A thiophene production recycling system

Abstract

The present invention discloses a thiophene production recycling system. Two mixers are arranged successively before and after on the reaction pipeline. The butadiene inlet pipeline is communicated with the side part of the first production mixer. The sulfur inlet pipeline is branched into two branches, which are respectively communicated with the tops of the first production mixer and the second production mixer. The gas-liquid outlet is arranged below the second production mixer. A heat exchanger assembly is provided in the tar separator. The gas-liquid mixture coming out from the top end of the gas outlet of the tar separator enters the condenser, and thiophene is separated out from the outlet of the condenser. The gas-liquid mixture treated by the condenser successively enters two pressure-reducing and temperature-reducing processors. The liquefied gas coming out from the second pressure-reducing and temperature-reducing processor is recycled to the butadiene inlet pipeline through a pipeline, and the hydrogen sulfide gas coming out from the top enters the hydrogen sulfide recycling station. The purpose of the present invention is to provide a production system that can effectively reduce the generation of tar in the reaction system, improve the thiophene yield and effectively treat other hydrogen components and heavy components.

Description

Technical Field

[0001] The present invention relates to chemical production equipment, and particularly to a thiophene production cycle recycling system. Background Art

[0002] Thiophene, a five-membered heterocyclic compound containing a sulfur heteroatom. The systematic name is 1-thia-2,4-cyclopentadiene. From the structural formula, thiophene is a heterocyclic compound and also a thioether. Its molecular formula is C4H4S, molecular weight 84.14. Melting point -38 °C, boiling point 84 °C, density 1.051 g / cm3. At room temperature, thiophene is a colorless, malodorous, and lacrimatory liquid. Thiophene naturally exists in petroleum, with a content that can be as high as several percentage points. Industrially, it is used for the denaturation of ethyl alcohols. Like furan, thiophene is aromatic. One of the two pairs of lone electrons of the sulfur atom conjugates with the two double bonds to form a delocalized Π bond. The aromaticity of thiophene is only slightly weaker than that of benzene. Natural thiophene mainly exists in coal tar and shale oil, and the crude benzene from coking contains about 0.5% of thiophene. In the early days, thiophene products were all separated from crude benzene, with very low purity, generally around 98%. Thiophene has aromaticity and can be used as a raw material for making fuels and plastics instead of benzene. Due to the relatively active nature of thiophene, it is more easily metabolized in the animal body, so thiophene has more special uses in the pharmaceutical industry. It is mainly used for the synthesis of thiophenethylpyridine, thiophene diamine, cephalosporin, etc. Thiophene is a good industrial solvent. In the medical field, many derivatives of thiophene have been gradually discovered to have various pharmacological activities, and derivatives of thiophene are gradually replacing some derivatives of benzene. In agriculture, sulfonylurea derivatives of thiophene are ultra-high-efficiency and low-toxic new herbicides, and thiophene can also be used as a synthetic raw material for pesticides, germicides, biological growth promoters, etc.

[0003] As an important basic chemical product, thiophene is widely used in the chemical and pharmaceutical industries, with a wide market and good economic benefits. According to incomplete statistics, the world annually produces and consumes about more than 8,000 tons of thiophene and its derivatives. The main consumption fields include pharmaceutical synthesis, pesticide synthesis, dye synthesis, and β-position thiophene derivatives are also used in perfume synthesis.

[0004] Thiophene was first extracted from the acid washing solution of the benzene fraction of coal tar, but its separation process is complex, and a large amount of sulfuric acid is used in the production process, which causes serious corrosion to the equipment; not only is the production cost extremely high, but also the product quality is poor and the purity is low. The thiophene content is only 95% - 98%, and it contains benzene that is difficult to separate, unable to meet the requirements of the pharmaceutical industry for raw materials. Due to the existence of these problems, this method has been eliminated and replaced by chemical synthesis processes.

[0005] There are mainly four chemical synthesis processes for thiophene: butane-hydrogen sulfide process (Socony-Vacuum method), furan-hydrogen sulfide process, butane-sulfur process, and C4 compound-carbon disulfide process.

