Process system for effectively preventing methyl mercaptan side reaction in carbonyl sulfide hydrolysis technology

Abstract

The invention relates to the technical field of carbonyl sulfide hydrolysis, and particularly discloses a process system for effectively preventing methyl mercaptan side reaction in carbonyl sulfide hydrolysis technology, which comprises a catalyst sulfuration subsystem and a catalyst heating subsystem which are mutually independent and are respectively matched with a COS hydrolyzer, the catalyst vulcanization subsystem comprises a circulating compressor, a hydrolysis gas and fuel gas heat exchanger and an electric heater which are connected in sequence, the outlet end of the electric heater is communicated with the inlet end of the COS hydrolyzer, and a low-pressure steam supplementing pipeline is arranged between the outlet of the hydrolysis gas and fuel gas heat exchanger of the catalyst vulcanization system and the inlet of the electric heater. A medium-pressure steam supplementing pipeline is arranged between an outlet of a steam-liquid separator of a heating system and an inlet of a process gas and synthesis gas heat exchanger, online water supplementing can be performed on a catalyst for two key water loss links of vulcanization and heating, and methyl mercaptan side reaction caused by water shortage of the catalyst is avoided fundamentally.

Description

Technical Field

[0001] This invention relates to the field of carbonyl sulfur hydrolysis technology, and in particular to a process system for effectively preventing methanethiol side reactions in carbonyl sulfur hydrolysis technology. Background Technology

[0002] In the coal chemical industry, the syngas produced from coal typically contains sulfur-containing components such as hydrogen sulfide (H2S) and carbonyl sulfide (COS). These sulfur-containing components not only corrode equipment in subsequent production systems but also cause environmental emissions to exceed standards. Therefore, desulfurization processes are necessary to treat the syngas.

[0003] Currently, mainstream desulfurization processes in the industry, such as the alkanolamine method, low-temperature methanol washing, and ZnO method, can effectively remove H2S from syngas, but their absorption efficiency for COS is extremely low. To achieve effective control of total sulfur in syngas, a COS hydrolysis stage needs to be incorporated at the upstream end of the desulfurization process. Using a COS hydrolysis catalyst packed in a hydrolyzer, COS is converted into H2S, which is easily removed by the desulfurization process. The H2S is then removed by subsequent desulfurization processes, ultimately achieving the total sulfur control target.

[0004] COS hydrolysis catalysts require sulfidation activation to acquire the activity needed to convert COS, and a temperature of at least 130°C must be maintained during normal operation to ensure a conversion efficiency of over 90%. Therefore, two core auxiliary systems are formed: a catalyst sulfidation system and a heating system. The specific operating mechanism is as follows: Catalyst Sulfation System: During initial startup, the catalyst needs to be converted from its oxidized state to its sulfidized state via a circulating sulfation system. In this system, the circulating gas from the compressor outlet passes through a hydrolysis gas / fuel gas heat exchanger (the heat exchanger carries two media: fuel gas on the tube side and hydrolysis gas on the shell side, with the two gases exchanging heat with each other) and an electric heater. After heating, it mixes with H2 and CS2 and enters the COS hydrolyzer. H2 and CS2 react on the catalyst surface to generate H2S, which further reacts with the catalyst to convert it to its sulfidized state. To ensure catalyst activation, N2 and H2 need to be added to the pipeline from the hydrolysis gas / fuel gas heat exchanger outlet to the electric heater inlet, controlling the H2 content in the circulating gas to ≥20%. If the H2 content is <20%, part of the fuel gas needs to be vented to adjust the H2 concentration, and the remaining fuel gas is returned to the compressor inlet for reuse. The entire vulcanization process needs to be carried out in stages: during the heating period, the circulating fan and electric heater are started, and H2 is added when the bed temperature reaches 200℃; during the initial activation stage, CS2 is added after the H2 content is >20%; after the H2S at the hydrolyzer outlet is ≥0.5g / Nm³, the heating continues; during the main activation stage, the bed temperature is maintained at 350℃ for a sufficient time; during the cooling and replacement stage, the electric heater is stopped, and the addition of H2 and CS2 is stopped when the bed temperature is <300℃; after nitrogen replacement until the outlet H2S is ≤0.15g / Nm³, isolation and pressure maintenance are carried out.

