Apparatus for producing 1,3-butadiene and method for producing 1,3-butadiene

Abstract

An apparatus for producing 1,3-butadiene according to one embodiment of the present invention comprises: a first reactor that generates acetaldehyde by a dehydrogenation reaction of ethanol; a second reactor that generates 1,3-butadiene from acetaldehyde and ethanol; an ethanol supply line that has a branch point; an intermediate line for supplying an outlet fluid of the first reactor to the second reactor; a recycle line that is connected to the intermediate line and supplies acetaldehyde separated from an outlet fluid of the second reactor to the second reactor; a bypass line that is branched from the branch point of the ethanol supply line and is connected to the intermediate line; a pressure gauge that is provided on the downstream side of the branch point of the ethanol supply line and on the upstream side of the connection point between the recycle line and the intermediate line or on the upstream side of the connection point between the bypass line and the intermediate line; and a pressure control valve for adjusting the pressure in the first reactor on the basis of the measurement value of the pressure gauge.

Description

1,3-Butadiene Production Apparatus and 1,3-Butadiene Production Method

[0001] The present disclosure relates to a 1,3-butadiene production apparatus and a 1,3-butadiene production method.

[0002] As an ETB (Ethanol To Butadiene) process for producing 1,3-butadiene from a raw material containing ethanol, there are a one-step method (Lebedev method) that converts ethanol to butadiene in one step, and a two-step method (Ostromislensky method) that involves a reaction of dehydrogenating ethanol to synthesize acetaldehyde and a reaction of synthesizing butadiene from ethanol and acetaldehyde. In the two-step method, it is known to recycle unreacted acetaldehyde or ethanol entrained in the produced 1,3-butadiene.

[0003] Patent Document 1 (International Publication No. 2022 / 207884) describes a process for producing 1,3-butadiene from ethanol and acetaldehyde involving catalyst regeneration, comprising: a) reacting a feed containing ethanol and acetaldehyde in a reactor having at least one adiabatic reaction zone containing a supported catalyst; and b) regenerating the supported catalyst.

[0004] Patent Document 2 (Japanese Patent Application Laid-Open No. 2023-31584) describes a method for producing 1,3-butadiene by continuously producing 1,3-butadiene from an ethanol-containing gas, comprising: a first conversion step of subjecting the ethanol-containing gas to contact treatment with a first catalyst to convert a part of the ethanol in the ethanol-containing gas to acetaldehyde and obtaining an intermediate gas containing ethanol and acetaldehyde; and a second conversion step of subjecting a mixed gas obtained by mixing the intermediate gas or the intermediate gas and a gas containing ethanol to contact treatment with a second catalyst to convert ethanol and acetaldehyde in the intermediate gas or the mixed gas to 1,3-butadiene and obtaining a 1,3-butadiene-containing gas, and controlling the hydrogen concentration in the intermediate gas or the mixed gas to less than 15% by volume.

[0005] Patent Document 3 (U.S. Patent Application Publication No. 2023 / 0373892) describes a method for dehydrogenating a feedstock containing ethanol, using at least one multitube reactor, the reactor preferably comprising a plurality of tubes containing at least one dehydrogenation catalyst and a calender, the feedstock being introduced into the tubes in gaseous form, the inlet temperature being 240°C or higher, the pressure being 0.1 to 1.0 MPa, and the WWH being 2 to 15 h. －１ The present invention describes a method in which the flow rate of the heat transfer fluid as it flows through the calender is such that the weight ratio of the heat transfer fluid to the supply material is 1.0 or more, and the inlet temperature when introducing the heat transfer fluid into the calender in the form of a gas is 260°C or higher, and the inlet pressure is 0.10 to 1.10 MPa, and the heat transfer fluid exits the calender in the form of a liquid at least partially.

[0006] Patent Document 4 (Japanese Patent No. 6594416) describes a method for producing butadiene from an ethanol supply raw material containing at least 80% by weight of ethanol, comprising at least: a step A of converting ethanol to acetaldehyde, a step B of converting the ethanol / acetaldehyde mixture to butadiene, a step C1 of treating hydrogen, a step D1 of extracting butadiene, a first step D2 of purifying butadiene, a subsequent step D3 of purifying butadiene, a step E1 of treating effluent, a step E2 of removing impurities and brown oil, and a step F of washing with water.