[0006] The butane-hydrogen sulfide process (Socony-Vacuum method) uses butane and hydrogen sulfide as raw materials to cyclize and produce thiophene without a catalyst at 600 °C, with a yield of about 40%. There are multiple variant processes, including using sulfur or pyrite instead of hydrogen sulfide for the reaction. It is the earliest chemical synthesis process for thiophene abroad.

[0007] At the same time, butane (or mixed C4) is an inexpensive by-product of refineries, and hydrogen sulfide belongs to the acidic waste gas of refineries. Using it to synthesize thiophene is a waste recycling, with low raw material prices. However, this method has defects such as low yield, strong corrosiveness, large pollution, and difficulty in treating thiophene tar, and it has been phased out abroad since the 1950s.

[0008] The furan-hydrogen sulfide process uses furan and hydrogen sulfide as raw materials, and under the condition of 300-400 °C, a metal oxide treated with heteropolyacid is used as a catalyst for gas-phase reaction to produce thiophene. At the same time, methylfuran can be used instead of furan to prepare methylthiophene. This process has high product quality, good yield, long catalyst life and does not require regeneration, but furan is expensive, and there needs to be a hydrogen sulfide resource at the production site, with high raw material costs, and it has currently been abandoned.

[0009] The butane-sulfur process is a method of continuous reaction of butane and sulfur at a high temperature of 600 °C without a catalyst, without the need for external heating, and produces thiophene with a high yield. Calculated by butane, the yield is about 40%, and at the same time, a large amount of thiophene tar with a strong odor is produced. This process has defects such as strong corrosiveness, large pollution, and great difficulty in treating thiophene tar, and it has been phased out abroad since the 1950s.

[0010] The C4 compound-carbon disulfide process uses a metal oxide treated with alkali as a catalyst. In a fixed-bed reactor, butane and carbon disulfide react at a high temperature to synthesize thiophene by ring closure. Using carbon disulfide as a sulfur source, methane and carbon dioxide are generated after the reaction. This process not only solves the defects of the original Socony-Vacuum method such as low yield and large environmental pollution, but also the prices of C4 compounds and carbon disulfide are cheap, and it is currently the main production method abroad.

[0011] In China, the butadiene-sulfur process is currently mainly used to synthesize thiophene. This process was first described in a patent of DuPont Company in the United States (US2410401). In this process, butadiene and sulfur react to synthesize thiophene in the gas phase and at high temperature. However, the reaction produces coke, which easily causes blockages in pipelines and condensers, resulting in the inability to continue the reaction. The patent applied by Nippon Steel Chemical Co., Ltd. (Japanese Patent Publication No. Sho 54-76574) solved the problem of coke formation in DuPont's patent. The method is to add water to the reactants and make water, butadiene, and sulfur react at 420-470°C under atmospheric pressure. The continuous reaction time can last for more than 14 days. However, due to the blockage of pipelines and condensers by unreacted sulfur after the reaction products are cooled, and the problem of not being able to recover thiophene in the tail gas well, the above patents have not been industrialized. Since the boiling point of thiophene is relatively low, a large amount of thiophene is entrained in the reaction by-product gas hydrogen sulfide and discharged from the tail gas. It is impossible to completely cool down the thiophene in it only by relying on a water condenser. However, in order to prevent blockage of the freezer, this problem was solved by using multi-stage cooling and increasing the cooling area.

[0012] Chinese patent applications (publication numbers CN 1335313 A and CN 1420116 A) disclose the production process and equipment for synthesizing thiophene from butadiene and sulfur. The reaction is the same as the method in the Japanese patent, but the reaction yield is not high and the production cost is relatively large. Patent CN 101654449 B reported an improvement to this process, proposing a production process and device for synthesizing thiophene from butadiene and sulfur with high purity, high yield, low energy consumption, and no pollution. However, the actual production process cannot achieve the effects stated in the patent. There are two reasons: First, the molar ratio of sulfur to butadiene is too large. Second, the mixing effect of the sulfur gas stream and the butadiene gas stream is very poor.

