Method for purifying and refining industrial sulfur from low-quality sulfur

Abstract

The present application relates to the technical field of sulfur purification and refining, and particularly relates to a method for purifying and refining low-quality sulfur into industrial sulfur, a process of which comprises separation, mixing, sulfur melting, stepwise temperature rising, gasification, condensation and cooling, sulfur shaping, washing and slagging, and the method utilizes the difference between the boiling point and volatility of sulfur and impurities, and realizes the stepwise separation of coal powder, coke powder, tar and other impurities and the efficient purification of sulfur through the mode of'stepwise temperature rising + phase change purification'. The quality of the final product sulfur meets the technical index requirements of the national standard (GB / T2449.1) of industrial sulfur, and provides an effective way for the high-value resource utilization of low-quality sulfur. Meanwhile, the stepwise recycling of heat is realized, which is conducive to reducing the operation cost and improving the economic benefits of enterprises.

Description

Technical Field

[0001] This invention relates to the field of sulfur purification and refining technology, and in particular to a method for purifying and refining industrial sulfur from low-quality sulfur. Background Technology

[0002] Currently, coke oven gas desulfurization generally employs a wet oxidation process. During desulfurization, hydrogen sulfide in the coke oven gas is first absorbed by the desulfurization liquid and then oxidized to elemental sulfur under the action of a catalyst. The elemental sulfur remains in the sulfur foam as suspended particles. Due to the complex composition of coke oven gas, in addition to hydrogen sulfide, it also carries impurities such as coal dust, coke dust, and tar. These impurities enter the desulfurization liquid during the desulfurization washing process and eventually mix into the sulfur foam.

[0003] Currently, sulfur is mainly recovered through two methods: one is to use a plate and frame filter press to process sulfur foam and produce raw sulfur; the other is to use a sulfur melting kettle to melt and purify sulfur and produce cooked sulfur. However, when using the above two methods, the raw or cooked sulfur produced contains impurities such as coal powder, coke powder, tar, and by-product salts. The finished product has a gray-black or dark brown appearance and a purity of only 70% to 80%, which is far from the industrial sulfur product standard and belongs to low-quality sulfur.

[0004] Low-quality sulfur faces severe limitations in both market sales and applications. Industries such as rubber vulcanization, chemical synthesis, and pharmaceuticals have high requirements for sulfur purity, and low-purity sulfur cannot meet these industry standards, leading to difficulties in market sales. Large quantities of low-quality sulfur accumulate due to ineffective utilization, not only wasting sulfur resources but also easily forming new solid waste and posing environmental pollution risks. Furthermore, the economic value of low-purity sulfur is far lower than that of refined sulfur, failing to contribute to improving the economic benefits of enterprises.

[0005] Existing sulfur purification methods are not specifically designed for low-quality sulfur produced by the wet oxidation desulfurization process of coke oven gas, resulting in poor applicability. Therefore, a new sulfur purification technology is needed to efficiently remove impurities such as coal dust, coke dust, and tar from the sulfur produced as a byproduct of the wet oxidation desulfurization process of coke oven gas, significantly improving sulfur purity, enabling the resource utilization of low-purity sulfur, and solving the problems of market sales difficulties and solid waste pollution. Summary of the Invention

[0006] This invention provides a method for purifying and refining low-quality sulfur into industrial sulfur. Utilizing the differences in boiling point and volatility between sulfur and impurities, a "step-by-step heating + phase change purification" approach is used to achieve the step-by-step separation of impurities such as coal powder, coke powder, and tar, and the efficient purification of sulfur. The final sulfur product meets the technical requirements of the national standard for "Industrial Sulfur" (GB / T2449.1), providing an effective way to utilize low-quality sulfur resources at high value. Simultaneously, it achieves step-by-step heat recovery and utilization, which helps reduce operating costs and improve the economic benefits of enterprises.