[0007] Patent document 5 (Japanese Patent Publication No. 2024-512679) describes a process for producing 1,3-butadiene in which at least a portion of the second fraction containing acetaldehyde and the third fraction containing ethanol, which are separated from the second-stage effluent containing 1,3-butadiene, are reused.

[0008] Patent document 6 (Japanese Patent Publication No. 2023-31384) describes a method for producing butadiene by passing a raw material gas through a first reactor that converts ethanol to acetaldehyde, an inorganic gas separator that separates inorganic gas produced as a by-product in the first reactor, and a second reactor that converts ethanol and acetaldehyde to butadiene, wherein the acetaldehyde-containing gas and the second ethanol-containing gas recovered from the purification section 5 are reused.

[0009] International Publication No. 2022 / 207884, Japanese Patent Publication No. 2023-31584, U.S. Patent Application Publication No. 2023 / 0373892, Japanese Patent No. 6594416, Japanese Patent Publication No. 2024-512679, Japanese Patent Publication No. 2023-31384

[0010] The reaction to produce 1,3-butadiene from ethanol is carried out using two reactors. In the first reactor, acetaldehyde is produced from ethanol by a dehydrogenation reaction, and in the second reactor, 1,3-butadiene is produced from acetaldehyde and ethanol with the elimination of two molecules of water.

[0011] The dehydrogenation reaction carried out in the first reactor is an equilibrium reaction in which the conversion rate from ethanol to acetaldehyde is determined by temperature and pressure, and the reaction product contains acetaldehyde and unreacted alcohol. Under constant temperature conditions, the conversion rate is high at low pressure, so it is desirable to suppress the increase in the operating pressure of the first reactor in order to maintain a high conversion rate.

[0012] In the ETB (Ethanol To Butadiene) reaction carried out in the second reactor, unreacted ethanol and acetaldehyde are generally present along with the target product, 1,3-butadiene. These unreacted substances are recovered as recycled ethanol and recycled acetaldehyde, respectively, in the purification and separation process. The recycled ethanol is returned to the dehydrogenation and ETB reactions, and the recycled acetaldehyde is returned to the ETB reaction, and these are reused in the production of 1,3-butadiene.

[0013] By connecting the first and second reactors in series, the dehydrogenation and ETB reactions are carried out continuously. Downstream of the second reactor, a multi-stage configuration of distillation columns, absorption columns, separation columns, decongestion columns, recovery columns, and washing columns is arranged for the purification and separation process. Immediately before the purification and separation process, a compressor is placed in the ethanol separation column, which carries out the first purification and separation process, to increase the pressure of the outlet fluid of the second reactor in order to make 1,3-butadiene the top effluent. The operating pressure of the first and second reactors is determined by the sum of the pressure losses Δp of the piping and equipment installed upstream of the compressor, starting from the suction pressure of the compressor.

[0014] From the start of operation (SOR) to the end of operation (EOR), the catalysts placed inside the first and second reactors become inactive over time due to carbon deposits (coking). As a result, the content of unreacted ethanol and acetaldehyde in the outlet fluid of the second reactor increases from SOR to EOR. When the amount of recycled ethanol supplied to the second reactor increases, the pressure loss Δp in the second reactor, the piping and coolers located downstream of the second reactor increases, and consequently, the operating pressure of the first reactor also rises. This reduces the conversion rate of acetaldehyde in the dehydrogenation reaction under constant temperature conditions, and changes the composition of the outlet fluid of the first reactor. This also causes fluctuations in the amount of 1,3-butadiene produced, destabilizing the operation of the 1,3-butadiene production plant.

[0015] This disclosure provides an apparatus and method capable of stably producing 1,3-butadiene from ethanol, even when operated continuously for a long period of time using recycled acetaldehyde and recycled ethanol.

[0016] The inventors have found that by installing a pressure gauge at a specific location in the piping system of a 1,3-butadiene production apparatus and adjusting the pressure in the first reactor based on the pressure gauge reading, fluctuations in the equilibrium composition of the dehydrogenation reaction can be suppressed, allowing the dehydrogenation reaction to proceed stably in the first reactor, thereby enabling the stable production of 1,3-butadiene as a whole.

