Methods and systems for exothermic reactions using tubular reactors

Abstract

The invention provides a method and a system for performing exothermic reaction by using a tubular reactor. The method comprises the following steps: S1, carrying out an exothermic reaction on a part of a reaction raw material A and a reaction raw material B in tubes of a tubular reactor to obtain a reaction product C; s2, enabling the other part of the reaction raw material A to enter a shell pass of a tubular reactor to perform first heat exchange with the reaction product C; according to the method and the system, the energy consumption required by the exothermic reaction can be greatly reduced, the cost is saved, meanwhile, the heat exchange effect at the blind area of the baffle plate can be improved, the temperature runaway phenomenon in the tube nest is avoided, and the safety and the stability of the exothermic reaction are greatly improved.

Description

Technical Field

[0001] The present invention relates to the technical field of chemical synthesis, and in particular to a method and system for performing exothermic reaction using a shell-and-tube reactor. Background Art

[0002] Exothermic reaction is an important reaction in the chemical production process, and common reactions include oxidation, hydrogenation and alkylation. The reaction generally occurs in an axially fixed bed reactor, which includes an adiabatic reactor and a shell-and-tube reactor. When the reaction raw materials reach the initial reaction temperature, they enter the reactor equipped with a catalyst and react under the action of the catalyst. In this process, preventing the reactor from overheating plays an important role in safe production and catalyst protection. In industry, it is common to increase the stoichiometric ratio of the reaction raw materials, increase the number of reactor sections (number of units), and introduce a cooling medium into the shell to achieve heat removal to control the temperature in the reactor, but this comes at the cost of increased energy consumption.

[0003] Patents CN102464565A and CN107935805B disclose methods for producing cumene and ethylbenzene, respectively. These methods utilize a multi-stage reactor, with recycled benzene introduced once and propylene or dry gas introduced in stages. The stoichiometric ratio of benzene to propylene or ethylene far exceeds the stoichiometric ratio. This method uses a high benzene-to-olefin ratio to control the reactor temperature rise, but this increases the energy consumption of the device, primarily due to the energy required to heat the benzene to the initial reaction temperature and the subsequent separation of the benzene from the product. Furthermore, the heat released by the reaction is not effectively utilized.

[0004] CN103553864A discloses a method for preparing butadiene by oxidative dehydrogenation of butene. This method uses a shell-and-tube reactor with the shell side divided into multiple distinct zones. A cooling medium is introduced into each zone to control the reactor temperature. This method effectively controls the reaction temperature rise, but the cooling medium passes through the shell side once, resulting in low turbulence and poor heat transfer. Furthermore, the heat released by the reaction is not effectively utilized.

[0005] CN104437269A discloses a shell-and-tube reactor and method for producing vinyl acetate. This method improves catalyst activity and selectivity by optimizing the internal components of the shell-and-tube reactor. However, due to structural reasons, the baffles have large flow blind spots where they connect to the shell side, such as opposite the cutting line of single-bow baffles, at the edge of annular baffles, and in the center of disc-shaped baffles. The catalyst in the shell-and-tube reactor in these flow blind spots is prone to temperature fluctuations, posing a safety hazard. Summary of the Invention

[0006] In order to solve one of the above-mentioned technical problems existing in the prior art, the present invention provides a method and system for performing an exothermic reaction using a shell-and-tube reactor. The use of the method and system of the present invention can greatly save the energy consumption of the exothermic reaction, while also avoiding temperature runaway in the shell and tube, thereby improving the safety performance of the exothermic reaction.

[0007] A first aspect of the present invention provides a method for performing an exothermic reaction using a shell-and-tube reactor, comprising the following steps:

[0008] S1. An exothermic reaction occurs in the tubes of a shell-and-tube reactor with a portion of the reaction material A and the reaction material B to obtain a reaction product C;

[0009] S2. Allow another portion of the reaction raw materials A to enter the shell side of the shell-and-tube reactor to perform a first heat exchange with the reaction product C.

[0010] The method of the present invention uses self-heat exchange between reaction raw materials and reaction products in a shell-and-tube heat exchanger, coupling the cooling capacity brought by the reaction raw materials themselves and the heat released by the reaction, thereby saving the energy consumption required for heating the reaction raw materials and the energy consumption required for cooling the reaction products.

[0011] In some embodiments, the method further comprises the steps of:

[0012] S3. Mixing the reaction raw material A after the first heat exchange in the shell side in step S2 with the reaction product C after the first heat exchange in the tubes to perform a second heat exchange.