[0007] To achieve the above objectives, the present invention employs the following technical solution: A method for purifying and refining low-quality sulfur into industrial sulfur includes the following steps: (1) Separation: The sulfur foam from the wet oxidation desulfurization section is first filtered to remove large particles of coke powder and coal powder, and then the solid-liquid two-phase separation is completed. All the separated desulfurization liquid is sent to the washing unit, and the separated sulfur paste enters the mixing unit. (2) Mixing: The sulfur paste sent from the separation unit is mixed evenly with part of the molten sulfur liquid sent from the sulfur melting unit, and the prepared sulfur slurry is sent to the sulfur melting unit. (3) Sulfur melting: The sulfur slurry from the mixing unit enters the sulfur melting tower for heating and melting. After being heated, the solid sulfur undergoes a phase change and melts into liquid sulfur. The liquid sulfur discharged from the bottom of the sulfur melting tower is sent to the liquid sulfur intermediate tank for initial separation of water vapor, and then transferred to the stepped heating unit. Part of the molten sulfur liquid discharged from the top of the sulfur melting tower is sent back to the mixing unit to dilute the sulfur paste, and the rest is sent to the washing unit along with the desulfurization liquid. (4) Step-by-step heating: Liquid sulfur from the sulfur melting unit first enters a level balancing tank to maintain a constant liquid level in the subsequent heating and gasification reactors. It then flows sequentially into the primary and secondary heating reactors for gradual heating, eventually reaching the gasification unit. In the primary heating reactor, the liquid is heated to 260–340°C, achieving coarse separation of water vapor, impurities, and liquid sulfur. In the secondary heating reactor, it is heated to 340–410°C, achieving fine separation of impurities and liquid sulfur. Both the primary and secondary heating reactors are equipped with stirring devices. Both reactors operate under positive pressure, and the discharged VOCs are sent to the washing unit. (5) Gasification: The liquid sulfur delivered from the stepped heating unit is heated to over 445°C in the gasification kettle and converted into high-purity gaseous sulfur; the gasification kettle is equipped with a stirring device. (6) Condensation cooling: The gaseous sulfur produced by the gasification unit enters the condenser for condensation and cooling. After phase change, the liquid sulfur generated by re-liquefaction is sent to the liquid sulfur product tank for buffering, and then pumped to the sulfur forming unit. (7) Sulfur molding: The liquid sulfur produced by the condensation and cooling unit is sent to the sulfur forming equipment, where it undergoes a phase change after further cooling and solidifies into solid sulfur. (8) Washing: The VOCs discharged from the stepped heating unit are mixed with the non-condensable gas discharged from the condensation and cooling unit and then sent to the scrubbing tower to be washed in reverse with the desulfurization liquid to remove gaseous sulfur components. (9) Slag removal: The sulfur slag at the bottom of the primary heating kettle, secondary heating kettle and gasification kettle periodically falls into the water-immersed scraper slag remover by gravity. After being cooled and solidified by water immersion, it is scooped out by the scraper and sent to the coal yard for recycling.

[0008] In the process (1), the sulfur foam first passes through a pipeline filter to intercept large particles of coke powder and coal powder, and then uses filtration or centrifugal separation to complete the solid-liquid two-phase separation. The separated sulfur paste flows into the mixing unit by gravity.

[0009] In process (2), sulfur paste and molten sulfur liquid are forcibly stirred evenly in a mixing tank to prepare sulfur slurry, and the sulfur slurry is pumped to the sulfur melting unit; the concentration of suspended sulfur in the sulfur slurry is controlled at 100-220 g / L, and the residence time in the mixing tank is not less than 0.5 h.

[0010] In the process (3), the liquid sulfur discharged from the bottom of the sulfur melting tower is sent into the liquid sulfur intermediate tank for buffering by its own pressure. After the water vapor is initially separated, it is then pumped to the stepped heating unit. The heat source required for heating the sulfur melting tower is the heat transfer medium sent by the condensation cooling unit. If it is insufficient, low-pressure saturated steam is used as a supplement.