[0013] Since the molecular form, composition of sulfur element are closely related to the temperature it is in. As described on page 97 of the 7th issue of Guangdong Chemical Industry in 2009, ordinary sulfur exists in the form of an S8 ring structure at room temperature, and its melting point is 159°C. As the temperature rises, the form of sulfur changes from solid to liquid, and at the same time, the ring structure begins to break. When the temperature rises above 444.6°C, the liquid sulfur vaporizes, and the sulfur element will coexist in the form of S8, S6, S4, and S2 molecules. When the temperature is higher than 750°C, it will mainly exist in the form of S2 molecules. Only above 1000°C, the sulfur element exists in the form of S2 molecules.

[0014] Since the molecular form of sulfur element is closely related to temperature, it is difficult to write the chemical equation of butadiene and sulfur to truly reflect the reaction. To avoid deviating from the research object described in the technical solution, the sulfur element form will be replaced by sulfur atoms, which is a common practice in textbooks. For example, when writing chemical equations to represent chemical reactions, zinc atoms are used to replace zinc molecules, and sodium atoms are used to replace sodium molecules. The chemical equation for the reaction between butadiene and sulfur element can be expressed as follows:

[0015]

[0016] Research shows that only by approaching the material ratio in the chemical equation can a product with high practical value be obtained; otherwise, the cost will be high. Sulfur and oxygen belong to the same group and have very similar chemical properties. When excessive oxygen reacts with organic substances, carbon dioxide and water are produced. Similarly, when excessive sulfur reacts with organic substances, carbon disulfide and hydrogen sulfide are produced. The dehydrogenation reaction of sulfur yellow and organic substances is extremely likely to occur, and the presence of sulfur in excess of the stoichiometric amount of the chemical reaction can easily cause the carbonization of organic substances and the formation of tarry substances. In both examples of patent document CN101654449B, the molar mass ratio of sulfur atom molecules to butadiene molecules is 3. Practice has proved that as long as the molar ratio of sulfur atoms to butadiene molecules exceeds 2.5, the yield of the reaction product thiophene is less than 50%, the amount of tar produced during the production process is too large, and the tar in the reactor often clogs, and the reactor needs to be cleaned of tar within seven days of continuous production.

[0017] The large amount of tar produced during the production of thiophene is caused by a high proportion of sulfur. The direct reason for using excessive sulfur in the reaction is that sulfur and butadiene are not well mixed evenly at the beginning of the reaction, resulting in incomplete reaction of butadiene.

[0018] 2,5 - Dihydrothiophene is generated during the reaction process, indicating that this reaction process occurs in two steps. The chemical equations are as follows:

[0019]

[0020] According to the above reaction occurring in two steps, it is more reasonable and feasible to add sulfur to the reaction system in two portions. This can reduce the amount of sulfur used and the generation of tar in the reaction system.

[0021] In addition, other substances generated during the production of thiophene need to be further recycled to avoid releasing harmful substances into the environment. The hydrogen sulfide generated in the tail gas, if released into the environment, will cause environmental pollution. If it is further recycled, it can save energy and protect the environment. Summary of the Invention

[0022] The purpose of the present invention is to provide a production recovery and utilization system that can effectively reduce the generation of tar in the reaction system, improve the yield of thiophene, and effectively treat other hydrogen components and heavy components.

[0023] To achieve the above object, the present invention is realized through the following technical solutions:

[0024] A thiophene production system, comprising:

[0025] Mixers, with two mixers arranged successively on the reaction pipeline, namely the first production mixer and the second production mixer respectively. The butadiene inlet pipeline is communicated with the side of the first production mixer. The sulfur inlet pipeline is branched into two, and is respectively communicated with the tops of the first production mixer and the second production mixer. The gas-liquid outlet is arranged below the second production mixer;

[0026] A tar separator, in which a heat exchanger assembly is provided. Its inlet is arranged above the connection of the lower head, the outlet is arranged at the top of the tar separator, and the tar discharge port is arranged at the bottommost of the tar separator;

[0027] A condenser, the gas-liquid mixture coming out from the top of the gas outlet of the tar separator enters the condenser, and thiophene is separated from the outlet of the condenser;

[0028] A pressure reduction and temperature reduction processor, the gas-liquid mixture processed by the condenser enters two pressure reduction and temperature reduction processors in sequence. The volume of the second pressure reduction and temperature reduction processor is twice that of the first pressure reduction and temperature reduction processor; the liquefied gas coming out from the second pressure reduction and temperature reduction processor is circulated through a pipeline to the butadiene inlet pipeline.