[0005] Catalyst heating system: Before each unit startup, the catalyst needs to be preheated to the target temperature using nitrogen through the heating system. Nitrogen enters the system from the syngas pipeline, and passes sequentially through the process gas / syngas heat exchanger (the heat exchanger carries two media, process gas on the tube side and syngas on the shell side, with the two gases exchanging heat with each other), the syngas cooler, and the vapor-liquid separator. Then, it is heated by medium-pressure steam in the hydrolyzer inlet heater, and the high-temperature nitrogen enters the hydrolyzer to heat the catalyst. After the heat exchange, the nitrogen, which has cooled down, is then processed by the hydrolysate / fuel gas heat exchanger and the hydrolysate cooler before being discharged to the flare.

[0006] However, current technology fails to recognize the methanethiol side reaction that occurs in catalysts under water-deficient conditions. When the catalyst is dehydrated, H2S in the syngas reacts to form methanethiol, which cannot be absorbed by the subsequent desulfurization process, directly leading to a high total sulfur content in the desulfurized syngas and posing a risk of exceeding environmental emission standards. Further analysis reveals that neither the existing sulfidation system nor the heating system has a catalyst dehydration protection design, indicating a clear catalyst dehydration process during production. The catalyst needs to be maintained at a high temperature of 200-350℃ for 2-4 days. This process leads to a large amount of water adsorbed on the catalyst surface, adsorbed water inside the pores, and even water of crystallization being lost through volatilization, resulting in severe water shortage in the catalyst. When the system is first put into operation, the methanethiol side reaction is severe, causing sulfur emissions to exceed the standard. Even if the catalyst is slowly moistened by the syngas in subsequent operation, it will take at least 1-2 days to reduce the side reaction to a normal level. During this stage, the syngas can only be discharged to the flare, which not only wastes resources but also aggravates environmental pollution.

[0007] Before each unit startup, the catalyst is heated to ≥130℃ with nitrogen. Since nitrogen itself contains no moisture, it continuously carries away moisture from the catalyst. Furthermore, when the temperature rises above 80℃, the rate of moisture evaporation from the catalyst accelerates, further leading to moisture loss. This results in a more intense methanethiol side reaction during the initial startup phase compared to normal operation. This not only increases the risk of exceeding total sulfur emissions standards at the downstream end but also exacerbates equipment corrosion and worsens sulfate crystallization problems in subsequent systems, severely impacting process stability and equipment lifespan. Summary of the Invention

[0008] Therefore, the technical problem to be solved by the present invention is that in the existing coal chemical synthesis gas COS hydrolysis process, neither the sulfidation system nor the heating system has a water shortage prevention design. The lack of water in the catalyst will trigger the methanethiol side reaction, and the subsequent desulfurization process cannot remove the methanethiol, resulting in the total sulfur emission exceeding the standard.

[0009] The above-mentioned technical problems are solved by the following technical solution: The present invention proposes a process system for effectively preventing methanethiol side reactions in carbonyl sulfur hydrolysis technology, which includes a catalyst sulfidation subsystem and a catalyst heating subsystem that are independent of each other and adapted to the COS hydrolyzer. The catalyst sulfidation subsystem includes a circulating compressor, a hydrolysis gas and fuel gas heat exchanger, and an electric heater connected in sequence. The outlet end of the electric heater is connected to the inlet end of the COS hydrolyzer. A low-pressure steam inlet pipeline for replenishing steam into the system is provided on the pipeline between the outlet of the hydrolysis gas and fuel gas heat exchanger and the inlet of the electric heater. The low-pressure steam inlet pipeline is equipped with a first flow meter, a first flow regulating valve, a first check valve, and a first shut-off valve for measuring steam flow.

[0010] In a preferred embodiment of the process system for effectively preventing methanethiol side reactions in the carbonyl sulfide hydrolysis technology of the present invention: the catalyst heating subsystem includes a process gas and syngas heat exchanger, a syngas cooler, and a vapor-liquid separator connected in sequence. The outlet end of the vapor-liquid separator is connected to the inlet end of the COS hydrolyzer. A medium-pressure steam injection pipeline for injecting steam into the system is provided on the pipeline between the outlet of the vapor-liquid separator and the inlet of the process gas and syngas heat exchanger. The medium-pressure steam injection pipeline is equipped with a second flow meter, a second flow regulating valve, a second check valve, and a second shut-off valve for measuring the steam flow rate.

[0011] In a preferred embodiment of the process system for effectively preventing methanethiol side reactions in the carbonyl sulfur hydrolysis technology of the present invention: the low-pressure steam supplied by the low-pressure steam feed pipeline has a pressure range of 0.4~0.45 MPa.

[0012] In a preferred embodiment of the process system for effectively preventing methanethiol side reactions in the carbonyl sulfur hydrolysis technology of the present invention: the COS hydrolyzer is provided with catalyst beds distributed vertically, and temperature measuring points for monitoring the bed temperature are arranged at each of the vertically distributed catalyst beds.