[0011] In the process (4), the residence time of the liquid flow in the primary heating kettle is not less than 1 hour; the residence time in the secondary heating kettle is not less than 1 hour; electromagnetic heating or heat transfer medium heating is used when heating the liquid sulfur in the primary heating kettle and the secondary heating kettle; most of the coal powder and coke powder entrained in the liquid sulfur are deposited at the bottom of the primary heating kettle and the secondary heating kettle to become sulfur slag, which is periodically discharged into the slag removal unit.

[0012] In the process (5), the residence time of liquid sulfur in the gasification vessel is not less than 1 hour; the remaining trace amounts of coal powder and coke powder carried in the liquid sulfur remain at the bottom of the gasification vessel as sulfur slag, which is periodically discharged into the slag removal unit; the gasification vessel adopts electromagnetic heating.

[0013] In the process (6), the heat released during the condensation and cooling process of gaseous sulfur is preferentially absorbed and transferred by the heat transfer medium, and then absorbed and transferred by the boiler water to generate low-pressure saturated steam; the uncondensed sulfur-containing gaseous components are sent to the washing unit as non-condensable gas.

[0014] In the process (7), the sulfur forming equipment includes a flake machine and a granulator; the solid sulfur is packaged and sold externally; the heat released during the liquid sulfur cooling process is carried out and removed by the circulating cooling water.

[0015] In the process (8), the washed gas is sent back to the gas pipeline through the pressure balance system, and the washed desulfurization liquid is sent back to the wet oxidation desulfurization section for recycling.

[0016] During the process (9), the operating water temperature inside the slag remover is controlled below 60°C, and a built-in baffle liquid seal is installed at the sulfur slag inlet of the slag remover to prevent the escape of sulfur-containing gas.

[0017] Compared with the prior art, the beneficial effects of the present invention are: (1) By utilizing the difference in boiling point and volatility between sulfur and impurities (including coal powder, coke powder, tar, etc.), the impurities such as coal powder, coke powder and tar are separated step by step and sulfur is purified efficiently through the method of "step heating + phase change purification". (2) The heat source required for heating the molten sulfur is preferably the heat transfer medium sent from the condensation and cooling step. If the heat is insufficient, low-pressure saturated steam is used as a supplement. The heat released during the condensation and cooling process of gaseous sulfur is preferably absorbed and transferred by the heat transfer medium, and then the boiler water is selected to absorb and transfer the heat to generate low-pressure saturated steam. This realizes the cascade recovery and utilization of heat, which is conducive to reducing operating costs and improving the economic benefits of enterprises. (3) The VOCs generated during the cascade heating process are washed with desulfurization liquid and then sent back to the gas pipeline through the pressure balancing system, with no external pollution discharge. (4) Both the stepped heating kettle and the gasification kettle are equipped with stirring devices to eliminate local overheating inside the kettle and make the internal temperature field distribution relatively uniform and stable; at the same time, it inhibits the adhesion of sulfur slag to the wall, avoids the accumulation of slag layer causing a decrease in heat transfer coefficient, and ensures long-term efficient and stable operation of the equipment. (5) The final product has a sulfur purity of ≥99.5% and meets the technical requirements of the national standard for industrial sulfur (GB / T2449.1), providing an effective way to utilize low-quality sulfur resources at high value. Attached Figure Description

[0018] Figure 1 This is a process flow diagram of a method for purifying and refining low-quality sulfur into industrial sulfur according to the present invention. Detailed Implementation

[0019] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings: like Figure 1 As shown, the method for purifying and refining low-quality sulfur into industrial sulfur according to the present invention includes the following steps: (1) Separation: The sulfur foam delivered from the wet oxidation desulfurization section is first filtered to remove large particles of coke powder and coal powder, and then the solid and liquid phases are separated. All the separated desulfurization liquid is sent to the washing unit, and the separated sulfur paste enters the mixing unit.

[0020] As a preferred method, the sulfur foam is first filtered through a pipeline to remove large particles of coke powder and coal powder, and then the solid and liquid phases are separated by filtration or centrifugal separation. The separated sulfur paste flows into the mixing unit by gravity.

