Dicyclohexylamine clapboard tower refining process
阅读说明：本技术 二环己胺隔板塔精制工艺 (Dicyclohexylamine clapboard tower refining process ) 是由 陈秋强 于 2021-11-11 设计创作，主要内容包括：本发明公开了二环己胺隔板塔精制工艺,隔板塔内真空精馏,将二环己胺粗品液进入隔板塔的内进行预分馏、公共精馏段分离、公共提馏段分离,侧线采出,本方案首次将隔板塔应用在二环己胺的精制中,经大量实验得具体的工艺参数,二环己胺的纯度大幅提升,且相比传统的多级塔精馏装置,隔板塔以一级塔即可实现二环己胺的提纯,能耗降低,设备数量减少,成本降低。(The invention discloses a dicyclohexylamine clapboard tower refining process, wherein vacuum rectification is carried out in a clapboard tower, a crude dicyclohexylamine product liquid enters the clapboard tower to be subjected to prefractionation, common rectification section separation, common stripping section separation and side line extraction.)
1. The dicyclohexylamine clapboard tower refining process is characterized in that the vacuum rectification step in the clapboard tower is as follows:
1) the dicyclohexylamine crude product liquid enters a feeding section of a clapboard tower for pre-fractionation, light components and dicyclohexylamine enter an upper common rectification section, and heavy components and dicyclohexylamine enter a lower common stripping section;
2) the condensate of the components in the public rectification section has the following reflux ratio: 50-100, respectively entering a feeding section and a side line extraction section at two sides of the partition plate after passing through the common rectification section, wherein the liquid quality a and b distributed to enter the feeding section and the side line extraction section need to meet the following requirements: by mass, a is more than or equal to b, the temperature of the top of the tower is more than 130 ℃ in the public rectification process, and the pressure of the top of the tower is more than or equal to-90 kPa;
the common stripping section separates the heavy component and the dicyclohexylamine, the heavy component is distilled off from the tower bottom, and the component obtained by stripping and the component obtained by rectifying in the rectifying section enter a side line extraction section for extraction.
2. The dicyclohexylamine baffled column finishing process of claim 1, wherein: the concentration of dicyclohexylamine in the crude product liquid is more than 90%, the low-boiling-point substance is less than 1%, and the high-boiling-point substance is less than 9% by mass.
3. The dicyclohexylamine baffled column finishing process of claim 1, wherein: feed temperature range of crude liquid: 90-130 ℃, and the feed flow range of the crude product liquid: 1.0-2.5 t/h.
4. The dicyclohexylamine baffled column finishing process of claim 1, wherein: and the bottom liquid phase of the common rectification section is received by a distribution disc and pumped out by a pump outside the clapboard tower, and the liquid entering the feeding sections and the lateral line extraction sections at the two sides of the clapboard is distributed by a flow controller.
5. The dicyclohexylamine baffled column finishing process of claim 4, wherein: the first liquid level controller is added to control the liquid level of the bottom liquid phase of the public rectification section, the first flow controller and the second flow controller are respectively arranged on output pipelines of a pump to the feeding section and the side line extraction section, and the first liquid level controller regulates the flow of the first flow controller and the second flow controller in a cascade mode to control the liquid level of the bottom liquid phase.
6. The dicyclohexylamine baffled column finishing process of claim 1, wherein: and a third flow controller is arranged on a pipeline of the public rectification section, which is conveyed to the reflux tank, a second pump is installed at the outlet of the reflux tank, a fourth flow controller is arranged on a pipeline of a water outlet of the second pump, which is conveyed to the public rectification section, the reflux tank is provided with a second liquid level controller to control the liquid level in the reflux tank, and the second liquid level controller is used for adjusting the flow of the third flow controller and the flow of the fourth flow controller in a cascade manner to control the liquid level of the reflux tank.
