Reaction unit suitable for strong exothermic system
阅读说明：本技术 一种适用于强放热体系的反应装置 (Reaction unit suitable for strong exothermic system ) 是由 杨阿三 钟士琪 贾继宁 李琰君 屠美玲 张建庭 程榕 郑燕萍 于 2021-09-18 设计创作，主要内容包括：本发明公开了一种适用于强放热体系的反应装置,该反应装置为多级列管式分布结构,计量泵连接总管,每根总管连接2～(n-1)条支路管,一根总管的支路管与另一根总管的支路管通过预混合器连接n级列管,2～(n-1)根n级列管两两组合通过静态混合器连接n-1级列管,以此规律递减连接,直到2根2级列管通过静态混合器1根1级列管,静态混合器为三通管结构,三通管结构的入口两端设有喷嘴,两根列管间物料每一次的撞击混合增强了反应体系的混合效果,且可以均化物料配比,减少对反应的影响。静态混合器的出口处的内壁为圆弧凸起结构,减少静态混合器中混合腔体积,加强混合效果。本发明结构简单,混合效果好,传热传质效果好。(The invention discloses a reaction device suitable for a strong heat release system, which is of a multi-stage tubular distribution structure, wherein metering pumps are connected with header pipes, and each header pipe is connected with 2 n‑1 A branch pipe of one main pipe and a branch pipe of the other main pipe are connected with n-stage tubes through a premixer, 2 n‑1 The two-two combination of the n-level array pipes is connected with the n-1 level array pipe through the static mixer and is progressively decreased and connected according to the law until 2 level array pipes pass through 1 level array pipe of the static mixer, the static mixer is of a three-way pipe structure, nozzles are arranged at two ends of an inlet of the three-way pipe structure, the mixing effect of a reaction system is enhanced by each impact mixing of materials between the two array pipes, the material proportion can be homogenized, and the reaction rate is reducedThe influence of (c). The inner wall at the outlet of the static mixer is of an arc convex structure, so that the volume of a mixing cavity in the static mixer is reduced, and the mixing effect is enhanced. The invention has simple structure, good mixing effect and good heat and mass transfer effect.)
1. The reaction device is characterized in that the reaction device is of a multi-stage tubular distribution structure, metering pumps (1) are respectively connected with respective header pipes (3), and each header pipe (3) is connected with 2n-1The branch pipes (4) of one main pipe (3) are connected with the branch pipes (4) of the other main pipe (3) pairwise through the premixers (2), and the premixers (2) are connected with n-level tubes (6, 2)n-1The n-level array pipes (6) are combined in pairs and connected through a static mixer (5), the static mixer (5) is connected with n-1-level array pipes (7) and is connected in a descending manner according to the rule until 2-level array pipes (9) are connected through the static mixer (5), and the static mixer (5) is connected with 1-level array pipe (10).
2. The reaction device for the high heat release system according to claim 1, wherein the pre-mixer (2) and the static mixer (5) are in a three-way pipe structure, nozzles are arranged at two ends of an inlet of the three-way pipe structure, nozzles are arranged opposite to each other, and the inner wall of a fluid outlet between the nozzles is in a circular arc convex structure.
3. A reactor apparatus suitable for use in highly exothermic systems according to claim 1, wherein the array of tubes is straight tubes, spiral tubes, corrugated tubes or corrugated tubes.
4. A reactor assembly adapted for use in highly exothermic systems according to claim 1 wherein n varies with the magnitude of throughput and the adiabatic temperature rise of the reactor system.
5. The reaction device for a highly exothermic system according to claim 2, wherein the inner diameters of the nozzles in the pre-mixer (2) and the static mixer (5) are determined by the Reynolds number at the outlet of the nozzles, and the inner diameters of the static mixer (5) and the nozzles are the same, and when the two-phase flow is easily separated, the Reynolds number is in the range of 3000 to 6000; when the two-phase material flow is not easy to be layered, the Reynolds number ranges from 1000 to 2300; the distance between two nozzles in the premixer (2) is D ═ DLarger nozzle boreX (5-30), and the distance between two nozzles in the static mixer (5) is D ═ DNozzle bore×(5～30)。
6. A reactor device suitable for highly exothermic systems according to claim 1, wherein the maximum allowable internal diameter of the n-stage tubular array (6) is calculated by the formula
K is the heat transfer coefficient of the n-stage tube array (6), TaIs the temperature of the fluid medium outside the n-stage tube array (6), -Delta HRFor heat of reaction, TmaxThe maximum allowable temperature of the reaction system, -rA，nIs the maximum reaction rate allowed in the n stages of the tubes (6).
