A process and apparatus for removing dust from the SO2 production gas during sulfur foaming in coking plants.

Abstract

The present application belongs to the technical field of acid production, and particularly relates to a process and device for removing dust in SO2 process gas of sulfur foam in a coking plant. The present application is characterized in that a wet type cyclone dust removal, spray washing and clarification separation step are additionally arranged between the SO2 process gas outlet of a boiler and a power wave, and the process required device comprises a cyclone dust collector, a spray device and a clarification tank for clarification separation, the spray device is installed above the cyclone dust collector, and the clarification tank is installed below the cyclone dust collector. Most of the dust, incompletely combusted salt and sulfur powder carried in the SO2 process gas are removed through the cyclone dust removal, spray washing and clarification separation, and the resistance of the subsequent process of acid production is reduced to make the production proceed normally. In particular, the double dust removal of centrifugal separation + spray washing of dilute sulfuric acid can efficiently remove the sulfur powder and salt dust in the SO2 process gas, and the dilute sulfuric acid is closed-loop circulated and reused, so that the water consumption is low and the discharge is less.

Description

Technical Field

[0001] This invention belongs to the field of acid production technology, specifically relating to a process and apparatus for removing dust from the gas during the SO2 production process of sulfuric acid from coking plants. Background Technology

[0002] Currently, most coking plants use the HPS wet ammonia oxidation desulfurization process to remove H2S from coke oven gas, generating sulfur foam through catalytic oxidation regeneration. There are three processes for producing sulfuric acid using sulfur foam: Wet sulfur production foam pretreatment process: The sulfur foam is concentrated to separate most of the desulfurization liquid. The desulfurization liquid is returned to the desulfurization system for recycling. The concentrated sulfur foam is pumped directly to the sulfur incinerator and mixed with oxygen-enriched air to burn SO2 process gas in the temperature range of 1050-1150℃.

[0003] Semi-dry sulfuric acid production foam pretreatment process: The sulfur foam is concentrated to separate most of the desulfurization liquid, which is then recycled back to the desulfurization system. The concentrated sulfur foam is heated to 140-145℃ in a two-phase tower. The liquid sulfur at the bottom of the two-phase tower is burned and oxidized with air in the sulfur incinerator at a temperature range of 1050-1150℃ to generate SO2 gas. The clear liquid from the top of the two-phase tower is heated to 70-75℃ in a concentration tower and distilled under vacuum. The ammonia water from the top of the concentration tower is returned to the desulfurization system for recycling or returned to the ammonia water system for recycling. The concentrated salt from the bottom of the concentration tower is also burned in the sulfur incinerator at a temperature range of 1050-1150℃ to generate SO2 process gas.

[0004] Dry sulfuric acid production foam pretreatment process: The sulfur foam is concentrated to separate most of the desulfurization liquid, which is then recycled back to the desulfurization system. The concentrated sulfur foam undergoes primary drying to evaporate most of the moisture. The sulfur foam is then heated into liquid sulfur and enters secondary drying for further evaporation of moisture. Finally, it is cooled to become dry sulfur powder. The dry sulfur powder is directly fed into the sulfur incinerator and burned with air at a temperature range of 1050-1150℃ to generate SO2 process gas.

[0005] Acid production process description: The SO2 process gas, with a temperature of 1050-1150℃, is first cooled to about 300-350℃ by a waste heat boiler. The waste heat generates steam, which is then used externally. After being washed by a dynamic wave and cooled, demisted, and dried, the SO2 process gas enters the acid production system. In the conversion tower, the SO2 process gas is catalytically oxidized into SO3 gas. The SO3 gas is then absorbed by concentrated sulfuric acid in a primary and secondary absorption tower to produce 93% or 98% concentrated sulfuric acid.

[0006] The disadvantage of this process is that, regardless of whether it is dry, semi-dry, or wet sulfuric acid production, due to insufficient combustion time of concentrated salt and liquid sulfur (or dry sulfur powder) in the sulfur incinerator, a small amount of incompletely burned salt and sulfur powder enters the sulfuric acid production process with the SO2 process gas, causing blockages in the equipment and heat exchangers of subsequent processes. The system must be shut down every two months to clean the sulfur powder in the cooling and heat exchange equipment, with each cleaning taking at least 20 days. Frequent shutdowns and restarts not only affect the efficiency of equipment use but also seriously affect sulfuric acid production and enterprise profits. Summary of the Invention

[0007] The purpose of this invention is to provide a process and apparatus for removing dust from the SO2 process gas used in the sulfuric acid production of coking plants. By removing the incompletely burned salt and sulfur powder carried in the SO2 process gas, the resistance to subsequent acid production processes is reduced, allowing production to proceed normally.