[0021] (2) Mixing: The sulfur paste sent from the separation unit is mixed evenly with part of the molten sulfur liquid sent from the sulfur melting unit, and the prepared sulfur slurry is sent to the sulfur melting unit.

[0022] Preferably, sulfur paste and molten sulfur liquid are forcibly stirred evenly in a mixing tank to prepare sulfur slurry, and the sulfur slurry is pumped to the sulfur melting unit; the concentration of suspended sulfur in the sulfur slurry is controlled at 100-220 g / L, and the residence time in the mixing tank is not less than 0.5 h.

[0023] (3) Sulfur melting: The sulfur slurry sent from the mixing unit enters the sulfur melting tower for heating and melting. After being heated, the solid sulfur undergoes a phase change and melts into liquid sulfur. The liquid sulfur discharged from the bottom of the sulfur melting tower is sent to the liquid sulfur intermediate tank for initial separation of water vapor, and then transferred to the stepped heating unit. Part of the molten sulfur liquid discharged from the top of the sulfur melting tower is sent back to the mixing unit to dilute the sulfur paste, and the rest is sent to the washing unit along with the desulfurization liquid.

[0024] As a preferred option, the liquid sulfur discharged from the bottom of the sulfur melting tower is sent into the liquid sulfur intermediate tank for buffering by its own pressure. After the water vapor is initially separated, it is then pumped to the stepped heating unit. The heat source required for heating the sulfur melting tower is the heat transfer medium sent by the condensation cooling unit. If it is insufficient, low-pressure saturated steam is used as a supplement.

[0025] (4) Step-by-step heating: The liquid sulfur from the sulfur melting unit first enters the liquid level balance tank to maintain a constant liquid level in the subsequent heating kettle and gasification kettle; then it flows in full flow into the primary heating kettle and the secondary heating kettle for progressive heating, and finally flows in full flow to the gasification unit; the liquid flow is heated to 260-340°C in the primary heating kettle to achieve coarse separation of water vapor, impurities and liquid sulfur; in the secondary heating kettle it is heated to 340-410°C to achieve fine separation of impurities and liquid sulfur; both the primary heating kettle and the secondary heating kettle are equipped with stirring devices; both the primary heating kettle and the secondary heating kettle are maintained under positive pressure (slight positive pressure), and the discharged VOCs are sent to the washing unit.

[0026] Preferably, the residence time of the liquid flow in the primary heating vessel is not less than 1 hour; the residence time in the secondary heating vessel is not less than 1 hour; electromagnetic heating or heat transfer medium heating is used when heating the liquid sulfur in the primary and secondary heating vessels; most of the coal powder and coke powder entrained in the liquid sulfur are deposited at the bottom of the primary and secondary heating vessels as sulfur slag, which is periodically discharged into the slag removal unit.

[0027] (5) Gasification: The liquid sulfur delivered by the stepped heating unit is heated to above 445°C in the gasification kettle and converted into high-purity gaseous sulfur; the gasification kettle is equipped with a stirring device.

[0028] Preferably, the residence time of liquid sulfur in the gasification reactor is not less than 1 hour; the residual trace amounts of coal powder and coke powder carried in the liquid sulfur remain at the bottom of the gasification reactor as sulfur slag, which is periodically discharged into the slag removal unit; the gasification reactor adopts electromagnetic heating.

[0029] When electromagnetic heating is used, the primary heating vessel, secondary heating vessel, and gasification vessel are made of carbon steel lined with stainless steel.

[0030] (6) Condensation cooling: The gaseous sulfur produced by the gasification unit enters the condenser for condensation and cooling. After phase change, the liquid sulfur generated by re-liquefaction is sent to the liquid sulfur product tank for buffering, and then pumped to the sulfur forming unit.

[0031] Preferably, the heat released during the condensation and cooling process of gaseous sulfur is first absorbed and transferred by the heat transfer medium, and secondly by the boiler water to generate low-pressure saturated steam; the uncondensed sulfur-containing gaseous components are sent to the scrubbing unit as non-condensable gas.

