A method for removing CS and sulfur-containing compounds from a liquid light hydrocarbon stream by reaction and distillation 2 and sulfur-containing compounds

Abstract

The present invention belongs to the technical field of petroleum processing and petrochemical industry, and relates to a method for removing CS2 and sulfur-containing compounds from liquid light hydrocarbon streams by reaction and distillation. This method does not change the desulfurization reaction in the traditional process, enabling the desulfurized product to enter the distillation column and obtain qualified isoprene at the top of the column. The unique feature of this method is the reversible transformation of the sulfur-containing amine salts formed during the reaction. The sulfur-containing amine salts are separated using a filter, and under high-temperature carrier gas, the sulfur-containing amine salts undergo thermal decomposition to form organic amine and CS2. The regenerated organic amine can be recycled, and the regenerated CS2 is stored in low-temperature cold water. This method can significantly reduce the dosage of desulfurizing agent, solve the sewage problem caused by aqueous phase separation and the problem of pipeline blockage by salts, and make the entire process more environmentally friendly.

Description

Technical Field

[0001] The present invention belongs to the technical field of oil processing and petrochemical industry, and relates to a method for removing CS from liquid light hydrocarbon streams by reaction and distillation 2 and sulfur-containing compounds; in particular, a method for continuously obtaining low-CS 2 and low-sulfur liquid light hydrocarbon streams from light hydrocarbon streams rich in olefins by reaction, distillation and sulfur-containing salt decomposition. Background Art

[0002] Liquid light hydrocarbons (C3-C5) mainly come from atmospheric and vacuum distillation units, delayed coking, fluid catalytic cracking, hydrocracking, catalytic reforming topped oil and hydrocarbon steam cracking units in petrochemical industry. Among them, cracked C5 is rich in olefins, and components such as isoprene, piperylene, cyclopentadiene, and pentene can be obtained by distillation and can be further processed as raw materials to form high molecular compounds such as plastics, polyesters, and rubbers. With the deterioration of petroleum processing raw materials in recent years, the contents of sulfur, nitrogen, etc. in petroleum processing products have gradually increased, and the presence of sulfur-containing compounds will significantly affect the stability of light hydrocarbon components (when rich in olefins) and cause corrosion to catalysts, additives and metal equipment in subsequent processing technologies. Traditional methods for removing sulfur-containing compounds in hydrocarbons include hydrodesulfurization, adsorption desulfurization, oxidative desulfurization, complexation desulfurization, solvent desulfurization, biological desulfurization, etc. For C5 hydrocarbons (especially from cracked C5), their sulfur-containing components are mostly CS 2 , and secondly, it also contains a small amount of isopropyl mercaptan, dimethyl sulfide, etc. Common methods for removing sulfur-containing components (mostly) in C5 include: adsorption desulfurization (solid adsorbents, activated carbon fibers, etc.), catalytic hydrolysis desulfurization (CS 2 forming COS, and then forming H 2 S), liquid-phase physical adsorption desulfurization and liquid-phase solvent method desulfurization.

[0003] CN103182291A discloses a deep desulfurization adsorbent for cracked C5 fraction oil, which uses γ-Al 2 O 3 as a carrier impregnated with metals of Group IA or IIA such as zinc, copper, potassium, sodium, calcium, etc.; CN 111875469 A discloses a method for ultra-deep removal of carbon disulfide in isoprene (C5), and the adsorbent contains porous silica powder, alkaline earth metal oxide powder, pore-expanding agent and additives; CN 104907104 A discloses a method for low-temperature removal of CS 2 by using a core-shell catalyst, and prepares an activated carbon nanoparticle as the core and a layer of Fe 2 O 3Low-temperature desulfurization catalyst for the outer shell; CN109019535A discloses an active boron nitride absorbent; CN 114026203A realizes the removal of sulfur-containing species by grafting primary / secondary amino groups onto solid inorganic carriers (such as silica, alumina, magnesia, titanium dioxide, zirconia); Jilin University (Xu Yang. Research on Adsorptive Desulfurization of Sulfides in Isoprene [D]. Jilin University, 2015.) uses a composite adsorbent of activated carbon and molecular sieve and a composite adsorbent of activated carbon and zinc oxide for CS 2 desulfurization; China University of Petroleum (Meng Linggang. Research on the Adsorptive Removal of Carbon Disulfide in Isoprene by Modified Activated Alumina [D]. China University of Petroleum, 2020.) uses K 2 CO 3 / γ-Al 2 O 3 as the adsorbent, the breakthrough time is 158 hours, and the breakthrough sulfur capacity is 0.72. When the above adsorption method is used for the adsorptive desulfurization of liquid C5 light hydrocarbons, due to the limited sulfur capacity of the solid adsorbent, it is difficult to meet the desulfurization requirements of industrial products; at the same time, the harsh regeneration conditions and the inactivation of the adsorbent after regeneration make the industrial desulfurization of C5 light hydrocarbons mostly choose liquid-phase solvent desulfurization.

[0004] US 2,418,047 makes a hydrocarbon liquid react with dimethylamine in an aqueous solution to form an aminodithiocarbamate to remove carbon disulfide. EP 0053571 A1 contacts a solution of isoprene and pentane containing CS 2 with a polyamine (for example, tetraethylenepentamine). WO 2015 / 026649 A1 uses a polyamine (tetraethylenepentamine or diethylenetriamine), and at the same time, uses a quaternary ammonium salt as a phase transfer catalyst. CN 105451861 A uses a treatment composition containing at least one phase transfer catalyst to remove carbon disulfide from a hydrocarbon stream. The US Patent (US 9981889 B2) discloses a combined treatment composition using a carbon disulfide remover and at least one phase transfer catalyst. The carbon disulfide remover contains at least one polyamine molecule, H 2 N-(R1-NH)x-R 2 -(NH-R 3 )y-NH 2 . CN105112093A makes the C5 raw material react with the desulfurizer at a certain temperature and pressure for a period of time, and then separates sulfur-free cracked C5 from the top of the tower by distillation. The desulfurizer composition is: 3-8% triethanolamine, 3-8% acetonitrile, 3-8% toluene, 3-8% acetone, 8-12% benzene, 25-35% saturated ammonia water, 8-12% butyronitrile, 8-12% cyclohexane, 10-20% aniline, 3-8% 2-ethyltoluenediamine.

[0005] The use of sulfiding agents such as organic amines, polyamines, and alkanolamines can achieve better removal of sulfur-containing compounds. However, after the sulfiding agent combines with the sulfur-containing compound, the separation method from hydrocarbons is not efficient. In US 2,418,047, EP0053571A1, CN105451861 A, and US 9981889 B2, CS 2 forms RNH(CS)RNH with organic amines and polyamines, and isopropyl mercaptan forms RH 3 SCH(CH 3 ) 2 . Water needs to be added to the system to separate sulfur-containing compounds from hydrocarbons. The sulfur-containing compounds form dithiocarbamates and are transferred to the aqueous phase with the assistance of a phase-transfer quaternary ammonium salt. Since the separated isoprene needs to be washed with water multiple times, a large amount of sewage is generated. At the same time, the pipelines will be blocked during the regeneration of dithiocarbamates, resulting in process failures.

