Rectification equipment for cyclohexylamine rectification

Abstract

The utility model provides rectification equipment for cyclohexylamine rectification. The rectifying equipment comprises a rectifying tower with a cylindrical barrel structure, the rectifying tower is divided into a pre-fractionation section, a rectifying section, a stripping section and a middle discharging section, and a vertical partition plate is arranged in the tower to separate the pre-fractionation section from the middle discharging section. By utilizing the rectification equipment, the quantity of equipment can be reduced, the process flow is simplified, the device investment is reduced, the consumption of raw materials and energy in production is reduced, the production cost is reduced, and the carbon emission of a production device is reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of chemical distillation, in particular to distillation equipment for cyclohexylamine distillation. Background Art

[0002] Cyclohexylamine is miscible in most organic solvents and is mainly used as a solvent. It can also be used to prepare desulfurizers, rubber antioxidants, vulcanization accelerators, plastic and textile chemical additives, boiler feed water treatment agents, metal corrosion inhibitors, emulsifiers, preservatives, antistatic agents, latex coagulants, petroleum additives, fungicides, pesticides and dye intermediates. Dicyclohexylamine is used in organic synthesis and is also used as a pesticide, acid gas absorbent and steel rust inhibitor.

[0003] The organic mixture used in cyclohexylamine production typically contains cyclohexylamine at a mass concentration of ≥80%, aniline at a mass concentration of ≤5%, dicyclohexylamine at a mass concentration of ≤10%, and a small amount of light components. This organic mixture requires distillation and separation to recover the useful components. Existing production typically employs a two-step distillation process. Step 1: The organic mixture from the cyclohexylamine production system is first fed into distillation, separation, and recovery system I to separate target product 1—cyclohexylamine. Step 2: The remaining bottoms liquid is then fed into distillation, separation, and recovery system II to separate target product 2—aniline. The bottoms liquid from distillation, separation, and recovery system II serves as target product 3—dicyclohexylamine. The organic mixture containing cyclohexylamine, aniline, and dicyclohexylamine is separated and recovered through two distillation, separation, and recovery systems, resulting in low efficiency and high energy consumption. Distillation separation is the most mature and widely used separation technology in chemical production, but the distillation process consumes huge amounts of energy. More than 50% of the energy consumption in chemical production is used for separation, and distillation separation energy consumption accounts for 95% of it.

[0004] Therefore, it is necessary to improve the existing cyclohexylamine organic mixed liquid distillation separation and recovery equipment, and it is urgent to provide a distillation equipment for cyclohexylamine distillation with a short process, small footprint, low investment, stable operation, high efficiency and low energy consumption. Utility Model Content

[0005] The purpose of this utility model is to provide a distillation device for cyclohexylamine distillation. The device distills and separates a mixed organic liquid containing cyclohexylamine, aniline, and dicyclohexylamine from a cyclohexylamine production system in a vertical partition plate distillation tower. Unlike conventional distillation towers, the vertical partition plate distillation tower has not only a distillation section and a stripping section, but also a pre-fractionation section and an intermediate discharge section. Target product 1, cyclohexylamine, is recovered in the distillation section of the distillation tower as a product de-barrier; target product 2, aniline, is recovered in the intermediate discharge section of the distillation tower as a raw material and directly returned to the cyclohexylamine production system for use; and target product 3, dicyclohexylamine, is recovered from the bottom of the distillation tower reboiler as a by-product de-barrier.

[0006] By adopting the above distillation equipment, only one set of distillation equipment is needed to recover the target product for continuous production. It is a distillation equipment for cyclohexylamine distillation with stable operation, high efficiency and low energy consumption. The utility model aims to save energy and reduce consumption, reduce carbon emissions and protect the environment.