[0032] (7) Sulfur molding: The liquid sulfur produced by the condensation and cooling unit is sent to the sulfur forming equipment, where it undergoes a phase change after further cooling and solidifies into solid sulfur.

[0033] As a preferred option, the sulfur forming equipment includes a flake machine and a granulator; the solid sulfur is packaged and sold externally; the heat released during the cooling process of liquid sulfur is carried away and removed by circulating cooling water.

[0034] (8) Washing: The VOCs discharged from the stepped heating unit are mixed with the non-condensable gases discharged from the condensation and cooling unit and then sent to the scrubbing tower, where they are washed in a counter-current contact with the desulfurization liquid to remove gaseous sulfur components.

[0035] Preferably, the washed gas is returned to the gas pipeline through a pressure balancing system, and the washed desulfurization liquid is returned to the wet oxidation desulfurization section for recycling.

[0036] (9) Slag removal: The sulfur slag at the bottom of the primary heating kettle, secondary heating kettle and gasification kettle periodically falls into the water-immersed scraper slag remover by gravity. After being cooled and solidified by water immersion, it is scooped out by the scraper and sent to the coal yard for recycling.

[0037] As a preferred option, the operating water temperature inside the slag remover is controlled below 60℃, and a built-in baffle liquid seal is installed at the sulfur slag inlet of the slag remover to prevent the escape of sulfur-containing gas.

[0038] This invention discloses a method for purifying and refining low-quality sulfur into industrial sulfur, used to treat low-quality sulfur byproducts of the ammonia desulfurization process for coke oven gas. The process system consists of a separation unit, a mixing unit, a sulfur melting unit, a stepped heating unit, a gasification unit, a condensation and cooling unit, a sulfur forming unit, a washing unit, and a slag removal unit. The main process route is: separation → mixing → sulfur melting → stepped heating → gasification → condensation and cooling → sulfur forming. The VOCs (volatile organic compounds, including H2S, NH3, gaseous tar, gaseous sulfur, etc.) generated by the stepped heating unit are washed and then returned to the gas pipeline through a pressure balancing system, without being discharged externally. The sulfur slag (high-temperature liquid-solid mixture) periodically discharged from the stepped heating unit and gasification unit is cooled and solidified by the slag removal unit, then removed and sent to the coal yard for recycling.

[0039] To more intuitively illustrate the present invention, the embodiments of the present invention will be further described in conjunction with the examples. The following examples are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any technical solutions that can be obviously obtained by those skilled in the art within the scope of the technology disclosed in the present invention, including simple variations or equivalent substitutions, are all within the scope of protection of the present invention.

[0040] Example: In this embodiment, the method for purifying and refining low-quality sulfur into industrial sulfur according to the present invention is used to treat low-quality sulfur produced by the ammonia-based wet oxidation desulfurization process of coke oven gas. The specific process is as follows: 1. Separation: The sulfur foam from the desulfurization unit is first filtered through a basket filter to remove large particles of coke and coal dust, and then sent to a sulfur centrifuge for solid-liquid two-phase centrifugal separation. The separated desulfurization liquid flows by gravity into the desulfurization liquid tank, and is then pumped to the washing step; the separated wet sulfur paste falls into the mixing step by gravity.

[0041] 2. Mixing: The separated sulfur paste and part of the molten sulfur liquid from the sulfur melting unit are both fed into a mixing tank, where they are forcibly mixed evenly by an agitator to prepare a free-flowing sulfur slurry. The concentration of suspended sulfur in the sulfur slurry is controlled at 150 g / L, and the residence time of the sulfur slurry in the mixing tank is 1 hour before it is pumped to the sulfur melting unit.

[0042] 3. Sulfur melting: The sulfur slurry from the mixing unit enters the sulfur melting tower for heating and melting. Inside the sulfur melting tower, the sulfur slurry first exchanges heat with the molten sulfur liquid to recover the heat from the molten sulfur liquid, thereby reducing heat consumption during the heating and melting process and achieving energy saving and consumption reduction.

