A method for producing high-purity carbon disulfide by using inferior sulfur and methane as raw materials

Abstract

The application discloses a method for producing high-purity carbon disulfide by taking inferior sulfur and methane as raw materials, and belongs to the technical field of carbon disulfide production, and the technical scheme is characterized by comprising the following steps: S1, gasifying inferior liquid sulfur; S2, reacting gaseous sulfur with methane after heating; S3, cooling the reaction product by heat exchange to obtain a gas-liquid mixture; S4, carrying out gas-liquid separation on the gas-liquid mixture, and recycling the separated liquid-phase sulfur; S5, obtaining a gas-liquid mixture of carbon disulfide and hydrogen sulfide by cooling the separated gas phase in two stages; S6, feeding the gas-liquid mixture into an absorption tower, absorbing hydrogen sulfide by using refined liquid carbon disulfide, discharging waste gas from the top of the tower, and performing rectification on liquid carbon disulfide containing hydrogen sulfide to obtain high-purity carbon disulfide and hydrogen sulfide. After the gasification treatment of liquid sulfur, the impurities entering the reaction system are effectively reduced, and the operation cycle of the overall device is significantly improved.

Description

Technical Field

[0001] This invention relates to the field of carbon disulfide production technology, and in particular to a method for producing high-purity carbon disulfide using inferior sulfur and methane as raw materials. Background Technology

[0002] Carbon disulfide is an important industrial chemical, widely used in the production of viscose fibers, pesticides, banana vulcanizing agents, and carbon tetrachloride, among other products. Currently, the main industrial method for producing carbon disulfide is the natural gas process, the basic reaction of which is as follows: The typical process flow of existing natural gas-based processes is as follows: liquid sulfur and natural gas are preheated in a reactor and then introduced into the reaction system, where they react at 500-750°C. The reaction products are then separated from the sulfur and distilled to obtain carbon disulfide and hydrogen sulfide as a byproduct. However, existing methods have the following problems:

[0003] (1) Problem of raw material impurity accumulation: The existing process directly introduces liquid sulfur into the reaction system. The ash, organic matter, metal compounds and other impurities contained in the sulfur directly enter the high-temperature reaction zone with the liquid sulfur and gradually accumulate in the system. Usually, after 0.5-1 years of operation, the accumulated impurities will cause the system to be blocked, forcing the shutdown for cleaning, which seriously affects the long-term stable operation of the equipment.

[0004] (2) Problem of excessive sulfur emission loss: Excess sulfur in the existing process is discharged from the system at the reactor outlet by low temperature condensation. Since the operating conditions here are low temperature and high pressure, a large amount of carbon disulfide product is dissolved in the liquid sulfur and carried out, which not only causes product loss, but also poses a safety hazard because the liquid sulfur contains a large amount of carbon disulfide.

[0005] (3) High requirements for raw material quality: In order to obtain high-purity carbon disulfide and avoid system blockage, the existing process must strictly limit the quality of raw material sulfur, requiring the use of industrial sulfur that meets the national standard (GB / T2449) of superior or first grade (sulfur content ≥99.5%, ash content ≤0.10%). This results in high raw material costs and limited sources. If the raw material requirements are relaxed, impurities will accumulate rapidly in the high-temperature reaction zone, forcing the unit to shut down frequently for cleaning. At the same time, excessive sulfur will carry away a large amount of carbon disulfide product when condensed at low temperature, causing a decrease in purity and safety risks. Therefore, there is an urgent need for a production method of carbon disulfide that can be compatible with low-cost, low-quality sulfur, while achieving long-term stable operation and high purity. Summary of the Invention

[0006] To address the problems in the prior art, this invention provides a method for producing high-purity carbon disulfide using inferior sulfur and methane as raw materials. By gasifying the liquid sulfur, the amount of impurities entering the reaction system is effectively reduced, thus significantly improving the overall operating cycle of the device.