[0029] A hydrogen sulfide recovery station, the hydrogen sulfide gas coming out from the top of the second pressure reduction and temperature reduction processor enters the hydrogen sulfide recovery station. The hydrogen sulfide recovery station includes: a plurality of hydrogen sulfide pipelines, the initial ends of each hydrogen sulfide pipeline are respectively connected with the outlet of the scrubbing tower, a waste acid recovery pipeline is installed on each hydrogen sulfide pipeline, and all waste acid recovery pipelines are respectively connected with the main pipeline. The main pipeline is connected with the input end of the waste acid recovery tank.

[0030] Optionally, the mixer includes:

[0031] A first mixing chamber, the sulfur gas pipeline extends from the top into the first mixing chamber and extends to near the bottom of the first mixing chamber. A number of small holes are evenly arranged on the side wall of the sulfur gas pipeline, and the total area of the small holes is less than or equal to the cross-sectional area of the sulfur gas pipeline; the butadiene gas pipeline is arranged on the side of the first mixing chamber;

[0032] A throat pipe, the bottom of the first mixing chamber is tightened inward to reduce its diameter and extends downward;

[0033] A second mixing chamber, which expands outward from the bottom of the throat pipe to increase its diameter and extends downward.

[0034] Optionally, the sulfur gas pipeline is arranged at a right angle to the butadiene gas pipeline, such that the flow direction of the sulfur gas and the flow direction of the butadiene gas are at a right angle.

[0035] Optionally, the contraction angle between the first mixing chamber and the throat is 30 to 45 degrees; the expansion angle between the throat and the second mixing chamber is 8 to 20 degrees.

[0036] Optionally, the connecting pipelines between the mixers, the connecting pipelines between the mixer and the tar separator, and the connecting pipeline between the tar separator and the condenser are all assembled vertically or at a 45-degree angle.

[0037] Optionally, the volume of the tar separator is 5M 3 ~10M 3 , with a length-to-diameter ratio of 2 to 1 and installed vertically.

[0038] Optionally, condensation heat exchange tubes are additionally installed in the pressurization and cooling processor and installed vertically.

[0039] Optionally, the inlet position of the hydrogen sulfide gas entering the first pressurization and cooling processor is above the welding line of the lower head, and the hydrogen sulfide outlet is set at the highest position of the second pressurization and cooling processor.

[0040] Optionally, the output end of the waste acid recovery tank is connected to the inlet of the scrubbing tower.

[0041] The technical solution of the present invention has the following advantages:

[0042] This embodiment provides a thiophene production and recycling system, which significantly reduces the generation of tar, improves the thiophene production rate, recycles other hydrogen components and heavy component substances generated simultaneously; further recovers and processes the generated hydrogen sulfide gas, saving energy and protecting the environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0044] Figure 1 It is a schematic structural diagram of the mixer of the present invention;

[0045] Figure 2 It is a schematic structural diagram of the present invention;

[0046] Figure 3 It is a schematic structural diagram of the hydrogen sulfide gas recycling station. DETAILED DESCRIPTION OF THE INVENTION

[0047] The technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0048] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to the present invention.

[0049] In addition, the technical features involved in different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0050] Embodiment 1

[0051] The present invention also provides a thiophene production and recycling system. As shown in Figure 2 the figure, two mixers are arranged before and after on the reaction pipeline, namely the first production mixer 1 and the second production mixer 2 respectively. The sulfur gas pipeline branches off into another branch and extends into the top of the second production mixer 2. The connecting pipeline between the first production mixer 1 and the second production mixer 2 forms an angle of 45 degrees with the horizontal plane.