[0013] In some embodiments, the method further comprises the steps of:

[0014] S4. After the second heat exchange, the reaction material A is heated or directly returned to step S1 without being heated and undergoes an exothermic reaction with the reaction material B.

[0015] In some embodiments, the heating temperature in step S4 is 150-400°C.

[0016] In some embodiments, the method further comprises the steps of:

[0017] S5. The reaction product C after the second heat exchange is separated and purified.

[0018] In some embodiments, the shell-and-tube reactor has N baffles, where N ≥ 3, for example, N is 3, 4, 5, 6, 7, 8, 9, 10, etc., preferably 3 ≤ N ≤ 5, and more preferably N = 4. An arc tube is disposed above and below each baffle along an arc direction. The inlet of the arc tube is connected to the shell side of the shell-and-tube reactor and is located on the centerline of each baffle. The length of the arc tube is the same as the arc length of the baffle.

[0019] In some embodiments, the arc tube has openings, and the total area of the openings on each arc tube is 20% to 60% of the inlet cross-sectional area of the arc tube, for example, 20%, 30%, 35%, 40%, 50%, 60%, preferably 20% to 40%, and more preferably 20% to 30%.

[0020] In the present invention, the total opening area of an arc tube located above or below the nth baffle is recorded as S n , the cross-sectional area of the arc tube inlet is recorded as S0, when n is 1, S n / S0=0.20~0.25;when 2≤n≤N,S n / S0=0.20-0.35, preferably 0.20-0.30.

[0021] In some embodiments, step S2 includes:

[0022] The reaction raw material A is divided into N+1 streams, where N is the number of baffles, wherein the first stream of reaction raw material A enters the shell side of the shell and tube reactor from between the upper tube plate and the first baffle of the shell and tube reactor, and the nth stream of reaction raw material A enters the shell side of the shell and tube reactor from the upper and lower arc tubes of the n-1th baffle, 2≤n≤N+1; the N+1 streams of reaction raw material A entering the shell side of the shell and tube reactor undergo a first heat exchange with the reaction product C in the shell and tube in a parallel flow manner.

[0023] It should be noted that, in the present invention, the "first baffle" refers to the baffle closest to the upper tube plate of the shell-and-tube reactor.

[0024] In some embodiments, the reaction raw material A (i.e., the first stream of reaction raw material A) entering the shell side of the shell and tube reactor between the upper tube plate and the first baffle of the shell and tube reactor accounts for 70-95% of the total mass of the N+1 streams of reaction raw material A, preferably 80-90%.

[0025] In some embodiments, the reaction raw material A entering the shell side of the shell-and-tube reactor from the arc tubes of the N baffles accounts for 5-30% of the total mass of the N+1 streams of reaction raw material A, preferably 10-20%.

[0026] In some embodiments, the flow ratio of the reaction raw material A entering the shell side from the upper and lower arc tubes of the mth baffle (2≤m≤N, N is the number of baffles) to the reaction raw material A entering the shell side from the upper and lower arc tubes of the m-1th baffle is 0.7 to 1.0, preferably 0.8 to 0.9.

[0027] The exothermic reaction of the present invention includes, but is not limited to, an exothermic oxidation reaction, an exothermic hydrogenation reaction, or an exothermic alkylation reaction. In some embodiments, the reaction raw material A comprises one or more of aromatic hydrocarbons, unsaturated cycloalkanes, carbon oxides, and alkynes, preferably one or more of benzene, toluene, xylene, methylcyclopentylbenzene, carbon monoxide, and acetylene; the reaction raw material B comprises one or more of hydrogen and olefins, preferably one or more of hydrogen, ethylene, propylene, and butene.

[0028] In some embodiments, the reaction raw material A is benzene, the reaction raw material B is hydrogen, the reaction raw material A entering the shell side of the shell and tube reactor from the arc tubes of the N baffles accounts for 15% of the total mass of the reaction raw material A entering the shell side of the shell and tube reactor, the flow ratio of the reaction raw material A entering the shell side from the upper and lower arc tubes of the mth baffle (2≤m≤N, N is the number of baffles) to the reaction raw material A entering the shell side from the upper and lower arc tubes of the m-1th baffle is 0.8, the arc tube opening angle is 30°, the total opening area of each arc tube above or below the first baffle is 20% of the inlet cross-sectional area of the arc tube, the total opening area of each arc tube above or below the second baffle is 20% of the inlet cross-sectional area of the arc tube, and the total opening area of each arc tube above or below each of the remaining baffles is 30% of the inlet cross-sectional area of the arc tube.