[0007] The purpose of the utility model can be achieved through the following technical solutions:

[0008] A distillation device for rectifying cyclohexylamine comprises a condenser, a rectifying tower and a reboiler. The condenser has a tube side for carrying light components and a shell side for carrying circulating water. The top of the condenser is connected to a head via a light component outlet B. The top of the head is provided with a light component outlet A. The bottom of the condenser is connected to the top of the rectifying tower via a gas outlet reflux port E. The bottom of the rectifying tower is connected to the reboiler via a discharge reflux port J. The rectifying tower has a rectifying section at its top, a pre-fractionation section and an intermediate discharge section at its middle, and a stripping section at its bottom. A vertical partition plate is installed between the middle pre-fractionation section and the intermediate discharge section. The pre-fractionation section and the intermediate discharge section are both provided with a stripping layer and a rectifying layer. The cyclohexylamine liquid at the top of the tower is refluxed via the gas outlet reflux port E, and the steam at the bottom of the tower is refluxed via the discharge reflux port J.

[0009] As a preferred embodiment of the present invention, the condenser and the distillation tower are vertical cylindrical barrels, and the reboiler is a horizontal cylindrical barrel.

[0010] As a preferred embodiment of the present invention, the upper side shell side of the condenser is provided with a circulating return water outlet C, and the lower side shell side is provided with a circulating supply water inlet D.

[0011] As a preferred embodiment of the present invention, an organic mixed liquid feed inlet G is provided on the side shell side of the middle part of the pre-fractionation section of the distillation tower, a raw material feed pipe is horizontally installed at the organic mixed liquid feed inlet G, a first distillation layer is installed above the raw material feed pipe, a first liquid distributor is horizontally installed below the raw material feed pipe, and a first stripping layer is provided below the first liquid distributor.

[0012] As a preferred embodiment of the present invention, a fourth liquid distributor is horizontally installed on the upper part of the stripping section of the distillation tower, and a second stripping layer is provided below the fourth liquid distributor.

[0013] As a preferred embodiment of the present invention, an aniline outlet H is provided on the side shell side of the middle discharge section of the distillation tower, a fifth liquid distributor is horizontally installed below the aniline outlet H, and a third stripping layer is installed below the fifth liquid distributor.

[0014] As a preferred embodiment of the present invention, a cyclohexylamine outlet F is provided on the upper side shell side of the rectifying section of the rectifying tower, a second liquid distributor is horizontally installed below the cyclohexylamine outlet F, and a second rectifying layer is provided below the second liquid distributor.

[0015] As a preferred embodiment of the present invention, a dicyclohexylamine outlet M is provided on the bottom shell side of the reboiler; an opening is provided on the side of the reboiler, a horizontal heater is provided at the opening, a steam inlet K is provided on the top of the horizontal heater on the outer part of the reboiler shell side, and a condensate outlet L is provided at the bottom.

[0016] As a preferred embodiment of the present invention, the top of the first distillation layer is at the same height as or lower than the top of the vertical partition plate, and the tops of the first distillation layer and the third distillation layer are at the same height; the bottom of the first stripping layer is at the same height as or higher than the bottom of the vertical partition plate, and the bottoms of the first stripping layer and the third stripping layer are at the same height; the ratio of the horizontal cross-sectional area of ​​the first distillation layer to the third distillation layer and / or the first stripping layer to the third stripping layer is 1:10 to 10:1.

[0017] As a preferred embodiment of the present invention, the first, second and third rectification layers and the first, second and third stripping layers are all packing layers and have a height of 2 to 12 meters.

[0018] Beneficial effects of the utility model:

[0019] In the production of cyclohexylamine, the organic mixture contains trace amounts of light components, target product 1—cyclohexylamine—with a mass concentration of ≥80%, target product 2—aniline—with a mass concentration of ≤5%, and target product 3—dicyclohexylamine—with a mass concentration of ≤10%. These substances require effective separation to prevent them from affecting product quality and raw material recycling. The present utility model provides distillation equipment for the rectification of cyclohexylamine. This equipment replaces the existing two sets of distillation equipment with a vertical partition plate distillation equipment, enabling continuous distillation and separation of the components in the organic mixture. Compared to the existing two sets of distillation equipment, while maintaining the same production output and quality requirements, the vertical partition plate distillation equipment has a shorter process flow, uses less equipment, and can save approximately 30% of equipment investment. The equipment is also more energy-efficient, saving approximately 30% of energy consumption.