7. The dicyclohexylamine baffled column finishing process of claim 1, wherein: and a temperature controller is arranged at the tower kettle of the clapboard tower, a fifth flow controller is arranged on a heat carrier inlet pipeline of the reboiler, and the fifth flow controller is adjusted in cascade by the temperature controller to adjust the temperature of the tower kettle.
8. The dicyclohexylamine baffled column finishing process of claim 1, wherein: a flow controller six is arranged on a pipeline at the inlet of an intermediate tank for containing components extracted from a side extraction section, a pump three is arranged at the outlet of the intermediate tank, the outlet of the pump three is connected with the side extraction section of the partition tower through a pipeline, a flow controller seven is arranged on the pipeline, a liquid level controller three is arranged on the intermediate storage tank, the flow controller six is adjusted in a cascade mode through the liquid level controller three to control the liquid level in the intermediate tank, a liquid level controller four is arranged at the kettle of the partition tower, and the flow controller seven is adjusted in a cascade mode through the liquid level controller four to control the liquid level in the tower kettle.
Technical Field
The invention relates to the technical field of dicyclohexylamine purification, in particular to a dicyclohexylamine clapboard tower refining process.
Background
Dicyclohexylamine is mainly used for organic synthesis, and is also used as an insecticide, an acid gas absorbent and a steel antirust agent, and the traditional dicyclohexylamine refining is mainly carried out through a multistage tower, so that the cost is high, the energy consumption is high, and the industrial requirements are not met.
The clapboard tower has great advantage for multi-component separation, and is a completely thermally coupled rectifying tower, and is structurally characterized in that a vertical clapboard is arranged in a rectifying tower and is divided into an upper public rectifying section, a lower public stripping section, a rectifying and feeding section (a pre-rectifying tower) at two sides and a side line withdrawing section (a main tower). The partition plate tower becomes novel tower equipment which is ideal in thermodynamics due to the structural characteristics, and has the advantages of greatly improving the thermodynamic efficiency, reducing the energy consumption and reducing the equipment investment and the occupied area. At present, the aim of energy crisis is aggravated, the baffle tower rectification process is suitable for popularization, but the application cases of the baffle tower are few at present, and particularly, almost no precedent is found in the refining application of dicyclohexylamine, so that the method is used for refining dicyclohexylamine through the baffle tower.
Disclosure of Invention
In order to solve at least one technical defect, the invention provides the following technical scheme:
the application document discloses a dicyclohexylamine clapboard tower refining process, wherein the vacuum rectification step in the clapboard tower is as follows:
1) the dicyclohexylamine crude product liquid enters a feeding section of a clapboard tower for pre-fractionation, light components and dicyclohexylamine enter an upper common rectification section, and heavy components and dicyclohexylamine enter a lower common stripping section;
2) the condensate of the components in the public rectification section has the following reflux ratio: 50-100, respectively entering a feeding section and a side line extraction section at two sides of the partition plate after passing through the common rectification section, wherein the liquid quality a and b distributed to enter the feeding section and the side line extraction section need to meet the following requirements: by mass, a is more than or equal to b, the temperature of the top of the tower is more than 130 ℃ in the public rectification process, and the pressure of the top of the tower is more than or equal to-90 kPa;
the common stripping section separates the heavy component and the dicyclohexylamine, the heavy component is distilled off from the tower bottom, and the component obtained by stripping and the component obtained by rectifying in the rectifying section enter a side line extraction section for extraction.
In the whole process of rectification separation, the reflux ratio is the core of rectification, and the reflux ratio is an important parameter for the design and operation of rectification. If the reflux ratio is set too high, the consumption of the heating steam and the cooling water increases, and the operation cost increases. And the reflux ratio is too large, so that the difficulty of changing the tower during operation is increased, and the effect of adjusting the separation capacity of the tower is also greatly reduced.
To facilitate the desired separation, it is necessary to maintain a high concentration of dicyclohexylamine on the side draw tray. A large number of experiments are carried out to select a proper reflux ratio: 50-100. Generally, if the purity of the dicyclohexylamine product is lower, the reflux ratio can be increased appropriately, and if the reboiler energy consumption is higher, the reflux ratio can be decreased appropriately.