7. The reactor apparatus for highly exothermic systems according to claim 6, wherein the inner diameter ratio of the n-stage tubes (6), the inner diameter ratio of the n-1-stage tubes (7), and the inner diameter ratio of the n-2-stage tubes (8), … … 1, and the inner diameter ratio of the 891-stage tubes (10) are set to be equal to each other
8. A reactor device suitable for strongly exothermic systems according to claim 7, wherein the molar balance equation is
In the formula (2), dnIs the inner diameter of the tube array, L is the length of the tube, v0Is the volume flow rate, CAIs the concentration of the material;
the energy balance equation is
In the formula (3), m is the mass flow rate of the reaction system, CpCalculating the corresponding tube length L by adopting a numerical calculation method according to the formula (2) and the formula (3) for the average specific heat capacity of the reaction system, and substituting the maximum allowable inner diameter of the corresponding tube array as dnObtaining the shortest pipe length L of the corresponding array pipen，min。
9. A reactor device suitable for highly exothermic systems according to claim 1, wherein a temperature meter (11) is provided at the outlet of each tube row.
Technical Field
The invention belongs to the technical field of mixed reaction devices, and particularly relates to a reaction device suitable for a strong heat release system.
Background
In the chemical production process, most of the related chemical reactions have strong thermal effects. Such as: nitration reaction, polymerization reaction, oxidation reaction, esterification reaction, bromination reaction, condensation reaction, rearrangement reaction, diazotization reaction and the like. Generally, in the reaction process, in order to ensure the yield, quality and stability of the system, stirring equipment and a cooling system are usually added into the reactor to enhance the heat and mass transfer process in the reaction system. Otherwise, when the heat in the reaction system cannot be removed in time, the heat generated by the reaction is accumulated in the system, so that the temperature is increased or local hot spots are caused to reduce the product yield and quality, the reaction generates side reactions, the reaction selectivity is reduced, the reaction rate is further accelerated by the increase of the temperature, more and more heat is accumulated, and the explosion and fire accidents caused by the out-of-control reaction are caused.
The existing batch still reactor has the defects of long reaction time, high energy consumption and the like, and can locally accumulate if heat cannot be transferred in time for strong exothermic reaction, thereby causing explosion and even causing risks such as casualties, property loss and the like. When local thermal disturbance factors occur in the existing tubular reactor due to low mixing efficiency, local high temperature of the reactor and even temperature runaway accidents are caused, and great safety risk is brought to production. The common tube-type reactor has the problems of uneven proportioning among local materials, low reaction conversion rate, incomplete reaction and the like due to pipeline resistance, deformation in the use process and the like because a plurality of tubes are connected in parallel. Therefore, it is necessary to develop a reaction apparatus suitable for a strongly exothermic system.
Disclosure of Invention
In order to solve the above problems, it is an object of the present invention to provide a reaction apparatus suitable for a strongly exothermic system.
In order to achieve the purpose, the following technical scheme is provided:
the reaction device is of a multi-stage tubular distribution structure, the metering pumps are respectively connected with respective header pipes, and each header pipe is connected with 2n-1A branch pipe of one main pipe and a branch pipe of the other main pipe are connected in pairs through premixers, the premixers are connected with n-stage tubes, 2n-1The n-level array tubes are combined pairwise and connected through a static mixer, the static mixer is connected with the n-1-level array tubes and is connected in a descending manner according to the rule until 2-level array tubes are connected through the static mixer, and the static mixer is connected with 1-level array tube. The reaction device is a reaction device in which a main pipe is branched into a plurality of branches and then two branches are mixed into each level of tube array.
Furthermore, the pre-mixer and the static mixer are of a three-way pipe structure, nozzles are arranged at two ends of an inlet of the three-way pipe structure, nozzles of the nozzles are opposite, and the inner wall of a fluid outlet between the nozzles is of an arc convex structure.