[0020] The condenser is positioned vertically at the top of the distillation tower, creating a compact layout. This facilitates negative pressure operation of the distillation tower, lowering the boiling points of cyclohexylamine and aniline, and facilitating the separation of light components. Liquid cyclohexylamine in the condenser flows directly back into the distillation tower, eliminating the need for piping between the condenser and the distillation tower.

[0021] The distillation tower and the reboiler are directly connected, which reduces the equipment footprint and eliminates the need for a pipe connecting the distillation tower and the reboiler. Compared with discharging from the bottom of the distillation tower, discharging from the bottom of the reboiler results in a lower aniline content and a higher dicyclohexylamine content in the target product 3 under the same energy consumption.

[0022] By using the above distillation equipment, three target products can be obtained. It is a distillation equipment for cyclohexylamine distillation that is safe, environmentally friendly, has a high yield of target products, and has low energy consumption. This utility model aims to save energy and reduce consumption, reduce carbon emissions from production equipment, and protect the environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is the division diagram of the working section of the distillation equipment in this utility model

[0024] Figure 2 This is the distillation equipment diagram of this utility model

[0025] Figure 3 This is the process flow diagram of this utility model

[0026] Among them, the distillation tower 1, the raw material feed pipe 1-1, the first liquid distributor 1-2, the first distillation layer 1-3, the first stripping layer 1-4, the second distillation layer 1-5, the second stripping layer 1-6, the second liquid distributor 1-7, the third liquid distributor 1-8, the fourth liquid distributor 1-9, the third distillation layer 1-10, the third stripping layer 1-11, the fifth liquid distributor 1-12, the vertical partition plate 2, the condenser 3, the head 4, the reboiler 5, and the horizontal heater 6. DETAILED DESCRIPTION

[0027] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are some embodiments of the present invention, not all embodiments. The components of the embodiments of the present invention generally described and illustrated in the drawings herein can be arranged and designed in a variety of different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. All other embodiments derived by ordinary skill in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention. The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the drawings, where the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the drawings are illustrative and intended to explain the present invention, and should not be construed as limiting the present invention.

[0028] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0029] like Figure 1A distillation device for cyclohexylamine rectification comprises a condenser 3, a distillation tower 1 and a reboiler 5; the condenser 3 has a tube side for light components and a shell side for circulating water, and its top is connected to a head 4 via a light component outlet B, and the top of the head 4 is provided with a light component outlet A; the bottom of the condenser 3 is connected to the top of the distillation tower 1 via a gas outlet reflux port E, and the bottom of the distillation tower 1 is connected to the reboiler 5 via a discharge reflux port J; the distillation tower 1 is provided with a rectifying section at the top, a pre-fractionation section and an intermediate discharge section at the middle, and a stripping section at the bottom, with a vertical partition plate 2 installed between the middle pre-fractionation section and the intermediate discharge section; the cyclohexylamine liquid at the top of the tower is refluxed via the gas outlet reflux port E, and the steam at the bottom of the tower is refluxed via the discharge reflux port J.

[0030] The condenser 3 and the distillation tower 1 are vertical cylindrical barrels, and the reboiler 5 is a horizontal cylindrical barrel.

[0031] The upper side shell side of the condenser 3 is provided with a circulating water return outlet C, and the lower side shell side is provided with a circulating water supply inlet D.

[0032] An organic mixed liquid feed inlet G is provided on the side shell side of the middle part of the pre-fractionation section of the distillation tower 1, a raw material feed pipe 1-1 is horizontally installed at the organic mixed liquid feed inlet G, a first distillation layer 1-3 is installed above the raw material feed pipe 1-1, a first liquid distributor 1-2 is horizontally installed below the raw material feed pipe 1-1, and a first stripping layer 1-4 is provided below the first liquid distributor 1-2.

[0033] A fourth liquid distributor 1-9 is horizontally installed on the upper portion of the stripping section of the distillation tower 1, and a second stripping layer 1-6 is provided below the fourth liquid distributor 1-9.