[0013] In a preferred embodiment of the process system for effectively preventing methanethiol side reactions in the carbonyl sulfur hydrolysis technology of the present invention: the medium-pressure steam supplied by the medium-pressure steam feed pipeline has a pressure range of 4.5~4.8 MPa.

[0014] In a preferred embodiment of the process system for effectively preventing methanethiol side reactions in the carbonyl sulfide hydrolysis technology of the present invention: the catalyst sulfidation subsystem further includes a hydrolysis gas cooler and a vapor-water separator; the outlet end of the COS hydrolyzer is connected to the inlet end of the hydrolysis gas cooler, the outlet end of the hydrolysis gas cooler is connected to the inlet end of the vapor-water separator, and the outlet end of the vapor-water separator is connected to the inlet end of the circulating compressor, forming a circulation loop.

[0015] In a preferred embodiment of the process system for effectively preventing methanethiol side reactions in the carbonyl sulfur hydrolysis technology of the present invention: the catalyst heating subsystem further includes a hydrolyzer inlet heater; the outlet end of the vapor-liquid separator is connected to the inlet end of the hydrolyzer inlet heater, the outlet end of the hydrolyzer inlet heater is connected to the inlet end of the COS hydrolyzer, and the hydrolyzer inlet heater is equipped with a medium-pressure steam heating source.

[0016] In a preferred embodiment of the process system for effectively preventing methanethiol side reactions in the carbonyl sulfur hydrolysis technology of the present invention: the bottom of the gas-liquid separator is provided with a drain valve for discharging liquid water, and the drain valve is a valve structure that can be manually controlled to open and close.

[0017] In a preferred embodiment of the process system for effectively preventing methanethiol side reactions in the carbonyl sulfide hydrolysis technology of the present invention: in the catalyst sulfidation subsystem, when steam is introduced through the low-pressure steam injection pipeline, the temperature of the upper bed of the COS hydrolyzer is controlled to be no higher than 170°C, and the temperature of the lower bed is controlled to be no lower than 80°C.

[0018] In a preferred embodiment of the process system for effectively preventing methanethiol side reactions in the carbonyl sulfur hydrolysis technology of the present invention: in the catalyst heating subsystem, steam is introduced through the medium-pressure steam injection pipeline to raise the temperature of the lower bed of the COS hydrolyzer to 70~80°C; in the catalyst heating subsystem, when the nitrogen flow rate used for heating is 6000~18000 Nm³ / h, the amount of steam introduced through the medium-pressure steam injection pipeline is 160~480 Kg / h.

[0019] The beneficial effects of this invention are as follows: by setting a low-pressure steam injection pipeline between the outlet of the hydrolysis gas fuel gas heat exchanger and the inlet of the electric heater in the catalyst sulfidation system, and setting a medium-pressure steam injection pipeline between the outlet of the vapor-liquid separator and the inlet of the process gas syngas heat exchanger in the heating system, water can be added to the catalyst online for the two key water loss stages of sulfidation and heating, thereby fundamentally avoiding the side reaction of methanethiol caused by catalyst lack of water and solving the technical pain point that the subsequent desulfurization process cannot remove methanethiol.

[0020] Because the methanethiol side reaction is effectively suppressed, the syngas contains only H2S, which is easily removed by existing desulfurization processes. This ensures that the total sulfur content of the syngas after desulfurization is stably controlled within the environmental protection standard range, avoiding the problems of serious sulfur emissions exceeding the standard during the first use of existing technologies and high total sulfur emissions at the beginning of each start-up. This significantly improves the environmental compliance of the process.

[0021] In existing technologies, when a catalyst is first put into use and a severe side reaction occurs due to lack of water, the syngas needs to be vented to the flare for 1-2 days to wet the catalyst, resulting in a large waste of resources. This invention can directly avoid this step by replenishing water online, reducing the amount of syngas vented, reducing fuel resource consumption, and reducing pollutants emitted from flare combustion, thus alleviating the environmental burden.

[0022] Methanethiol and catalysts in a dehydrated state can exacerbate equipment corrosion, and byproducts of the reaction can easily lead to sulfate crystallization in subsequent systems. This invention can effectively mitigate equipment corrosion rates, reduce sulfate crystal accumulation, extend equipment lifespan, and lower system maintenance costs and failure risks by inhibiting methanethiol side reactions and maintaining a suitable moisture state for the catalyst.