[0043] The top pressure of the sulfur melting tower is controlled at 0.25 MPaG, and the bottom temperature of the sulfur melting tower is controlled at 135℃. After the sulfur slurry is heated in the sulfur melting tower, the solid sulfur in it undergoes a phase change and melts, and the resulting liquid sulfur is deposited at the bottom of the sulfur melting tower.

[0044] The liquid sulfur discharged from the bottom of the sulfur melting tower is sent into the intermediate liquid sulfur tank for buffering by its own pressure, where water vapor is initially separated, and then pumped to the stepped heating unit; part of the molten sulfur liquid discharged from the top of the sulfur melting tower is sent back to the mixing unit for diluting sulfur paste, and the rest is sent to the washing unit along with the desulfurization liquid.

[0045] 4. Step-by-step heating: The liquid sulfur delivered from the sulfur melting unit first enters the liquid level balance tank to maintain a constant liquid level in the subsequent heating kettle (including the primary heating kettle and the secondary heating kettle) and the gasification kettle; then the liquid sulfur flows into the primary heating kettle and the secondary heating kettle in sequence to raise the temperature step by step, and finally flows into the gasification unit.

[0046] Liquid sulfur is heated to 320°C in a primary heating reactor for 2 hours to achieve coarse separation of impurities such as water vapor and tar from the liquid sulfur. In a secondary heating reactor, it is heated to 380°C for fine separation of impurities such as tar from the liquid sulfur. Electromagnetic heating is used in both the primary and secondary heating reactors for heating the liquid sulfur.

[0047] Most of the fine coal powder and coke powder carried in the liquid sulfur are deposited at the conical bottom of the primary heating kettle and the secondary heating kettle, becoming sulfur slag, which is periodically discharged into the slag removal unit.

[0048] In this embodiment, both the primary heating kettle and the secondary heating kettle are made of carbon steel lined with 310S stainless steel and are equipped with a stirring device to eliminate local overheating inside the kettle, so that the internal temperature field distribution is relatively uniform and stable; at the same time, it inhibits the adhesion of sulfur slag to the wall, avoids the accumulation of slag layer leading to a decrease in heat transfer coefficient, and ensures long-term efficient and stable operation of the equipment.

[0049] Both the primary heating reactor and the secondary heating reactor maintain a slight positive pressure operation, and the discharged VOCs (including H2S, NH3, gaseous tar, gaseous sulfur and other components) are sent to the washing unit for treatment.

[0050] 5. Gasification: Liquid sulfur from the stepped heating unit enters the gasification reactor, where it undergoes further heating to complete the phase change from liquid to gas. Inside the gasification reactor, the liquid sulfur is heated to 450°C and converted into high-purity gaseous sulfur. Trace amounts of coal dust and coke dust carried in the liquid sulfur remain at the conical bottom of the gasification reactor as sulfur slag, which is periodically discharged into the slag removal unit.

[0051] In this embodiment, the gasification vessel adopts electromagnetic heating. The gasification vessel is made of carbon steel lined with 310S stainless steel and is equipped with a stirring device. This can not only eliminate local overheating inside the vessel and make the internal temperature field distribution relatively uniform and stable, but also prevent sulfur slag from adhering to the wall, avoid the accumulation of slag layer causing a decrease in heat transfer coefficient, and ensure the long-term efficient and stable operation of the equipment.

[0052] 6. Condensation cooling: The gaseous sulfur sent from the gasification unit enters the condenser for condensation and cooling. The gaseous sulfur undergoes a phase change and is reliquefied to generate liquid sulfur. The liquid sulfur is sent to the liquid sulfur product tank for buffering, and then pumped to the sulfur forming unit.

[0053] The heat released during the condensation and cooling process of gaseous sulfur is absorbed and transferred by the heat-conducting salt, and the temperature of the heat-conducting salt is controlled at 165℃.

[0054] After the gaseous sulfur is condensed and cooled, the remaining uncondensed sulfur-containing gaseous components are sent to the scrubbing unit for treatment as non-condensable gas.