[0034] The distillation tower 1 is provided with an aniline outlet H on the side shell side of the middle discharge section. A fifth liquid distributor 1-12 is horizontally installed below the aniline outlet H. A third stripping layer 1-11 is installed below the fifth liquid distributor 1-12.

[0035] The distillation tower 1 is provided with a cyclohexylamine outlet F on the side shell side of the upper part of the distillation section, a second liquid distributor 1-7 is horizontally installed below the cyclohexylamine outlet F, and a second distillation layer 1-5 is provided below the second liquid distributor 1-7.

[0036] The bottom shell of the reboiler 5 is provided with a dicyclohexylamine outlet M; the side of the reboiler 5 is provided with an opening, and a horizontal heater 6 is provided at the opening. The top of the horizontal heater 6 on the outer side of the shell of the reboiler 5 is provided with a steam inlet K, and the bottom is provided with a condensate outlet L.

[0037] The top of the first distillation layer 1-3 is not higher than the top of the vertical partition plate 2, and the tops of the first distillation layer 1-3 and the third distillation layer 1-10 are at the same height; the bottom of the first distillation layer 1-4 is not lower than the bottom of the vertical partition plate 2, and the bottoms of the first distillation layer 1-4 and the third distillation layer 1-11 are at the same height; the ratio of the horizontal cross-sectional area of ​​the first distillation layer 1-3 to the third distillation layer 1-10 and the first distillation layer 1-4 to the third distillation layer 1-11 is 26:10.

[0038] The first rectifying layer 1-3, the first stripping layer 1-4, the second rectifying layer 1-5, the second stripping layer 1-6, the third rectifying layer 1-10 and the third stripping layer 1-11 are packing layers and have a height of 3 meters.

[0039] In some more specific embodiments, the content is as follows:

[0040] An organic mixed liquid feed port G on the middle side of the distillation tower 1 is connected to a pipeline for delivering the raw material, the organic mixed liquid, from the cyclohexylamine production system; a cyclohexylamine outlet F on the upper side of the distillation tower 1 is connected to a pipeline for delivering the target product 1, the cyclohexylamine, from the de-boundary zone; an aniline outlet H on the middle side of the distillation tower 1 is connected to a pipeline for delivering the target product 2, the aniline, which is recycled from the de-boundary zone; and a dicyclohexylamine outlet M at the bottom of the reboiler 5 is connected to a pipeline for delivering the target product 3, the dicyclohexylamine solution, from the de-boundary zone.

[0041] The light component outlet A at the top of the top head 4 of the condenser 3 is connected to the light component vacuum pipeline of the deboundary area.

[0042] The shell-side circulating return water outlet C on the upper side of the condenser 3 is connected to the circulating return water pipeline of the delimited area, and the shell-side circulating supply water inlet D on the lower side of the condenser 3 is connected to the circulating supply water pipeline from the boundary area.

[0043] The steam inlet K at the top of the horizontal heater 6 is connected to the steam pipeline from the boundary zone, and the condensed water outlet L at the bottom of the horizontal heater 6 is connected to the condensed water pipeline to the boundary zone.

[0044] The method for rectifying cyclohexylamine using the above-mentioned rectifying equipment comprises the following steps:

[0045] (1) Pre-fractionation section: The raw material from the cyclohexylamine production system, an organic mixed liquid (temperature, cyclohexylamine mass concentration of 90.23%, aniline mass concentration of 2.17%, and dicyclohexylamine mass concentration of 6.5%), is fed from the organic mixed liquid feed port G on the side of the distillation tower 1 through the raw material feed pipe 1-1 into the first liquid distributor 1-2 of the distillation tower 1 for pre-fractionation. After pre-fractionation, the organic mixed liquid is initially fractionated. The mixed gas of light components, cyclohexylamine, and aniline flows upward and is first distilled in the first distillation layer 1-3 before being distilled in the distillation section; the mixed liquid of aniline and dicyclohexylamine flows downward and is first distilled in the first stripping layer 1-4 before being distilled in the stripping section.