[0029] In some embodiments, the temperature of the reaction raw material A is 15 to 60° C., for example, 20 to 35° C. In some embodiments, the temperature of the reaction raw material A is 60° C. to 180° C. In the above method of the present invention, the reaction raw material A in step S2 can be fresh reaction raw material A or reaction raw material A separated from the reaction system in step S1 and not involved in the reaction.

[0030] In some embodiments, the reaction temperature in the shell-and-tube reactor is 150° C. to 500° C., and the reaction pressure is 0.5 to 3.0 MPaG.

[0031] In some embodiments, the tubes of the shell-and-tube reactor are filled with a catalyst.

[0032] In some embodiments, in step S2, the reaction raw material A is further pretreated before entering the shell side of the shell-and-tube reactor, and the pretreatment includes pressurization treatment.

[0033] In some embodiments, the reaction raw material A is cooled before the pressurization treatment. In some embodiments, the cooling temperature is 15° C. to 180° C. In some embodiments, the reaction raw material A is buffered after the cooling treatment and / or before the pressurization treatment.

[0034] A second aspect of the present invention provides a system for performing an exothermic reaction using a shell-and-tube reactor, comprising:

[0035] (1) a shell-and-tube reactor, wherein the shell-and-tube reactor comprises a shell and a shell side, wherein the shell and the tube are used to cause a portion of the reaction raw material A to undergo an exothermic reaction with the reaction raw material B to obtain a reaction product C, and the shell side of the shell and the tube reactor is used to load another portion of the reaction raw material A and to perform a first heat exchange with the reaction product C;

[0036] (2) A mixing unit, which is used to mix the reaction product C flowing out of the tubes with the reaction raw material A flowing out of the shell side to perform a second heat exchange.

[0037] In some embodiments, the system further comprises: (3) a separation unit for separating the reaction raw material A and the reaction product C.

[0038] In some embodiments, the shell and tube reactor has N baffles, N ≥ 3, for example, N is 3, 4, 5, 6, 7, 8, 9, 10, etc., preferably 3 ≤ N ≤ 5, and an arc tube is arranged above and below each baffle along the arc direction, the inlet of the arc tube is connected to the shell side of the shell and tube reactor and is located on the center line of each baffle, and the length of the arc tube is the same as the arc length of the baffle.

[0039] In some embodiments, the system further comprises N+1 diversion pipes, wherein the N+1 diversion pipes are used to divide the reaction raw material A entering the shell side of the shell and tube reactor into N+1 streams, where N is the number of baffles, wherein the first stream of reaction raw material A enters the shell side of the shell and tube reactor from between the upper tube plate and the first baffle of the shell and tube reactor through the first diversion pipe, and the nth stream of reaction raw material A enters the shell side of the shell and tube reactor from the inlets of the upper and lower arc tubes of the n-1th baffle through the n-1th diversion pipe, and 2≤n≤N+1.

[0040] In some embodiments, the N+1 diversion pipes are configured so that the reaction raw material A entering the shell side of the shell-and-tube reactor through the arc-shaped pipes of the N baffles accounts for 5-30%, preferably 10-20%, of the total mass of the N+1 streams of reaction raw material A. In some embodiments, the N+1 diversion pipes are configured so that the flow ratio of the reaction raw material A entering the two arc-shaped pipes of the mth baffle (2≤m≤N, N is the number of baffles) to the reaction raw material A entering the two arc-shaped pipes of the m-1th baffle is 0.7-1.0, preferably 0.8-0.9.

[0041] In some embodiments, the shell side of the shell-and-tube reactor is provided with N+1 inlets, and the N+1 inlets of the shell side are respectively connected to the inlets of the N+1 branch pipes.

[0042] In some preferred embodiments, the arc-shaped tubes have openings for controlling the flow rate of the reaction material A entering the shell side of the shell-and-tube reactor from the arc-shaped tubes of the baffles. The smaller the opening area, the higher the flow rate and the greater the impact on the blind zone. Therefore, the total opening area needs to be controlled within an appropriate range.

[0043] In some embodiments, the total area of the openings on each arc tube is 20% to 60% of the inlet cross-sectional area of the arc tube, for example, 20%, 30%, 35%, 40%, 50%, 60%, preferably 20% to 30%.