[0023] The steam injection design of this invention includes control components such as flow meters and temperature measuring points, which can precisely adjust the amount and timing of water injection according to system pressure, circulation flow rate, and catalyst bed temperature to ensure a stable and controllable water injection process. At the same time, the sulfidation subsystem and the heating subsystem are injected with water independently to adapt to different operating conditions, further improving the overall reliability and stability of the COS hydrolysis process and ensuring continuous and smooth production. Attached Figure Description

[0024] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings of the embodiments of the present invention will be briefly described below. Obviously, the drawings described below only relate to some embodiments of the present invention and are not intended to limit the present invention. Wherein: Figure 1 The diagram shows the system before modification of the catalyst sulfidation subsystem in the process system for effectively preventing methanethiol side reactions in carbonyl sulfide hydrolysis technology; Figure 2 The diagram shows the system before modification of the catalyst heating subsystem in the process system for effectively preventing methanethiol side reactions in carbonyl sulfide hydrolysis technology; Figure 3 A schematic diagram of the overall framework of the process system for effectively preventing methanethiol side reactions in carbonyl sulfide hydrolysis technology is shown. Figure 4 A diagram of the catalyst sulfidation subsystem of the process system that effectively prevents the side reaction of methanethiol in carbonyl sulfide hydrolysis technology is shown. Figure 5 A diagram of the catalyst heating subsystem is shown for the process system in the carbonyl sulfur hydrolysis technology that effectively prevents the side reaction of methanethiol. Detailed Implementation

[0025] To enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0026] The terminology used in this invention is that which is currently widely used in the art in consideration of the function of the invention; however, these terms may vary according to the intent of those skilled in the art, precedent, or new technology in the art. Furthermore, specific terms may be chosen by the applicant, and in such cases, their detailed meanings will be described in the detailed description of the invention. Therefore, the terms used in this specification should not be construed as simple names, but rather based on their meanings and the overall description of the invention.

[0027] Reference Figures 1-5 This embodiment provides a process system for effectively preventing methanethiol side reactions in carbonyl sulfur hydrolysis technology. It includes solving the problems of excessive total sulfur emissions, resource waste, and equipment corrosion caused by the loss of water in the catalyst during sulfidation and heating processes in the existing COS hydrolysis process through low-pressure steam injection pipeline 14 and medium-pressure steam injection pipeline 24.

[0028] The catalyst sulfidation subsystem 1 and the catalyst heating subsystem 2 are independent of each other and are adapted to the COS hydrolyzer 3 respectively. The catalyst sulfidation subsystem 1 is used to convert the catalyst in the COS hydrolyzer 3 from the oxidized state to the sulfidated state during the first start-up, ensuring that the catalyst has COS conversion activity. The catalyst heating subsystem 2 is used to preheat the catalyst in the COS hydrolyzer 3 to the active temperature of ≥130℃ before each unit start-up. The two operate independently and can accurately replenish water for the two key water loss links of catalyst sulfidation and heating, respectively, to avoid the occurrence of methanethiol side reaction.

[0029] The catalyst sulfidation subsystem 1 includes a circulating compressor 11, a hydrolysis gas and fuel gas heat exchanger 12, and an electric heater 13 connected in sequence. The outlet end of the electric heater 13 is connected to the inlet end of the COS hydrolyzer 3. A low-pressure steam inlet pipeline 14 for adding steam to the system is provided on the pipeline between the outlet of the hydrolysis gas and fuel gas heat exchanger 12 and the inlet of the electric heater 13. The low-pressure steam inlet pipeline 14 is equipped with a first flow meter 141, a first flow regulating valve 142, a first check valve 143, and a first shut-off valve 144 for measuring the steam flow.

[0030] The catalyst sulfidation subsystem 1 includes a circulating compressor 11, a hydrolysis gas and fuel gas heat exchanger 12, and an electric heater 13 connected in sequence. The outlet of the electric heater 13 is connected to the inlet of the COS hydrolyzer 3, forming a gas circulation path for the sulfidation process. The circulating compressor 11 provides gas circulation power to the system. The hydrolysis gas and fuel gas heat exchanger 12 can utilize the waste heat in the system to preheat the circulating gas. The electric heater 13 is used to heat the circulating gas to the maximum temperature required for sulfidation, up to 350°C. A low-pressure steam injection pipeline 14 is provided on the pipeline between the outlet of the hydrolysis gas and fuel gas heat exchanger 12 and the inlet of the electric heater 13 for injecting steam into the system. The line is the core structure for water replenishment to the catalyst during the sulfidation process. The low-pressure steam replenishment pipeline 14 is equipped with a first flow meter 141, a first flow regulating valve 142, a first check valve 143, and a first shut-off valve 144 for measuring the steam flow. The first flow meter 141 monitors the steam replenishment amount in real time to ensure the accuracy of water replenishment. The first flow regulating valve 142 can adjust the steam flow according to the catalyst bed temperature and system pressure. The first check valve 143 prevents the circulating gas in the system, including H2, CS2, H2S, etc., from flowing back into the steam pipeline, avoiding pipeline corrosion or safety risks. The first shut-off valve 144 is used to control the start and stop of steam replenishment, realizing flexible control of the water replenishment process.

