipe 43, while the catalyst powder is deposited at the bottom of the cyclone separator 5 and then transported to the catalyst storage tank 9 for reuse. To further reduce the sulfur dioxide content in the reaction gas, the exhaust pipe 43 is connected to a catalytic pipe 44. When the reaction gas flows through the catalytic pipe 44, the unreacted oxygen inside reacts with sulfur dioxide to generate sulfur trioxide.

[0051] In order to reduce the catalyst powder carried in the reaction gas, the top of the cyclone separator 5 is provided with a dust separation bin 45, the dust separation bin 45 is provided with a filter disc 46 and an adapter pipe 47, one end of the adapter pipe 47 is connected with the catalytic pipe 44, the filter disc 46 is located between the adapter pipe 47 and the induced draft pipe 43; the filter disc 46 comprises a limiting ring 48 and a supporting shaft 49, the limiting ring 48 comprises a first ring body 50 and a second ring body 51, the first ring body 50 is arranged around the second ring body 51, and the first ring body 50 and the second ring body 51 are rotationally connected, the side wall of the first ring body 50 is sealingly connected with the inner wall of the dust separation bin 45, a plurality of supporting balls 52 are arranged between the first ring body 50 and the second ring body 51, the second ring body 51 is arranged around the supporting shaft 49, a circular filter screen 53 is arranged between the second ring body 51 and the supporting shaft 49, the circular filter screen 53 is connected with the supporting shaft 49, one end of the supporting shaft 49 is rotationally connected with the bottom of the dust separation bin 45, the other end of the supporting shaft 49 is rotationally connected with the top of the dust separation bin 45, a power motor 54 is installed at the top of the dust separation bin 45, and the power end of the power motor 54 is power-connected with the supporting shaft 49.

[0052] Since the filter disc 46 is located between the adapter pipe 47 and the induced draft pipe 43, the reaction gas is filtered by the filter disc 46 when passing through the induced draft pipe 43 into the adapter pipe 47, thereby further reducing the content of catalyst powder in the reaction gas, and thereby reducing the probability of catalyst powder polluting concentrated sulfuric acid. After the filter disc 46 is used for a period of time, the mesh of the filter disc 46 will be blocked by the catalyst powder, causing the flow speed of the reaction gas to be slow. Therefore, the supporting shaft 49 is introduced in the present scheme. The upper and lower ends of the supporting shaft 49 are rotationally connected with the dust separation bin 45, and the filter screen 53 is connected with the supporting shaft 49, so that the power motor 54 can drive the supporting shaft 49 and the filter screen 53 to rotate. This makes it only necessary to start the power motor 54, drive the filter screen 53 to rotate through the supporting shaft 49, and drive the blocked area away from the area between the induced draft pipe 43 and the adapter pipe 47, and at the same time send the unblocked area of the filter screen 53 to the area between the induced draft pipe 43 and the adapter pipe 47.

[0053] In the present scheme, the absorption tower 6 is also pipeline-connected with a sulfuric acid storage tank 11 and a generation tower 55, and the generation tower 55 is pipeline-connected with a water storage tank 56. The reaction gas pipeline is sent to the absorption tower 6, the concentrated sulfuric acid (concentration ≥98%) stored in the sulfuric acid storage tank 11 is delivered to the absorption tower 6, the sulfur trioxide is absorbed by the concentrated sulfuric acid, and oleum is generated, the oleum is delivered to the generation tower 55, at this time the water storage tank 56 sends water to the generation tower 55, the oleum is diluted with water, and sulfuric acid is prepared. This way, the reaction heat release is less, the operation is safer, and the oleum can be reused.

[0054] When the sulfuric acid in the generation tower 55 reaches a certain amount, a part of the sulfuric acid will be taken out for sale or other purposes.