[0006] If a new method can be used to react sulfides with sulfiding agents and effectively separate the formed sulfur-containing species from hydrocarbons after the reaction, it will be possible to solve the sewage problem and the problem of pipeline blockage caused by salts during aqueous phase separation, and more efficiently remove sulfides in light hydrocarbons. At the same time, the formation of azeotropes can also be avoided, and high-purity light hydrocarbon products can be obtained. Summary of the Invention

[0007] Based on the above existing problems, the present invention provides a method for removing CS 2 and sulfur-containing compounds from a liquid light hydrocarbon stream by using reaction and distillation. This method does not change the desulfurization reaction in the traditional process. After desulfurization, the product enters the distillation column, and qualified isoprene is obtained at the top of the column. The unique feature of this method is to reversibly transform the sulfur-containing amine salt formed during the reaction, separate the sulfur-containing amine salt by using a filter, and use a high-temperature carrier gas to thermally decompose the sulfur-containing amine salt to form organic amine and CS 2 , and the regenerated organic amine can be recycled, and the regenerated CS 2 is stored in low-temperature cold water. This method can greatly reduce the dosage of desulfurizing agent, solve the sewage problem and the problem of pipeline blockage caused by salts during aqueous phase separation, and make the whole process more environmentally friendly.

[0008] The present invention specifically provides the following technical solutions.

[0009] A method for removing CS 2 and sulfur-containing compounds from a liquid light hydrocarbon stream by using reaction and distillation, specifically including the following steps:

[0010] Step 1: Mix the sulfur-containing light hydrocarbon component with a desulfurizing agent, add it to a reactor, and react at a certain reaction temperature and reaction pressure;

[0011] Step 2: After the reaction is completed, the desulfurized components enter the distillation column, and light hydrocarbon components with qualified sulfur content are obtained from the top of the distillation column; Step 3: The salt-containing circulating solution in the bottom material of the column flows through the filtration and sulfur-containing salt regeneration system driven by a pump and then forms a filtered circulating liquid and returns to the distillation column; at the same time, after the purging and regeneration gas enters the filtration and sulfur-containing salt regeneration system, a regenerated decomposition gas is formed;

[0012] Step 4: The regenerated decomposition gas is condensed in the organic amine recovery tank, and the condensed liquid organic amine is discharged from the bottom of the organic amine recovery tank and can be recycled. The condensed gas product further goes to the cold water recovery tank. The tail gas is discharged from the top of the cold water recovery tank, and the enriched liquid sulfur-containing substances are sealed at the bottom of the cold water recovery tank

[0013] Further, in Step 1, the hydrocarbons in the sulfur-containing light hydrocarbon components are C3-C5 components, including liquefied petroleum gas, reforming topped oil, petroleum ether, cracked C5 components, light naphtha, etc., usually including at least one or more of propane, propylene, butane, butene, butadiene, n-pentane, isopentane, neopentane, cyclopentane, pentene, isopentene, pentadiene, isoprene, piperylene, cyclopentadiene, etc.; the sulfides in the sulfur-containing light hydrocarbon components usually include soluble H 2 S, COS, CS 2 , mercaptans, sulfides, disulfides, etc.

[0014] Further, in Step 1, the desulfurization agent can be an alcohol solvent, a sulfone solvent, an organic amine, a polyamine, an alkanolamine, an amide, a ketone solvent, an aldehyde solvent, an ether, ammonia water, a water-soluble inorganic amine salt, and a water-soluble inorganic base, or a mixed solvent of one or more of the above solvents.

[0015] Further, the alcohol solvents usually include water-soluble organic alcohols (such as methanol, ethanol, propanol, diol, etc.), polyethylene glycol, glycol, etc.

[0016] Further, the sulfone solvents usually include sulfolane and its derivatives.

[0017] Further, the organic amine contains primary amine, secondary amine, and tertiary amine organic compounds. Common organic amines include diethylamine. Further, the general molecular formula of the polyamine is: H 2 N-(R 1 -NH)x-R 2 -(NH-R 3 )y-NH 2 , where R 1 , R 2 , R 3 are the same or different and include H, aryl, C1-C4 alkyl; x and y are integers between 0 and 10.

[0018] Further, alkanolamines generally include monoethanolamine (MEA), diethanolamine, triethanolamine, diglycolamine (DGA), diisopropanolamine (DIPA), triethanolamine (TEA), N-methyldiethanolamine (MDEA), etc.

[0019] Further, amides generally include formamide, acetamide, dimethylformamide, carbamide, etc. At this time, the desulfurizer can be a liquid or an aqueous solution.

[0020] Further, water-soluble inorganic amine salts generally include ammonium formate, ammonium oxalate, urea, etc.

[0021] Further, water-soluble inorganic bases generally include NaOH, KOH, Ca(OH) 2 etc.

[0022] Further, in Step 1, the reaction temperature of the sulfur-containing light hydrocarbon component and the desulfurizer is -20 - 300 °C, preferably 0 - 100 °C.

[0023] Further, in Step 1, the reaction pressure of the sulfur-containing light hydrocarbon component and the desulfurizer should ensure that the hydrocarbons are in the liquid phase. For C5 components, it is at atmospheric pressure; for C3 and C4 components, the pressure of the C3 - C4 components is 0.1 - 2.0 Mpa, preferably 0.2 - 1.5 MPa.

[0024] Further, in Step 1, the contact time of the sulfur-containing light hydrocarbon component and the desulfurizer is 5 minutes - 24 hours, preferably 20 minutes - 6 hours.

[0025] Further, in Step 1, the ratio of the desulfurizer to the sulfur-containing light hydrocarbon component is 1 / 10000 - 1 / 10 (V / V) (100 ppm - 100000 ppm), preferably 1 / 2000 - 1 / 100 (V / V) (500 ppm - 10000 ppm).

[0026] Further, in Step 1, the reactor is one of a kettle reactor, a tubular reactor, a reactor with a solid particle bed layer, or a tower reactor.

[0027] Further, in Step 2, according to the product requirements, the distillation column can obtain the product through the top of the column or through the side line; it can include / not include a top condenser, include / not include an intermediate condenser, and include / not include a reboiler. When obtaining the product by the side line stripping method, it can include / not include a stripping column.

[0028] Further, the material enters the distillation column from the reactor as continuous feeding or batch feeding; according to the volumes of the reactor and the distiller, when batch feeding is used, it is one of distilling once after one reaction, distilling multiple times after one reaction, or centralized distillation after multiple reactions.

[0029] Further, in step 2, the hydrocarbon components in the light hydrocarbon component with qualified sulfur content and the sulfur-containing light hydrocarbon component are the same, which are C3-C5 components, including liquefied petroleum gas, reforming topped oil, petroleum ether, cracked C5 components, light naphtha, etc., and usually contain at least one or a combination of propane, propylene, butane, butene, butadiene, n-pentane, isopentane, neopentane, cyclopentane, pentene, isopentene, pentadiene, isoprene, piperylene, cyclopentadiene.

[0030] Further, the light hydrocarbon component with qualified sulfur content can be directly obtained as a product; when there is a small amount of water at the bottom of the distillation column, part of the water will distill out simultaneously with the light hydrocarbon component. At this time, an external light hydrocarbon liquid separation tank is needed. After the light hydrocarbon component and water are allowed to stand and separate, the light hydrocarbon component with qualified sulfur content without water can be obtained from the top, and a small amount of separated water can be recycled.