[0007] The present invention provides a method for producing high-purity carbon disulfide from inferior sulfur and methane as raw materials, which adopts the following technical solution:

[0008] A method for producing high-purity carbon disulfide from low-quality sulfur and methane as raw materials includes the following steps:

[0009] S1. Gasify liquid sulfur with a sulfur content ≥95% and ash content ≤5% at 450-500℃.

[0010] S2. Gaseous sulfur and methane are heated and then introduced into the reactor for reaction;

[0011] S3. The reaction products exiting the reactor are cooled by heat exchange, so that the excess sulfur in the reaction products is condensed to obtain a gas-liquid mixture.

[0012] S4. The gas-liquid mixture enters the gas-liquid separator for gas-liquid separation, and the separated liquid sulfur is recycled.

[0013] S5. After two-stage cooling, the gas phase separated in step S4 is mixed with partially condensed carbon disulfide and uncondensed hydrogen sulfide. S6. The gas-liquid mixture obtained in step S5 enters the absorption tower, where the gas phase is countercurrently washed with refined liquid carbon disulfide to dissolve the hydrogen sulfide in the liquid carbon disulfide. The waste gas is discharged from the top of the tower, and the liquid carbon disulfide containing hydrogen sulfide is distilled to obtain high-purity carbon disulfide and hydrogen sulfide.

[0014] In a preferred embodiment, the two-stage cooling in step S5 is as follows: the first stage uses circulating water to cool the gas phase, and the second stage uses chilled water to further cool the material.

[0015] In a preferred embodiment, in step S6, the operating temperature for countercurrent washing of the gas phase with refined liquid carbon disulfide is -5 to -10°C, and the operating pressure is 0 to 0.05 MPaG.

[0016] In a preferred embodiment, when the refined liquid carbon disulfide is used to countercurrently wash the gas phase, the molar ratio of carbon disulfide to hydrogen sulfide is (3-5):1.

[0017] In a preferred embodiment, the operating pressure in step S1 is 0.05-0.1 MPaG.

[0018] In a preferred embodiment, in step S2, gaseous sulfur and methane are heated to 630-670°C and then introduced into the reactor. The reaction time is 1-5 seconds, and the operating pressure is 0.05-0.1 MPaG.

[0019] In a preferred embodiment, in step S3, the reaction product is cooled to 180±5°C via heat exchange to obtain a gas-liquid mixture.

[0020] In a preferred embodiment, the mass content of carbon disulfide in the liquid sulfur obtained in step S4 is ≤0.3%.

[0021] By adopting the above technical solution, in the method for producing carbon disulfide using inferior sulfur instead of high-purity sulfur in the prior art, when the inferior liquid sulfur is heated and vaporized, the thermal decomposition or vaporization temperature of impurities such as ash (mainly metal sulfates and oxides) and tar-like organic matter in the sulfur is generally higher than 550℃. Controlling the vaporization temperature within the range of 450-500℃ ensures sufficient vaporization of the sulfur (boiling point 444.6℃) while retaining most impurities in the liquid phase. If the temperature is below 450℃, the sulfur vaporization rate is too low, affecting production efficiency; if it is above 500℃, some low-boiling-point impurities begin to azeotropically or are entrained into the gas phase, weakening the impurity removal effect. Therefore, setting the sulfur vaporization temperature significantly extends the operating cycle of the entire device, not only solving the problem of frequent process shutdowns for cleaning, but also reducing the production cost of carbon disulfide due to the use of inferior sulfur.

[0022] The reaction products (containing carbon disulfide, hydrogen sulfide, and excess sulfur vapor) are then cooled to 180±5℃ in a heat exchanger. Since the solubility of carbon disulfide in liquid sulfur decreases significantly with increasing temperature, the sulfur vapor in the reaction products liquefies at approximately 180℃ and is entrained in the gas phase. Due to the high operating temperature and low pressure during the heat exchange process, the amount of carbon disulfide dissolved in the liquid sulfur is extremely small, thus preventing a decrease in the purity of the carbon disulfide. The heat recovered during the heat exchange and cooling process is output in the form of medium and low pressure steam, realizing comprehensive energy utilization. Cooling the reaction product to 180±5℃ is the optimal balance point between energy consumption and carbon disulfide purity. If the temperature is too high, the sulfur will not condense completely and will enter the subsequent cooling system, causing blockage and hindering the energy consumption control of the subsequent two-stage cooling. If the temperature is too low, the solubility of carbon disulfide in liquid sulfur will increase sharply, causing a large amount of carbon disulfide product to be carried away by the circulating sulfur, reducing the purity of carbon disulfide.