The pressure of the rectifying tower directly influences the boiling point and the relative volatility of the separated system, and the lower the pressure is, the lower the boiling point of the substance is, and the less energy is required for rectification. For dicyclohexylamine, which is a higher boiling organic substance, vacuum rectification is usually used. Therefore, the pressure at the top of the rectifying column needs to be strictly controlled. The increased pressure results in a decrease in dicyclohexylamine purity and an increase in reboiler duty. The design requires that the gauge pressure at the tower top is not less than-90 kPa, the corresponding tower top temperature is more than 130 ℃, the temperature is about 160 ℃ at the maximum in the purification of dicyclohexylamine, and the design can be adjusted according to the boiling points of different light components.
The biggest difference between the baffle tower and the traditional rectifying tower is that liquid redistribution is needed in the middle section of the tower, and liquid gradually accumulates due to overlarge liquid holdup of the tower plate, so that part of the tower section is filled with the liquid, ascending gas is blocked, and the mass and heat transfer process of gas and liquid phases cannot be normally carried out. When the liquid is too little, the liquid on the tower plate is completely evaporated to form a dry plate. These phenomena are detrimental to the normal operation of the rectification column. Therefore, in order to maintain the normal operation of the rectification process at the two sides of the separation wall, the reflux liquid needs to be redistributed, the mass of the liquid entering the product side is not less than 1 time of the mass extracted from the side line after a large amount of experiments, if the temperature at one side is higher, the distribution amount at one side is properly increased, and if the purity of the product is lower, the reflux at the product extraction side can be properly increased.
To sum up, this scheme is used the baffle tower in dicyclohexylamine's refining for the first time, obtains specific technological parameter through a large amount of experiments, and dicyclohexylamine's purity promotes by a wide margin, and compares traditional multistage tower rectifier unit, and the baffle tower can realize dicyclohexylamine's purification with the one-level tower, and the energy consumption reduces, and equipment quantity reduces, cost reduction.
Furthermore, the concentration of dicyclohexylamine in the crude dicyclohexylamine solution is more than 90%, the content of low-boiling-point substances is less than 1%, and the content of high-boiling-point substances is less than 9%, by mass, through detection, the dicyclohexylamine crude solution contains impurities such as cyclohexylaniline, diphenylamine, cyclohexylamine, cyclohexanol and the like, and the impurities can directly influence the quality of dicyclohexylamine products. When the content of impurities in the raw materials is increased, the separation difficulty of the clapboard tower is increased, and the concentration range of the crude product liquid is preferably selected correspondingly so as to better purify the product.
Further, the feed temperature range of the crude liquid: 90-130 ℃, and the feed flow range of the crude product liquid: 1.0-2.5t/h, and the thermal state and flow rate of the feeding directly influence the flow rate of gas and liquid in the tower. When the heat brought into the tower by the feeding belt is increased, if the reflux ratio is kept constant, in order to keep the load of the condenser at the top of the tower constant, the more the feeding is, the less the heat supply at the bottom of the tower is, and the steam quantity rising from the bottom of the tower is reduced, so that the separation capacity of each tower plate at the stripping section is reduced; if the vaporization quantity in the tower kettle is kept unchanged, the heat quantity entering the tower is increased, the more steam rises in the rectifying section, the load of the condenser at the tower top is increased, and the feeding temperature range is preferably selected for ensuring the stable operation of refining.
Further, the bottom liquid phase of the public rectification section is received by a distribution disc and pumped out by a pump outside the partition tower, the liquid entering the feeding section and the side line extraction section at the two sides of the partition is distributed by the flow controller, and the flow controller is used for distributing the flow conveyed to the feeding section and the side line extraction section again and accurately, so that the purity of a finished product and the stability of equipment operation are improved.
