Liquid-solid phase fluidized bed reactor with multi-section structure

Abstract

The invention belongs to the technical field of chemical production, and particularly discloses a liquid-solid phase fluidized bed reactor with a multi-section structure. The liquid-solid phase fluidized bed reactor comprises a feed port, a fluid distributor, a reactor main body and a discharge port, the fluidized bed reactor main body sequentially comprises a fluidized state reaction section, a transition section and an overflow section from bottom to top, the fluid distributor is arranged above the feed port, and the discharge port is located above the overflow section of the fluidized bed reactor. The fluidization state reaction section and the fluidization transition section are equal-diameter runners, and the fluidization overflow section is in a runner linear narrowing or non-linear narrowing shape. The section shape of the fluidization overflow section 5 comprises an isosceles trapezoid, an isosceles triangle, a parabola and a conjugate hyperbolic line shape. Compared with a kettle type liquid-solid stirring reactor, the reactor has the characteristics of no flow field dead zone, high heat and mass transfer efficiency and easiness in amplification, and is particularly suitable for strong exothermic liquid-solid reactions for preparing nitramine energetic compounds by amine nitrolysis.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical production, and specifically discloses a liquid-solid phase fluidized bed reactor with a multi-stage structure. Background Art

[0002] Fluidized bed has the advantages of high heat and mass transfer efficiency, small dead zone of flow field, easy continuous operation and process control, and is widely used in chemical, biological, petroleum and other production fields. At present, the industrial preparation method of nitramine energetic compounds mainly adopts kettle-type intermittent or kettle-type continuous reactors. Although the technology of kettle reactor is relatively mature, it still has serious problems such as dead zone effect of flow field, high amount of work-in-progress, and difficulty in high-precision process control. In addition, the safety and quality of the product are difficult to be effectively guaranteed. The preparation of nitramine energetic compounds using liquid-solid fluidized bed reactor can effectively avoid the occurrence of such problems.

[0003] However, due to the inherent characteristics of fluidization technology and the diversity of factors affecting the fluidization process, the fluidized bed also has obvious limitations for liquid-solid fluidized bed reactors. The distribution of material residence time is difficult to control and the continuous transportation of suspensions is difficult, resulting in some fluids always carrying solid materials to circulate inside the reactor, and even forming accumulation. This not only increases the risk of the reaction process of nitramine energetic compounds, but also reduces the yield of the target product.

[0004] In order to meet the technical requirements for the reaction process of nitramine energetic compounds and solve the problems of difficult control of material residence time distribution and difficulty in continuous transportation of suspension in liquid-solid fluidized bed reactor, it is necessary to develop a multi-stage liquid-solid fluidized bed reactor. Summary of the invention

[0005] The present invention is achieved through the following technical solutions:

[0006] A multi-stage liquid-solid fluidized bed reactor, comprising a feed inlet 1, a fluid distributor 2, a fluidized bed reactor body and a discharge port 6, wherein the fluidized bed reactor body comprises a fluidized reaction section 3, a fluidized transition section 4 and a fluidized overflow section 5 from bottom to top;

[0007] The feed port 1 is connected to the bottom of the fluidized bed reactor body, and the discharge port 6 is connected to the top of the fluidized bed reactor body; the fluid distributor 2 is arranged at the bottom of the fluidized reaction section 3 on the feed port 1; the fluid distributor 2 is used to evenly distribute the suspension to avoid dead zones in the flow field;

[0008] The fluidized reaction section 3 and the fluidized transition section 4 are equal-diameter flow channels, and the fluidized overflow section 5 is a linearly narrowed or nonlinearly narrowed flow channel shape, which is used to increase the kinetic energy of the fluid;

[0009] The fluidized reaction section enables the liquid-solid suspension to strengthen the heat and mass transfer process at the liquid-solid interface in the fluidized state; the fluidized transition section is arranged at the end of the fluidized reaction section, and is used to stabilize the flow field in the fluidized reaction section and stably transition and transport the solid product to the overflow section; the fluidized overflow section converts the static pressure energy of the fluid in this section into kinetic energy by narrowing the flow channel, and the increased kinetic energy of this part of the fluid is transmitted to the solid particles with an upward movement speed close to zero at the end of the fluidized state through the shear force between the liquid and the solid, so that the solid particles generate upward acceleration, thereby realizing continuous output of the reaction products.