[0031] Further, in step 3, the salt in the salt-containing circulating solution comes from the salts generated by the reaction of sulfides in the sulfur-containing light hydrocarbon component with the desulfurizer; when the salt is in solution, it circulates normally; when the salt contains solid particles, a slurry pump is used for transportation.

[0032] Further, in step 3, the salt-containing circulating solution at the bottom of the distillation column circulates, and the operation of the filtration and sulfur-containing salt regeneration system is determined according to the formation condition of the sulfur-containing salt, and one of the following is carried out: circulation and regeneration during each distillation process, circulation and regeneration after each distillation, or circulation and regeneration after multiple reactions and distillations.

[0033] Further, at the beginning of the first distillation in step 3, a certain amount of solvent is added to the distillation column to increase the solubility of the sulfur-containing salt. The solvent can either only dissolve the sulfur-containing salt and not dissolve the light hydrocarbon, such as water; or it can dissolve both the sulfur-containing salt and the light hydrocarbon, such as furfural and other organic compounds. The ratio of the solvent to the light hydrocarbon is 0 - 0.80, preferably 0 - 0.20.

[0034] Further, in step 3, the filtration and sulfur-containing salt regeneration system includes multiple switching valves, and one or more filtration and sulfur-containing salt regenerators.

[0035] Further, the switching valve is a multi-way valve, including any one of a ten-way valve, an eight-way valve, a six-way valve, a four-way valve, a three-way valve, and a two-way valve; among them, a six-way switching valve can be replaced by two four-way switching valves, a four-way switching valve can be replaced by two three-way switching valves, and a three-way switching valve can be replaced by two two-way switching valves.

[0036] Furthermore, multiple filtration and sulfur salt regenerators are equivalent and can be of the same or different types. The filtration and sulfur salt regenerators can be externally heated or not. When externally heated, the heating method can be direct heating (such as fuel combustion) or indirect heating (such as oil bath, sand bath, resistance furnace, thermal radiation, electromagnetic induction, microwave, etc.). When not heated, it should be able to withstand the high temperature of the purge regeneration gas for a long time.

[0037] Furthermore, in step 3, the structure of the filtration and sulfur salt regeneration system includes multiple three-way switching valves and two independently externally heated filtration and sulfur salt regenerators; the salt-containing circulating solution enters the two filtration and sulfur salt regenerators through the front three-way switching valve, and then flows out through the rear three-way switching valve to form the filtered circulating liquid. The purge regeneration gas enters the two filtration and sulfur salt regenerators through the front three-way switching valve, and then flows out through the rear three-way switching valve to form the regenerated decomposition gas.

[0038] Furthermore, in step 3, the filtration and sulfur salt regeneration system includes: multiple three-way switching valves and one independently externally heated filtration and sulfur salt regenerator. The salt-containing circulating solution enters the filtration and sulfur salt regenerator through the front three-way switching valve, and then flows out through the rear three-way switching valve to form the filtered circulating liquid. The purge regeneration gas enters the filtration and sulfur salt regenerator through the front three-way switching valve, and then flows out through the rear three-way switching valve to form the regenerated decomposition gas. The front three-way switching valve and the rear three-way switching valve are connected by a bypass.

[0039] Furthermore, in step 3, the filtration and sulfur salt regeneration system includes: multiple four-way switching valves and two equivalent filtration and sulfur salt regenerators; the four interfaces of the front four-way switching valve are in sequence the salt-containing circulating solution, the filtration and sulfur salt regenerator, the purge regeneration gas, and the filtration and sulfur salt regenerator; the four interfaces of the rear four-way switching valve are in sequence the regenerated decomposition gas, the filtration and sulfur salt regenerator, the filtered circulating liquid, and the filtration and sulfur salt regenerator.

[0040] Furthermore, in step 3, the filtration and sulfur salt regeneration system includes: multiple four-way switching valves and one filtration and sulfur salt regenerator; the four interfaces of the front four-way switching valve are in sequence the salt-containing circulating solution, the filtration and sulfur salt regenerator, the purge regeneration gas, and the filtration and sulfur salt regenerator; the four interfaces of the rear four-way switching valve are in sequence the regenerated decomposition gas, the front four-way switching valve, the filtered circulating liquid, and the filtration and sulfur salt regenerator.

[0041] Furthermore, the filtration and sulfur salt regeneration system can also adopt the step-by-step method, using ordinary filtration equipment, including conventional filtration equipment such as plate and frame filter presses, chamber filter presses, tubular filters, rotary drum pressure filters, etc. to collect sulfur salt precipitates, and further decompose the collected sulfur salt precipitates on high-temperature resistant equipment, or sell the collected sulfur salt precipitates as products.

[0042] Furthermore, in step 3, the purge regeneration gas can be nitrogen, inert gas, water vapor or reducing gas (such as hydrogen). When the purge regeneration gas is an oxidizing gas (such as air, oxygen), the pipeline can be purged with an inert gas (such as nitrogen) in advance.

[0043] Furthermore, in step 3, the temperature of the purge regeneration gas is normal temperature or high temperature. When using a high-temperature purge gas, it can be directly purged without reheating; the inlet temperature of the regeneration gas should be higher than the decomposition temperature of the sulfur-containing salt, while ensuring that the filter and the sulfur-containing salt regenerator are not damaged; the temperature is 30 - 1000 °C, preferably 50 - 800 °C, optimally 60 - 600 °C; the purge time is 10 minutes - 24 hours, preferably 20 minutes - 6 hours.

[0044] Furthermore, in step 3, when the temperature of the purge regeneration gas is normal temperature, a filter and a sulfur-containing salt regenerator that can be independently heated should be selected. At this time, the temperature of the regenerator should be higher than the decomposition temperature of the sulfur-containing salt, while ensuring that the filter and the sulfur-containing salt regenerator are not damaged; the temperature is 30 - 1000 °C, preferably 50 - 800 °C, optimally 60 - 600 °C; the purge time is 10 minutes - 24 hours, preferably 20 minutes - 6 hours.

[0045] Furthermore, in step 4, the organic amine recovery tank is the liquid product obtained after the regeneration decomposition gas is condensed. The temperature of the organic amine recovery tank is higher than the boiling point of the sulfide in the sulfur-containing light hydrocarbon component under the device pressure and lower than the boiling point of the desulfurizer.

[0046] Furthermore, in step 4, the cold water recovery tank is mainly used to capture and liquid-recover sulfur-containing compounds. The temperature of the cold water recovery tank is lower than the boiling point of the recovered sulfur-containing compounds; when the density of the recovered sulfur-containing compound is greater than that of water (such as CS 2 )), it can be directly stored at the bottom of the cold water recovery tank for sealing, and the regeneration tail gas is discharged from the top of the cold water recovery tank;. When the density of the recovered sulfur-containing compound is less than that of water (mercaptans and thioethers), it can be directly stored at the top of the cold water recovery tank for sealing; the regeneration tail gas is discharged through an additional discharge pipe at the bottom of the cold water recovery tank.