[0055] 7. Sulfur molding: The liquid sulfur produced by the condensation and cooling unit is periodically fed into the sulfur flake machine, where it undergoes a phase change after further cooling and solidifies into solid sulfur, ultimately yielding flake sulfur products with a diameter of 3-5 mm and a thickness of 1.5-1.8 mm. The finished products are then bagged by an automatic packaging machine and sold externally.

[0056] 8. Washing: The VOCs discharged from the cascade heating unit are mixed with the non-condensable gases discharged from the condensation and cooling unit and then sent to the scrubbing tower for counter-current contact with the desulfurization liquid to remove gaseous sulfur components. The scrubbed gas is returned to the gas pipeline through a pressure balancing system and is not discharged externally; the scrubbed desulfurization liquid is returned to the wet oxidation desulfurization section for recycling.

[0057] 9. Slag Removal: The sulfur slag at the bottom of the primary heating kettle, secondary heating kettle, and gasification kettle is a high-temperature liquid-solid mixture. It periodically falls into the water-immersed scraper slag remover by gravity. After being cooled by immersion in water and solidified, it is scooped out by the scraper and sent to the coal yard for recycling.

[0058] The operating water temperature inside the slag remover is controlled at 40℃. The slag remover is equipped with a built-in baffle-type liquid seal at the sulfur slag inlet to prevent the escape of sulfur-containing gas.

[0059] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for purifying and refining low-quality sulfur into industrial sulfur, characterized in that, The process includes the following: (1) Separation: The sulfur foam from the wet oxidation desulfurization section is first filtered to remove large particles of coke powder and coal powder, and then the solid-liquid two-phase separation is completed. All the separated desulfurization liquid is sent to the washing unit, and the separated sulfur paste enters the mixing unit. (2) Mixing: The sulfur paste sent from the separation unit is mixed evenly with part of the molten sulfur liquid sent from the sulfur melting unit, and the prepared sulfur slurry is sent to the sulfur melting unit. (3) Sulfur melting: The sulfur slurry from the mixing unit enters the sulfur melting tower for heating and melting. After being heated, the solid sulfur undergoes a phase change and melts into liquid sulfur. The liquid sulfur discharged from the bottom of the sulfur melting tower is sent to the liquid sulfur intermediate tank for initial separation of water vapor, and then transferred to the stepped heating unit. Part of the molten sulfur liquid discharged from the top of the sulfur melting tower is sent back to the mixing unit to dilute the sulfur paste, and the rest is sent to the washing unit along with the desulfurization liquid. (4) Step-by-step heating: Liquid sulfur from the sulfur melting unit first enters a level balancing tank to maintain a constant liquid level in the subsequent heating and gasification reactors. It then flows sequentially into the primary and secondary heating reactors for gradual heating, eventually reaching the gasification unit. In the primary heating reactor, the liquid is heated to 260–340°C, achieving coarse separation of water vapor, impurities, and liquid sulfur. In the secondary heating reactor, it is heated to 340–410°C, achieving fine separation of impurities and liquid sulfur. Both the primary and secondary heating reactors are equipped with stirring devices. Both reactors operate under positive pressure, and the discharged VOCs are sent to the washing unit. (5) Gasification: The liquid sulfur delivered from the stepped heating unit is heated to over 445°C in the gasification kettle and converted into high-purity gaseous sulfur; the gasification kettle is equipped with a stirring device. (6) Condensation cooling: The gaseous sulfur produced by the gasification unit enters the condenser for condensation and cooling. After phase change, the liquid sulfur generated by re-liquefaction is sent to the liquid sulfur product tank for buffering, and then pumped to the sulfur forming unit. (7) Sulfur molding: The liquid sulfur produced by the condensation and cooling unit is sent to the sulfur forming equipment, where it undergoes a phase change after further cooling and solidifies into solid sulfur. (8) Washing: The VOCs discharged from the stepped heating unit are mixed with the non-condensable gas discharged from the condensation and cooling unit and then sent to the scrubbing tower to be washed in reverse with the desulfurization liquid to remove gaseous sulfur components. (9) Slag removal: The sulfur slag at the bottom of the primary heating kettle, secondary heating kettle and gasification kettle periodically falls into the water-immersed scraper slag remover by gravity. After being cooled and solidified by water immersion, it is scooped out by the scraper and sent to the coal yard for recycling.