Furthermore, a first liquid level controller is added to control the liquid level of the bottom liquid phase of the public rectification section, a first flow controller and a second flow controller are respectively arranged on output pipelines of the pump to the feeding section and the side line extraction section, and the first liquid level controller adjusts the flow of the first flow controller and the second flow controller in a cascade mode to control the liquid level of the bottom liquid phase, accurately distributes the flow and enables the bottom liquid phase to be maintained at a proper liquid level, and stable operation of equipment is facilitated.
Furthermore, a third flow controller is arranged on a pipeline of the public rectification section to the reflux tank, a second pump is installed at the outlet of the reflux tank, a fourth flow controller is arranged on a pipeline of a water outlet of the second pump to the public rectification section, a second liquid level controller is arranged on the reflux tank to control the liquid level in the reflux tank, and the second liquid level controller is used for adjusting the flow of the third flow controller and the flow of the fourth flow controller in a cascade mode to control the liquid level of the reflux tank, so that stable operation of equipment is facilitated.
Furthermore, a temperature controller is arranged at the tower kettle of the clapboard tower, a fifth flow controller is arranged on a heat carrier inlet pipeline of the reboiler, and the flow of the fifth flow controller is adjusted in a cascade mode through the temperature controller so as to adjust the temperature of the tower kettle, so that stable operation of equipment is facilitated.
Furthermore, a flow controller six is arranged on a pipeline at the inlet of an intermediate tank for containing components extracted from a side extraction section, a pump three is arranged at the outlet of the intermediate tank, an outlet of the pump three and a side extraction section of the partition tower are connected through a pipeline, a flow controller seven is arranged on the pipeline, a liquid level controller three is arranged on the intermediate storage tank, the flow controller six is adjusted in a three-cascade mode by the liquid level controller to control the liquid level in the intermediate tank, a liquid level controller four is arranged at the tower kettle of the partition tower, and the flow controller seven is adjusted in a four-cascade mode by the liquid level controller to control the liquid level of the tower kettle, so that stable operation of equipment is facilitated.
Compared with the prior art, the invention has the beneficial effects that:
1. the invention applies the clapboard tower to the refining of the dicyclohexylamine for the first time, and selects specific technological parameters, so that the purity of the refined dicyclohexylamine is greatly improved, the energy consumption is reduced, the cost is reduced, and the method is suitable for popularization.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
FIG. 1 is a schematic diagram of the present dividing wall column configuration;
FIG. 2 is a schematic diagram of a liquid level regulating structure of a bottom liquid phase of a public rectification section;
FIG. 3 is a schematic view of a reflux drum level adjustment configuration;
FIG. 4 is a schematic view of a tundish level adjustment configuration;
FIG. 5 is a schematic view of a column bottom temperature regulation structure;
FIG. 6 is a schematic diagram of a liquid level regulating structure of a tower kettle;
wherein the reference numerals are:
1. a baffle tower; 2. a preheater; 3. a reflux tank; 4. an intermediate tank; 5. a reboiler; 6. a first pump; 7. a first flow controller; 8. a second flow controller; 9. a first liquid level controller; 10. a second liquid level controller; 11. a third flow controller; 12. a second pump; 13. a fourth flow controller; 14. a fifth flow controller; 15. a third liquid level controller; 16. a flow controller six; 17. a third pump; 18. a liquid level controller IV; 19. a seventh flow controller; 20. a temperature controller.
Detailed Description
The invention is further described with reference to the following figures and specific examples.
As shown in figure 1, the number of theoretical plates of the partition tower is 25-35, a middle tank 4 is arranged outside the partition tower corresponding to a side extraction section to contain extracted components, a reflux tank 3 is arranged outside the partition tower corresponding to a public rectification section, a preheater 2 is arranged at an inlet of a feeding section of the partition tower, and a reboiler 5 is arranged outside a tower kettle.