[0052] Specifically, for thiophene production, butadiene and sulfur need to be fully mixed in the early stage of the reaction. This embodiment provides a mixer designed independently. As shown in Figure 1 the figure, it includes:

[0053] The first mixing chamber 30. The sulfur gas pipeline 10 extends from the top and extends to the near bottom of the first mixing chamber 30. 2 to 6 small holes 50 are evenly arranged on the side wall of the sulfur gas pipeline 10, and the total area of the small holes is less than or equal to the cross-sectional area of the sulfur gas pipeline 10. The butadiene gas pipeline 20 is arranged on the side of the first mixing chamber 30.

[0054] The throat pipe 40 has a diameter of 100 mm, the reaction pipe has a diameter of 219 mm, and the length of the throat pipe is 100 mm to 150 mm. It tapers inward at the bottom of the first mixing chamber 30 to reduce its diameter and extends downward. The throat pipe is a process of energy accumulation. This energy is also the maximum hybrid force of the shear force formed between the two gases. The throat pipe is also the place where the two gases are most mixed. Due to the short mixing time, it is necessary to add a mixing expansion section to utilize the energy accumulated at the throat pipe to continue the shear mixing in the expansion section. The diameter of the throat pipe needs to be determined according to the flow rates of the two gases and is obtained through CFD simulation calculations. The diameter and length of the throat pipe in this embodiment are based on the specific process of this application. If the throat pipe section is too long, the resistance is too large and the production cost is high. The contraction angle of the contraction section 70 is 30 to 45 degrees. In this embodiment, 30 degrees is adopted. In the pipeline, the two gases must be sheared and mixed with each other during mixing. This shear mixing process requires energy supply. Therefore, only by contracting the pipeline to accumulate energy can this process be realized. When contracting the pipeline, resistance will inevitably be generated. In order to reduce the resistance of the gas flow rate, it is necessary to contract at a certain angle. CFD simulation calculations show that when contracting at an angle of 30 to 45 degrees, the resistance is the smallest and the energy loss is the smallest.

[0055] The expansion angle of the expansion section 80 is 8 to 20 degrees. In this embodiment, it is 20 degrees. The two gases are sheared and mixed in the expansion section by using the energy released in the expansion section from the energy accumulated at the throat pipe. Through CFD simulation at this angle, the energy loss is the smallest when the pipeline diameter expands at this angle. In the pipeline expansion section, the two gases can also be maximally sheared and mixed during the process of releasing energy. If there is no expansion section, that is, a 90-degree angle diameter change, the pressure difference drop in the pipeline is maximized and the energy loss is the largest, and the two gases have not reached the maximum or the greatest degree of mixing.

[0056] The second mixing chamber 60 expands outward from the bottom of the throat pipe 40 to increase its diameter and extends downward.

[0057] The flow direction of the sulfur gas and the flow direction of the butadiene gas are at a right angle; during mixing, the maximum shear force mixing of the two gases is achieved through the angle to make them mix to the greatest extent.

[0058] The momentum ratio of the sulfur gas to the butadiene gas is 1 - 5, that is, the sulfur gas flow cannot be sprayed onto the pipe wall, but is almost to the pipe wall, and the effect is the best.

[0059] While the sulfur gas and the butadiene gas need to be fully mixed, the sulfur needs to be added to the reaction system in two times so that the molar ratio of sulfur to butadiene does not exceed 2. First, the sulfur and butadiene are mixed and reacted in two times:

[0060] The molar ratio of sulfur atoms to butadiene in the first mixing ratio is 1.0 - 1.7;

[0061] The molar ratio of sulfur atoms to butadiene in the second mixing ratio is 0.5 - 1.2;

[0062] The total molar ratio of sulfur atoms to butadiene in the raw materials is 1.8 - 2.0.

[0063] In terms of the mixing ratio, reducing the molar ratio of sulfur by no more than 2 will reduce the formation of carbon disulfide and also produce a small amount of dihydrothiophene. Recycling the unreacted raw material butadiene and dihydrothiophene significantly increases the reaction yield and significantly reduces the tar content. The light components of the distillation column and the heavy components below 130 °C participate in the cyclic reaction.