[0031] The catalyst heating subsystem 2 includes a process gas and syngas heat exchanger 21, a syngas cooler 22, and a vapor-liquid separator 23 connected in sequence. The outlet end of the vapor-liquid separator 23 is connected to the inlet end of the COS hydrolyzer 3. A medium-pressure steam injection pipeline 24 for injecting steam into the system is provided on the pipeline between the outlet of the vapor-liquid separator 23 and the inlet of the process gas and syngas heat exchanger 21. The medium-pressure steam injection pipeline 24 is equipped with a second flow meter 241, a second flow regulating valve 242, a second check valve 243, and a second shut-off valve 244 for measuring the steam flow. The catalyst heating subsystem 2 includes a process gas and syngas heat exchanger 21, a syngas cooler 22, and a vapor-liquid separator 23 connected in sequence. The outlet of the vapor-liquid separator 23 is connected to the inlet of the COS hydrolyzer 3, forming a gas flow path for nitrogen heating. The process gas and syngas heat exchanger 21 can utilize the waste heat of the syngas to preheat the nitrogen. The syngas cooler 22 is used to cool the syngas after heat exchange. The vapor-liquid separator 23 separates any liquid water that may be carried in the nitrogen, preventing moisture from affecting the heating efficiency during subsequent heating. Furthermore, a system is installed on the pipeline between the outlet of the vapor-liquid separator 23 and the inlet of the process gas and syngas heat exchanger 21. There is a medium-pressure steam injection pipeline 24 for injecting steam into the system. This pipeline is a key structure for catalyst water replenishment during the heating process. The medium-pressure steam injection pipeline 24 is equipped with a second flow meter 241, a second flow regulating valve 242, a second check valve 243, and a second shut-off valve 244 for measuring the steam flow. The second flow meter 241 monitors the steam injection amount to ensure it matches the nitrogen flow rate. The second flow regulating valve 242 adjusts the steam amount according to the nitrogen flow rate and the catalyst bed temperature. The second check valve 243 prevents nitrogen from backflowing into the steam pipeline. The second shut-off valve 244 controls the start and stop of steam injection to meet the water replenishment needs during the heating process.

[0032] The low-pressure steam supplied by low-pressure steam feed line 14 has a pressure range of 0.4~0.45MPa. This pressure range ensures that the steam diffuses smoothly during the sulfidation process within the system, matching the system pressure and the outlet pressure of the circulating compressor, and fully contacts the catalyst to achieve water replenishment. It also avoids a sudden increase in system pressure caused by high-pressure steam, or damage to the catalyst's pore structure due to excessively high steam pressure, which would affect catalytic activity.

[0033] The COS hydrolyzer 3 has two catalyst beds distributed vertically, with temperature monitoring points at each bed level. These beds, corresponding to R4001A and R4001B, are filled with catalysts to ensure sufficient contact and reaction between COS and the catalyst. Real-time monitoring of the bed temperatures allows for precise determination of the catalyst's sulfidation or heating status. For example, during sulfidation, the upper bed temperature must be ≤170℃ and the lower bed temperature ≥80℃. During heating, the lower bed temperature must reach 70~80℃ before water replenishment is initiated. This provides a basis for adjusting the timing and flow rate of steam replenishment, preventing catalyst deactivation or aggravated side reactions due to abnormal temperatures.

[0034] The medium-pressure steam supplied by the medium-pressure steam feed line 24 has a pressure range of 4.5~4.8MPa. This pressure range is compatible with the medium-pressure steam heating source pressure of the hydrolyzer inlet heater 25 in the heating system. This ensures that the steam vaporizes rapidly and relatively stably with nitrogen heating pressure within the heating system, mixes with nitrogen, and uniformly contacts the catalyst to achieve water replenishment. At the same time, it avoids the ineffective diffusion of low-pressure steam due to insufficient pressure, or the turbulent nitrogen flow caused by high-pressure steam, which affects the uniformity of heating.

[0035] The catalyst sulfidation subsystem 1 also includes a hydrolysis gas cooler 15 and a steam-water separator 16; the outlet end of the COS hydrolyzer 3 is connected to the inlet end of the hydrolysis gas cooler 15, the outlet end of the hydrolysis gas cooler 15 is connected to the inlet end of the steam-water separator 16, and the outlet end of the steam-water separator 16 is connected to the inlet end of the circulating compressor 11, forming a circulating loop.