Further, the array pipe is a straight pipe, a spiral pipe, a corrugated pipe or a corrugated pipe.
Further, n varies with the magnitude of the production capacity and the adiabatic temperature rise of the reaction system.
Further, the internal diameters of the nozzles in the premixer and static mixer are determined by the Reynolds numbers at the nozzle outlets, and the static mixer and the two internal diameters of the nozzles are equalMeanwhile, when the two-phase material flow is easy to separate, the Reynolds number ranges from 3000 to 6000; when the two-phase material flow is not easy to be layered, the Reynolds number ranges from 1000 to 2300; two nozzles in the premixer are spaced apart by D ═ DLarger nozzle boreX (5-30), and the distance between two nozzles in the static mixer is D ═ DNozzle bore×(5～30)。
Further, the maximum allowable inner diameter of the n-stage tube array is calculated by the formula
K is the heat transfer coefficient of n-stage tubes, TaIs the temperature of the fluid medium outside the n-stage tube array, -Delta HRFor heat of reaction, TmaxThe maximum allowable temperature of the reaction system, -rA，nAnd calculating the maximum reaction rate according to the inlet concentration of the n-stage tubes to obtain the maximum allowable inner diameter of the n-stage tubes.
Further, the inner diameter ratio of n-stage tube arrays, n-1-stage tube arrays and n-2-stage tube array inner diameter … … 1 is equal toThe inner diameters of other tube arrays can be obtained according to the maximum allowable inner diameter of the n-stage tube arrays and the proportional relation between the tube arrays, and the inlet and outlet concentration of each tube array can be obtained according to the calculation formula of the inner diameter and the maximum allowable inner diameter.
Further, the molar balance equation is
In the formula (2), dnIs the inner diameter of the tube array, L is the length of the tube, v0Is the volume flow rate, CAIs the concentration of the material;
the energy balance equation is
In the formula (3), m is the mass flow rate of the reaction system, CpIs the average specific heat capacity of the reaction system, TmaxIs based on the maximum reaction temperature of key components in the reaction system, namely the safe temperature, -delta HRAccording to the reaction heat of different reaction systems, according to the formula (2) and the formula (3), calculating by adopting a numerical calculation method through combining software with a molar balance equation and an energy balance equation to obtain the corresponding tube length L, and substituting the maximum allowable inner diameter of the corresponding tube array as dnObtaining the shortest pipe length L of the corresponding array pipen，min. On the basis, a safety response control system is established, and flow control is completed by temperature monitoring through numerical value and software calculation.
Furthermore, temperature instruments are arranged at the outlets of all stages of tube arrays.
The invention has the beneficial effects that:
1) the invention is suitable for strong exothermic reaction, the reaction is violent in the initial stage of the reaction, the heat release is large, the tube array adopts thinner inner diameter when the reaction materials are just contacted, the specific surface area is higher, which is beneficial to heat transfer, the invention conforms to the reaction characteristics of the strong exothermic reaction, the inner diameter can be changed according to the adiabatic temperature rise of the reaction system, the thinner inner diameter can be adopted when the adiabatic temperature rise is larger, the spiral tube, the corrugated tube or the corrugated tube can be adopted as the n-grade tube array, and the effect of mass and heat transfer is better than that of a straight tube.
2) Traditional shell and tube reactor, under the certain condition of total ratio, because reasons such as pipeline resistance, equipment warp can appear local ratio unusual, lead to the local ratio of reaction system uneven to influence the conversion rate of reaction, lead to the reaction incomplete, yield reduction scheduling problem, and this device adopts multistage distribution mode, is branched into 2 respectively by two house stewardn-1The branch pipes are mixed two by two and enter n-level array pipes, and the n-level array pipes are mixed two by two, so that the materials finally flow out from 1 level array pipe, the proportion among the materials can be homogenized, the liquid-liquid phase mass transfer is further strengthened, the influence on a reaction system is reduced, and the ideal reaction is approached to the maximum extent.
3) Two kinds of materials are under static mixer's nozzle, and nozzle fluid exit static mixer inner wall is crooked, can guide the drainage, reduces the backmixing, and the mixer part mixing chamber volume of fluid collision department reduces, has strengthened the mixed effect, mixes more evenly between the material, has strengthened mass transfer efficiency, guarantees that the material reacts effectually at the fast reaction stage.