[0010] Preferably, the cross-sectional shape of the fluidized overflow section 5 includes an isosceles trapezoid, an isosceles triangle, a parabola, or a conjugate hyperbola.

[0011] Preferably, the length of the fluidized overflow section 5 is 0.3 to 3 times the radius of the fluidized reaction section 3 , and the end radius of the fluidized overflow section 5 is 0.1 to 0.6 times the radius of the fluidized reaction section 3 .

[0012] In a second aspect, the present invention provides an application of the multi-stage liquid-solid fluidized bed reactor described in the first aspect for an exothermic liquid-solid reaction system.

[0013] Preferably, the liquid-solid reaction system comprises an amine nitration reaction.

[0014] Furthermore, when the liquid-solid fluidized bed reactor is used for amine nitration reaction, the tower diameter of the fluidized reaction section 3 is ≤0.15m; and the heights of the fluidized reaction section 3 and the fluidized transition section 4 are set according to the feeding operation conditions so that the material stays in the fluidized reaction section and the transition section for ≤60min.

[0015] Furthermore, the fluidized reaction section 3 of the fluidized bed reactor has a radius of 0.1 m, a material residence time of <30 min, an inlet liquid-solid mass flow ratio of 0.25, and a main body of the fluidized bed reactor begins to change diameter at 0.4 m to form a fluidized overflow section 5. The length of the fluidized overflow section 5 is 0.2 m, and the pipe diameter is uniformly reduced to be equal to the pipe diameter at the discharge port.

[0016] Furthermore, the fluidized reaction section 3 of the fluidized bed reactor has a radius of 0.08 m, the fluid distributor 2 is an isosceles trapezoid with a height of 0.06 m; the fluidized overflow section 5 is also an isosceles trapezoid with a height of 0.06 m, and the tower diameter change rate is 67%;

[0017] The suspension material is introduced at a flow rate of 0.002m / s to 0.005m / s, wherein the density of the liquid material is 1.2 to 1.6g / cm 3 , the liquid viscosity is 0.0005~0.002Pa·s, and the solid density is 1.5~2.0g / cm 3 .

[0018] The present invention realizes the functions of efficient mass and heat transfer between liquid and solid phases in fluidized state, stable flow field in reaction section and continuous discharge respectively through the design of reactor main body reaction section, transition section and overflow section. The liquid-solid fluidized bed of the present invention is a process intensification method of full mixed flow. Compared with kettle-type liquid-solid stirred reactor, it has the characteristics of no dead zone in flow field, high heat and mass transfer efficiency and easy scale-up. It is particularly suitable for strong exothermic liquid-solid reactions such as nitration of amines to prepare energetic compounds containing nitramines.

[0019] The beneficial effects of the present invention are:

[0020] The liquid-solid phase fluidized bed reactor of the present invention realizes the strengthening of the heat and mass transfer process of the fluidized liquid-solid suspension to the liquid-solid interface in the fluidized phase reaction section by designing the fluidized phase reaction section, the transition section and the overflow section. The flow field in the fluidized phase reaction section is stabilized by the fluidized transition section arranged at the end of the fluidized phase reaction section, and the solid product is stably transitioned and transported to the overflow section. The fluidized overflow section converts the static pressure energy of the fluid in this section into kinetic energy by narrowing the flow channel. The increased kinetic energy of this part of the fluid is transmitted to the solid particles at the end of the fluidized phase whose upward movement speed is close to zero through the shear force between the liquid and the solid, so that the solid particles are accelerated upward, thereby realizing the continuous output of the reaction products from the discharge port of the liquid-solid phase fluidized bed reactor. The multi-stage structure liquid-solid phase fluidized bed reactor of the present invention is particularly suitable for highly exothermic liquid-solid reactions such as the preparation of nitramine energetic compounds by nitration of amines. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the structure of a liquid-solid phase fluidized bed reactor with a multi-stage structure of the present invention;

[0022] Figure 2 It is the real-time solid volume flow rate at the inlet and outlet of the fluidized bed reactor of Example 6.

[0023] Figure 3 Schematic diagram illustrating the mass conservation of material flow in the fluidized overflow section of a liquid-solid fluidized bed reactor. DETAILED DESCRIPTION

[0024] In order to better illustrate the purpose, technical solutions and advantages of the present invention, further description is given below in conjunction with the accompanying drawings and embodiments. It should be understood that the embodiments are only used to illustrate the technical effects of the present invention, rather than to limit the protection scope of the present invention.