[0036] The catalyst sulfidation subsystem 1 also includes a hydrolysis gas cooler 15 and a vapor-water separator 16. The outlet of the COS hydrolyzer 3 is connected to the inlet of the hydrolysis gas cooler 15, the outlet of the hydrolysis gas cooler 15 is connected to the inlet of the vapor-water separator 16, and the outlet of the vapor-water separator 16 is connected to the inlet of the circulating compressor 11, forming a complete gas circulation loop. The gas at the outlet of the COS hydrolyzer 3 contains H2S, unreacted H2 / CS2, water vapor, etc. It is first cooled by the hydrolysis gas cooler 15 to condense some of the water vapor, and then enters the vapor-water separator 16 to separate liquid water, avoiding liquid water from entering the circulating compressor 11 and causing equipment damage. The gas after water separation is then sent back into the system by the circulating compressor 11 to realize gas recycling and reduce raw material consumption and exhaust emissions.

[0037] The catalyst heating subsystem 2 also includes a hydrolyzer inlet heater 25; the outlet of the vapor-liquid separator 23 is connected to the inlet of the hydrolyzer inlet heater 25, and the outlet of the hydrolyzer inlet heater 25 is connected to the inlet of the COS hydrolyzer 3. The hydrolyzer inlet heater 25 is equipped with a medium-pressure steam heating source. The hydrolyzer inlet heater 25 is the core equipment for heating nitrogen to a target temperature ≥130℃. The medium-pressure steam heating source provides stable heat, ensuring nitrogen heating efficiency and temperature stability, and meeting the preheating requirements for catalyst activity.

[0038] The bottom of the vapor-liquid separator 23 is equipped with a drain valve for discharging liquid water. This drain valve is manually controllable. During the heating process, the liquid water separated by the vapor-liquid separator 23 can be discharged manually by opening the drain valve, preventing liquid water from accumulating inside the separator and affecting nitrogen drying and heating efficiency. The manual control method allows for flexible operation based on the liquid level inside the separator, reducing the complexity and cost of automatic control. In the catalyst sulfidation subsystem 1, when steam is introduced through the low-pressure steam injection pipeline 14, the temperature of the upper bed of the COS hydrolyzer 3 is controlled to be no higher than 170℃, and the temperature of the lower bed is controlled to be no lower than 80℃. Maintaining an upper bed temperature ≤170℃ prevents rapid vaporization of steam at high temperatures, which would prevent the catalyst from fully adsorbing moisture, and also prevents abnormal reactions between H2S and steam at high temperatures. Maintaining a lower bed temperature ≥80℃ ensures that the catalyst is in a relatively active adsorption state, facilitating the absorption of moisture by the catalyst surface and pores, and preventing moisture condensation at the bottom of the bed due to low temperatures, which would cause uneven hydration of the catalyst.

[0039] In the catalyst heating subsystem 2, steam is introduced through the medium-pressure steam injection line 24 to raise the temperature of the lower bed of the COS hydrolyzer 3 to 70-80°C. At this temperature range, the moisture in the catalyst begins to evaporate. Initiating water injection at this time can replenish the moisture lost by the catalyst in time, avoiding excessive moisture loss and the occurrence of methanethiol side reactions. If water is injected too early at a temperature <70°C, the amount of moisture evaporated from the catalyst will be small, which may lead to excessive moisture accumulation. If water is injected too late at a temperature >80°C, the catalyst has already shown significant water loss, and the risk of side reactions increases. In the catalyst heating subsystem 2, when the nitrogen flow rate used for heating is 6000-18000 Nm³ / h, the amount of steam injected through the medium-pressure steam injection line 24 is 160-480 Kg / h. The matching relationship between this steam volume and the nitrogen flow rate can ensure that the steam is evenly dispersed in the nitrogen, forming an airflow with suitable humidity. This satisfies the catalyst water injection requirements without causing excessive nitrogen humidity due to excessive steam, which would affect the heating rate or cause water accumulation in the catalyst bed.

[0040] In the catalyst heating subsystem 2, when the nitrogen flow rate used for heating is 6000~18000 Nm³ / h, the amount of steam supplied through the medium-pressure steam supply pipeline 24 is 160~480 Kg / h.

[0041] Confirm that the pipelines connecting the circulating compressor 11, the hydrolysis gas and fuel gas heat exchanger 12, the electric heater 13, the hydrolysis gas cooler 15, the steam-water separator 16, and the COS hydrolyzer 3 are connected normally. Close the first shut-off valve 144 on the low-pressure steam inlet pipeline 14, open the drain valve at the bottom of the steam-water separator 16 to drain the residual liquid, and then close it.