[0023] After heat exchange, the gas-liquid mixture enters a gas-liquid separator for gas-liquid separation, allowing liquid sulfur to be discharged from the bottom of the separator for recycling. The separated gas phase undergoes two-stage cooling via a primary cooler and a secondary cooler. The primary cooler uses circulating water for cooling, while the secondary cooler uses chilled water. After two-stage cooling, carbon disulfide (boiling point 46℃) partially condenses, while hydrogen sulfide (boiling point -60℃) remains mainly in gaseous form. This results in a gas-liquid mixture of partially condensed carbon disulfide and a large amount of uncondensed hydrogen sulfide. This gas-liquid mixture is directly fed into the hydrogen sulfide absorption tower without prior separation, thus avoiding the need for additional complex gas-liquid separation and desulfurization equipment.

[0024] The gas-liquid mixture fed into the hydrogen sulfide absorption tower mainly contains hydrogen sulfide, partially condensed carbon disulfide, and a small amount of uncondensed components. The bottom of the absorption tower is equipped with a circulating heat exchanger to maintain the required low temperature. At -5 to -10°C, refined liquid carbon disulfide is used to countercurrently wash the hydrogen sulfide in the gas phase, dissolving the hydrogen sulfide in the carbon disulfide. The unabsorbed hydrogen sulfide-containing waste gas is discharged from the top of the tower. If the absorption temperature is too low, it will increase refrigeration energy consumption and engineering investment, and may also increase the viscosity of the carbon disulfide, affecting mass transfer. If the temperature is too high, the hydrogen sulfide absorption efficiency will decrease significantly. The liquid phase containing hydrogen sulfide and carbon disulfide is fed into a distillation column at the bottom of the tower. The difference in boiling points between hydrogen sulfide and carbon disulfide is used for distillation separation. High-purity hydrogen sulfide is collected from the top of the column, and carbon disulfide is collected from the bottom. Part of the carbon disulfide product is sent out as a product, and the other part is cooled and returned to the absorption tower as an absorbent for recycling.

[0025] In summary, the present invention has the following beneficial effects:

[0026] 1. This application uses inferior sulfur for gasification treatment, and the impurities are retained in the liquid phase sulfidation at the bottom of the gasification tower and will not enter the reaction system, thereby enabling the operation cycle of the device to reach 2-5 years. Compared with the existing non-gasification device with an operation cycle of 0.5-1 year, this application completely solves the problem of frequent shutdowns for cleaning in the existing process.

[0027] 2. The preparation method of this application allows the use of low-quality sulfur with a sulfur content of ≥95% and ash content of ≤5% (far below the national standard requirements for qualified products). It can utilize low-cost raw materials such as sulfur recovered from pyrite and sulfur containing impurities in refineries, thereby reducing production costs.

[0028] 3. When using the preparation method of this application, carbon disulfide has extremely low solubility in liquid sulfur, and the circulating sulfur does not carry carbon disulfide, thereby eliminating product loss and safety risks.

[0029] 4. The preparation method of this application yields high-quality products, with carbon disulfide meeting the superior grade standard specified in GB / T 1615. The byproduct, high-purity hydrogen sulfide, can be directly sold as a chemical raw material, thereby improving the overall economic benefits of the project. Attached Figure Description

[0030] Figure 1 This is a process flow diagram of the production process of carbon disulfide in this application. Detailed Implementation

[0031] The present invention will be further described in detail below with reference to embodiments. All details not specifically stated herein are based on conventional conditions or conditions recommended by the manufacturer. All reagents and instruments, unless otherwise stated below, are commercially available conventional reagent products.