[0017] This disclosure encompasses the following embodiments: [Embodiment 1] A 1,3-butadiene production apparatus for producing 1,3-butadiene from an ethanol-containing raw material, comprising: a first reactor that generates acetaldehyde by a dehydrogenation reaction of ethanol contained in the ethanol-containing raw material; a second reactor that generates 1,3-butadiene from acetaldehyde and ethanol; an ethanol supply line having a branch point that supplies at least a portion of the ethanol-containing raw material to the first reactor; an intermediate line for supplying the outlet fluid of the first reactor to the second reactor; a recycling line connected to the intermediate line that supplies acetaldehyde separated from the outlet fluid of the second reactor to the second reactor; a bypass line branching from the branch point of the ethanol supply line and connected to the intermediate line, for supplying a portion of the ethanol-containing raw material to the second reactor as needed; and a pressure gauge provided downstream of the branch point of the ethanol supply line and upstream of the connection point between the recycling line and the intermediate line or upstream of the connection point between the bypass line and the intermediate line. A 1,3-butadiene production apparatus comprising: a pressure regulating valve that adjusts the pressure in the first reactor based on the measurement value of the pressure gauge; [Aspect 2] The 1,3-butadiene production apparatus according to aspect 1, further comprising a purification and separation device provided downstream of the second reactor, wherein the purification and separation device separates acetaldehyde and ethanol from the outlet fluid of the second reactor and supplies them to the recycling line and the ethanol supply line, respectively, and the pressure regulating valve is provided upstream of the purification and separation device; [Aspect 3] The 1,3-butadiene production apparatus according to aspect 1 or 2, wherein the pressure gauge is provided upstream of the connection point between the recycling line and the intermediate line, and upstream of the connection point between the bypass line and the intermediate line; [Aspect 4] The 1,3-butadiene production apparatus according to any one of aspects 1 to 3, wherein at least a portion of the recycling line and at least a portion of the bypass line merge to form a common line, and the common line is connected to the intermediate line;[Aspect 5] The 1,3-butadiene production apparatus according to any one of aspects 1 to 4, wherein the pressure regulating valve is located downstream of the branching point of the ethanol supply line, upstream of the connection point between the recycling line and the intermediate line, and upstream of the connection point between the bypass line and the intermediate line. [Aspect 6] The 1,3-butadiene production apparatus according to any one of aspects 1 to 5, wherein the first reactor is an adiabatic reactor or an isothermal reactor. [Aspect 7] The 1,3-butadiene production apparatus according to any one of aspects 1 to 6, further comprising a flow control valve for controlling the mass flow rate of the ethanol-containing raw material supplied to the first reactor. [Aspect 8] A method for producing 1,3-butadiene from an ethanol-containing raw material using the 1,3-butadiene production apparatus according to any one of aspects 1 to 7, comprising adjusting the pressure in the first reactor to a range of ±50% of a set pressure using the pressure regulating valve based on the measurement value of the pressure gauge. [Aspect 9] A method for producing 1,3-butadiene according to aspect 8, comprising adjusting the mass flow rate of the ethanol-containing raw material supplied to the first reactor so that the mass flow rate of the ethanol-containing raw material supplied to the first reactor is within the range of a set flow rate ± 50%. [Aspect 10] A method for producing 1,3-butadiene according to aspect 9, comprising adjusting the temperature inside the first reactor so that the temperature inside the first reactor is within the range of a set temperature ± 50°C. [Aspect 11] A method for producing 1,3-butadiene according to any one aspect of aspects 8 to 10, wherein the temperature inside the first reactor is 220°C to 300°C and the pressure is 0.2 MPaG to 0.9 MPaG.

[0018] According to this disclosure, 1,3-butadiene can be stably produced from ethanol even when the system is operated continuously for a long period of time using recycled acetaldehyde and recycled ethanol.

[0019] The above description should not be considered to disclose all embodiments of the present invention or all advantages relating to the present invention.

[0020] This is a schematic diagram illustrating a production apparatus and method for 1,3-butadiene according to one embodiment. This is a schematic diagram illustrating a production apparatus and method for 1,3-butadiene according to another embodiment.

[0021] The present invention will be described in more detail below with reference to the drawings, illustrating typical embodiments, but the present invention is not limited to these embodiments. Reference numerals in the drawings indicate that elements with the same or similar numerals in different drawings are the same or similar elements.