[0008] Process flow description: A process for removing dust from SO2 process gas in sulfuric acid production from coking plants involves the following steps: The SO2 process gas, with a temperature of 1050-1150℃, is first cooled to 300-350℃ by a waste heat boiler. After purification and cooling by a power wave, the SO2 process gas is demisted and dried before entering the acid production system. In a conversion tower, the SO2 process gas is catalytically oxidized to SO3 gas. The SO3 gas is then absorbed by concentrated sulfuric acid in a primary and secondary absorption tower to produce 93% or 98% concentrated sulfuric acid. This invention adds a wet cyclone dust collector, spray washing, and clarification separation step between the SO2 process gas outlet in the boiler and the power wave. The cyclone dust collector removes a portion of the dust carried in the SO2 process gas. The salt and sulfur powder carried by the SO2 process gas are mostly removed by spraying with dilute sulfuric acid to reduce clogging of downstream equipment and pipelines. The dilute sulfuric acid, which has absorbed the salt and sulfur dust, flows by gravity to the clarification process, where some salt and sulfur powder are separated. The clarified dilute sulfuric acid is then pumped out and indirectly cooled to 40-60°C by circulating water. The cooled dilute sulfuric acid is then used as a spraying liquid for spray washing. The dilute sulfuric acid is recycled. The purified SO2 process gas then enters the pneumatic wave washing process.

[0009] The apparatus for implementing the above-mentioned dust removal process in SO2 process gas from coking plant sulfur foam production includes: a cyclone dust collector for SO2 process gas dust removal, a spray device for spray washing, and a clarification tank for clarification and separation. The spray device is installed inside the cyclone dust collector at the top, and the clarification tank is installed below the cyclone dust collector. An isolation plate is installed inside the clarification tank, dividing it into a clarification chamber and a storage chamber. The SO2 process gas enters from the top and side of the cyclone dust collector, flows along the guide vanes of the outer cylinder to the bottom of the dust collector, and removes some dust through centrifugal force. To further remove dust carried in the SO2 process gas, spray filters are installed at the top of the outer cylinder and the inner cylinder of the cyclone dust collector. Each of the top-mounted spray devices uses cooled dilute sulfuric acid to spray and wash away most of the salt and sulfur powder carried by the SO2 process gas. The dilute sulfuric acid, which has absorbed the salt and sulfur dust, flows by gravity from the bottom of the cyclone dust collector to the clarification tank. The dilute sulfuric acid liquid coming out of the bottom of the wet cyclone dust collector first enters the clarification chamber of the clarification tank, where the salt and sulfur powder separated by the cyclone separator are clarified and separated. The clarified dilute sulfuric acid flows to the storage chamber and is pumped out by a dilute sulfuric acid pump. It is then indirectly cooled to 40-60°C by circulating water in a dilute sulfuric acid cooler before being sent to the top spray device of the cyclone separator.

[0010] The outer shell of the cyclone separator and clarifier is made of Q235 material, and the inner lining is made of high temperature resistant, acid and alkali resistant material.

[0011] Compared with existing technologies, the present invention has the following advantages: By adding cyclone dust removal, spray washing, and clarification separation steps between the boiler outlet and the power wave, and by adding cooled dilute sulfuric acid spraying at the top of the cyclone dust collector to clarify the spray liquid, dust carried in the SO2 process gas was effectively removed, with a removal rate of over 50%. This created favorable conditions for reducing resistance and ensuring normal operation of subsequent acid production processes. The resistance of the acid production system was reduced from 35 kPa to less than 20 kPa, the annual downtime for maintenance was reduced from 99 days to less than 30 days, and an additional 3,600 tons of sulfuric acid were produced, generating an additional 1.8 million yuan in benefits for the company. Attached Figure Description

[0012] The invention will be further described below with reference to the accompanying drawings and embodiments.

[0013] Figure 1 A flowchart of the new process in this invention.

[0014] In the diagram: 1. Cyclone dust collector, 2. Spraying device, 3. Sprayer head, 4. Dilute sulfuric acid cooler, 5. Sulfuric acid pump, 6. Clarification tank, 7. Storage room, 8. Isolation plate, 9. Clarification chamber, 10. Waste heat boiler. Detailed Implementation

[0015] The technical solution and its effects of the present invention will be further described below through specific embodiments and accompanying drawings.

[0016] Liquid sulfur or dry sulfur powder enters the sulfur incinerator along with the combustion air, where it is oxidized and burned at a high temperature of 1050-1150℃ to become SO2 process gas. The SO2 process gas then recovers waste heat through waste heat boiler 10, reducing the temperature of the SO2 process gas at the outlet of waste heat boiler 10 to between 300-350℃. In the original process, the SO2 process gas directly entered the power wave purification and cooling system. This process involves adding wet cyclone dust removal, spray washing, and clarification separation steps between the boiler SO2 gas outlet and the power wave. Cyclone dust removal removes some of the powder carried in the SO2 process gas. The salt and sulfur powder carried in the SO2 process gas are mostly removed by spray washing, reducing clogging of subsequent acid production equipment and pipelines. The dilute sulfuric acid, which has absorbed the salt and sulfur dust, flows by gravity to the clarification process. In this clarification process, some salt and sulfur powder are separated. The clarified dilute sulfuric acid is extracted by a dilute sulfuric acid pump and indirectly cooled to 40-60°C by circulating water. The cooled dilute sulfuric acid is then sent to the spray washing as a spray liquid. The dilute sulfuric acid is recycled. The purified SO2 process gas then enters the pneumatic wave purification and cooling process.