[0044] In some embodiments, the total opening area of an arc tube located above or below the nth baffle is recorded as S n , the inlet cross-sectional area of the arc tube is recorded as S0, when n is 1, S n / S0=0.20~0.25;when 2≤n≤N,S n / S0=0.20-0.35, preferably 0.20-0.30.

[0045] In some embodiments, the arc tube located above the baffle has two rows of openings, one row of which are horizontal holes, and the other row of holes are inclined downward, preferably at an angle of 30 to 60° (for example, 30°, 35°, 40°, 45°, 50°, 55°, 60°, etc.), and the spacing between each row of holes is the same.

[0046] In some embodiments, the arc tube located below the baffle has two rows of openings, one row of horizontal holes, and the other row of holes inclined upward, preferably at an angle of 30 to 60° (for example, 30°, 35°, 40°, 45°, 50°, 55°, 60°, etc.), and the spacing between each row of holes is the same.

[0047] The system of the present invention sprays the reaction raw materials from openings at different positions of the arc tube along the blind area of the baffle, and further increases the turbulence level and heat exchange effect in the blind area by adjusting the opening direction of the arc tube, avoiding temperature fluctuations in the tube array at the blind area of the reactor, and greatly improving the reaction safety and stability.

[0048] In order to further ensure the temperature control effect at the blind spot position, the present invention optimizes the feed amount of the baffle arc tube at different positions. At the inlet of the tube, the concentration of the reaction product is low, the reaction driving force is large, and the heat release is intense. This part of the blind spot is more prone to temperature runaway in the tube. Therefore, the flow rate and the inlet and outlet pressure difference must be guaranteed at the first baffle. As the reaction proceeds, the intensity of the reaction gradually decreases, and the feed demand for subsequent baffle arc tubes gradually decreases. Therefore, the feed amount of the first baffle accounts for the largest proportion, and the feed pipeline is not equipped with a flow regulating valve. The opening area of the arc hole accounts for the lowest cross-sectional area of the feed pipeline. This ensures the flow rate, pressure difference and injection speed of the feed of the first baffle arc tube, and further increases the degree of turbulence to ensure the heat exchange effect and avoid temperature runaway.

[0049] In some embodiments, the system further comprises:

[0050] (4) A buffer unit, which is used to perform buffering treatment on the reaction raw material A.

[0051] In some embodiments, the system further comprises:

[0052] (5) A pressurizing unit, which is used to pressurize the reaction raw material A after the buffering treatment.

[0053] In some embodiments, the inlets of the N+1 branch pipes are connected to the outlet of the pressurizing unit.

[0054] In some embodiments, the system further comprises:

[0055] (6) A cooling unit, comprising a temperature control device, for cooling the reaction raw material A.

[0056] In some embodiments, a cooling medium is provided in the temperature control device of the cooling unit, and the temperature of the cooling unit outlet is adjusted by controlling the flow rate of the cooling medium.

[0057] In some embodiments, the system further comprises:

[0058] (7) A heating unit, comprising a temperature control device, for heating the reaction raw material A.

[0059] In some embodiments, a heating medium is provided in the temperature control device of the heating unit, and the temperature at the outlet of the heating unit is adjusted by controlling the flow rate or heating power of the heating medium.

[0060] In the present invention, if the temperature of the reaction raw material A after the second heat exchange has reached the reaction temperature with the raw material B, the heating unit may not be activated, and the reaction raw material A passes directly through the heating unit, and then mixes with the raw material B and enters the tubes of the shell-and-tube reactor to undergo an exothermic reaction.

[0061] Compared with the prior art, the method and device of the present invention save the energy consumption required for heating the reaction raw materials and cooling the reaction products in the exothermic reaction. When the device is operating stably, the reaction system can achieve almost zero energy consumption operation, greatly reducing the production cost. The present invention also improves the baffles of the shell and tube reactor, improves the heat exchange effect in the blind area of the baffles, avoids the "temperature runaway" phenomenon in the shell and tube, greatly improves the safety and stability of the exothermic reaction, and at the same time can optimize the catalyst performance in the shell and tube, achieving very good technical effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] Figure 1 The system and process flow of an exothermic reaction using a shell-and-tube reactor according to an embodiment of the present invention are shown, wherein 1 is the reaction raw material A from the separation unit; 2 is the reaction raw material A after cooling; 3 is the reaction raw material A after buffering in the buffer tank; 4 is the reaction raw material A after being pressurized by the pump; 5 is the main flow of reaction raw material A entering the reactor; 6 is the auxiliary flow of reaction raw material A entering the reactor; 7 is the reaction raw material A entering the second baffle arc tube; 8 is the reaction raw material A entering the fourth baffle arc tube; 9 is the reaction raw material A entering the third baffle arc tube 10 is the reaction raw material A entering the first baffle arc tube; 11 is the reaction raw material A exiting the reactor; 12 is the heated reaction raw material A; 13 is the reaction raw material B; 14 is the reaction raw material entering the reactor tube side; 15 is the reaction product; R-101 is a shell and tube reactor; E-101 is a reaction raw material A cooler, E-102 is a reaction raw material A heater, E-103 is a heat exchanger for reaction products and reaction raw materials, P-101 is a reaction raw material A booster pump; V-101 is a reaction raw material A buffer tank.