[0032] This invention addresses the shortcomings of existing technologies by providing a reconstructed process involving gasification pre-separation of impurities, high-temperature sulfur recovery, and low-temperature physical absorption of hydrogen sulfide. This systematically solves the problems of impurity accumulation and product loss caused by inferior sulfur. The core of this solution lies in: using the gasification step to intercept impurities outside the reaction system, thus resolving impurity accumulation; utilizing the physical properties at high temperatures to reduce the solubility of carbon disulfide in liquid sulfur, thus resolving carbon disulfide product loss; and employing a low-temperature countercurrent washing method to absorb hydrogen sulfide from refined carbon disulfide, thereby reducing the hydrogen sulfide content in the waste gas and increasing its purity. Combined with distillation, high-purity carbon disulfide and hydrogen sulfide are obtained, forming a technical solution that enables the long-term, low-cost, and efficient production of high-purity carbon disulfide from inferior raw materials.

[0033] Example 1

[0034] A method for producing high-purity carbon disulfide from low-quality sulfur and methane, the process flow is as follows: Figure 1 As shown, it includes the following steps:

[0035] S1. Liquid sulfur with a sulfur content of 98.5%, ash content of 0.18%, and organic matter content of 0.60% is fed into a sulfur gasification tower. The sulfur gasification temperature is controlled at 470℃ and the pressure is 0.07MPaG, so that the sulfur escapes from the top of the gasification tower in a gaseous state. The ash content and organic matter content in the sulfur at the bottom of the tower are detected.

[0036] S2. Gaseous sulfur and methane are mixed and then fed into a heating furnace. The mixture is heated to 650°C in the furnace and then fed into a reactor. The reactor is filled with non-metallic random packing material (Pall rings). A non-catalytic reaction is carried out at 650°C for 3 seconds and at a reaction pressure of 0.05 MPaG.

[0037] S3. The reaction products (containing carbon disulfide, hydrogen sulfide, and excess sulfur vapor) exiting the reactor are introduced into a heat exchanger and cooled to 185°C. At this point, the sulfur is reliquefied and carried in the gas phase in liquid form. The amount of carbon disulfide dissolved in the liquid sulfur is very small. The mass content of carbon disulfide in the liquid sulfur is detected. The heat recovered during the cooling process is reused. After heat exchange and cooling, a gas-liquid mixture is obtained.

[0038] S4. The gas-liquid mixture enters the gas-liquid separator and is separated under the conditions of 180℃ and 0.1MPa. The separated liquid sulfur is sent from the bottom of the gas-liquid separator into the gasification tower for recycling, while the gas phase enters the two-stage cooling system.

[0039] S5. In the two-stage cooling system, the first stage uses circulating water to cool the mixture to 85°C, and the second stage uses chilled water to further cool the material at 85°C to -5°C. After the two-stage cooling, carbon disulfide is partially liquefied, while hydrogen sulfide still exists mainly in gaseous form, thus obtaining a gas-liquid mixture of partially condensed carbon disulfide and uncondensed hydrogen sulfide, which is then sent into the hydrogen sulfide absorption tower.

[0040] S6. The hydrogen sulfide absorption tower is equipped with a circulating heat exchanger to maintain the tower temperature at -5℃ and the operating pressure at 0.03MPaG. The top of the tower uses a countercurrent wash of the gas phase with cooled and purified liquid carbon disulfide returned from the carbon disulfide distillation tower to ensure that the hydrogen sulfide is fully dissolved in the liquid carbon disulfide. The molar ratio of carbon disulfide to hydrogen sulfide is controlled at 3:1. The hydrogen sulfide-containing waste gas that cannot be absorbed is discharged from the top of the tower for waste gas treatment, and the hydrogen sulfide content (volume fraction %) in the waste gas is detected. The liquid carbon disulfide containing hydrogen sulfide is then fed into the distillation tower.