[0064] In the production process of thiophene, the kinetic energies of the two fluids, sulfur gas and butadiene, are not very different. Therefore, it is not suitable to use a typical Venturi mixer for the mixer. If it must be used, the momentum of one fluid must be increased. Generally, the flow rate of hot steam is increased, which will significantly increase the production cost. The mixer in this embodiment solves the problem that the momentum difference between the two fluids is not large and does not affect the flow resistance of the other fluid. In addition, butadiene is a reactive substance and very easy to polymerize, so it is not suitable to exist in a pressure system and is not suitable to increase the fluid kinetic energy by pressurization.

[0065] The process flow of using the above production mixer is as follows:

[0066] Heat liquid sulfur and water together to 450 - 550 °C to form steam-sulfur gas; mix the vaporized butadiene with water and heat to 250 - 350 °C to form steam-butadiene gas. Mix the steam-sulfur gas and steam-butadiene gas and react under the conditions of 360 - 460 °C and slightly positive pressure. The residence time of the material in the reactor is 3 - 8 seconds to obtain a gas reaction product. The mass ratio of sulfur entering the reactor twice in this process is set to 1.5, that is, the molar ratio to butadiene is 2.0, and the molar mass of sulfur per unit time is 1.2 to 0.8.

[0067] Preferably, both the mixer and the pipe reactor are assembled vertically or at a 45-degree angle. The main reason is that tar is always generated during the reaction. Such assembly is conducive to removing the tar from the reaction system and can continuously produce for a long time.

[0068] A tar separator 3 needs to be set in the production system. The tar separator 3 requires a certain volume and also has the function of a heat exchanger. The temperature of the gas entering the tar separator 3 is as high as above 350 °C, and the temperature at the outlet of the tar separator 3 is controlled between 180 °C and 200 °C. The material of the tar separator is stainless steel, with a volume of 5M 3 to 10M 3, with a length-to-diameter ratio of 2:1, installed vertically, the air inlet is set above the connection of the lower head, the gas outlet is set at the top of the tar separator, and the tar discharge is set at the lowest end of the tar separator. There is sufficient separation space, the pressure drop is obvious, the gas flow rate is significantly reduced, and the liquefied or atomized high-boiling substances and tar can be easily separated from the gas by their own weight, maximizing the separation of gas and tar.

[0069] After the reaction ends when the gas enters the tar separator, the subsequent is the physical treatment process. Recycling the unreacted raw material butadiene in the tail gas significantly increases the reaction yield and significantly reduces the tar content. The light components and the heavy components below 130 °C in the distillation column participate in the cyclic reaction.

[0070] The gas-liquid mixture coming out from the top of the gas outlet of the tar separator enters the condenser 4, and thiophene is separated from the outlet of the condenser 4;

[0071] The gas-liquid mixture treated by the condenser 4 enters two pressurizing and cooling processors in sequence. The volume of the second pressurizing and cooling processor 6 is twice that of the first pressurizing and cooling processor 5; the liquefied gas coming out from the second pressurizing and cooling processor 6 is circulated to the butadiene inlet pipeline through a pipeline. Specifically, for the pressurizing and cooling processor of the 3000-ton thiophene production device per year, that is, the volume of the first hydrogen sulfide processor (collection tank) is 9.5 M 3 , and the volume of the second hydrogen sulfide processor is 23 M 3 , aiming to reduce the gas flow rate and maximize the separation of gas-liquid substances; 5 M is respectively added in the two hydrogen sulfide processors 2 condensing heat exchange tubes, which are set above the processor (collection tank), aiming to condense the gas more fully and maximize the separation of the liquid: the inlet position of the hydrogen sulfide gas entering the hydrogen sulfide collection tank is above the welding line of the lower head, and the hydrogen sulfide outlet is set at the highest position of the collection tank; both condensers need to be installed vertically, aiming to have a large gas-liquid separation space and a long gas residence time. The condensing temperature of the first condenser is controlled within the range of 5 - 10 °C, and the pressure is set at 10 - 12 Mpa, mainly collecting thiophene and part of carbon disulfide substances. The temperature of the second condenser is controlled at -10 — -5 °C, and the pressure is set at 20 - 23 Mpa, mainly collecting low-boiling substances such as butadiene and a small amount of carbon disulfide, also known as tail gas liquefied gas.