[0063] Figure 2 Shown Figure 1 The structure of the arc tube in the middle baffle, where A is the overall schematic diagram of the arc tube above the baffle, B is a partial enlarged view of the arc tube above the baffle, C is the overall schematic diagram of the arc tube below the baffle, and D is a partial enlarged view of the arc tube below the baffle. The angle between the two rows of holes in the figure is 30 degrees.

[0064] Figure 3The process flow of an exothermic reaction using a shell-and-tube reactor in the prior art is shown, wherein 1 is the reaction raw material A from the separation unit; 2 is the reaction raw material A after cooling; 3 is the reaction raw material A after buffering in the buffer tank; 4 is the reaction raw material A after pressurization by a pump; 5 is the reaction raw material A after heating; 6 is the reaction raw material A entering the reactor; 7 is the reaction raw material B entering the first-stage reactor; 8 is the reaction raw material B entering the second-stage reactor; 9 is the reaction raw material B entering the third-stage reactor; 10 is the reaction raw material B entering the fourth-stage reactor; 11 is the reaction product; R-101 is an adiabatic fixed-bed reactor; E-101 is a reaction raw material A cooler, E-102 is a reaction raw material A heater, E-103 is a heat exchanger for reaction products and reaction raw materials, P-101 is a reaction raw material A booster pump; V-101 is a reaction raw material A buffer tank. DETAILED DESCRIPTION

[0065] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments and drawings. The specific embodiments described herein are only used to illustrate the present invention and are not intended to constitute any limitation to the present invention.

[0066] As a specific embodiment of the present invention, the method for performing an exothermic reaction using a shell-and-tube reactor comprises the following steps:

[0067] 1) Providing a shell-and-tube reactor R-101 having N (N≥3) baffles on the shell side, a reaction raw material A cooler E-101, a reaction raw material A heater E-102, a reaction raw material A buffer tank V-101, a reaction raw material A booster pump P-101 or a compressor C-101, and a flow control device; wherein, an arc tube is provided above and below each baffle in R-101 along an arc direction, the arc tube above the baffle having two rows of holes, one row of horizontal holes and one row of holes with an oblique downward angle, the spacing between the holes in each row being the same; the arc tube below the baffle having two rows of holes, one row of horizontal holes and one row of holes with an oblique upward angle, the spacing between the holes in each row being the same; the inlet of the arc tube is connected to the shell side of R-101 and is located on the center line of each baffle, and the length of the arc tube is the same as the length of the arc of the baffle;

[0068] 2) Reaction material A enters E-101, where it is either cooled or passes directly through it. It is then buffered in V-101 and then pressurized in P-101 or C-101. The pressurized stream is split into two streams. One stream enters the R-101 shell side between the upper tube sheet and the first baffle, and the other stream is further split into multiple streams, entering the R-101 shell side through the arc tubes at the upper and lower ends of each baffle. The stream entering the R-101 shell side at the first baffle has no flow control, while the remaining streams entering the R-101 shell side have flow control.

[0069] 3) The reaction material A entering the shell side of R-101 undergoes a first heat exchange in parallel with the reaction products in the tubes. The reaction material A is heated and the reaction products are cooled. The heated reaction material A enters E-103 for a second heat exchange with the reaction products. The reaction material A then enters E-102, where it is either heated or passes directly through. It is then mixed with the reaction material B and enters the tubes of R-101 containing the catalyst, where an exothermic reaction occurs. The reaction products, after exchanging heat with the reaction material A, enter the separation unit.