[0047] Furthermore, a solvent is added to the reactor or distillation column. The solvent is water or an organic solvent, including reagents such as furfural, ionic liquid or phase transfer agent that significantly dissolve sulfur-containing salts.

[0048] Compared with the existing similar technologies, the beneficial effects of the present invention are as follows.

[0049] A reversible transformation is carried out on the sulfur-containing amine salt formed during the reaction process. After the sulfur-containing compound forms a sulfur-containing salt with the desulfurizer, it decomposes to re-obtain the organic amine and the sulfur-containing compound. The sulfur-containing amine salt is separated by a filter, and the sulfur-containing amine salt is thermally decomposed at high temperature by a carrier gas to form an organic amine and CS 2; The regenerated organic amine can be recycled, and the regenerated CS 2 is stored in cold water at low temperature. To achieve continuous industrial operation, filtration and regeneration can be carried out alternately in-situ. At this time, a filtration and sulfur salt regeneration system can be constructed using switching valves and filters. High temperature can be obtained by directly introducing high-temperature carrier gas or passing normal-temperature carrier gas through a heatable filter assembly. To save costs, when the reaction is carried out in batch operation, the filtration and regeneration processes can also be carried out step by step. At this time, sulfur salts can be filtered and enriched through conventional filtration equipment, and then the enriched sulfur salts can be heated and decomposed separately to recover organic amines and sulfur compounds. Different from previous patents, this method can greatly reduce the dosage of desulfurizer and solve the problems of sewage generated by water phase separation and salt blockage of pipelines. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 The present invention removes CS 2 and the process flow chart of the method for sulfur-containing compounds.

[0051] Figure 2 The flow chart of the filtration and sulfur salt regeneration system of the present invention.

[0052] Among them, 1 is the sulfur-containing light hydrocarbon component, 2 is the desulfurizer, 3 is the reactor, 4 is the distillation column, 6 is the salt-containing circulating solution, 7 is the filtration and sulfur salt regeneration system, 8 is the filtered circulating liquid, 9 is the purge and regeneration gas, 10 is the regeneration and decomposition gas, 11 is the organic amine recovery tank, 12 is the cold water recovery tank, 13 is the tail gas, 14 is the enriched liquid, 15 is the liquid organic amine recovery liquid, 16 is the light hydrocarbon liquid separation tank, 17 is the sulfur content qualified light hydrocarbon component without moisture, 18 is the separated water, 19 is the solvent, 20, 24, 26, 29 are the front three-way switching valves, 21, 22, 27, 32, 33, 36 are the filtration and sulfur salt regenerators, 23, 25, 28, 30 are the rear three-way switching valves, 31, 35 are the front four-way switching valves, and 34, 37 are the rear four-way switching valves. SPECIFIC EMBODIMENTS

[0053] The following will describe in detail the specific embodiments of the present invention. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0054] As Figure 1 , Figure 2 shown, a method for removing CS 2 and sulfur-containing compounds from a liquid light hydrocarbon stream by using reaction and distillation specifically includes the following steps:

[0055] Step 1: Mix the sulfur-containing light hydrocarbon component 1 with the desulfurizer 2, add them into the reactor 3, and carry out the reaction at a certain reaction temperature and reaction pressure;

[0056] Step 2: After the reaction is completed, the desulfurized components enter the distillation column 4, and light hydrocarbon components 5 with qualified sulfur content are obtained from the top of the distillation column.

[0057] Step 3: The salt-containing circulating solution 6 in the bottom material of the column flows through the filtration and sulfur-containing salt regeneration system 7 driven by a pump and then forms a filtered circulating liquid 8 and returns to the distillation column; at the same time, the purging and regenerating gas 9 enters the filtration and sulfur-containing salt regeneration system 7 and then forms a regenerated decomposition gas 10.

[0058] Step 4: The regenerated decomposition gas 10 is condensed in the organic amine recovery tank 11, the gas product goes to the cold water recovery tank 12, the condensed liquid organic amine 15 is discharged from the bottom of the organic amine recovery tank 11 and can be recycled. The condensed gas product further goes to the cold water recovery tank 12, the tail gas 13 is discharged from the top of the cold water recovery tank 12, and the enriched liquid 14 is sealed at the bottom of the cold water recovery tank 12.

[0059] Furthermore, in Step 1, the hydrocarbons in the sulfur-containing light hydrocarbon component 1 are C3-C5 components, including liquefied petroleum gas, reforming topped oil, petroleum ether, cracked C5 components, light naphtha, etc., usually containing at least one or more of propane, propylene, butane, butene, butadiene, n-pentane, isopentane, neopentane, cyclopentane, pentene, isopentene, pentadiene, isoprene, piperylene, cyclopentadiene, etc.; the sulfides in the sulfur-containing light hydrocarbon component 1 usually include soluble H 2 S, COS, CS 2 , mercaptans, sulfides, disulfides, etc.

[0060] Furthermore, in Step 1, the desulfurizer 2 can be an alcohol solvent, a sulfone solvent, an organic amine, a polyamine, an alkanolamine, an amide, a ketone solvent, an aldehyde solvent, an ether, ammonia water, a water-soluble inorganic amine salt, and a water-soluble inorganic base, or a mixed solvent of one or more of the above solvents.

[0061] Furthermore, alcohol solvents usually include water-soluble organic alcohols (such as methanol, ethanol, propanol, diol, etc.), polyethylene glycol, glycol, etc.

[0062] Furthermore, sulfone solvents usually include sulfolane and its derivatives.

[0063] Furthermore, organic amines include primary amines, secondary amines, and tertiary amine organic compounds. Common organic amines include diethylamine. Furthermore, the general molecular formula of polyamines is: H 2 N-(R 1 -NH)x-R 2 -(NH-R 3 )y-NH 2 , where R 1 , R 2 , R 3are the same or different and include H, aryl, C1-C4 alkyl; x and y are integers between 0 and 10.

[0064] Further, the alkanolamines generally include monoethanolamine (MEA), diethanolamine, triethanolamine, diglycolamine (DGA), diisopropanolamine (DIPA), triethanolamine (TEA), N-methyldiethanolamine (MDEA), etc.

[0065] Further, the amides generally include formamide, acetamide, dimethylformamide, carbamide, etc., and at this time the desulfurizer can be a liquid or an aqueous solution.

[0066] Further, the water-soluble inorganic amine salts generally include ammonium formate, ammonium oxalate, urea, etc.

[0067] Further, the water-soluble inorganic bases generally include NaOH, KOH, Ca(OH) 2 and so on.

[0068] Further, in Step 1, the reaction temperature of the sulfur-containing light hydrocarbon component 1 and the desulfurizer 2 is -20 - 300 °C, preferably 0 - 100 °C.

[0069] Further, in Step 1, the reaction pressure of the sulfur-containing light hydrocarbon component 1 and the desulfurizer 2 should ensure that the hydrocarbons are in the liquid phase. For C5 components, it is at atmospheric pressure; for C3 and C4 components, the pressure of the C3-C4 components is 0.1 - 2.0 Mpa, preferably 0.2 - 1.5 MPa.

[0070] Further, the sulfur-containing light hydrocarbon component 1 and the desulfurizer 2 are in full contact under the reaction temperature and reaction pressure to ensure that the sulfur-containing components of the sulfur-containing light hydrocarbon component 1 are effectively removed to meet the product requirements.