[0072] Furthermore, the hydrogen sulfide outlet enters the hydrogen sulfide recovery and treatment station, see Figure 3As shown in the figure, it specifically includes: mainly composed of a hydrogen sulfide pipeline, a neutralization waste liquid recovery pipeline, a main pipeline, a waste liquid recovery tank, etc.; five hydrogen sulfide pipelines are arranged in parallel and at intervals, and the initial ends of each hydrogen sulfide pipeline are respectively connected to the outlets of the corresponding scrubbing towers; that is, the first scrubbing tower 101 is connected to the first hydrogen sulfide pipeline 105, the second scrubbing tower 102 is connected to the second hydrogen sulfide pipeline 106, the third scrubbing tower 103 is connected to the third hydrogen sulfide pipeline 107, the fourth scrubbing tower 104 is connected to the fourth hydrogen sulfide pipeline 109, and the fifth scrubbing tower 112 is connected to the fifth hydrogen sulfide pipeline 108. Ammonia water is used in the scrubbing tower to neutralize hydrogen sulfide.

[0073] Corresponding waste liquid recovery pipelines 110 are respectively arranged at the low points of each hydrogen sulfide pipeline. The five waste liquid recovery pipelines 110 converge to a main pipeline, and the main pipeline is connected to the input end at the top of the waste liquid recovery tank 111. An output end is arranged at the bottom of the waste liquid recovery tank 111, and the output end is connected to the bottom inlet of the fifth scrubbing tower 112. The neutralization waste liquid in the hydrogen sulfide pipeline flows into the fifth scrubbing tower 112 by gravity, which not only avoids environmental pollution caused by the discharge of waste acid but also realizes the recycling of ammonium sulfide.

[0074] The other equipment not described in the equipment flow chart is mainly functional equipment for separating gas-liquid substances, cooling, and collecting the products thiophene and hydrogen sulfide.

[0075] Experimental Example 1

[0076] Without using tail gas liquefied gas circulation and without using a mixer, when the molar ratio of butadiene to sulfur atoms in the feed ratio is 1:2.5, the tar production rate is relatively fast, and the tar storage tank is blocked on the seventh day, and the production is stopped for treatment.

[0077] Experimental Example 2

[0078] Without using tail gas liquefied gas circulation and using a mixer, when the molar ratio of butadiene to sulfur atoms in the feed ratio is 1:2.5, the tar storage tank is blocked on the 20th day, and the production is stopped for treatment. The increase in the thiophene yield is not obvious.

[0079] Experimental Example 3

[0080] Using tail gas liquefied gas circulation and using a mixer, when the molar ratio of butadiene to sulfur atoms in the feed ratio is 1:2.5, the tar storage tank is blocked on the 25th day, and the production is stopped for treatment. The thiophene yield increases by 4%.

[0081] Experimental Example 4

[0082] Using tail gas liquefied gas circulation and using a mixer, when the molar ratio of butadiene to sulfur atoms in the feed ratio is 1:2.1, the tar storage tank is blocked on the 50th day, and the production is stopped for treatment. The product yield increases by 10%.

[0083] Experimental Example 5

[0084] By adopting tail gas liquefied gas circulation and using a mixer, when the molar ratio of butadiene to sulfur atoms in the formulation is 1:2, the tar storage tank becomes blocked on the 68th day and the operation is stopped for treatment. The product yield is increased by 12%.

[0085] Experimental Example 6

[0086] By adopting tail gas liquefied gas circulation and using a mixer, when the molar ratio of butadiene to sulfur atoms in the formulation is 1:1.8, the tar storage tank becomes blocked on the 85th day and the operation is stopped for treatment. The product yield is increased by 15%.

[0087] Obviously, the above embodiments are merely examples given for clear illustration and not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to enumerate all the implementation manners here. And the obvious changes or modifications derived therefrom are still within the protection scope of the present invention.