[0055] The reaction gas after being absorbed by the concentrated sulfuric acid is transported by pipeline to the spray tower 7, which is connected with the lye storage tank 12 and the recovery tank 13. The lye storage tank 12 transports the lye stored inside to the spray tower 7, and reacts with the unreacted sulfur trioxide, sulfur dioxide and part of the acid gas in the reaction gas in the spray tower 7 to generate water and precipitated salt. The precipitated salt is then sent to the recovery tank 13, and the reaction gas after being treated by the spray tower 7 has reached the emission standard and can be discharged to the outside.

[0056] In summary, the advantages of the present scheme are: under the guidance of the turbulence column 24, the tail gas, oxygen and catalyst powder can be fully mixed. Since the catalyst powder has a large surface area, it can accelerate the reaction speed of sulfur dioxide and oxygen in the tail gas, thereby accelerating the generation efficiency and quality of sulfur trioxide. The production of concentrated sulfuric acid is increased, the amount of lye is reduced, the environment is protected from tail gas pollution, the industrial added value is improved, and the production cost is reduced.

[0057] The present application is not limited to the above specific embodiments, and various modifications made by those skilled in the art without creative labor, all of which fall within the scope of the present application.

Claims

1. A flue gas recovery system for a zinc sulfide roasting process, comprising a waste heat recovery boiler (1), a bag filter (2), an electrostatic precipitator (3), a mixing converter (4), a cyclone separator (5), an absorption tower (6), and a spray tower (7) connected in sequence by pipelines, wherein a medium storage tank (8) is provided between the waste heat recovery boiler (1) and the mixing converter (4), characterized in that, The mixing converter (4) is also connected by pipelines to a catalyst storage tank (9) and an oxygen storage tank (10). The mixing converter (4) includes an outer cavity (14), an inner cavity (15), and a tail gas inlet pipe (16). The outer cavity (14) is arranged around the inner cavity (15). The tail gas inlet pipe (16) is connected to one end of the inner cavity (15). A medium inlet (17) is provided at the end of the outer cavity (14) away from the tail gas inlet pipe (16). A medium outlet (18) is provided at the end of the outer cavity (14) away from the medium inlet (17). The medium inlet (17) is connected to... A medium inlet pipe (19) is provided between the waste heat recovery boiler (1), and a medium outlet pipe (20) is provided between the medium outlet (18) and the medium storage tank (8); a tail gas outlet pipe (21) is provided at the end of the inner cavity (15) away from the tail gas inlet pipe (16), an oxygen inlet (22) and a powder inlet (23) are installed on the side wall of the inner cavity (15), the oxygen inlet (22) is connected to the oxygen storage tank (10) by a pipeline, the powder inlet (23) is connected to the catalyst storage tank (9) by a pipeline, and a turbulence column (24) is provided inside the inner cavity (15). The inner cavity (15) includes a first cavity (26) and a second cavity (27). The turbulence column (24) is located inside the first cavity (26). The exhaust gas inlet pipe (16) is connected to the end of the first cavity (26) away from the second cavity (27). The exhaust gas outlet pipe (21) is connected to the end of the second cavity (27) away from the exhaust gas inlet pipe (16). The oxygen inlet (22) is located between the exhaust gas inlet pipe (16) and the turbulence column (24). The powder inlet (23) is connected to the side wall of the second cavity (27). A guide column (29) is provided inside the second cavity (27). The structure of the guide column (29) is the same as that of the turbulence column (24). A third cavity (28) is provided between the first cavity (26) and the second cavity (27). The third cavity (28) includes a first segment (39), a second segment (40), and a third segment (41). The first segment (39) is located between the first cavity (26) and the second segment (40), and the third segment (41) is located between the second segment (40) and the second cavity (27). The inner diameter of the first segment (39) is a, the inner diameter of the second segment (40) is b, and the inner diameter of the third segment (41) is c. Along the direction from the first cavity (26) to the second cavity (27), the inner diameter a gradually decreases until a=b; along the direction from the first cavity (26) to the second cavity (27), the inner diameter c gradually increases.