[0042] During the vulcanization stage, the circulating compressor 11 is started, so that the circulating gas is heated by the hydrolysis gas and fuel gas heat exchanger 12 and the electric heater 13 in sequence before entering the COS hydrolyzer 3. The heating period is completed according to the existing vulcanization process. When the bed temperature reaches 200℃, H2 is added. After the H2 content is >20% in the initial activation stage, CS2 is added. After the outlet H2S ≥0.5g / Nm³, the temperature continues to rise. During the main activation period, the bed temperature is maintained at 350℃. During this period, the temperature of the upper and lower bed layers of the COS hydrolyzer 3 is monitored by temperature measuring points.

[0043] After the sulfidation stage is completed, the system is purged with nitrogen until the concentrations of H2S and CS2 meet the standards, and the temperature of the lower bed of COS hydrolyzer 3 is not lower than 80℃. Then, the first shut-off valve 144 of the low-pressure steam injection pipeline 14 is opened to introduce low-pressure steam at a pressure of 0.4~0.45MPa. The flow rate is monitored by the first flow meter 141, and the injection rate is adjusted by the first flow regulating valve 142 according to the following gradient: 40~50Kg / h for the first 1~2 hours, 70~80Kg / h for the third~4 hours, and 100Kg / h from the fifth hour onwards. At the same time, the upper bed temperature is controlled to be ≤170℃ and the lower bed temperature is controlled to be ≥80℃ by the temperature measuring point. The first check valve 143 prevents gas backflow.

[0044] During the steam replenishment period, open the bottom drain valve of the steam-water separator 16 every hour. After observing the discharge of liquid water, continue to replenish steam for 4 to 8 hours. Then close the first shut-off valve 144 to stop replenishing steam. Maintain the system gas circulation for 4 to 5 hours, turn off the electric heater 13, and continue circulation until the bed temperature of COS hydrolyzer 3 drops to about 120°C. Stop the circulation compressor 11, isolate the system to maintain pressure, and the operation of the sulfidation subsystem is completed.

[0045] Confirm that the pipelines between the process gas and syngas heat exchanger 21, syngas cooler 22, vapor-liquid separator 23, hydrolyzer inlet heater 25 and COS hydrolyzer 3 are unobstructed, close the second shut-off valve 244 on the medium-pressure steam supply pipeline 24, and ensure that the medium-pressure steam heating source of the hydrolyzer inlet heater 25 is normal.

[0046] Nitrogen gas is introduced from the gasification synthesis gas pipeline to start the nitrogen heating process. It passes through the process gas and synthesis gas heat exchanger 21, the synthesis gas cooler 22, and the vapor-liquid separator 23 in sequence before entering the hydrolyzer inlet heater 25. Medium-pressure steam is used to heat the nitrogen gas. The high-temperature nitrogen gas enters the COS hydrolyzer 3 to heat the catalyst. The nitrogen flow rate is controlled at 6000~18000 Nm³ / h.

[0047] Medium-pressure steam is introduced by monitoring the temperature of the lower bed of COS hydrolyzer 3 through temperature measuring points. When the temperature rises to 70~80℃, the second shut-off valve 244 of the medium-pressure steam introduction pipeline 24 is opened to introduce medium-pressure steam with a pressure of 4.5~4.8MPa. The flow rate is monitored by the second flow meter 241, and the second flow regulating valve 242 is used to control the introduction amount at 160~480Kg / h to match the nitrogen flow rate. The second check valve 243 prevents gas backflow. During this period, liquid water can be discharged through the drain valve at the bottom of the vapor-liquid separator 23.

[0048] When the heating process is completed, wait for the catalyst temperature of COS hydrolyzer 3 to rise to the target temperature of ≥130℃. After the heating is completed, simultaneously close the second shut-off valve 244 of the medium-pressure steam injection pipeline 24 and the medium-pressure steam heating source of the hydrolyzer inlet heater 25, and stop the supply of nitrogen. The operation of the heating subsystem is then complete.

[0049] Finally, it should be noted that the methods and devices described in detail above are merely embodiments, and those skilled in the art can modify these embodiments in different ways as long as they do not depart from the scope of the present invention.