4) The length of n-grade tubes obtained by a heat transfer basic equation and molar balance can ensure that the strong exothermic reaction fully reacts at the n-grade tubes in the strong exothermic section, the reaction effect is good, and the rapid temperature rise caused by the accumulation of local heat when the temperature in the tubes reaches the critical hot point temperature due to the strong exothermic reaction is prevented, so that the reaction selectivity is reduced, even the temperature runaway phenomenon is caused, the reaction is out of control, and accidents such as explosion are easy to generate.
5) The n-stage tube arrays are connected with the n-1-stage tube arrays through the static mixer, the n-1-stage tube arrays are connected with the n-2-stage tube arrays through the static mixer, the n-2-stage tube arrays are connected with the 1-stage tube arrays through the static mixer, and each time the reaction materials are mixed under the static mixer, a new collision is formed, so that the mixing effect is enhanced, the materials are mixed more uniformly, and the mass transfer efficiency is enhanced.
Drawings
FIG. 1 is a schematic view of an apparatus of the present invention;
FIG. 2 is a cross-sectional view of the inside of the static mixer of the present invention;
FIG. 3 is a graph comparing the theoretical outlet temperature and the experimental outlet temperature of example 1;
FIG. 4 is a graph comparing the theoretical outlet temperature and the experimental outlet temperature of example 2;
FIG. 5 is a graph comparing the theoretical outlet temperature and the experimental outlet temperature of example 3;
in the figure: 1. a metering pump; 2. a premixer; 3. a header pipe; 4. a branch pipe; 5. a static mixer; 6. n-stage tube arrays; 7. n-1 level of tube array; 8. n-2 stage tube array; 9. 2-stage tube array; 10. 1-stage tube array; 11. a temperature meter.
Detailed Description
The invention will be further described with reference to the drawings and examples in the following description, but the scope of the invention is not limited thereto.
As shown in figure 1, the reaction device suitable for the strong heat release system comprises 2 metering pumps 1, 2 header pipes 3, and 2 connecting pipes 3 respectivelyn-1The branch pipes 4, 2n-1N-stage tubes 6, 2n-2Root n-1 grade array pipes 7, 2n-3N-2 level array pipes 8 … … 2, 2 level array pipes 9 and 1 level array pipe 10, wherein n is 5, and the two materials respectively enter 2 main pipes 3 through a metering pump 1 and are respectively branched into 2n-1The branch pipes 4 are mixed two by the premixer 2 and enter the n-stage tube arrays 6, 2n-1The n-level tubes 6 are combined pairwise and enter the n-1-level tubes 7 through the static mixer 5, the combination is reduced according to the rule, finally, 2-level tubes 9 enter 1-level tube 10 through the static mixer 5 and then are discharged, and each level tube is provided with a temperature instrument 11; the amount of capacity can be varied by varying the flow rate and number of tube rows of the metering pump 1. Each level of tube array is a straight tube, a spiral tube, a corrugated tube or a corrugated tube.
As shown in fig. 2, the pre-mixer 2 and the static mixer 5 are of a three-way pipe structure, nozzles are arranged at two ends of an inlet of the three-way pipe structure, nozzles of the nozzles are opposite, and the inner wall of a fluid outlet between the nozzles is of an arc convex structure, so that the volume of a mixing cavity can be reduced, and the mixing effect can be enhanced.