[0022] Figure 1 shows a schematic diagram of a 1,3-butadiene production apparatus according to one embodiment. The 1,3-butadiene production apparatus 10 is an apparatus for producing 1,3-butadiene from an ethanol-containing raw material, and comprises: a first reactor 11 that generates acetaldehyde by a dehydrogenation reaction of ethanol contained in the ethanol-containing raw material; a second reactor 12 that generates 1,3-butadiene from acetaldehyde and ethanol; an ethanol supply line 14 having a branching point 13 that supplies at least a portion of the ethanol-containing raw material to the first reactor 11; an intermediate line 15 for supplying the outlet fluid of the first reactor 11 to the second reactor 12; and a line connected to the intermediate line 15 that supplies the outlet fluid of the second reactor 12 The reactor comprises: a recycling line 16 that supplies the separated acetaldehyde to the second reactor 12; a bypass line 17 that branches off from the branching point 13 of the ethanol supply line 14 and is connected to the intermediate line 15, and supplies a portion of the ethanol-containing raw material to the second reactor 12 as needed; a pressure gauge 20 provided downstream of the branching point 13 of the ethanol supply line 14 and upstream of the connection point 18 between the recycling line 16 and the intermediate line 15 or upstream of the connection point 19 between the bypass line 17 and the intermediate line 15; and a pressure regulating valve 21 that adjusts the pressure in the first reactor 11 based on the measurement value of the pressure gauge 20.

[0023] The first reactor 11 and the second reactor 12 are not particularly limited as long as they can bring the gas into contact with the catalyst at a set pressure and a set temperature. Examples of the first reactor 11 and the second reactor 12 include fixed-bed reactors, moving-bed reactors, and fluidized-bed reactors.

[0024] As the catalyst placed inside the first reactor 11, a known dehydrogenation catalyst that produces acetaldehyde from ethanol can be used, for example, a supported catalyst or bulk catalyst containing at least one selected from the group consisting of copper, zinc, silver, chromium, magnesium, and nickel. Examples of supports for the supported catalyst include silicon dioxide, aluminum oxide, titanium oxide, and zeolite.

[0025] As the catalyst placed inside the second reactor 12, a known ETB catalyst that produces 1,3-butadiene from acetaldehyde and ethanol can be used. Examples include a supported catalyst or a bulk catalyst containing at least one selected from the group consisting of titanium, zirconium, hafnium, vanadium, niobium, and tantalum. Examples of supports for the supported catalyst include silicon dioxide, aluminum oxide, titanium oxide, and zeolite.

[0026] The first reactor 11 is preferably an adiabatic reactor or an isothermal reactor. In adiabatic and isothermal reactors, it is desirable to set the reaction temperature according to the pressure in order to achieve the target acetaldehyde conversion rate. Adiabatic reactors have the advantage of simplifying the reactor design because heat is supplied only from the inlet. Isothermal reactors have the advantage of eliminating the endothermic effect of the dehydrogenation reaction by supplying heat from the reactor wall in addition to the inlet, allowing for a reactor design that eliminates the effect of endothermic reactions.

[0027] Since both the dehydrogenation reaction and the ETB reaction are endothermic reactions, it is preferable that the first reactor 11 and the second reactor 12 be equipped with heating devices, such as heat jackets, that can supply heat from the outside.

[0028] The ethanol-containing raw material includes ethanol supplied from an external source and recycled ethanol, and may also contain water. The ethanol-containing raw material is vaporized using a vaporizer as needed and heated in a heating step to a set temperature desirable for the dehydrogenation reaction. At least a portion of the ethanol-containing raw material is supplied to the first reactor 11 through the ethanol supply line 14.

[0029] Preferably, the 1,3-butadiene production apparatus 10 further includes a flow control valve 23 for controlling the mass flow rate of the ethanol-containing raw material supplied to the first reactor 11. As the amount of recycled ethanol increases from SOR to EOR, if the flow rate of ethanol supplied from the outside is kept constant, the flow rate of the ethanol-containing raw material increases. By using the flow control valve 23 to adjust the mass flow rate of the ethanol-containing raw material supplied to the first reactor 11 so that the mass flow rate of the ethanol-containing raw material supplied to the first reactor 11 is preferably within the range of set flow rate ± 50%, more preferably set flow rate ± 30%, and even more preferably set flow rate ± 10%, complicated control or operation such as flow rate adjustment linked to pressure changes in the system and changes in the operating conditions of the vaporizer due to an increase in the pressure loss Δp in the first reactor 11 can be avoided, and in some cases the deterioration of the catalyst performance in the first reactor 11 can be suppressed.