2. The method for purifying and refining low-quality sulfur into industrial sulfur according to claim 1, characterized in that, In the process (1), the sulfur foam first passes through a pipeline filter to intercept large particles of coke powder and coal powder, and then uses filtration or centrifugal separation to complete the solid-liquid two-phase separation. The separated sulfur paste flows into the mixing unit by gravity.

3. The method for purifying and refining low-quality sulfur into industrial sulfur according to claim 1, characterized in that, In process (2), sulfur paste and molten sulfur liquid are forcibly stirred evenly in a mixing tank to prepare sulfur slurry, and the sulfur slurry is pumped to the sulfur melting unit; the concentration of suspended sulfur in the sulfur slurry is controlled at 100-220 g / L, and the residence time in the mixing tank is not less than 0.5 h.

4. The method for purifying and refining low-quality sulfur into industrial sulfur according to claim 1, characterized in that, In the process (3), the liquid sulfur discharged from the bottom of the sulfur melting tower is sent into the liquid sulfur intermediate tank for buffering by its own pressure. After the water vapor is initially separated, it is then pumped to the stepped heating unit. The heat source required for heating the sulfur melting tower is the heat transfer medium sent by the condensation cooling unit. If it is insufficient, low-pressure saturated steam is used as a supplement.

5. The method for purifying and refining low-quality sulfur into industrial sulfur according to claim 1, characterized in that, In the process (4), the residence time of the liquid flow in the primary heating kettle is not less than 1 hour; the residence time in the secondary heating kettle is not less than 1 hour; electromagnetic heating or heat transfer medium heating is used when heating the liquid sulfur in the primary heating kettle and the secondary heating kettle; most of the coal powder and coke powder entrained in the liquid sulfur are deposited at the bottom of the primary heating kettle and the secondary heating kettle to become sulfur slag, which is periodically discharged into the slag removal unit.

6. The method for purifying and refining industrial sulfur from low-quality sulfur according to claim 1, characterized in that, In the process (5), the residence time of liquid sulfur in the gasification vessel is not less than 1 hour; the remaining trace amounts of coal powder and coke powder carried in the liquid sulfur remain at the bottom of the gasification vessel as sulfur slag, which is periodically discharged into the slag removal unit; the gasification vessel adopts electromagnetic heating.

7. The method for purifying and refining low-quality sulfur into industrial sulfur according to claim 1, characterized in that, In the process (6), the heat released during the condensation and cooling of gaseous sulfur is first absorbed and transferred by the heat transfer medium, and then absorbed and transferred by the boiler water to generate low-pressure saturated steam. Uncondensed sulfur-containing gaseous components are sent to the scrubbing unit as non-condensable gases.

8. The method for purifying and refining low-quality sulfur into industrial sulfur according to claim 1, characterized in that, In the process (7), the sulfur forming equipment includes a flake machine and a granulator; the solid sulfur is packaged and sold externally; the heat released during the liquid sulfur cooling process is carried out and removed by the circulating cooling water.

9. The method for purifying and refining low-quality sulfur into industrial sulfur according to claim 1, characterized in that, In the process (8), the washed gas is sent back to the gas pipeline through the pressure balance system, and the washed desulfurization liquid is sent back to the wet oxidation desulfurization section for recycling.

10. A method for purifying and refining low-quality sulfur into industrial sulfur according to claim 1, characterized in that, During the process (9), the operating water temperature inside the slag remover is controlled below 60°C, and a built-in baffle liquid seal is installed at the sulfur slag inlet of the slag remover to prevent the escape of sulfur-containing gas.

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