In order to conveniently adjust the split flow, as shown in fig. 2, the bottom liquid phase of the common rectification section is supported by a distribution tray and is pumped out by a pump I6 outside the partition tower, the pump I6 is respectively provided with a flow controller I7 and a flow controller II 8 on output pipelines of the feeding section and the lateral line extraction section so as to distribute the liquid entering the feeding section and the lateral line extraction section, a liquid level controller I9 is arranged so as to control the liquid level of the bottom liquid phase of the common rectification section, and the flow controllers I7 and II 8 are adjusted in series by the liquid level controller I9 so as to control the liquid level of the bottom liquid phase.
In order to conveniently adjust the liquid level of the reflux tank, as shown in fig. 3, a third flow controller 11 is installed on a pipeline which is transmitted to the reflux tank 3 by the public rectification section, a second pump 12 is installed at an outlet of the reflux tank 3, a fourth flow controller 13 is installed on a pipeline which is transmitted to the public rectification section by a water outlet of the second pump, a second liquid level controller 10 is installed on the reflux tank 3, and the second liquid level controller 10 serially adjusts the flow sum of the third flow controller 11 and the fourth flow controller 13 to control the liquid level in the reflux tank, so that the stable operation of equipment is facilitated.
In order to conveniently adjust the liquid levels of the intermediate tank and the tower kettle, as shown in fig. 4 and 6, a flow controller six 16 is installed on a pipeline of the side line extraction section, which is conveyed to the intermediate tank 4, and is communicated with the intermediate tank 4 through a pump three 17, a flow controller seven 19 is installed on an outlet of the pump three 17 and a pipeline of the side line extraction section, a liquid level controller three 15 is installed on the intermediate tank 4, the flow controller six 16 is cascaded through the liquid level controller three 15 to adjust the liquid level in the intermediate tank, and a liquid level controller four 18 is installed at the partition tower kettle to adjust the liquid level in the tower kettle through the flow controller seven cascaded through the liquid level controller four.
As shown in fig. 5, a temperature controller 20 is installed at the tower, and a fifth flow controller 14 is installed on the heat carrier inlet pipe of the reboiler 5, so that the fifth flow controller is cascaded to adjust the temperature in the tower.
The following examples are further illustrated by the above-described apparatus for the example which is the above-described dividing wall column and the theoretical plate number is 30.
Example 1
The dicyclohexylamine partition tower refining process is characterized in that dicyclohexylamine is refined by vacuum distillation in a partition tower, and the method comprises the following steps:
1) the dicyclohexylamine crude product liquid is preheated by a preheater and then enters a feeding section of a clapboard tower for prefractionation, the feeding temperature and the flow rate are shown in table 1, light components and dicyclohexylamine enter an upper common rectification section, and heavy components and dicyclohexylamine enter a lower common stripping section.
2) In the public rectification process, the temperature of the top of the tower is about 130 ℃, the pressure of the top of the tower is about-90 kPa, after the public rectification section is separated, light components are discharged, condensate liquid in a reflux tank flows back, the reflux ratio is 60, the light components respectively enter a feeding section and a side line extraction section at two sides of a partition board after passing through the public rectification section to form reflux, and the liquid quality a and b distributed to enter the feeding section and the side line extraction section need to meet the following requirements: on the basis of mass, the mass of a is the same as that of b, namely the liquid separation ratio is 1, and the refined component is extracted from the side line section at the extraction flow rate of 2.51m3/h。
The common stripping section separates the heavy component and the dicyclohexylamine, the heavy component is obtained at the bottom of the tower, and the extraction flow rate is 0.21m3And/h, feeding the components obtained by stripping and the components obtained by rectifying in the rectifying section into a side line extraction section, and extracting the components into an intermediate tank, wherein the concentration of dicyclohexylamine is 99.74 percent as shown in Table 1.