Claims

1. A process system for effectively preventing methanethiol side reactions in carbonyl sulfur hydrolysis technology, characterized in that: It includes a catalyst sulfidation subsystem (1) and a catalyst heating subsystem (2) that are independent of each other and adapted to the COS hydrolyzer (3). The catalyst sulfidation subsystem (1) includes a circulating compressor (11), a hydrolysis gas and fuel gas heat exchanger (12), and an electric heater (13) connected in sequence. The outlet end of the electric heater (13) is connected to the inlet end of the COS hydrolyzer (3). A low-pressure steam inlet pipeline (14) for adding steam to the system is provided on the pipeline between the outlet of the hydrolysis gas and fuel gas heat exchanger (12) and the inlet of the electric heater (13). The low-pressure steam inlet pipeline (14) is equipped with a first flow meter (141), a first flow regulating valve (142), a first check valve (143), and a first shut-off valve (144) for measuring the steam flow.

2. The process system for effectively preventing methanethiol side reactions in the carbonyl sulfur hydrolysis technology according to claim 1, characterized in that: The catalyst heating subsystem (2) includes a process gas and syngas heat exchanger (21), a syngas cooler (22), and a vapor-liquid separator (23) connected in sequence. The outlet end of the vapor-liquid separator (23) is connected to the inlet end of the COS hydrolyzer (3). A medium-pressure steam injection pipeline (24) for injecting steam into the system is provided on the pipeline between the outlet of the vapor-liquid separator (23) and the inlet of the process gas and syngas heat exchanger (21). The medium-pressure steam injection pipeline (24) is equipped with a second flow meter (241), a second flow regulating valve (242), a second check valve (243), and a second shut-off valve (244) for measuring the steam flow.

3. The process system for effectively preventing methanethiol side reactions in the carbonyl sulfur hydrolysis technology according to claim 2, characterized in that: The low-pressure steam supplied by the low-pressure steam supply pipeline (14) has a pressure range of 0.4~0.45MPa.

4. The process system for effectively preventing methanethiol side reactions in the carbonyl sulfur hydrolysis technology according to claim 3, characterized in that: The COS hydrolyzer (3) has a catalyst bed distributed vertically inside, and temperature measuring points for monitoring the bed temperature are provided at each of the catalyst beds distributed vertically.

5. The process system for effectively preventing methanethiol side reactions in the carbonyl sulfide hydrolysis technology according to claim 4, characterized in that: The medium-pressure steam supplied by the medium-pressure steam feed line (24) has a pressure range of 4.5~4.8MPa.

6. The process system for effectively preventing methanethiol side reactions in the carbonyl sulfide hydrolysis technology according to claim 5, characterized in that: The catalyst sulfidation subsystem (1) further includes a hydrolysis gas cooler (15) and a steam-water separator (16); the outlet end of the COS hydrolyzer (3) is connected to the inlet end of the hydrolysis gas cooler (15), the outlet end of the hydrolysis gas cooler (15) is connected to the inlet end of the steam-water separator (16), and the outlet end of the steam-water separator (16) is connected to the inlet end of the circulating compressor (11), forming a circulating loop.

7. The process system for effectively preventing methanethiol side reactions in the carbonyl sulfide hydrolysis technology according to claim 6, characterized in that: The catalyst heating subsystem (2) also includes a hydrolyzer inlet heater (25); the outlet end of the vapor-liquid separator (23) is connected to the inlet end of the hydrolyzer inlet heater (25), the outlet end of the hydrolyzer inlet heater (25) is connected to the inlet end of the COS hydrolyzer (3), and the hydrolyzer inlet heater (25) is equipped with a medium-pressure steam heating source.

8. The process system for effectively preventing methanethiol side reactions in the carbonyl sulfur hydrolysis technology according to claim 7, characterized in that: The bottom of the gas-liquid separator (23) is provided with a drain valve for discharging liquid water, and the drain valve is a valve structure that can be manually controlled to open and close.

9. The process system for effectively preventing methanethiol side reactions in the carbonyl sulfide hydrolysis technology according to claim 8, characterized in that: In the catalyst sulfidation subsystem (1), when steam is supplied through the low-pressure steam supply line (14), the temperature of the upper bed of the COS hydrolyzer (3) is controlled at no higher than 170°C and the temperature of the lower bed is controlled at no lower than 80°C.

10. The process system for effectively preventing methanethiol side reactions in the carbonyl sulfur hydrolysis technology according to claim 9, characterized in that: In the catalyst heating subsystem (2), steam is supplied through the medium-pressure steam supply line (24) to raise the temperature of the lower bed of the COS hydrolyzer (3) to 70~80℃. In the catalyst heating subsystem (2), when the nitrogen flow rate used for heating is 6000~18000Nm³ / h, the amount of steam supplied through the medium-pressure steam supply line (24) is 160~480Kg / h.

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