[0071] Further, in Step 1, the contact time of the sulfur-containing light hydrocarbon component 1 and the desulfurizer 2 is 5 minutes - 24 hours, preferably 20 minutes - 6 hours.

[0072] Further, in Step 1, the ratio of the desulfurizer 2 to the sulfur-containing light hydrocarbon component 1 is 1 / 10000 - 1 / 10 (V / V) (100 ppm - 100000 ppm), preferably 1 / 2000 - 1 / 100 (V / V) (500 ppm - 10000 ppm).

[0073] Further, in Step 1, the reactor 3 is one of a kettle reactor, a tubular reactor, a reactor with a solid particle bed layer, or a tower reactor to ensure that the sulfur-containing light hydrocarbon component 1 and the desulfurizer 2 react fully in the reactor 3.

[0074] Further, in step 2, according to product requirements, the distillation column 4 can obtain products from the top of the column or from the side lines; it may or may not include a top condenser, may or may not include an intermediate condenser, and may or may not include a reboiler. When obtaining products by side line stripping, a stripping column may or may not be included.

[0075] Further, the material entering the distillation column 4 from the reactor 3 can be continuously fed or batch fed; depending on the volumes of the reactor and the distiller, when batch feeding is adopted, it can be distilling once after one reaction, distilling multiple times after one reaction, or distilling collectively after multiple reactions.

[0076] Further, in step 2, the hydrocarbon components in the light hydrocarbon component 5 with qualified sulfur content and the sulfur-containing light hydrocarbon component 1 are the same, which are C3-C5 components, including liquefied petroleum gas, reforming topped oil, petroleum ether, cracked C5 components, light naphtha, etc., and usually contain at least one or a combination of propane, propylene, butane, butene, butadiene, n-pentane, isopentane, neopentane, cyclopentane, pentene, isopentene, pentadiene, isoprene, piperylene, cyclopentadiene.

[0077] Further, the light hydrocarbon component 5 with qualified sulfur content can be directly obtained as a product; when there is a small amount of water at the bottom of the distillation column, part of the water will distill out simultaneously with the light hydrocarbon component. At this time, an external light hydrocarbon liquid separation tank 16 is required. After the light hydrocarbon component and water are allowed to stand and separate, the light hydrocarbon component 17 with qualified sulfur content and no water is obtained from the top, and a small amount of separated water 18 can be recycled.

[0078] Further, in step 3, the salt in the salt-containing circulating solution 6 comes from the salts generated by the reaction of sulfides in the sulfur-containing light hydrocarbon component 1 with the desulfurizer 2; when the salts are in solution, normal circulation is carried out; when the salts contain solid particles, a slurry pump is used for transportation.

[0079] Further, in step 3, the circulation, filtration and regeneration of the sulfur-containing salt of the salt-containing circulating solution 6 at the bottom of the distillation column and the operation of the sulfur-containing salt regeneration system 7 are determined according to the formation condition of the generated sulfur-containing salt, and circulation and regeneration are carried out during each distillation process, after each distillation, or after multiple reactions and distillations.

[0080] Further, in step 3, at the beginning of the first distillation, a certain amount of solvent is added to the distillation column to increase the solubility of the sulfur-containing salt. The solvent can either only dissolve the sulfur-containing salt and not dissolve the light hydrocarbon, such as water, or can dissolve both the sulfur-containing salt and the light hydrocarbon, such as furfural and other organic compounds. The ratio of the solvent to the light hydrocarbon is 0 - 0.80, preferably 0 - 0.20.

[0081] Further, in step 3, the filtration and sulfur-containing salt regeneration system 7 includes multiple switching valves and one or more filtration and sulfur-containing salt regenerators.

[0082] Furthermore, the switching valve is a multi-way valve, including any one of a ten-way valve, an eight-way valve, a six-way valve, a four-way valve, a three-way valve, and a two-way valve; among them, a six-way switching valve can be replaced by two four-way switching valves, a four-way switching valve can be replaced by two three-way switching valves, and a three-way switching valve can be replaced by two two-way switching valves.

[0083] Furthermore, multiple filtration and sulfur salt regenerators are equivalent, and their types can be the same or different; the filtration and sulfur salt regenerator can be externally heated or not heated. When externally heated, the heating method can be direct heating (such as fuel combustion) and indirect heating (such as oil bath, sand bath, resistance furnace, thermal radiation, electromagnetic induction, microwave, etc.). When not heated, it should be able to withstand the high temperature of the purge regeneration gas 9 for a long time.

[0084] Furthermore, in step 3, as Figure 2 shown in Figure -A, the structure of the filtration and sulfur salt regeneration system 7 can include multiple three-way switching valves and two independently externally heated filtration and sulfur salt regenerators; the salt-containing circulating solution 6 enters the two filtration and sulfur salt regenerators 21, 22 through the front three-way switching valve 20, and then flows out through the rear three-way switching valve 23 to form the filtered circulating liquid 8. The purge regeneration gas 9 enters the two filtration and sulfur salt regenerators through the front three-way switching valve 24, and then flows out through the rear three-way switching valve 25 to form the regenerated decomposition gas 10.

[0085] Furthermore, in step 3, as Figure 2 shown in Figure -B, in order to save costs and reduce the number of filtration and sulfur salt regenerators, the filtration and sulfur salt regeneration system 7 includes: multiple three-way switching valves and one independently externally heated filtration and sulfur salt regenerator; the salt-containing circulating solution 6 enters the filtration and sulfur salt regenerator 27 through the front three-way switching valve 26, and then flows out through the rear three-way switching valve 28 to form the filtered circulating liquid 8. The purge regeneration gas 9 enters the filtration and sulfur salt regenerator 27 through the front three-way switching valve 29, and then flows out through the rear three-way switching valve 30 to form the regenerated decomposition gas 10. The front three-way switching valves 26, 29 and the rear three-way switching valves 28, 30 are connected by a bypass.

[0086] Furthermore, in step 3, as Figure 2As shown in Figure -C, the filtration and sulfur salt regeneration system 7 includes: multiple four-way switching valves and two equivalent filtration and sulfur salt regenerators; the four interfaces of the front four-way switching valve 31 are in sequence the salt-containing circulating solution 6, the filtration and sulfur salt regenerator 32, the purging and regenerating gas 9, and the filtration and sulfur salt regenerator 33; the four interfaces of the rear four-way switching valve 34 are in sequence the regenerated decomposition gas 10, the filtration and sulfur salt regenerator 32, the filtered circulating liquid 8, and the filtration and sulfur salt regenerator 33; the four-way valve can be flexibly switched in-situ according to the formation of sulfur salts to realize the simultaneous progress of the bottom sulfur discharge material circulation process and the regeneration process.

[0087] Further, in step 3, as Figure 2 As shown in Figure -D, when aiming to save costs and reduce the number of filtration and sulfur salt regenerators, the filtration and sulfur salt regeneration system 7 includes: multiple four-way switching valves and one filtration and sulfur salt regenerator; the four interfaces of the front four-way switching valve 35 are in sequence the salt-containing circulating solution 6, the filtration and sulfur salt regenerator 36, the purging and regenerating gas 9, and the filtration and sulfur salt regenerator 36; the four interfaces of the rear four-way switching valve 37 are in sequence the regenerated decomposition gas 10, the front four-way switching valve 35, the filtered circulating liquid 8, and the filtration and sulfur salt regenerator 36; the four-way valve can be flexibly switched in-situ according to the formation of sulfur salts, and the bottom distillate material circulation is not affected during the regeneration process.