[0070] like Figure 1 As shown in FIG. 1 , as a specific embodiment, the system for performing an exothermic reaction using a shell-and-tube reactor according to the present invention comprises: a shell-and-tube reactor R-101; a reaction raw material A cooler E-101; a reaction raw material A heater E-102; a reaction product and reaction raw material heat exchanger E-103; a reaction raw material A booster pump P-101; and a reaction raw material A buffer tank V-101. The shell side of the shell-and-tube reactor R-101 is provided with N (N≥3) baffles, and an arc tube is provided above and below each baffle in an arc direction (the arc tube structure is shown in FIG. 1 ). Figure 2 shown).

[0071] Logistics 1 from the reaction unit passes through E-101 to obtain logistics 2, logistics 2 enters V-101 for buffering to obtain logistics 3, logistics 3 is pressurized by P-101 to obtain logistics 4, logistics 4 is divided into two streams, one is logistics 5, which enters the shell side of R-101 from between the upper tube plate of R-101 and the first baffle, logistics 6 is further divided into logistics 7, 8, 9 and 10, which enter the shell side of R-101 from the upper and lower arc tubes of each baffle respectively, the reaction raw material A obtains logistics 11 after heat exchange, logistics 11 enters E-103 and E-102 to obtain logistics 12, logistics 12 is mixed with logistics 13 to obtain logistics 14, logistics 14 enters the tube array containing the catalyst to react to obtain reaction product logistics 15, logistics 15 enters the separation unit.

[0072] Example 1

[0073] A 100,000 t / a benzene and ethylene alkylation plant for producing ethylbenzene uses Figure 1 The process flow shown and the catalyst synthesized in the aforementioned specific embodiment and Example 1 of CN114471672B are shown. Reactant A is stream 1 containing benzene, and reactant B is stream 13 containing ethylene. Upon plant startup, the electric heating of E-102 was activated. When the temperature of stream 15 at the shell-side outlet of R-101 reached 320°C, the temperature control device of E-102 was activated. The heating power was adjusted to stabilize the outlet temperature of E-102 at 415°C. The main process operating parameters during operation are listed in Table 1.

[0074] Table 1

[0075]

[0076]

[0077] Example 2

[0078] A 10,000 ton / year benzene and hydrogen alkylation plant for producing cyclohexylbenzene uses Figure 1 The process flow shown and the catalyst used in the above-mentioned specific embodiment and Example 1 of CN114130421A are shown. Reaction feedstock A is stream 1 containing benzene, and reaction feedstock B is stream 13 containing hydrogen. At plant startup, the electric heating of E-102 is activated. When the temperature of stream 11 at the shell-side outlet of R-101 reaches 173°C, the temperature control device of E-102 is activated, and the heating power is adjusted to stabilize the outlet temperature of E-102 at 173°C. The main process operating parameters during operation are listed in Table 2.

[0079] Table 2

[0080]

[0081]

[0082] Comparative Example 1

[0083] A 100,000 t / a benzene and ethylene alkylation plant for producing ethylbenzene uses Figure 3 The process flow shown and the catalyst synthesized in the above-described embodiment and Example 1 of CN114471672B are shown. Reactant A is stream 1 containing benzene, and reactant B is streams 7, 8, 9, and 10 containing ethylene. Unlike Example 1, R-101 utilizes an axially adiabatic fixed bed containing four catalyst stages. Ethylene enters the catalyst bed in four stages, with the same feed rate for each stage. The process parameters during operation are listed in Table 3.

[0084] Table 3

[0085] project parameter Temperature of logistics 1, ℃ 150 Temperature of logistics 2, ℃ 150 Temperature of logistics 6, ℃ 345 Logistics 11 temperature, ℃ 382 The highest temperature in the reactor, ℃ 382 Benzene-olefin molar ratio 4.0 Ethylene conversion, % 99.3 Ethyl selectivity, % 99.0 Reaction pressure, MPaG 1.0 Reaction system power consumption kW / ton ethylbenzene 124 Reaction system cooling water (32℃ inlet / 42℃ return) consumption t / ton ethylbenzene 0

[0086] Comparative Example 2

[0087] Different from Comparative Example 1, the benzene-olefin molar ratio was 5.0. The process parameters during operation are listed in Table 4.

[0088] Table 4

[0089]

[0090]

[0091] Comparative Example 3

[0092] A 10,000 ton / year benzene and hydrogen alkylation plant for producing cyclohexylbenzene uses Figure 1 The process flow shown in the figure and the catalyst used in the above-mentioned specific embodiment and Example 1 of CN114130421A are shown. Reaction feedstock A is stream 1 containing benzene, and reaction feedstock B is stream 13 containing hydrogen. Unlike Example 2, R-101 lacks a baffled arc-shaped tube feed port. During stable operation, a temperature runaway phenomenon occurred within the tubes connecting the baffles to the shell side, reaching a maximum temperature of 260°C. This caused severe localized coking of the catalyst and reduced the selectivity of cyclohexylbenzene to 68%.