[0041] S7. Liquid carbon disulfide containing hydrogen sulfide at the bottom of the absorption tower is pressurized to 1 MPaG by a pump and then sent to a carbon disulfide distillation tower. The operating pressure of the distillation tower is 0.8 MPaG. A reboiler is installed at the bottom of the tower and a reflux condenser is installed at the top. The distillation separation is achieved by utilizing the significant difference in boiling points between hydrogen sulfide and carbon disulfide. The distillate at the top of the tower is hydrogen sulfide gas, which, after testing, has a purity of 99.2% and can be directly used in the production of downstream chemical products such as methanethiol and dimethyl sulfide. The bottom of the tower contains liquid carbon disulfide, which, after testing, meets the requirements for superior grade products in GB / T1615. A portion of the carbon disulfide is output, and a portion is recycled back to the carbon disulfide absorption tower as an absorbent for hydrogen sulfide.

[0042] The specifications for superior grade products in GB / T1615 are as follows:

[0043] Appearance: Colorless and transparent liquid; Distillation rate (45.6-46.6℃, 101.32kPa): ≥97.5%; Density (20℃): 1.262-1.265g / mL; Non-volatile matter: ≤0.005%; Iodine reducing agent (as... (Calculated): ≤0.0002%; Sulfate: Passed inspection; Free acid: Passed inspection; Sulfur and other sulfides: Passed inspection.

[0044] Example 2

[0045] A method for producing high-purity carbon disulfide from low-quality sulfur and methane as raw materials includes the following steps:

[0046] S1. Liquid sulfur with a sulfur content of 96.5%, ash content of 4.2%, and organic matter content of 0.80% is fed into a sulfur gasification tower. The sulfur gasification temperature is controlled at 455℃ and the pressure is 0.1MPaG, so that the sulfur escapes from the top of the gasification tower in a gaseous state. The ash content and organic matter content in the sulfur at the bottom of the tower are detected.

[0047] S2. Gaseous sulfur and methane are mixed and then fed into a heating furnace. The mixture is heated to 630°C in the furnace and then fed into a reactor. The reactor is filled with non-metallic random packing material (Pall rings). A non-catalytic reaction is carried out at 630°C for 5 seconds and at a reaction pressure of 0.1 MPaG.

[0048] S3. The reaction products (containing carbon disulfide, hydrogen sulfide, and excess sulfur vapor) exiting the reactor are introduced into a heat exchanger and cooled to 180°C. At this point, the sulfur is reliquefied and carried in the gas phase in liquid form. The amount of carbon disulfide dissolved in the liquid sulfur is very small. The mass content of carbon disulfide in the liquid sulfur is detected. The heat recovered during the cooling process is reused. After heat exchange and cooling, a gas-liquid mixture is obtained.

[0049] S4. The gas-liquid mixture enters the gas-liquid separator and is separated under the conditions of 180℃ and 0.1MPa. The separated liquid sulfur is sent from the bottom of the gas-liquid separator into the gasification tower for recycling, while the gas phase enters the two-stage cooling system.

[0050] S5. In the two-stage cooling system, the first stage uses circulating water to cool the mixture to 85°C, and the second stage uses chilled water to further cool the material at 85°C to -5°C. After the two-stage cooling, carbon disulfide is partially liquefied, while hydrogen sulfide still exists mainly in gaseous form, thus obtaining a gas-liquid mixture of partially condensed carbon disulfide and uncondensed hydrogen sulfide, which is then sent into the hydrogen sulfide absorption tower.

[0051] S6. The hydrogen sulfide absorption tower is equipped with a circulating heat exchanger to maintain the tower temperature at -5℃ and the operating pressure at 0.02MPaG. The top of the tower uses a countercurrent wash of the gas phase with cooled and purified liquid carbon disulfide returned from the carbon disulfide distillation tower to ensure that the hydrogen sulfide is fully dissolved in the liquid carbon disulfide. The molar ratio of carbon disulfide to hydrogen sulfide is controlled at 4:1. The hydrogen sulfide-containing waste gas that cannot be absorbed is discharged from the top of the tower for waste gas treatment, and the hydrogen sulfide content (volume fraction %) in the waste gas is detected. The liquid carbon disulfide containing hydrogen sulfide is then fed into the distillation tower.