[0046] (2) Distillation section: The mixed gas of light components, cyclohexylamine and aniline from the pre-fractionation section of the distillation tower 1 is distilled in the distillation section. The mixed gas of light components, cyclohexylamine and aniline flows upward and is first distilled in the second distillation layer 1-5, and performs heat and mass transfer with the cyclohexylamine distributed by the second liquid distributor 1-7 refluxed from the gas reflux port E at the top of the distillation tower 1. The aniline solution flows downward and is distributed by the third liquid distributor 1-8 and then enters the intermediate discharge section. The mixed gas of light components and cyclohexylamine after distillation flows upward and exits the distillation section of the distillation tower 1 from the gas reflux port E at the top of the distillation tower 1 through the bottom of the condenser 3 and enters the condenser 3 pipe side. In condenser 3, cyclohexylamine is condensed into a liquid by circulating water and refluxed from the bottom of condenser 3 through reflux port E into the rectifying section of rectifying tower 1. A portion of the refluxed cyclohexylamine (temperature 84°C, cyclohexylamine content 99.46% by mass) is discharged as target product 1 from the second liquid distributor 1-7 through cyclohexylamine outlet F on the upper side of rectifying tower 1 to the delimited zone. Light component gas (temperature 60°C, vacuum 0.079 MPa) in condenser 3 is discharged from light component outlet B at the top of condenser 3 through light component outlet A at top header 4 to the delimited zone vacuum system. Circulating feed water (temperature 25°C) from the delimited zone enters the shell side of condenser 3 through shell-side circulating feed water inlet D on the lower side of condenser 3. Circulating water (temperature 35°C) after heat exchange in condenser 3 is discharged as circulating return water from the shell-side circulating return water outlet C on the upper side of condenser 3 to the delimited zone.

[0047] (3) Distillation section: The mixed liquid of aniline and dicyclohexylamine from the pre-fractionation section of the distillation tower 1 is stripped in the stripping section. The mixed liquid of aniline and dicyclohexylamine flows downward and is distributed through the fourth liquid distributor 1-9 and then enters the second stripping layer 1-6. It conducts heat and mass transfer with the reflux gas phase (temperature 155°C) at the bottom discharge reflux port J of the distillation tower 1. The stripped aniline gas flows upward and enters the middle discharge section, and the dicyclohexylamine solution flows downward and exits the distillation tower 1 from the bottom discharge reflux port J of the distillation tower 1. The distillation section enters reboiler 5, where the dicyclohexylamine solution is heated by horizontal heater 6. Aniline in the dicyclohexylamine solution (155°C) is heated and evaporated into a gas (155°C). This gas exits reboiler 5 as the vapor phase through reflux outlet J at the bottom of rectifying tower 1 and enters the stripping section of rectifying tower 1. The dicyclohexylamine solution at the bottom of reboiler 5 (155°C, containing 97.26% dicyclohexylamine by mass) exits reboiler 5 through dicyclohexylamine outlet M at the bottom of reboiler 5 as target product 3 and is transported to the delimited zone. Water vapor (183°C, 1.1 MPa) from the delimited zone enters the horizontal heater 6 tube side through steam inlet K at the top tube side of horizontal heater 6. Condensed water (183°C) after heat exchange in reboiler 5 exits the delimited zone through condensate outlet L at the bottom tube side of horizontal heater 6.

[0048] (4) Intermediate discharging section: Aniline solution flowing downward from the rectifying section of the rectifying tower 1 into the third rectifying layer 1-10 of the rectifying tower 1 is subjected to heat and mass transfer with aniline gas flowing upward from the stripping section of the rectifying tower 1 into the intermediate discharging section of the rectifying tower 1. Aniline is rectified in the third rectifying layer 1-10 and enters the fifth liquid distributor 1-12 after rectification. A portion of the aniline in the fifth liquid distributor 1-12 (containing aniline at a mass concentration of 99.6%) is discharged as the target product 2 from the aniline outlet H of the intermediate discharging section of the rectifying tower 1 to the cyclohexylamine production system for reuse, while the remaining portion of the aniline flows downward into the third stripping layer 1-11 and is subjected to heat and mass transfer with the gas phase from the stripping section.