[0093] It can be seen from the operating parameters of Example 1 and Comparative Example 1 that when the technical solution of the present invention is adopted, the "temperature runaway" of the bed can be effectively controlled, the maximum temperature is reduced from 382°C to 330°C, and the selectivity of ethyl is higher; it can be seen from the operating parameters of Example 1 and Comparative Example 2 that when the technical method of the present invention is adopted, not only the temperature runaway of the reactor can be limited, but also energy consumption can be saved, and the power consumption of one ton of ethylbenzene is reduced from 202kW to 124kW; it can be seen from the operating parameters of Example 2 and Comparative Example 3 that the arrangement of arc tubes at the baffle can effectively reduce the reaction temperature in the blind area tube array, greatly improve the safety of the device and the catalyst performance, and achieve good technical effects.

[0094] The technical solution of the present invention is not limited to the above-mentioned specific embodiments. Any technical variations made according to the technical solution of the present invention fall within the protection scope of the present invention.

Claims

1. A method for carrying out an exothermic reaction using a shell-and-tube reactor, comprising the following steps: S1. An exothermic reaction occurs in the tubes of a shell-and-tube reactor with a portion of the reaction material A and the reaction material B to obtain a reaction product C; S2. Allow another portion of the reaction raw materials A to enter the shell side of the shell-and-tube reactor to perform a first heat exchange with the reaction product C.

2. The method according to claim 1, characterized in that The method further comprises the steps of: S3. The reaction raw material A after the first heat exchange in the shell side in step S2 is mixed with the reaction product C after the first heat exchange in the tubes to perform a second heat exchange; Preferably, the method further comprises the steps of: S4. After the second heat exchange, the reaction material A is heated or returned directly to step S1 without heating and undergoes an exothermic reaction with the reaction material B; preferably, the heating temperature in step S4 is 150 to 400°C; Preferably, the method further comprises the steps of: S5. The reaction product C after the second heat exchange is separated and purified.

3. The method according to claim 1 or 2, characterized in that The shell-and-tube reactor has N baffles, N ≥ 3, preferably 3 ≤ N ≤ 5, and an arc tube is provided above and below each baffle along the arc direction. The inlet of the arc tube is connected to the shell side of the shell-and-tube reactor and is located on the center line of each baffle. The length of the arc tube is the same as the arc length of the baffle. Preferably, the arc tube has openings, and the total area of the openings on each arc tube is 20% to 60% of the inlet cross-sectional area of the arc tube, preferably 20 to 30%; More preferably, the total opening area of an arc tube located above or below the nth baffle is recorded as S n , the cross-sectional area of the arc tube inlet is recorded as S0, when n is 1, S n / S0=0.20~0.25;when 2≤n≤N,S n / S0=0.20~0.

35.

4. The method according to claim 3, characterized in that Step S2 includes: The reaction raw material A is divided into N+1 streams, where N is the number of baffles, wherein the first stream of reaction raw material A enters the shell side of the shell and tube reactor between the upper tube plate and the first baffle of the shell and tube reactor, and the nth stream of reaction raw material A enters the shell side of the shell and tube reactor through the upper and lower arc tubes of the n-1th baffle, 2≤n≤N+1; the N+1 streams of reaction raw material A entering the shell side of the shell and tube reactor undergo a first heat exchange with the reaction product C in the tubes in a parallel flow manner; Preferably, the reaction raw material A entering the shell side of the shell-and-tube reactor from the arc tubes of the N baffles accounts for 5-30% of the total mass of the N+1 streams of reaction raw material A, preferably 10-20%; Preferably, the flow ratio of the reaction raw material A entering the shell side from the upper and lower arc tubes of the mth baffle to the reaction raw material A entering the shell side from the upper and lower arc tubes of the m-1th baffle is 0.7-1.0, preferably 0.8-0.9, 2≤m≤N.