[0025] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0026] A multi-stage liquid-solid phase fluidized bed reactor comprises a feed inlet 1, a fluid distributor 2, a fluidized bed reactor body and a discharge port 6, wherein the fluidized bed reactor body comprises a fluidized reaction section (3), a transition section (4) and an overflow section (5) from bottom to top. The fluid distributor (2) is arranged above the feed inlet (1), and the discharge port (6) is located above the overflow section (5) of the fluidized bed reactor.

[0027] The suspension enters from the feed port (1) and passes through the fluid distributor (2). The fluid distributor (2) connects the feed port (1) and the fluidized reaction section (3) to achieve uniform material transportation through diameter change and avoid dead zones in the flow field.

[0028] The fluidized reaction section (3) allows the liquid-solid suspension to perform heat and mass transfer on the liquid-solid interface in a fluidized state. According to the product quantity requirement of the nitramine energetic compound reaction process, the fluidized reaction section tower diameter is ≤1.5m, and the feed operation conditions and the fluidized reaction section height are mutually restricted, so that the material stays in the fluidized reaction section and the transition section for ≤60min.

[0029] Then, the fluidized transition section (4) arranged at the end of the fluidized reaction section (3) stabilizes the flow field in the fluidized reaction section, and the solid product is stably transferred to the fluidized overflow section 5.

[0030] The fluidized overflow section (5) converts the static pressure energy of the fluid into kinetic energy by narrowing the flow channel. The increased kinetic energy of this part of the fluid is transmitted to the solid particles at the end of the fluidized state whose upward movement speed is close to zero through the shear force between the liquid and the solid, causing them to accelerate upward, thereby achieving continuous output of the reaction products from the discharge port (6) of the liquid-solid fluidized bed reactor.

[0031] Example 1

[0032] In this embodiment, the radius of the fluidized bed reactor is 0.08m, the fluid distributor is an isosceles trapezoid with a height of 0.06m; the fluidized overflow section 5 is also an isosceles trapezoid with a height of 0.06m, and the tower diameter change rate is 67%. The suspension material is introduced at a flow rate of 0.002m / s to 0.005m / s at the inlet, wherein the liquid material density is 1.5g / cm 3 , the liquid viscosity is 0.001Pa·s, and the solid density is 1.8g / cm 3 The particle size is 100 μm. The material flows into the fluidized reaction section through a fluid distributor. The residence time is 20 minutes and the bed expansion height is 0.67 m.

[0033] Under the same conditions, compared with the fluidized bed technology of general structure, in this embodiment, no dead zone of flow field appears, the solid phase particles are evenly distributed, and under the same reaction conditions, the mixing efficiency is improved by 19%.

[0034] Example 2

[0035] In this embodiment, the radius of the fluidized bed reactor is 0.08m, the fluid distributor is an isosceles trapezoid with a height of 0.06m, the fluidized overflow section 5 is also an isosceles trapezoid, and the tower diameter change rate is 67%. The suspension material is introduced at a flow rate of 0.002m / s to 0.005m / s at the inlet, wherein the liquid material density is 1.5g / cm 3 , the liquid viscosity is 0.001Pa·s, and the solid density is 2.1g / cm 3 The particle size is 100 μm. The material flows into the fluidized reaction section through the fluid distributor. The residence time is 20 minutes and the bed expansion height is 0.49 m.

[0036] Under the same conditions, compared with the fluidized bed technology of general structure, in this embodiment, no dead zone of flow field appears, the solid phase particles are evenly distributed, and under the same reaction conditions, the mixing efficiency is improved by 14%.

[0037] Example 3

[0038] In this embodiment, the radius of the fluidized bed reactor is 0.08m, the fluid distributor 2 is an isosceles trapezoid with a height of 0.06m, the fluidized overflow section 5 is also an isosceles trapezoid, and the tower diameter change rate is 67%. The suspension material is introduced at a flow rate of 0.004m / s to 0.008m / s at the inlet, wherein the liquid material density is 1.5g / cm 3 , the liquid viscosity is 0.001Pa·s, and the solid density is 1.8g / cm 3 The particle size is 100 μm. The material flows into the fluidized reaction section through a fluid distributor. The residence time is 20 minutes and the bed expansion height is 0.92 m.