[0030] The set flow rate of the ethanol-containing raw material can be appropriately determined according to the type and volume of the first reactor 11 and the second reactor 12, the amount of 1,3-butadiene produced, etc. For example, the set flow rate of the ethanol-containing raw material is preferably 0.25 h, defined as the liquid space velocity (WHSV) obtained by dividing the mass flow rate of the ethanol solution under standard conditions by the mass of the dehydrogenation catalyst. －１ ~100h －１ More preferably 0.5h －１ ~60h －１ More preferably 0.5h －１ ~30h －１ It will be set to be as follows.

[0031] In the first reactor 11, a portion of the ethanol is converted to acetaldehyde by a dehydrogenation reaction, and an outlet fluid containing acetaldehyde and unreacted ethanol is produced.

[0032] The temperature inside the first reactor 11 is preferably set to a range of 200°C to 350°C, more preferably 220°C to 300°C, and even more preferably 240°C to 270°C. The temperature inside the first reactor 11 is preferably adjusted to a range of ±50°C of the set temperature, more preferably ±30°C of the set temperature, and even more preferably ±20°C of the set temperature. By setting the temperature inside the first reactor 11 to the above range, or adjusting it from the set temperature to within the above range, the performance of the catalyst can be maximized, and acetaldehyde can be obtained with a high conversion rate.

[0033] The difference between the inlet temperature and outlet temperature of the first reactor 11 (inlet temperature - outlet temperature) is preferably controlled to be within the range of ±20°C, more preferably ±10°C, and even more preferably ±5°C. By controlling the difference between the inlet temperature and outlet temperature to a predetermined range, the rate of catalyst degradation can be suppressed.

[0034] The pressure inside the first reactor 11 is preferably set to a range of 0.1 MPaG to 1.2 MPaG, more preferably 0.2 MPaG to 0.9 MPaG, and even more preferably 0.3 MPaG to 0.8 MPaG. By setting the pressure inside the first reactor 11 to the above range, the performance of the catalyst can be maximized, and acetaldehyde can be obtained with a high conversion rate.

[0035] The temperature and pressure inside the first reactor 11 are preferably set to a range of 200°C to 350°C and 0.1 MPaG to 1.2 MPaG, more preferably 220°C to 300°C and 0.2 MPaG to 0.9 MPaG, and even more preferably 240°C to 270°C and 0.3 MPaG to 0.8 MPaG. By setting the temperature and pressure inside the first reactor 11 within the above ranges, the performance of the catalyst can be maximized, and acetaldehyde can be obtained with a high conversion rate.

[0036] It is preferable not to change the set temperature and set pressure of the first reactor 11 from SOR to EOR. Thereby, the capacity of the first reactor 11 can be stabilized. It is more preferable not to change the set temperature and set pressure of the first reactor 11 from SOR to EOR, and the set flow rate of the ethanol-containing raw material. Thereby, deterioration of the catalyst performance in the first reactor 11 can be suppressed.

[0037] The outlet fluid containing acetaldehyde and unreacted ethanol generated in the first reactor 11 passes through the intermediate line 15, is heated to a set temperature desirable for the ETB reaction in the heating step, and then supplied to the second reactor 12. The recycled acetaldehyde separated from the outlet fluid of the second reactor 12 is supplied to the second reactor 12 through the recycle line 16 connected to the intermediate line 15 at the connection point 18.

[0038] A part of the ethanol-containing raw material may be supplied from the branch point 13 of the ethanol supply line 14 to the second reactor 12 through the bypass line 17. The bypass line 17 is connected to the intermediate line 15 at the connection point 19. In the above embodiment for adjusting the mass flow rate of the ethanol-containing raw material supplied to the first reactor 11, the flow rate of the ethanol-containing raw material supplied to the second reactor 12 through the bypass line 17 gradually increases as the operation of the 1,3-butadiene production apparatus 10 continues.

[0039] Similarly, the recycled acetaldehyde and a part of the ethanol-containing raw material are also supplied to the second reactor 12 after being heated to a set temperature desirable for the ETB reaction in the heating step.

[0040] In one embodiment, as shown in FIG. 2, at least a part of the recycle line 16 and at least a part of the bypass line 17 merge to form a common line 24, and the common line 24 is connected to the intermediate line 15. In this embodiment, the connection point 25 between the common line 24 and the intermediate line 15 is also the connection point 18 between the recycle line 16 and the intermediate line 15, and is also the connection point 19 between the bypass line 17 and the intermediate line 15.