[0049] The results of the operation of the utility model are shown in Table 1.

[0050] Table 1 Performance evaluation results of cyclohexylamine distillation unit in 2,000 tons / year cyclohexylamine production

[0051]

[0052]

Claims

1. A distillation equipment for cyclohexylamine rectification, characterized in that: The distillation equipment comprises a condenser (3), a distillation tower (1) and a reboiler (5); the top of the condenser (3) is connected to the head (4) via a light component outlet B, the top of the head (4) is provided with a light component outlet A, the bottom of the condenser (3) is connected to the top of the distillation tower (1) via a gas outlet reflux port E, and the bottom of the distillation tower (1) is connected to the reboiler (5) via a discharge reflux port J; the distillation tower (1) is provided with a distillation section at the top, a pre-fractionation section and an intermediate discharge section at the middle, and a stripping section at the bottom, a vertical partition plate (2) is installed between the middle pre-fractionation section and the intermediate discharge section, and the pre-fractionation section and the intermediate discharge section are both provided with a stripping layer and a distillation layer.

2. The distillation equipment according to claim 1, characterized in that: The condenser (3) and / or the distillation tower (1) are vertical cylindrical shells, and the reboiler (5) is a horizontal cylindrical shell.

3. The distillation equipment according to claim 1, characterized in that: The upper side shell side of the condenser (3) is provided with a circulating water return outlet C, and the lower side shell side is provided with a circulating water supply inlet D.

4. The distillation equipment according to claim 1, characterized in that: An organic mixed liquid feed inlet G is provided on the side shell side of the middle part of the pre-fractionation section of the distillation tower (1); a raw material feed pipe (1-1) is horizontally installed at the organic mixed liquid feed inlet G; a first distillation layer (1-3) is provided above the raw material feed pipe (1-1); a first liquid distributor (1-2) is horizontally installed below the raw material feed pipe (1-1); and a first stripping layer (1-4) is provided below the first liquid distributor (1-2).

5. The distillation equipment according to claim 1, characterized in that: A fourth liquid distributor (1-9) is horizontally installed on the upper part of the stripping section of the distillation tower (1), and a second stripping layer (1-6) is provided below the fourth liquid distributor (1-9).

6. The distillation equipment according to claim 1, characterized in that: An aniline outlet H is provided on the side shell side of the middle discharge section of the distillation tower (1), a fifth liquid distributor (1-12) is horizontally installed below the aniline outlet H, and a third stripping layer (1-11) is installed below the fifth liquid distributor (1-12).

7. The distillation equipment according to claim 1, characterized in that: The distillation tower (1) is provided with a cyclohexylamine outlet F on the side shell side of the distillation section at the upper part, a second liquid distributor (1-7) is horizontally installed below the cyclohexylamine outlet F, and a second distillation layer (1-5) is provided below the second liquid distributor (1-7).

8. The distillation equipment according to claim 1, characterized in that: The bottom shell side of the reboiler (5) is provided with a dicyclohexylamine outlet M; the side of the reboiler (5) is provided with an opening, and a horizontal heater (6) is provided at the opening; the top of the horizontal heater (6) on the outer part of the shell side of the reboiler (5) is provided with a steam inlet K, and the bottom is provided with a condensed water outlet L.

9. The distillation equipment according to claim 1, characterized in that: The top of the rectifying layer is at the same height as or lower than the top of the vertical partition plate (2), and the bottom of the stripping layer is at the same height as or higher than the bottom of the vertical partition plate (2); and the ratio of the horizontal cross-sectional area of ​​the rectifying layer of the pre-fractionation section to that of the intermediate discharge section and / or the ratio of the horizontal cross-sectional area of ​​the stripping layer of the pre-fractionation section to that of the intermediate discharge section is 1:10 to 10:

1.

10. The distillation equipment according to claim 1, characterized in that: The rectification layer and / or stripping layer is a packing layer and has a height of 2 to 12 meters.

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