[0088] Further, the filtration and sulfur salt regeneration system 7 can also adopt the step-by-step method, using ordinary filtration equipment, including conventional filtration equipment such as plate and frame filter presses, chamber filter presses, tubular filters, rotary drum pressure filters, etc. to collect sulfur salt precipitates, and further decompose the collected sulfur salt precipitates on high-temperature-resistant equipment, or sell the collected sulfur salt precipitates as products.

[0089] Further, in step 3, the purging and regenerating gas 9 can be nitrogen, inert gas, water vapor or reducing gas (such as hydrogen). When the purging and regenerating gas 9 is an oxidizing gas (such as air, oxygen), the pipeline can be purged with inert gas (such as nitrogen) in advance to avoid danger caused by the presence of light hydrocarbon components in the pipeline.

[0090] Further, in step 3, the temperature of the purging and regenerating gas 9 is normal temperature or high temperature. When using high-temperature purging gas, the inlet temperature of the regenerating gas should be higher than the decomposition temperature of the sulfur salt, and at the same time ensure that the filtration and sulfur salt regenerator is not damaged, with the temperature being 30 - 1000 °C, preferably 50 - 800 °C, and optimally 60 - 600 °C; the purging time is 10 minutes - 24 hours, preferably 20 minutes - 6 hours.

[0091] Further, in Step 3, when the temperature of the purging regeneration gas 9 is at room temperature, a filter and sulfur salt regenerator that can be independently heated should be selected. At this time, the temperature of the heated filter and sulfur salt regenerator should be higher than the decomposition temperature of the sulfur salt, while ensuring that the filter and sulfur salt regenerator is not damaged, with a temperature of 30 - 1000 °C, preferably 50 - 800 °C, and optimally 60 - 600 °C. The purging time is 10 minutes - 24 hours, preferably 20 minutes - 6 hours.

[0092] Further, in Step 4, the regeneration decomposition gas 10 is the product remaining on the filter and sulfur salt regenerator and decomposed by heating with the purging regeneration gas 9, usually the hydrocarbons of the desulfurizer 2 and sulfides in the sulfur-containing light hydrocarbon component 1 obtained after decomposition, and also includes the decomposition products of the desulfurizer 2.

[0093] Further, in Step 4, the organic amine recovery tank 11 is the liquid product obtained after the condensation of the regeneration decomposition gas 10. The temperature of the organic amine recovery tank 11 is higher than the boiling point of the sulfides in the sulfur-containing light hydrocarbon component 1 under the device pressure and lower than the boiling point of the desulfurizer 2, ensuring that the liquid organic amine recovery liquid 15 is obtained through simple gas-liquid separation.

[0094] Further, in Step 4, the cold water recovery tank 12 is mainly used to capture and recover the sulfur-containing compound 14 in liquid form. The temperature of the cold water recovery tank 12 is lower than the boiling point of the recovered sulfur-containing compound 14 so that the sulfur-containing compound 14 exists in liquid form; when the density of the recovered sulfur-containing compound 14 is greater than that of water (such as CS 2 ), it can be directly stored at the bottom of the cold water recovery tank 12 for sealing, and the regeneration tail gas 13 is discharged from the top of the cold water recovery tank 12; when the density of the recovered sulfur-containing compound 14 is less than that of water (mercaptans and thioethers), it can be directly stored at the top of the cold water recovery tank 12 for sealing; the regeneration tail gas 13 is discharged through an additional discharge pipe at the bottom of the cold water recovery tank 12.

[0095] Further, to increase the solubility of the sulfur salt produced by the desulfurization reaction, a small amount of solvent 19 is added to the reactor 3 or the distillation column 4.

[0096] Further, the solvent 19 is used to dissolve the sulfur salt produced by the sulfur-containing light hydrocarbon component 1 and the desulfurizer 2, enhancing the contact between the sulfur-containing light hydrocarbon component 1 and the desulfurizer 2 in the reactor 3; in the distillation column 4, it is beneficial for bottom circulation and prevents pipeline blockage; the solvent 19 can be water or an organic solvent, including reagents such as furfural, ionic liquids, or phase transfer agents that significantly dissolve the sulfur salt.

[0097] Comparative Example 1.

[0098] 30wt% of composite amine was selected as the desulfurizing agent, and the desulfurizing agent and sulfur-containing isoprene with a sulfur content of 80mg / L were added to the closed reactor at a volume ratio of 1:200 (V / V) of agent to oil. The desulfurization temperature was controlled at 25°C, and the desulfurizing agent and crude isoprene were fully contacted and reacted for 120 minutes. After desulfurization, the residual sulfur content in the isoprene solution was 9.02mg / L, and the alkaline nitrogen content was 90mg / L. At 25°C, multi-stage water washing and coalescence filtration were used, and the amount of water used for each washing was V H2O / V C5 = 0.1. Washing with circulating water 13 times and then with deionized water twice can reduce the total nitrogen in isoprene to less than 10 mg / L.

[0099] Example 1.

[0100] 30wt% of composite amine was selected as the desulfurizing agent. The desulfurizing agent and sulfur-containing isoprene with a sulfur content of 80mg / L were added to a closed reactor at a volume ratio of 1:200 (V / V) of agent to oil. At the beginning of the reaction, the desulfurization temperature was controlled at 25°C, and the desulfurizing agent and crude isoprene were fully contacted and reacted for 120 minutes. After desulfurization, the residual sulfur content in the refined isoprene solution was 8.98mg / kg, and the alkali nitrogen content was about 95mg / kg. After each reaction, the generated isoprene-containing mixed material was pumped into the distillation tower at one time, and refined isoprene was further obtained by distillation. After distillation, the total nitrogen content of the light hydrocarbon product at the top of the tower was less than 10mg / L. During the distillation process, the circulating pump was turned on to circulate the bottom material of the tower. The path of the reaction material at the bottom of the tower is: the material at the bottom of the distillation tower enters the switching valve, passes through the first filter, and the circulating liquid returns to the distillation tower after filtration. When distilling again, the material at the bottom of the distillation tower is introduced into another filter through the switching valve, and the circulating liquid returns to the distillation tower after filtration. At this time, the first filter is regenerated. The regeneration gas is nitrogen at room temperature, and the outside of the filter contains a heating component. The regeneration gas material path is: the regeneration gas enters the filter to be regenerated to form regeneration tail gas. During regeneration, the temperature of the heated regeneration gas can be controlled at 350°C, and the regeneration time is 2 hours. The regeneration tail gas formed enters the organic amine recovery tank and is condensed to 80°C through heat exchange. The gas components enter the cold water recovery tank and are further cooled to 20°C. The tail gas without sulfur and nitrogen is slowly discharged in the water by bubbling.

[0101] Example 2.