[0039] Under the same conditions, compared with the fluidized bed technology of general structure, in this embodiment, no dead zone of flow field appears, the solid phase particles are evenly distributed, and under the same reaction conditions, the mixing efficiency is improved by 25%.

[0040] Example 4

[0041] In this embodiment, the radius of the fluidized bed reactor is 0.08m, the fluid distributor 2 is an isosceles trapezoid with a height of 0.06m, the fluidized overflow section 5 is also an isosceles trapezoid, and the tower diameter change rate is 67%. The suspension material is introduced at a flow rate of 0.002m / s to 0.005m / s at the inlet, wherein the liquid material density is 1.5g / cm 3 , the liquid viscosity is 0.001Pa·s, and the solid density is 1.8g / cm 3 The particle size is 50μm. The material flows into the fluidized reaction section through the fluid distributor. The residence time is 20min and the bed expansion height is 1.18m.

[0042] Under the same conditions, compared with the fluidized bed technology of general structure, in this embodiment, no dead zone of flow field appears, the solid phase particles are evenly distributed, and under the same reaction conditions, the mixing efficiency is improved by 10%.

[0043] Example 5

[0044] In this embodiment, the radius of the fluidized bed reactor is 0.08m, the fluid distributor 2 is an isosceles trapezoid with a height of 0.06m, the overflow section 5 is also an isosceles trapezoid, and the tower diameter change rate is 67%. The suspension material is introduced at a flow rate of 0.002m / s to 0.005m / s at the inlet, wherein the liquid material density is 1.5g / cm 3 , the liquid viscosity is 0.003Pa·s, and the solid density is 1.8g / cm 3 The particle size is 100μm, the material flows into the fluidized reaction section through the fluid distributor, the residence time is 20min, and the bed expansion height is 1.05m.

[0045] Under the same conditions, compared with the fluidized bed technology of general structure, in this embodiment, no dead zone of flow field appears, the solid particles are evenly distributed, and under the same reaction conditions, the mixing efficiency is improved by 12%.

[0046] Example 6

[0047] The radius of the fluidized bed reactor is 0.1 m. The reactor begins to change diameter at 0.4 m to form an overflow section 5. The overflow section 5 is an isosceles trapezoid with a length of 0.2 m until the diameter is reduced to be equal to the diameter of the discharge port 4.

[0048] After the implementation of this embodiment, the status is as follows Figure 2 As shown, the discharge amount continues to fluctuate around the feed amount after being nearly stable. The design of the variable diameter of the overflow section flow channel enables the solid product to be stably transported to the overflow section, and the reaction product is continuously output from the discharge port of the liquid-solid phase fluidized bed reactor. Compared with general fluidized bed technology, the material residence time in this embodiment is controllable, and the yield is increased by 10%.

[0049] The cross-sectional structural shape design of the fluidized overflow section 5 isosceles trapezoid, and the static pressure energy of the fluid in this section is converted into kinetic energy by narrowing the flow channel. The increased kinetic energy of this part of the fluid is transmitted to the solid particles at the end of the fluidized state whose upward movement speed is close to zero through the shear force between the liquid and the solid, so that they generate acceleration upward, thereby realizing the continuous output of the reaction product. The cross-sectional structural shape design of the fluidized overflow section includes but is not limited to isosceles trapezoid, isosceles triangle, parabola and conjugate hyperbola.

[0050] like Figure 3The figure shows the mass conservation diagram of the material flow in the fluidized overflow section of the liquid-solid fluidized bed reactor. From section 1-1 to section 2-2, according to the mass conservation, while keeping the radius of the liquid-solid fluidized bed reactor, the liquid-solid flow ratio and the solid phase residence time unchanged, the cross-sectional area of ​​the fluidized overflow section from section 1-1 to section 2-2 shrinks linearly, and the material fluidization velocity will change from u f When it increases to u, the nitration reaction product will obtain fluidization kinetic energy in the fluidization overflow section. The increased kinetic energy of this part of the fluid is transmitted to the solid particles at the end of the fluidization state whose upward movement speed is close to zero through the shear force between the liquid and the solid, causing them to accelerate upward, thereby achieving continuous output of the reaction product. The material residence time is shortened to the greatest extent.