[0041] In the second reactor 12, acetaldehyde and ethanol are converted to 1,3-butadiene by the ETB reaction. In addition to the target compound 1,3-butadiene, the outlet fluid contains by-products such as unreacted acetaldehyde, unreacted ethanol, water, hydrogen gas, and diethyl ether. The temperature and pressure in the second reactor 12 can be appropriately determined according to the conversion rate and selectivity of 1,3-butadiene, etc.

[0042] The pressure gauge 20 is provided on the downstream side of the branch point 13 of the ethanol supply line 14, and on the upstream side of the connection point 18 between the recycle line 16 and the intermediate line 15 or on the upstream side of the connection point 19 between the bypass line 17 and the intermediate line 15. By providing the pressure gauge 20 at the above position in the system, the pressure in the first reactor 11 can be directly measured, or the pressure loss Δp in the first reactor 11 can be observed to estimate the pressure in the first reactor 11.

[0043] The pressure gauge 20 is preferably provided on the upstream side of the connection point 18 between the recycle line 16 and the intermediate line 15, and on the upstream side of the connection point 19 between the bypass line 17 and the intermediate line 15. At the above installation location of the pressure gauge 20, the flow rate fluctuation of the fluid passing through the pipe is small, so the pressure gauge 20 can measure the pressure in the first reactor 11 more accurately. Also, since the flow rate fluctuation is small, the operation of the pressure regulating valve 21 can be facilitated, and the necessity of using a pressure regulating valve 21 with excessive capacity can be eliminated.

[0044] The installation location of the pressure regulating valve 21 is not particularly limited as long as it can adjust the pressure in the first reactor 11 based on the measured value of the pressure gauge 20, but it is preferably arranged on the downstream side of the branch point 13 of the ethanol supply line 14, on the upstream side of the connection point 18 between the recycle line 16 and the intermediate line 15, and on the upstream side of the connection point 19 between the bypass line 17 and the intermediate line 15. Thereby, the pressure in the first reactor 11 can be controlled more precisely.

[0045] In one embodiment, the 1,3-butadiene production apparatus 10 further includes a purification and separation apparatus 22 located downstream of the second reactor 12. The outlet fluid of the second reactor 12 is partially liquefied through a cooling process and further cooled through a heat exchanger 26. The gas phase is pressurized by a compressor 27 and sent to the purification and separation apparatus 22, while the liquid phase is sent directly to the purification and separation apparatus 22. In the purification and separation apparatus 22, the outlet fluid is separated into the product 1,3-butadiene, recycled acetaldehyde, recycled ethanol, and other by-products. The recycled acetaldehyde is supplied to the recycling line 16 by the purification and separation apparatus 22, and the recycled ethanol is supplied to the ethanol supply line 14 as an ethanol-containing raw material. In this embodiment, a pressure control valve 21 is located upstream of the purification and separation apparatus 22.

[0046] In one embodiment of the method for producing 1,3-butadiene, the pressure inside the first reactor 11 is adjusted to ±50% of the set pressure by the pressure control valve 21 based on the measurement value of the pressure gauge 20. The pressure inside the first reactor 11 is preferably adjusted to within the range of ±30% of the set pressure, and more preferably within the range of ±10% of the set pressure. This suppresses fluctuations in the equilibrium composition of the dehydrogenation reaction in the first reactor 11, allowing the dehydrogenation reaction to proceed stably in the first reactor 11, and thereby enabling the stable production of 1,3-butadiene overall.

[0047] In relation to the effects of this disclosure, the 1,3-butadiene production process from SOR to EOR will be explained using the case where the suction pressure P4 of the compressor 27 shown in Figure 1 is fixed and controlled at 0.10 MPaG as an example. In the 1,3-butadiene production apparatus shown in Figure 1, the operating pressures of the first reactor 11 and the second reactor 12 are determined by the sum of the pressure losses Δp of the piping and equipment installed upstream of the compressor 27, starting from the suction pressure P4 of the compressor 27. For example, the outlet pressure P3 of the second reactor 12 is 0.27 MPaG, the outlet pressure P2 of the first reactor is 0.45 MPaG, and the pressure P1 of the ethanol-containing raw material is 0.85 MPaG.