[0052] S7. Liquid carbon disulfide containing hydrogen sulfide at the bottom of the absorption tower is pressurized to 1 MPaG by a pump and then sent to a carbon disulfide distillation tower. The operating pressure of the distillation tower is 0.8 MPaG. A reboiler is installed at the bottom of the tower and a reflux condenser is installed at the top. The distillation separation is achieved by utilizing the significant difference in boiling points between hydrogen sulfide and carbon disulfide. The distillate at the top of the tower is hydrogen sulfide gas, which, after testing, has a purity of 99.6% and can be directly used in the production of downstream chemical products such as methanethiol and dimethyl sulfide. The bottom of the tower contains liquid carbon disulfide, which, after testing, meets the requirements for superior grade products in GB / T1615. A portion of the carbon disulfide is output, and a portion is recycled back to the carbon disulfide absorption tower as an absorbent for hydrogen sulfide.

[0053] Example 3

[0054] A method for producing high-purity carbon disulfide from low-quality sulfur and methane as raw materials includes the following steps:

[0055] S1. Liquid sulfur with a sulfur content of 95.8%, ash content of 4.7%, and organic matter content of 0.85% is fed into a sulfur gasification tower. The sulfur gasification temperature is controlled at 500℃ and the pressure is 0.05MPaG, so that the sulfur escapes from the top of the gasification tower in a gaseous state. The ash content and organic matter content in the sulfur at the bottom of the tower are detected.

[0056] S2. Gaseous sulfur and methane are mixed and then fed into a heating furnace. The mixture is heated to 630°C in the furnace and then fed into a reactor. The reactor is filled with non-metallic random packing material (Pall rings). A non-catalytic reaction is carried out at 670°C for 1 second and at a reaction pressure of 0.07 MPaG.

[0057] S3. The reaction products (containing carbon disulfide, hydrogen sulfide, and excess sulfur vapor) exiting the reactor are introduced into a heat exchanger and cooled to 175°C. At this point, the sulfur is reliquefied and is also entrained in the gas phase in liquid form. The amount of carbon disulfide dissolved in the liquid sulfur is very small. The mass content of carbon disulfide in the liquid sulfur is detected. The heat recovered during the cooling process is reused. After heat exchange and cooling, a gas-liquid mixture is obtained.

[0058] S4. The gas-liquid mixture enters the gas-liquid separator and is separated under the conditions of 180℃ and 0.1MPa. The separated liquid sulfur is sent from the bottom of the gas-liquid separator into the gasification tower for recycling, while the gas phase enters the two-stage cooling system.

[0059] S5. In the two-stage cooling system, the first stage uses circulating water to cool the mixture to 85°C, and the second stage uses chilled water to further cool the material at 85°C to -5°C. After the two-stage cooling, carbon disulfide is partially liquefied, while hydrogen sulfide still exists mainly in gaseous form, thus obtaining a gas-liquid mixture of partially condensed carbon disulfide and uncondensed hydrogen sulfide, which is then sent into the hydrogen sulfide absorption tower.

[0060] S6. The hydrogen sulfide absorption tower is equipped with a circulating heat exchanger to maintain the tower temperature at -10℃ and the operating pressure at 0.05MPaG. The top of the tower uses a countercurrent wash of the gas phase with cooled and purified liquid carbon disulfide returned from the carbon disulfide distillation tower to ensure that the hydrogen sulfide is fully dissolved in the liquid carbon disulfide. The molar ratio of carbon disulfide to hydrogen sulfide is controlled at 5:1. The hydrogen sulfide-containing waste gas that cannot be absorbed is discharged from the top of the tower for waste gas treatment, and the hydrogen sulfide content (volume fraction %) in the waste gas is detected. The liquid carbon disulfide containing hydrogen sulfide is then fed into the distillation tower.