[0017] The apparatus used in the above process includes: a cyclone dust collector 1 for SO2 process gas dust removal, a spray device 2 for spray washing, and a clarification tank 6 for clarification and separation. The spray device 2 is installed above the cyclone dust collector 1, and the clarification tank 6 is installed below the cyclone dust collector 1. An isolation plate 8 is installed inside the clarification tank 6, dividing it into a clarification chamber 9 and a storage chamber 7. The SO2 process gas enters from the top side of the cyclone dust collector, flows along the guide vanes of the outer cylinder to the bottom of the dust collector, and removes some dust through centrifugal force. Then, it rises through the guide vanes of the inner cylinder to the top outlet of the dust collector, where further dust is removed by centrifugal force. To further remove dust carried in the SO2 process gas, a cyclone dust collector is further degassed by centrifugal force. Spray nozzles 3 are installed at the top and the top of the inner cylinder, respectively. Cooled dilute sulfuric acid is sprayed to remove most of the salt and sulfur powder carried by the SO2 process gas. The dilute sulfuric acid that has absorbed the salt and sulfur dust flows by gravity from the bottom of the cyclone dust collector to the clarification chamber 9 of the clarification tank 6. Here, the salt and sulfur powder separated by the cyclone separator are clarified and separated. The clarified dilute sulfuric acid flows to the storage chamber 7 and is extracted by the sulfuric acid pump 5. It is indirectly cooled to 40-60°C by circulating water through the dilute sulfuric acid cooler 4. The cooled dilute sulfuric acid is then sent to the top of the cyclone separator for spraying to further remove the dust carried by the SO2 process gas. The dilute sulfuric acid is recycled and reused after cooling, resulting in low water consumption and minimal discharge.

[0018] The outer shell of the cyclone separator 1 and the clarifier tank 6 is made of Q235 material, and the inner lining is made of high temperature resistant, acid and alkali resistant material.

Claims

1. A process for removing dust from the gas produced during the sulfur foaming process of acid production in a coking plant, characterized in that: In the sulfur foam acid production process of a coking plant, a wet cyclone dust removal, spray washing, and clarification separation process is added between the SO2 process gas outlet of the boiler and the power wave. The cyclone dust removal removes some of the powder carried in the SO2 process gas. The salt and sulfur powder carried in the SO2 process gas are mostly removed by spray washing, reducing the blockage of subsequent acid production equipment and pipelines. The dilute sulfuric acid that has absorbed the salt and sulfur dust is sprayed and flows by gravity to the clarification process. In this clarification process, some salt and sulfur powder are separated. The clarified dilute sulfuric acid is extracted by a sulfuric acid pump and indirectly cooled to 40-60°C by circulating water. The cooled dilute sulfuric acid is then sent to the spray washing as a spray liquid. The dilute sulfuric acid is recycled. The purified SO2 process gas then enters the pneumatic power wave purification and cooling process.

2. An apparatus for implementing the process of removing dust from the SO2 production gas of a coking plant using sulfur foam as described in claim 1, characterized in that... include: The system comprises a cyclone dust collector for SO2 process gas dust removal, a spray system for scrubbing, and a clarification tank for separation. The spray system is installed at the top inside the cyclone dust collector, and the clarification tank is installed at the bottom. An internal partition plate divides the clarification tank into a clarification chamber and a storage chamber. The SO2 process gas enters from the top and side of the cyclone dust collector, flowing along the guide vanes of the outer cylinder to the bottom. Centrifugal force removes some dust. To further remove dust carried in the SO2 process gas, spray systems are installed at the top of the outer and inner cylinders of the cyclone dust collector, using cooled... Dilute sulfuric acid is sprayed to wash away most of the salt and sulfur powder carried by the SO2 process gas. The dilute sulfuric acid, which has absorbed the salt and sulfur dust, flows by gravity from the bottom of the cyclone dust collector to the clarification tank. The dilute sulfuric acid liquid coming out of the bottom of the cyclone dust collector first enters the clarification chamber of the clarification tank, where the salt and sulfur powder separated by the cyclone separator are clarified and separated. The clarified dilute sulfuric acid flows to the storage chamber and is pumped out by a sulfuric acid pump. It is then indirectly cooled to 40-60°C by circulating water in a dilute sulfuric acid cooler and sent to the spray device at the top of the cyclone separator.

3. The apparatus used in the process of removing dust from the SO2 production gas of a coking plant to remove sulfur foam as described in claim 2, characterized in that... The outer shell of the cyclone separator and clarifier is made of Q235 material, and the inner lining is made of high temperature resistant, acid and alkali resistant material.

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