[0102] 30wt% of composite amine was selected as the desulfurizing agent. The desulfurizing agent and sulfur-containing isoprene with a sulfur content of 80mg / L were added to a closed reactor at a volume ratio of 1:200 (V / V) of agent to oil. At the beginning of the reaction, the desulfurization temperature was controlled at 25°C, and the desulfurizing agent and crude isoprene were fully contacted and reacted for 120 minutes. After desulfurization, the residual sulfur content in the refined isoprene solution was 8.90mg / kg, and the alkali nitrogen content was about 95mg / kg. After each reaction, the generated isoprene-containing mixed material was pumped into the distillation tower at one time, and refined isoprene was further obtained by distillation. At the beginning of the first distillation, 0.20 of the total volume of isoprene was added to the distillation tower. After distillation, the total nitrogen content of the light hydrocarbon product at the top of the tower was less than 10mg / L. During the distillation process, the circulating pump was turned on to circulate the bottom material. The bottom reaction material path is: the bottom material of the distillation tower enters the switching valve, passes through the filter, and the filtered circulating liquid returns to the distillation tower. After 5 reactions and distillation, the salt on the filter is heated and decomposed for regeneration under nitrogen circulation. Specifically, the bottom material of the distillation tower and the circulating liquid after filtration are blocked by a switching valve. The filter is regenerated. The regeneration gas is nitrogen at room temperature, and the outside of the filter contains a heating component. The regeneration gas material path is: the regeneration gas enters the filter to be regenerated to form a regenerated tail gas. During regeneration, the temperature of the heated regeneration gas can be controlled at 350°C, and the regeneration time is 2 hours. The regenerated tail gas formed enters the organic amine recovery tank and is condensed to 80°C by heat exchange. The gas components enter the cold water recovery tank and are further cooled to 20°C. The tail gas without sulfur and nitrogen is slowly discharged in the water by bubbling. After the regeneration is completed, the bottom material of the distillation tower and the circulating liquid after filtration are connected by a switching valve, the regeneration pipeline is blocked, and the bottom material circulation of the distillation tower continues.

[0103] Example 3.

[0104] 30wt% of composite amine was selected as the desulfurizing agent. The desulfurizing agent and sulfur-containing isoprene with a sulfur content of 80mg / L were added to a closed reactor at a volume ratio of 1:100 (V / V) of agent to oil. At the beginning of the reaction, the desulfurization temperature was controlled at 25°C, and the desulfurizing agent and crude isoprene were fully contacted and reacted for 180 minutes. After desulfurization, the residual sulfur content in the refined isoprene solution was 7.79mg / kg, and the alkali nitrogen content was about 125mg / kg. After each reaction, the generated isoprene-containing mixed material was continuously pumped into the distillation tower, and refined isoprene was further obtained by distillation. At the beginning of the first distillation, furfural with a total volume of 0.20 of isoprene was added to the distillation tower. After distillation, the total nitrogen content of the light hydrocarbon product at the top of the tower was less than 10mg / L. During the distillation process, the circulating pump was turned on to allow the bottom material of the distillation tower to be continuously circulated back to the distillation tower through the filter. A four-way valve and two equivalent filters and regenerators were used to ensure the continuity of the bottom material circulation and regeneration process. Specifically, the material at the bottom of the distillation tower flows through one of the filters through a four-way valve, and the filtered solution enters the bottom of the distillation tower for circulation. The regenerated gas flows through another filter regenerator through a four-way valve, and the regenerated tail gas formed enters the subsequent regenerated gas treatment device. As needed, when the salt in the filter is obviously blocked, switch the four-way valve to make the process continuous. The regenerated gas is 300℃ nitrogen, and the regeneration time is 4 hours. The regenerated tail gas formed enters the organic amine recovery tank and is condensed to 60℃ through heat exchange. The gas components enter the cold water recovery tank to further cool down to 20℃, and the tail gas is discharged by slow bubbling in the water.

[0105] Example 4.

[0106] Select 30 wt% compound amine as the desulfurizer, and add the desulfurizer and sulfur-containing isoprene with a sulfur content of 80 mg / L to the closed reactor at a volume ratio of desulfurizer to oil of 1:100 (V / V); at the beginning of the reaction, add to control the desulfurization temperature at 25 °C, and the desulfurizer and crude isoprene are fully contacted and reacted for 180 minutes. After desulfurization, the residual sulfur content in the refined isoprene solution is 7.79 mg / kg, and the basic nitrogen content is about 125 mg / kg. After each reaction, the generated isoprene-containing mixed material is pumped into the distillation column at one time, and distillation is used to further obtain refined isoprene. At the beginning of the first distillation, add water with a volume of 0.20 of the total volume of isoprene in the distillation column. After distillation, the total nitrogen content of the light hydrocarbon product at the top of the column is less than 10 mg / L. During the distillation process, turn on the circulation pump to continuously circulate the bottom material of the distillation column back to the distillation column through the filter. After 5 reactions and distillations are completed, the salt on the filter is heated and decomposed for regeneration. Specifically: rotate the four-way valve so that the bottom material of the distillation column does not pass through the filter and continuously circulates back to the distillation column, and the regeneration gas passes through the four-way valve and flows through the filter regenerator, and the formed regeneration tail gas enters the subsequent regeneration gas treatment device. The regeneration gas is 350 °C steam, and the regeneration time is 4 hours. The formed regeneration tail gas enters the organic amine recovery tank, is heat-exchanged and condensed to 120 °C, and the gas-phase components enter the cold water recovery tank to be further cooled to 20 °C. Excessive condensate water in the cold water recovery tank can be discharged as needed.

[0107] Table 1 shows the light hydrocarbon desulfurization conditions and effects of Examples 1-4 and the comparative example.

[0108]

[0109]

[0110]

[0111] By comparing Example 1 with the comparative example, it is found that the distillation method can directly obtain light hydrocarbon components with qualified nitrogen content, and there is no sewage discharge during the distillation process, while the comparative case needs to be washed 15 times to obtain a product with qualified nitrogen content. After 10 reactions, distillation processes, and regeneration processes, the total sewage discharge can be reduced by about 2.5 times the volume of the raw materials for a single reaction. At the same time, the sulfur-containing salt formed in the reaction can be decomposed in the heated filter, and organic amine recovery and CS 2 capture can be carried out, enabling the reaction to proceed continuously.

[0112] The desulfurization method of Example 2 is the same as that of Example 1, but deionized water with a water-oil volume ratio of 0.20 is added at the beginning of distillation. The addition of water increases the solubility of the sulfur-containing salt and improves the circulation performance of the bottom liquid of the column, making the regeneration process not too frequent. Through the decomposition and regeneration of the sulfur-containing salt, the reaction can proceed continuously.

[0113] The desulfurization method in Example 3 is the same as that in Example 2. However, a furfural solution with an oil-to-agent volume ratio of 0.20 is added at the beginning of distillation. The addition of furfural also increases the solubility of sulfur-containing salts and improves the circulation performance of the bottom liquid. The material after reaction desulfurization can be continuously pumped into the distillation column. Due to the use of a four-way valve and two high-temperature filters, in-situ regeneration can be carried out according to the actual situation of sulfur-containing salt formation, enabling continuous reaction distillation regeneration.