[0061] S7. Liquid carbon disulfide containing hydrogen sulfide at the bottom of the absorption tower is pressurized to 1 MPaG by a pump and then sent to a carbon disulfide distillation tower. The operating pressure of the distillation tower is 0.8 MPaG. A reboiler is installed at the bottom of the tower and a reflux condenser is installed at the top. The distillation separation is achieved by utilizing the significant difference in boiling points between hydrogen sulfide and carbon disulfide. The distillate at the top of the tower is hydrogen sulfide gas, which, after testing, has a purity of 99.8% and can be directly used in the production of downstream chemical products such as methanethiol and dimethyl sulfide. The bottom of the tower contains liquid carbon disulfide, which, after testing, meets the requirements for superior grade products in GB / T1615. A portion of the carbon disulfide is output, and a portion is recycled back to the carbon disulfide absorption tower as an absorbent for hydrogen sulfide.

[0062] Comparative Example 1

[0063] A method for producing carbon disulfide from inferior sulfur and methane as raw materials differs from Example 2 in that, in step S3, the temperature is lowered to 120°C by heat exchange, while the remaining steps are the same as in Example 2. The mass content of carbon disulfide in the liquid phase sulfur is detected, and the rest are the same as in Example 2.

[0064] Comparative Example 2

[0065] A method for producing carbon disulfide using inferior sulfur and methane as raw materials differs from Example 2 in that, in step S6, the temperature inside the hydrogen sulfide absorption tower is 10°C, and the content of hydrogen sulfide in the waste gas is detected. All other steps are the same as in Example 2.

[0066] Comparative Example 3

[0067] A method for producing carbon disulfide using inferior sulfur and methane as raw materials differs from Example 2 in that the gasification temperature in step S1 is 520°C, the pressure is 0.1 MPa, and the ash and organic matter content in the sulfur at the bottom of the tower is detected. All other aspects are the same as in Example 2.

[0068] Comparison Example

[0069] The preparation steps for carbon disulfide using traditional methods are as follows:

[0070] Natural gas and liquid sulfur (sulfur content 99.95%, ash content ≤0.03%, organic matter <0.03%) were mixed and added to a heating furnace. The furnace temperature was raised to 650°C and then the mixture was introduced into a reactor. The reactor was filled with non-metallic random packing material (Pall rings). A non-catalytic reaction was carried out at 650°C for 3 seconds and at a reaction pressure of 0.05 MPaG.

[0071] The reaction products (containing carbon disulfide and hydrogen sulfide) exiting the reactor are separated into excess liquid sulfur by a sulfur cooler (separation conditions: 180℃, pressure: 0.1MPa), and the content of carbon disulfide in the liquid sulfur is detected. The separated gas phase enters a separation tower, and after two separations at a temperature of 120℃ and a pressure of 0.5MPaG, hydrogen sulfide gas is obtained at the top of the tower and carbon disulfide is obtained at the bottom of the tower.

[0072] The detection results of steps S1, S3, S6 and S7 in the above embodiments and comparative examples were recorded. Step S1 detected the content of ash and organic matter in the bottom sulfidation; step S3 detected the mass content of carbon disulfide in liquid sulfur; step S6 detected the volume fraction of hydrogen sulfide in the exhaust gas; and step S7 detected the purity of the final carbon disulfide product and the purity of the hydrogen sulfide gas at the top of the tower. The detection results are shown in Table 1.

[0073]

[0074] Note: In the table above, " / " indicates that the data was not detected.

[0075] Compared with the comparative method, the production method of this application can effectively retain the ash and organic matter in the sulfur at the bottom of the tower after the sulfur gasification treatment, so that carbon disulfide can be produced using inferior sulfur. The obtained carbon disulfide product meets the requirements of superior grade and has a purity of more than 98%, which has broad application prospects. In addition, when using the preparation method of this application, the hydrogen sulfide content in the exhaust gas is much lower than that in the comparative example, which further illustrates that the method of this application can effectively reduce the hydrogen sulfide content in the exhaust gas. Moreover, the preparation method of this application can enable the reactor to operate without shutdown for more than 3 years, while the preparation method of the comparative example requires shutdown and maintenance after less than 1 year of operation.