[0088] Obviously, the above embodiments are merely examples given for clear illustration and not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to enumerate all the implementation manners here. And the obvious changes or modifications derived therefrom are still within the protection scope of the present invention.

Claims

1. A thiophene production recycling system, characterized in that, Comprising: Mixers, with two mixers arranged successively before and after on the reaction pipeline, namely the first production mixer and the second production mixer respectively. The outlet of the first production mixer is connected to the inlet of the second production mixer, the outlet of the second production mixer is connected to the inlet of the tar separator, the butadiene inlet pipeline communicates with the side of the first production mixer, the sulfur inlet pipeline is branched into two, and respectively communicates with the tops of the first production mixer and the second production mixer. The gas-liquid outlet is arranged below the second production mixer; Tar separator, in which a heat exchanger assembly is provided. Its air inlet is arranged above the connection of the lower head, the air outlet is arranged at the top of the tar separator, and the tar discharge outlet is arranged at the bottommost of the tar separator; Condenser, the gas-liquid mixture coming out from the top of the gas outlet of the tar separator enters the condenser, and thiophene is separated from the outlet of the condenser; Pressurizing and cooling processor, the gas-liquid mixture after being processed by the condenser enters two pressurizing and cooling processors in sequence. The volume of the second pressurizing and cooling processor is twice that of the first pressurizing and cooling processor; the liquefied gas coming out from the second pressurizing and cooling processor is circulated to the butadiene inlet pipeline through a pipeline; Hydrogen sulfide recovery station, the hydrogen sulfide gas coming out from the top of the second pressurizing and cooling processor enters the hydrogen sulfide recovery station. The hydrogen sulfide recovery station includes: a plurality of hydrogen sulfide pipelines, the initial ends of each hydrogen sulfide pipeline are respectively connected to the outlet of the scrubbing tower, a waste acid recovery pipeline is installed on each hydrogen sulfide pipeline, and all waste acid recovery pipelines are respectively connected to the main pipeline. The main pipeline is connected to the input end of the waste acid recovery tank; The mixer includes: The first mixing chamber, the sulfur gas pipeline extends from the top into the first mixing chamber and extends to near the bottom of the first mixing chamber. A number of small holes are evenly arranged on the side wall of the sulfur gas pipeline, and the total area of the small holes is less than or equal to the cross-sectional area of the sulfur gas pipeline; the butadiene gas pipeline is arranged on the side of the first mixing chamber; Throat pipe, the bottom of the first mixing chamber is tightened inward to reduce its diameter and extend downward; The second mixing chamber, the bottom of the throat pipe expands outward to increase its diameter and extend downward; The contraction angle between the first mixing chamber and the throat pipe is 30 to 45 degrees; the expansion angle between the throat pipe and the second mixing chamber is 8 to 20 degrees.

2. The thiophene production recycling system according to claim 1, characterized in that The sulfur gas pipeline and the butadiene gas pipeline are arranged at a right angle, so that the flowing direction of the sulfur gas and the flowing direction of the butadiene gas are at a right angle.

3. The thiophene production recycling system according to claim 1, wherein The connecting pipelines between the mixers, the connecting pipelines between the mixer and the tar separator, and the connecting pipeline between the tar separator and the condenser are all assembled in a vertical or 45-degree angle.

4. The thiophene production recycling system according to claim 1, characterized in that, The volume of the said tar separator is 5M 3 ~10M 3 , the aspect ratio is 2:1, and it is installed vertically.

5. The thiophene production recycling system according to claim 1, characterized in that, Condensing heat exchange pipes are respectively added in the pressurizing and cooling processors and installed vertically.

6. The thiophene production recycling system according to claim 1, characterized in that, The inlet position of the hydrogen sulfide gas entering the first pressurizing and cooling processor is above the welding line of the lower head, and the hydrogen sulfide outlet is arranged at the highest position of the second pressurizing and cooling processor.

7. The thiophene production recycling system according to claim 1, characterized in that The output end of the waste acid recovery tank is connected to the inlet of the scrubbing tower.

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