[0048] In SOR, the entire amount of acetaldehyde produced in the first reactor 11 is consumed in the second reactor 12 and mainly converted to 1,3-butadiene. When the conversion rate to 1,3-butadiene is high, the amount of unreacted ethanol and acetaldehyde contained in the outlet fluid of the second reactor 12 is small. Therefore, the flow rate of recycled acetaldehyde supplied to the second reactor 12 and the flow rate of recycled ethanol supplied to the ethanol supply line 14 are small. Fanning's equation: (In the above equation, pressure loss Δp, pipe length L, pipe diameter D, and fluid density ρ) ｆ Given the fluid velocity u and Fanning's coefficient of pipe friction f), and assuming the pipe diameter D and pipe length L are fixed, the pressure loss Δp is proportional to the square of the fluid velocity u. Therefore, in the SOR, the pressure loss Δp in the second reactor 12 and in the piping, coolers, and other equipment installed downstream of the second reactor 12 is small, and the total pressure loss Δp accumulated starting from the suction pressure P4 of the compressor 27 is also small. As a result, the first reactor 11 can be operated at a lower operating pressure. This is advantageous for the dehydrogenation reaction, where the conversion rate of acetaldehyde is higher at lower pressures.

[0049] In the second reactor 12, the conversion rate of 1,3-butadiene decreases from SOR to EOR. If almost all of the unreacted ethanol is used as recycled ethanol, the flow rate of recycled ethanol increases as it approaches EOR. If the amount of ethanol-containing raw material supplied to the first reactor 11 is controlled to a constant amount, the flow rate of ethanol-containing raw material supplied to the second reactor 12 through the bypass line 17 also increases. As the amount of recycled acetaldehyde also increases, the flow rate of recycled acetaldehyde to the second reactor 12 also increases.

[0050] The reduced activity of the catalyst in the second reactor 12 lowers the conversion rate of 1,3-butadiene in the second reactor 12. However, the increased flow rate of recycled acetaldehyde suppresses fluctuations in the amount of 1,3-butadiene produced. On the other hand, the pressure loss Δp in the second reactor 12 and in the piping, coolers, and other equipment installed downstream of the second reactor 12 increases. As a result, the total pressure loss Δp accumulated starting from the suction pressure P4 of the compressor 27 increases, and in conjunction with this, the outlet pressure of the first reactor 11 rises compared to when it is under stress rot.

[0051] When the outlet pressure of the first reactor 11 increases, the conversion rate of acetaldehyde decreases due to equilibrium shift, and the amount of acetaldehyde produced in the first reactor 11 is no longer sufficient to meet the target production volume of 1,3-butadiene. As a result, the acetaldehyde deficit is consumed from recycled acetaldehyde, disrupting the balance between the production and supply of recycled acetaldehyde, making it difficult to operate the 1,3-butadiene production apparatus 10 stably. Even if the operation of the 1,3-butadiene production apparatus 10 is stabilized, the amount of 1,3-butadiene produced will also decrease compared to the target production volume as the amount of acetaldehyde produced in the first reactor 11 decreases.

[0052] Thus, as the operating pressure of the first reactor 11 increases from SOR to EOR, the operation of the 1,3-butadiene production apparatus 10 becomes unstable, and the amount of 1,3-butadiene produced also decreases.

[0053] In the method for producing 1,3-butadiene described herein, the pressure in the first reactor 11 is adjusted to ±50% of the set pressure by the pressure control valve 21 based on the measurement value of the pressure gauge 20. Specifically, in SOR, the amount of recycled aldehyde and recycled ethanol is small, so the measurement value of the pressure gauge 20 is small. Therefore, by narrowing the opening of the pressure control valve 21 based on this measurement value, a pressure loss Δp is generated in the pressure control valve 21, and the pressure in the first reactor 11 is maintained within a certain range from the set pressure, regardless of the degree of catalyst activity in the second reactor 12. In EOR, the flow rate of recycled aldehyde and recycled ethanol supplied to the second reactor 12 increases, so the measurement value of the pressure gauge 20 also increases. Therefore, by widening the opening of the pressure control valve 21 based on this measurement value, the pressure loss Δp in the pressure control valve 21 is minimized, and the pressure in the first reactor 11 is maintained within a certain range from the set pressure.