[0076] Compared with Example 2, when the same inferior sulfur was used, the content of carbon disulfide in the liquid phase sulfur increased significantly after the heat exchange in step S3 was cooled to a lower temperature.

[0077] Compared with Example 2, when the temperature inside the hydrogen sulfide absorption tower is higher, the content of hydrogen sulfide in the exhaust gas increases, which not only affects the environment but also wastes hydrogen sulfide.

[0078] Compared with Example 2, when the same inferior sulfur is used, the higher vaporization temperature in step S1 increases the volatilization of organic matter and ash. Therefore, the ash and organic matter content in the liquid sulfur at the bottom of the tower is significantly lower than that in Example 2. Over time, this will effectively shorten the operating cycle of the entire system.

[0079] The embodiments described herein are merely illustrative of preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, all equivalent changes made in accordance with the structure, shape, and principle of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A method for producing high-purity carbon disulfide from inferior sulfur and methane as raw materials, characterized in that, Includes the following steps: S1. Gasify liquid sulfur with a sulfur content ≥95% and ash content ≤5% at 450-500℃. S2. Gaseous sulfur and methane are heated and then introduced into the reactor for reaction; S3. The reaction products exiting the reactor are cooled by heat exchange, so that the excess sulfur in the reaction products is condensed to obtain a gas-liquid mixture. S4. The gas-liquid mixture enters the gas-liquid separator for gas-liquid separation, and the separated liquid sulfur is recycled. S5. After the gas phase separated in step S4 is cooled in two stages, a partially condensed mixture of carbon disulfide and uncondensed hydrogen sulfide is obtained. S6. The gas-liquid mixture obtained in step S5 enters the absorption tower. The gas phase is washed countercurrently with refined liquid carbon disulfide to dissolve hydrogen sulfide in the liquid carbon disulfide. The waste gas is discharged from the top of the tower. The liquid carbon disulfide containing hydrogen sulfide is then distilled to obtain high-purity carbon disulfide and hydrogen sulfide.

2. The method for producing high-purity carbon disulfide from inferior sulfur and methane as raw materials according to claim 1, characterized in that: The two-stage cooling in step S5 is as follows: the first stage uses circulating water to cool the gas phase, and the second stage uses chilled water to further cool the material.

3. The method for producing high-purity carbon disulfide from inferior sulfur and methane as raw materials according to claim 1, characterized in that: In step S6, the operating temperature for countercurrent washing of the gas phase with refined liquid carbon disulfide is -5 to -10°C, and the operating pressure is 0 to 0.05 MPaG.

4. The method for producing high-purity carbon disulfide from inferior sulfur and methane as raw materials according to claim 1, characterized in that: When the purified liquid carbon disulfide is used to countercurrently wash the gas phase, the molar ratio of carbon disulfide to hydrogen sulfide is (3-5):

1.

5. The method for producing high-purity carbon disulfide from inferior sulfur and methane as raw materials according to claim 1, characterized in that: The operating pressure in step S1 is 0.05-0.1 MPaG.

6. The method for producing high-purity carbon disulfide from inferior sulfur and methane as raw materials according to claim 1, characterized in that: In step S2, gaseous sulfur and methane are heated to 630-670°C and then introduced into a reactor. The reaction time in the reactor is 1-5 seconds, and the operating pressure is 0.05-0.1 MPaG.

7. The method for producing high-purity carbon disulfide from inferior sulfur and methane as raw materials according to claim 1, characterized in that: In step S3, the reaction product is cooled to 180±5℃ via heat exchange to obtain a gas-liquid mixture.

8. The method for producing high-purity carbon disulfide from inferior sulfur and methane as raw materials according to claim 1, characterized in that: The mass content of carbon disulfide in the liquid sulfur obtained in step S4 is ≤0.3%.

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