[0051] The multi-stage liquid-solid fluidized bed reactor of the present invention comprehensively considers the flux characteristics of the reactor, the amount of products in process, the reaction residence time and other target parameters, and scientifically designs the tower radius, the reactor reaction section height, the variable diameter interval and other structures, so as to better achieve the enhancement of the heat and mass transfer process between the liquid-solid two phases in the fluidized reaction section of the fluidized liquid-solid suspension. At the same time, through the design of the reactor main reaction section, transition section and overflow section, the function of stabilizing the reaction section flow field and continuous discharge is achieved.

[0052] The above description is only a specific example of the present invention and does not constitute any limitation to the present invention. For professionals in this field, after understanding the content and principle of the present invention, it is possible to make various modifications and changes in form and details without departing from the principle and structure of the present invention, but these modifications and changes based on the idea of ​​the present invention are still within the scope of protection of the claims of the present invention.

Claims

1. A multi-stage liquid-solid fluidized bed reactor, characterized in that: It comprises a feed inlet (1), a fluid distributor (2), a fluidized bed reactor body and a discharge port (6), wherein the fluidized bed reactor body comprises, from bottom to top, a fluidized reaction section (3), a fluidized transition section (4) and a fluidized overflow section (5); The feed port (1) is connected to the bottom of the fluidized bed reactor body, and the discharge port (6) is connected to the top of the fluidized bed reactor body; the fluid distributor (2) is arranged at the bottom of the fluidized reaction section (3) above the feed port (1) to evenly distribute the feed; The fluidized reaction section (3) and the fluidized transition section (4) are flow channels with constant diameters, and the fluidized overflow section (5) is a flow channel with linear narrowing or nonlinear narrowing.

2. The multi-stage liquid-solid fluidized bed reactor according to claim 1, characterized in that: The cross-sectional shape of the fluidized overflow section (5) includes an isosceles trapezoid, an isosceles triangle, a parabola, and a conjugate hyperbola.

3. The multi-stage liquid-solid fluidized bed reactor according to claim 1, characterized in that: The length of the fluidized overflow section (5) is 0.3 to 3 times the radius of the fluidized reaction section (3), and the end radius of the fluidized overflow section (5) is 0.1 to 0.6 times the radius of the fluidized reaction section (3).

4. Use of the multi-stage liquid-solid fluidized bed reactor according to any one of claims 1 to 3 in an exothermic liquid-solid reaction system.

5. The use of the multi-stage liquid-solid fluidized bed reactor according to claim 4 for an exothermic liquid-solid reaction system, characterized in that: The liquid-solid reaction system includes an amine nitration reaction.

6. The use of the multi-stage liquid-solid fluidized bed reactor according to claim 5 for an exothermic liquid-solid reaction system, characterized in that: When the liquid-solid phase fluidized bed reactor is used for nitration reaction of amines, the diameter of the fluidized reaction section (3) is ≤0.15 m; and the heights of the fluidized reaction section (3) and the fluidized transition section (4) are set according to the feeding operation conditions so that the material stays in the fluidized reaction section and the transition section for ≤60 min.

7. Application of the multi-stage liquid-solid fluidized bed reactor according to claim 6 for an exothermic liquid-solid reaction system, characterized in that: The fluidized reaction section (3) of the fluidized bed reactor has a radius of 0.1 m, a material residence time of less than 30 min, an inlet liquid-solid mass flow ratio of 0.25, and a main body of the fluidized bed reactor begins to change diameter at 0.4 m to form a fluidized overflow section (5). The length of the fluidized overflow section (5) is 0.2 m, and the pipe diameter is uniformly reduced to be equal to the pipe diameter at the discharge port.

8. The use of the multi-stage liquid-solid fluidized bed reactor according to claim 6 for an exothermic liquid-solid reaction system, characterized in that: The fluidized reaction section (3) of the fluidized bed reactor has a radius of 0.08 m, the fluid distributor (2) is an isosceles trapezoid with a height of 0.06 m; the fluidized overflow section (5) is also an isosceles trapezoid with a height of 0.06 m, and the tower diameter change rate is 67%; the suspension material is introduced at a flow rate of 0.002 m / s to 0.005 m / s, wherein the liquid material density is 1.2 to 1.6 g / cm 3 , the liquid viscosity is 0.0005~0.002Pa·s, and the solid density is 1.5~2.0g / cm 3 .

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