2. The flue gas recovery system in the zinc sulfide roasting process according to claim 1, characterized in that, The turbulence column (24) is composed of several curved blades (25), adjacent curved blades (25) are cross-connected, and adjacent curved blades (25) are located on different planes.

3. The flue gas recovery system in the zinc sulfide roasting process according to claim 2, characterized in that, The turbulence column (24) is located between the exhaust gas inlet pipe (16) and the exhaust gas outlet pipe (21), and the oxygen inlet (22) and the powder inlet (23) are both located between the exhaust gas inlet pipe (16) and the turbulence column (24).

4. The flue gas recovery system in the zinc sulfide roasting process according to claim 1, characterized in that, The guide column (29) is provided with an air hood (30) at one end facing the turbulence column (24). The air hood (30) includes a fixing ring (31) and a cover (32). The fixing ring (31) is sealed to the inner wall of the second cavity (27). The cover (32) is rotatably connected to the fixing ring (31). The cover (32) includes an inner cavity. The inner cavity is circular. Several air hoods (33) are provided on the side wall of the cover (32). Several air hoods (33) are evenly arranged around the inner cavity. The end of the air hood (33) facing the inner cavity is tangent to the inner cavity.

5. The flue gas recovery system in the zinc sulfide roasting process according to claim 4, characterized in that, A connecting post (34) is provided between the end of the cover (32) away from the fixed ring (31) and the guide post (29). A transition post (35) is provided at the end of the guide post (29) away from the connecting post (34). The transition post (35) is rotatably connected to the end of the second cavity (27) away from the first cavity (26). The powder inlet (23) is located between the air hood (30) and the guide post (29).

6. A flue gas recovery system for the calcination of zinc sulfide according to claim 4, characterized in that, The fixed ring (31) includes an inner ring body (36) and an outer ring body (37). The outer ring body (37) is arranged around the inner ring body (36) and is rotatably connected to the inner ring body (36). The outer ring body (37) is sealed to the inner wall of the second cavity (27). The inner ring body (36) is arranged around the cover (32). A plurality of rolling balls (38) are arranged between the inner ring body (36) and the outer ring body (37).

7. The flue gas recovery system for the calcination of zinc sulfide according to claim 1, characterized in that, A receiving pipe (42) is installed on the side wall of the cyclone separator (5). The receiving pipe (42) is connected to the exhaust gas outlet pipe (21). An air duct (43) is provided in the inner cavity of the cyclone separator (5). The axis of the air duct (43) coincides with the axis of the cyclone separator (5). A catalyst pipe (44) is connected to the top of the air duct (43). The catalyst pipe (44) is filled with a catalyst.

8. A flue gas recovery system for the calcination of zinc sulfide according to claim 7, characterized in that, The top of the cyclone separator (5) is provided with a dust-proof chamber (45), and a filter disc (46) and a transfer pipe (47) are provided inside the dust-proof chamber (45). One end of the transfer pipe (47) is connected to the catalytic pipe (44), and the filter disc (46) is located between the transfer pipe (47) and the induced draft pipe (43). The filter disc (46) includes a limiting ring (48) and a support shaft (49). The limiting ring (48) includes a first ring body (50) and a second ring body (51). The first ring body (50) is arranged around the second ring body (51), and the first ring body (50) and the second ring body (51) are rotatably connected. The sidewall of the first ring body (50) is connected to the dust-proof chamber. The inner wall of the chamber (45) is sealed. A plurality of support balls (52) are provided between the first ring body (50) and the second ring body (51). The second ring body (51) is arranged around the support shaft (49). A circular filter screen (53) is provided between the second ring body (51) and the support shaft (49). The circular filter screen (53) is connected to the support shaft (49). One end of the support shaft (49) is rotatably connected to the bottom of the dust-proof chamber (45). The other end of the support shaft (49) is rotatably connected to the top of the dust-proof chamber (45). A power motor (54) is installed on the top of the dust-proof chamber (45). The power end of the power motor (54) is poweredly connected to the support shaft (49).

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