Example 1
In the embodiment, the raw materials are red-based KD solution with volume concentration of 50% and sodium nitrite solution with volume concentration of 24%, the flow rates are 100L/h and 128L/h respectively, the reaction device is placed in a constant-temperature ice-water bath, and the temperature is controlled to be Ta0 deg.C, maximum temperature set to TmaxThe reaction rate equation is 10 DEG C
Wherein the reaction activation energy E is 72.88kJ/mol, the gas constant unit R is 8.314J/(mol.K), X is the conversion rate, and the reaction heat-delta HR95kJ/mol and a heat transfer coefficient K of 200 w/(m)2·℃)，CpThe average specific heat capacity is 484J/(mol)K), the red base KD solution and the sodium nitrite solution respectively flow into two header pipes 3 through a metering pump 1 and are branched into 2n-1Branch line, then enters 2 through the premixer 2n-1N number of tubes 6, initial concentration C after mixingA，nIs 1087mol/m3，CB，nIs 2030mol/m3The maximum possible reaction rate-r is calculated from the formula (4)A，nIs 41.3mol/m3S (temperature T in calculation is Tmax) D is calculated by the formula (1)max＝2.04×10-3m, selecting stainless steel tube with inner diameter of 2mm and 2.4 × 0.2mm, and taking n-stage row tubes 6 with flow rate of 0.7m/s to obtain 28.8 rows of n-stage row tubes, and taking 32 rows, namely 2 rowsn-1The tube is a 6-stage tube array with 32, i.e. n is 6, and each stage of tube array adopts a spiral tube shape.
The inlet and outlet concentrations of each stage of tube array can be obtained by the formula (1), so that the minimum length of each stage of tube array can be obtained by the formulas (2), (3) and (4), and relevant parameters of each stage of tube array and relevant parameters of nozzles in the tube array can be seen from the following table 1 and table 2:
TABLE 1 respective stage tubulation related parameters
TABLE 2 nozzle-related parameters in the tube rows at various levels
Number of stages
Caliber/mm of two nozzles
Reynolds number at two nozzles
Nozzle pitch/mm
6
0.4，0.9
4145，4087
10
5
1，1
4700，4700
15
4
2，2
4700，4700
20
3
4，4
4700，4700
30
2
8，8
4700，4700
40
1
16，16
4700，4700
80
When the conversion rate in the 1-stage tube array 10 reached 40%, the concentration of the red base KD at the outlet of the 1-stage tube array 10 was calculated to be 62mol/m3The total conversion rate of the device reaches 94.3 percent, and the selectivity of the product red base KD diazonium salt is 90 percent.
After the device actually runs stably for 1h, the discharged materials of the 1-level tube nest 10 are collected, and the measured concentration of the red base KD is 60mol/m3The total conversion rate of the device reaches94.5 percent, the selectivity of the product red base KD diazonium salt is 91 percent, and the outlet temperature of each level of tube array is compared with the theoretical outlet temperature as shown in the following figure 3.
Example 2
In the embodiment, the raw materials are 55 volume percent haematochrome KD solution and 25 volume percent sodium nitrite solution, and the flow rates are 400L/h and 512L/h respectively. Other conditions were the same as in example 1, total initial concentration CA，nIs 1200mol/m3，CB，nIs 1862mol/m3The maximum possible reaction rate-r is calculated from the formula (4)A，nIs 41.8mol/m3S (temperature T in calculation is Tmax) D is calculated by the formula (1)maxIs 2.02 multiplied by 10-3m, selecting stainless steel tube with inner diameter of 2mm and 2.4 × 0.2mm, selecting n-stage row tubes 6 with flow rate of 0.7m/s to obtain n-stage row tubes 6 with number of 115, and selecting 128, i.e. 2n-1128, namely n is 8, 8 stages of tubes 6 are adopted, and each stage of tube is in a corrugated tube shape.
The inlet and outlet concentrations of each stage of tube array can be obtained by the formula (1), so that the minimum length of each stage of tube array can be obtained by the formulas (2), (3) and (4), and the relevant parameters of each stage of tube array and the relevant parameters of nozzles in the tube array can be seen from the following table 3 and table 4:
TABLE (3) tabulation-related parameters for each stage
TABLE (4) nozzle-related parameters in the tube arrays at various levels
Number of stages
Caliber/mm of two nozzles
Reynolds number at two nozzles
Nozzle pitch/mm
8
0.5，1
3316，3678
15
7
1.2，1.2
3920，3920
15
6
2.4，2.4
3920，3920
20
5
4，4
4704，4704
30
4
7，7
5376，5376
35
3
14，14
5376，5376
90
2
30，30
5018，5018
150
1
60，60
5018，5018
300
When the conversion rate of the 1-stage tube nest 10 is 22 percent, the concentration of the red base KD at the outlet of the first-stage tube nest 10 is calculated to be 104.4mol/m3The total conversion rate of the device reaches 91.3 percent, and the selectivity of the product red base KD diazonium salt is 93 percent.