[0054] These controls allow the operating pressure of the first reactor 11 to be maintained within a certain range from SOR to EOR, suppressing fluctuations in the equilibrium composition of the dehydrogenation reaction in the first reactor 11, thereby enabling the dehydrogenation reaction to proceed stably within the first reactor 11 and stabilizing the amount of 1,3-butadiene produced.

[0055] It will be apparent to those skilled in the art that the above embodiments can be modified in various ways without departing from the basic principles of the present invention. It will also be apparent to those skilled in the art that various improvements and modifications of the present invention can be implemented without departing from the spirit and scope of the present invention.

[0056] 10 1,3-Butadiene production apparatus 11 First reactor 12 Second reactor 13 Branch point 14 Ethanol supply line 15 Intermediate line 16 Recycle line 17 Bypass line 18 Connection point between recycle line and intermediate line 19 Connection point between bypass line and intermediate line 20 Pressure gauge 21 Pressure regulating valve 22 Purification and separation apparatus 23 Flow control valve 24 Common line 25 Connection point between common line and intermediate line 26 Heat exchanger 27 Compressor

Claims

1. A 1,3-butadiene production apparatus for producing 1,3-butadiene from an ethanol-containing raw material, comprising: a first reactor that generates acetaldehyde by a dehydrogenation reaction of ethanol contained in the ethanol-containing raw material; a second reactor that generates 1,3-butadiene from acetaldehyde and ethanol; an ethanol supply line having a branching point that supplies at least a portion of the ethanol-containing raw material to the first reactor; an intermediate line for supplying the outlet fluid of the first reactor to the second reactor; a recycling line connected to the intermediate line that supplies acetaldehyde separated from the outlet fluid of the second reactor to the second reactor; a bypass line branching from the branching point of the ethanol supply line and connected to the intermediate line, for supplying a portion of the ethanol-containing raw material to the second reactor as needed; and a pressure gauge provided downstream of the branching point of the ethanol supply line and upstream of the connection point between the recycling line and the intermediate line or upstream of the connection point between the bypass line and the intermediate line. A 1,3-butadiene production apparatus comprising: a pressure regulating valve that adjusts the pressure in the first reactor based on the measurement value of the pressure gauge; 2. The 1,3-butadiene production apparatus according to claim 1, further comprising a purification and separation device provided downstream of the second reactor, wherein the purification and separation device separates acetaldehyde and ethanol from the outlet fluid of the second reactor and supplies them to the recycling line and the ethanol supply line, respectively, and the pressure control valve is provided upstream of the purification and separation device.

3. The 1,3-butadiene production apparatus according to claim 1 or 2, wherein the pressure gauge is provided upstream of the connection point between the recycling line and the intermediate line, and upstream of the connection point between the bypass line and the intermediate line.

4. The 1,3-butadiene production apparatus according to claim 1 or 2, wherein at least a portion of the recycling line and at least a portion of the bypass line merge to form a common line, and the common line is connected to the intermediate line.

5. The 1,3-butadiene production apparatus according to claim 1 or 2, wherein the pressure regulating valve is located downstream of the branching point of the ethanol supply line, upstream of the connection point between the recycling line and the intermediate line, and upstream of the connection point between the bypass line and the intermediate line.

6. The 1,3-butadiene production apparatus according to claim 1 or 2, wherein the first reactor is an adiabatic reactor or an isothermal reactor.

7. The 1,3-butadiene production apparatus according to claim 1 or 2, further comprising a flow control valve for controlling the mass flow rate of the ethanol-containing raw material supplied to the first reactor.

8. A method for producing 1,3-butadiene from an ethanol-containing raw material using the 1,3-butadiene production apparatus described in claim 1 or 2, comprising adjusting the pressure in the first reactor to within a range of ±50% of a set pressure using the pressure control valve based on the measurement value of the pressure gauge.

9. A method for producing 1,3-butadiene according to claim 8, comprising adjusting the mass flow rate of the ethanol-containing raw material supplied to the first reactor so that the mass flow rate of the ethanol-containing raw material supplied to the first reactor is within a range of ±50% of a set flow rate.

10. A method for producing 1,3-butadiene according to claim 9, comprising adjusting the temperature inside the first reactor so that the temperature inside the first reactor is within the range of a set temperature ± 50°C.

11. The method for producing 1,3-butadiene according to claim 8, wherein the temperature inside the first reactor is 220°C to 300°C and the pressure is 0.2 MPaG to 0.9 MPaG.

Images