The feed, temperature, flow rate, etc. of dicyclohexylamine are shown in table 1:
TABLE 1
Description of the invention
Feeding of the feedstock
Light component
Heavy fraction
Dicyclohexylamine
Mass fraction
wt％
wt％
wt％
wt％
Hexane (C)
0.0135
2.17％
0.00％
0.00％
Cyclohexylamine
0.2997
55.76％
0.00％
0.00％
HexOH
0.0060
0.81％
0.00％
0.00％
Dicyclohexylamine
95.4443
41.08％
63.34％
99.74％
High boiling substance
3.8861
0.04％
34.25％
0.00％
Low boiling point substance
0.1939
0.08％
0.41％
0.29％
Diimines
0.0011
0.00％
0.04％
0.01％
Cyclohexylaniline
0.0090
0.00％
0.12％
0.00％
Diphenylamine
0.1461
0.01％
1.88％
0.01％
Aniline
0.0003
0.04％
0.00％
0.00％
Volume flow (m)3/h)
2.5
0.35
0.21
2.51
Example 2
The steps required by the baffle tower refining process of dicyclohexylamine are consistent with those in example 1, and the difference is that:
in the crude liquid, the concentration of dicyclohexylamine was 97%, the overhead temperature was about 140 ℃, the overhead pressure was about-95 kPa, the reflux ratio was 80, the partition ratio was 1.5, the concentration of dicyclohexylamine produced was 99.84%, and others are shown in table 2.
TABLE 2
Description of the invention
Feeding of the feedstock
Light component
Heavy fraction
Dicyclohexylamine
Mass fraction
wt％
wt％
wt％
wt％
Hexane (C)
0.03％
2.17％
0.00％
0.00％
Cyclohexylamine
0.75％
55.76％
0.00％
0.00％
HexOH
0.01％
0.81％
0.00％
0.00％
Dicyclohexylamine
97.00％
41.08％
63.34％
99.84％
High boiling substance
1.75％
0.04％
34.25％
0.00％
Low boiling point substance
0.30％
0.08％
0.41％
0.15％
Diimines
0.01％
0.00％
0.04％
0.01％
Cyclohexylaniline
0.01％
0.00％
0.12％
0.00％
Diphenylamine
0.16％
0.01％
1.88％
0.01％
Aniline
0.00％
0.04％
0.00％
0.00％
Volume flow (m)3/h)
2.5
0.35
0.21
2.51
Example 3
The steps required by the baffle tower refining process of dicyclohexylamine are consistent with those in example 1, and the difference is that:
in the crude liquid, the concentration of dicyclohexylamine was 96%, the overhead temperature was about 150 ℃, the overhead pressure was about-100 kPa, the reflux ratio was 100, the partition ratio was 2, the concentration of dicyclohexylamine produced was 99.79%, and the others are shown in table 3.
TABLE 3
Description of the invention
Feeding of the feedstock
Light component
Rectifying tower bottoms
Dicyclohexylamine
Mass fraction
wt％
wt％
wt％
wt％
Hexane (C)
0.03％
2.17％
0.00％
0.00％
Cyclohexylamine
0.75％
55.76％
0.00％
0.00％
HexOH
0.01％
0.81％
0.00％
0.00％
Dicyclohexylamine
96.00％
41.08％
63.34％
99.79％
High boiling substance
2.75％
0.04％
34.25％
0.00％
Low boiling point substance
0.30％
0.08％
0.41％
0.20％
Diimines
0.01％
0.00％
0.04％
0.01％
Cyclohexylaniline
0.01％
0.00％
0.12％
0.00％
Diphenylamine
0.16％
0.01％
1.88％
0.01％
Aniline
0.00％
0.04％
0.00％
0.00％
Volume flow (m)3/h)
2.5
0.35
0.21
2.51
Through analysis, compared with the original multi-stage tower process, the cost for preparing dicyclohexylamine by the process is reduced by about 30 percent.
The above is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above-mentioned embodiments, and all technical solutions belonging to the idea of the present invention belong to the protection scope of the present invention. It should be noted that modifications and embellishments within the scope of the invention may occur to those skilled in the art without departing from the principle of the invention, and are considered to be within the scope of the invention.
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