[0114] Example 4 is for the desulfurization of cracked C5. The sulfur-containing species in the raw material are relatively complex. A high-content desulfurizer is used for the reaction. Deionized water with a water-to-oil volume ratio of 0.20 is added at the beginning of distillation. The addition of water increases the solubility of sulfur-containing salts and improves the circulation performance of the bottom liquid. The regeneration atmosphere can use not only nitrogen but also superheated steam. Even if the raw material is relatively complex, the sulfur-containing salts after desulfurization can still be regenerated to enable continuous reaction distillation. A small amount of condensed water formed after the regeneration gas is condensed can be discharged from the cold water recovery tank.

[0115] Compared with the traditional reaction water washing process, the present invention reversibly decomposes the sulfur-containing amine salts formed during the reaction instead of dissolving and storing the sulfur-containing amine salts with water; separates the sulfur-containing amine salts using a filter, and thermally decomposes the sulfur-containing amine salts under high-temperature regeneration gas to form organic amines and CS 2 , and the regenerated organic amines can be recycled. Different from previous patents, this method can greatly reduce the amount of desulfurizer used, fundamentally solve the sewage problem caused by water phase separation and the problem of pipeline blockage by salts, and save energy, reduce emissions and increase efficiency.

Claims

1. A method for removing sulfur compounds from a liquid light hydrocarbon stream by reaction and distillation, characterized in that, specifically includes the following steps: Step 1: Mix the sulfur-containing light hydrocarbon component with a desulfurizing agent, add it to a reactor, and carry out a reaction under a certain reaction temperature and reaction pressure; the reaction temperature of the sulfur-containing light hydrocarbon component and the desulfurizing agent is -20 - 300 °C, the reaction pressure of the sulfur-containing light hydrocarbon component and the desulfurizing agent should ensure that the hydrocarbons are in a liquid phase, the volume ratio of the desulfurizing agent to the sulfur-containing light hydrocarbon component is 1 / 10000 - 1 / 10, and the contact time of the sulfur-containing light hydrocarbon component and the desulfurizing agent is 5 minutes - 24 hours; Step 2: After the reaction is completed, the desulfurized component enters a distillation column, and a light hydrocarbon component with qualified sulfur content is obtained from the top of the distillation column; Step 3: The salt-containing circulating solution in the bottom material of the column flows through a filtration and sulfur-containing salt regeneration system driven by a pump and then forms a filtered circulating liquid and returns to the distillation column; at the same time, after the purge and regeneration gas enters the filtration and sulfur-containing salt regeneration system, a regenerated decomposition gas is formed; Step 4: The regenerated decomposition gas is condensed in an organic amine recovery tank, the gas product goes to a cold water recovery tank, the tail gas is discharged from the top of the cold water recovery tank, and the enriched liquid is sealed at the bottom of the cold water recovery tank; the liquid organic amine recovery liquid is discharged from the bottom of the organic amine recovery tank; A solvent is added to the reactor or the distillation column, the solvent is water or an organic solvent, and the ratio of the solvent to the light hydrocarbon is 0 - 0.

80.

2. The method for removing sulfur compounds from a liquid light hydrocarbon stream by reaction and distillation according to claim 1, characterized in that, when there is a small amount of moisture at the bottom of the distillation column, an external light hydrocarbon liquid separation tank is connected.

3. The method for removing sulfur compounds from a liquid light hydrocarbon stream by reaction and distillation according to claim 1, characterized in that, in the said Step 3, the filtration and sulfur-containing salt regeneration system includes a plurality of switching valves, one or more filtration and sulfur-containing salt regenerators.

4. The method for removing sulfur compounds from a liquid light hydrocarbon stream by reaction and distillation according to claim 3, characterized in that, the structure of the filtration and sulfur-containing salt regeneration system includes: a plurality of three-way switching valves and two independently externally heated filtration and sulfur-containing salt regenerators; the salt-containing circulating solution enters the two filtration and sulfur-containing salt regenerators through a pre-positioned three-way switching valve, and then flows out through a post-positioned three-way switching valve to form a filtered circulating liquid, and the purge and regeneration gas enters the two filtration and sulfur-containing salt regenerators through a pre-positioned three-way switching valve, and then flows out through a post-positioned three-way switching valve to form a regenerated decomposition gas.

5. The method for removing sulfur compounds from a liquid light hydrocarbon stream by reaction and distillation according to claim 3, characterized in that, the filtration and sulfur-containing salt regeneration system includes: a plurality of three-way switching valves and one independently externally heated filtration and sulfur-containing salt regenerator; the salt-containing circulating solution enters the filtration and sulfur-containing salt regenerator through a pre-positioned three-way switching valve, and then flows out through a post-positioned three-way switching valve to form a filtered circulating liquid, and the purge and regeneration gas enters the filtration and sulfur-containing salt regenerator through a pre-positioned three-way switching valve, and then flows out through a post-positioned three-way switching valve to form a regenerated decomposition gas, and the pre-positioned three-way switching valve and the post-positioned three-way switching valve are connected by a bypass.

6. The method for removing sulfur-containing compounds from a liquid light hydrocarbon stream by reaction and distillation according to claim 3, characterized in that, the filtration and sulfur-containing salt regeneration system includes: a plurality of four-way switching valves and two equivalent filtration and sulfur-containing salt regenerators; the four interfaces of the front four-way switching valve are in sequence the salt-containing circulating solution, the filtration and sulfur-containing salt regenerator, the purge and regeneration gas, and the filtration and sulfur-containing salt regenerator; the four interfaces of the rear four-way switching valve are in sequence the regeneration decomposition gas, the filtration and sulfur-containing salt regenerator, the filtered circulating liquid, and the filtration and sulfur-containing salt regenerator.

7. The method for removing sulfur-containing compounds from a liquid light hydrocarbon stream by reaction and distillation according to claim 3, characterized in that, the filtration and sulfur-containing salt regeneration system includes: a plurality of four-way switching valves and one filtration and sulfur-containing salt regenerator; the four interfaces of the front four-way switching valve are in sequence the salt-containing circulating solution, the filtration and sulfur-containing salt regenerator, the purge and regeneration gas, and the filtration and sulfur-containing salt regenerator; the four interfaces of the rear four-way switching valve are in sequence the regeneration decomposition gas, the front four-way switching valve, the filtered circulating liquid, and the filtration and sulfur-containing salt regenerator.

8. The method for removing sulfur-containing compounds from a liquid light hydrocarbon stream by reaction and distillation according to claim 1, characterized in that, in step 3, the temperature of the purge and regeneration gas is normal temperature or high temperature; when using a high-temperature purge gas, it can be directly purged without reheating, the inlet temperature of the regeneration gas should be higher than the decomposition temperature of the sulfur-containing salt, while ensuring that the filtration and sulfur-containing salt regenerator is not damaged, the temperature is 30 - 1000 °C, and the purge time is 10 minutes - 24 hours; when the temperature of the purge and regeneration gas is normal temperature, a filter and sulfur-containing salt regenerator that can be independently heated is selected, the temperature of the regenerator should be higher than the decomposition temperature of the sulfur-containing salt, while ensuring that the filtration and sulfur-containing salt regenerator is not damaged, the temperature is 30 - 1000 °C, and the purge time is 10 minutes - 24 hours.

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