5. The method according to any one of claims 1 to 4, characterized in that The exothermic reaction is an oxidation exothermic reaction, a hydrogenation exothermic reaction or an alkylation exothermic reaction; and / or, The reaction raw material A includes one or more of aromatic hydrocarbons, unsaturated cycloalkanes, carbon oxides, and alkynes, preferably includes one or more of benzene, toluene, xylene, methylcyclopentylbenzene, carbon monoxide, and acetylene; the reaction raw material B includes one or more of hydrogen and olefins, preferably includes one or more of hydrogen, ethylene, propylene, and butene; and / or, The temperature of the reaction raw material A is 15 to 60° C. or 60 to 180° C.; and / or, The reaction temperature in the shell-and-tube reactor is 150° C. to 500° C., and the reaction pressure is 0.5 to 3.0 MPaG; and / or, The tubes of the shell-and-tube reactor are filled with catalyst.

6. The method according to any one of claims 1 to 5, characterized in that In step S2, the reaction raw material A is pretreated before entering the shell side of the shell-and-tube reactor, and the pretreatment includes pressurization treatment; Optionally, the reaction raw material A is subjected to cooling treatment and / or buffering treatment before the pressurization treatment. Preferably, the temperature of the cooling treatment is 15°C to 180°C.

7. A system for performing an exothermic reaction using a shell-and-tube reactor, comprising: (1) a shell-and-tube reactor, wherein the shell-and-tube reactor comprises a shell and tube side, wherein the shell and tube side is used to cause a portion of the reaction raw material A to undergo an exothermic reaction with the reaction raw material B to obtain a reaction product C, and the shell side is used to load another portion of the reaction raw material A and allow it to undergo a first heat exchange with the reaction product C; (2) A mixing unit, which is used to mix the reaction product C flowing out of the tubes with the reaction raw material A flowing out of the shell side to perform a second heat exchange.

8. The system according to claim 7, characterized in that The shell-and-tube reactor has N baffles, N ≥ 3, preferably 3 ≤ N ≤ 5, and an arc tube is provided above and below each baffle along the arc direction, the inlet of the arc tube is connected to the shell side of the shell-and-tube reactor and is located on the center line of each baffle, and the length of the arc tube is the same as the arc length of the baffle; Preferably, the system further comprises N+1 diversion pipes, wherein the N+1 diversion pipes are used to divide the reaction raw materials A entering the shell side of the shell and tube reactor into N+1 streams, where N is the number of baffles, wherein the first stream of reaction raw materials A enters the shell side of the shell and tube reactor from between the upper tube plate and the first baffle of the shell and tube reactor through the first diversion pipe, and the nth stream of reaction raw materials A enters the shell side of the shell and tube reactor from the inlets of the upper and lower arc tubes of the n-1th baffle through the n-1th diversion pipe, and 2≤n≤N+1.

9. The system according to claim 8, characterized in that The arc tube has an opening for controlling the flow rate of the reaction material A entering the shell side of the tubular reactor from the arc tube of the baffle; Preferably, the total area of the openings on each arc tube is 20% to 60% of the inlet cross-sectional area of the arc tube, preferably 20% to 30%; Preferably, the total area of the openings of an arc tube located above or below the nth baffle is recorded as S n , the inlet cross-sectional area of the arc tube is recorded as S0, when n is 1, S n / S0=0.20~0.25;when 2≤n≤N,S n / S0=0.20~0.35; Preferably, the arc tube located above each baffle has two rows of openings, one row of which are horizontal holes, and the other row of holes are inclined downward, preferably at an angle of 30 to 60 degrees downward, and preferably, the spacing between each row of holes is the same; and / or, the arc tube located below each baffle has two rows of openings, one row of which are horizontal holes, and the other row of holes are inclined upward, preferably at an angle of 30 to 60 degrees upward, and preferably, the spacing between each row of holes is the same.

10. The system according to any one of claims 7 to 9, characterized in that: The system further comprises: (3) a separation unit for separating the reaction raw material A and the reaction product C; Preferably, the system further comprises: (4) a buffer unit, which is used to buffer the reaction raw material A; Preferably, the system further comprises: (5) a pressurizing unit, which is used to pressurize the reaction raw material A after the buffering treatment; Optionally, the system further comprises: (6) a cooling unit, comprising a temperature control device, for cooling the reaction raw material A; and / or, (7) a heating unit, comprising a temperature control device, for heating the reaction raw material A; Preferably, a cooling medium is provided in the temperature control device of the cooling unit, and the temperature of the cooling unit outlet is adjusted by controlling the flow rate of the cooling medium; Preferably, a heating medium is provided in the temperature control device of the heating unit, and the temperature at the outlet of the heating unit is adjusted by controlling the flow rate or heating power of the heating medium.

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