After the device actually runs stably for 1h, the discharged materials of the 1-level tube nest 10 are collected, and the measured concentration of the red base KD is 103mol/m3The total conversion rate of the device reaches 91.4%, the selectivity of the product red base KD diazonium salt is 93.5%, and the outlet temperature of each level of tube array is compared with the theoretical outlet temperature as shown in figure 4.
Example 3
In this example, the raw materials were 60% volume red-based KD solution and 20% volume sodium nitrite solution, the flow rates were 200L/h and 256L/h, respectively, the other conditions were the same as in example 1, and the initial concentration C wasA，nIs 1304mol/m3，CB，nIs 1690mol/m3The maximum possible reaction rate-r is calculated from the formula (4)A，nIs 41.8mol/m3S (temperature T in calculation is Tmax) D is calculated by the formula (1)maxIs 2.02 multiplied by 10-3m, selecting stainless steel tube with inner diameter of 2mm and 2.4 × 0.2mm, and collecting n-stage tubes 6 with flow rate of 0.7m/s to obtain 6 n-stage tubes with flow rate of 59, and collecting 64 tubes (2)n-1The number of the rows 6 is 64, that is, n is 7, and each row adopts a bellows shape.
The inlet and outlet concentration of each stage of tube array can be obtained by the formula (1), and the minimum length of each stage of tube array can be obtained by the formulas (2), (3) and (4). The parameters associated with each stage of the tube array and the parameters associated with the nozzles in the tube array can be seen in tables 5 and 6:
TABLE 5 tabulation-related parameters for each stage
TABLE 6 nozzle-related parameters in the tube rows at various stages
Number of stages
Nozzle caliber/mm
Reynolds number at nozzle
Nozzle pitch/mm
7
0.3，0.7
5530，5250
15
6
0.9，0.9
5230，5230
15
5
1.6，1.6
5880，5880
20
4
3.5，3.5
5376，5376
25
3
7，7
5376，5376
35
2
15，15
5018，5018
80
1
30，30
5018，5018
150
When the conversion rate of the 1-stage tube nest 10 is 40%, the concentration of the red base KD at the outlet of the 1-stage tube nest 10 is 67.8mol/m3The total conversion rate of the device reaches 94.8 percent, and the selectivity of the product red base KD diazonium salt is 92 percent.
After the device actually runs stably for 1h, the discharged materials of the 1-level array tube 10 are collected, and the measured concentration of the red base KD is 64mol/m3The total conversion rate of the device reaches 95.1%, the selectivity of the product red base KD diazonium salt is 92.7%, and the outlet temperature of each level of tube array is compared with the theoretical outlet temperature as shown in figure 5.
Comparative example:
in the embodiment, the raw materials are 60 volume percent of red base KD solution and 20 volume percent of sodium nitrite solution, the reaction device is arranged in a constant temperature ice water tank, the temperature is controlled to be 0 ℃, the flow rate of the red base KD solution passing through a metering pump 1 is 200L/h, the flow rate of the sodium nitrite solution passing through the metering pump 1 is 256L/h, the red base KD solution and the sodium nitrite solution flow into a header pipe 3 and then are respectively branched into 1 branch circuit to be mixed, and the mixture enters a section of straight pipe through a premixer 2 to be discharged, a nozzle is not arranged in the premixer 2, the inner diameter of the straight pipe is 2mm, the discharge is performed within the same retention time of the embodiment 3, a temperature instrument 11 on the outlet of the straight pipe is stable at about 273K, the conversion rate of the red base KD at the outlet of the straight pipe reaches 42.35%, and the selectivity of the product red base KD diazonium salt reaches 75.3.
And (4) conclusion: the theoretical calculation result is compared with the actual experiment result, and the result can be obtained, during the actual experiment, the outlet temperature trend of each level of tube array basically accords with the theoretical calculation result, and the actual conversion rate and the selectivity of the device are slightly larger than the theoretical value, which shows that the device can be applied to a strong heat release system, has good heat and mass transfer effect and good mixing effect, reduces the influence of material proportioning on the experiment, has good product selectivity, and greatly improves the safety.
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