Rectification method for deep dehydration of triethylamine

Abstract

The invention belongs to the technical field of triethylamine dehydration, and provides a rectification method for deep dehydration of triethylamine, which comprises the following steps: mixing crude triethylamine and a sodium hydroxide solution, carrying out preliminary dehydration, carrying out three times of rectification on the pretreated triethylamine, collecting a front fraction at the tower top after each rectification, and continuously rectifying the residual material to obtain the triethylamine. Deeply dehydrated triethylamine is obtained from the tower kettle after the third rectification; the water content of the deeply dehydrated triethylamine is less than or equal to 0.2%. According to the invention, the crude triethylamine is refined by adopting a method of combining chemical dehydration and rectification; in the rectification process, the characteristic that triethylamine and water are azeotropic at 75.8 DEG C is utilized, water can be removed from tower top fraction discharge, the water content of a tower kettle material triethylamine is controlled to be lower than 0.2%, and the requirement for recycling glyphosate is met; compared with a solid caustic soda dehydration method, the method disclosed by the invention is environment-friendly, and compared with a direct rectification method, the method disclosed by the invention is small in heat loss and low in cost; and continuous intelligent operation can be realized.

Description

Technical Field

[0001] The invention relates to the technical field of triethylamine dehydration, in particular to a distillation method for deep dehydration of triethylamine. Background Art

[0002] Crude triethylamine cannot be directly used for glyphosate synthesis because it contains 2-5% water. It needs to be further dehydrated and refined to make its water content less than 0.2% before recycling. At present, the deep dehydration and refining of crude triethylamine adopts the solid alkali dehydration method. The water in triethylamine is absorbed by the solid alkali, and the solid alkali becomes liquid alkali for pH adjustment of glyphosate mother liquor. The crude triethylamine is dehydrated to a water content of less than 0.2% and returned to the system for application. This solid alkali deep dehydration process has been used for a long time and is stable and mature, but its shortcomings continue to emerge: ① Because the recovery process is intermittent operation, the production cycle is long, the equipment production capacity is low, and the investment is large; it is difficult to adapt to the control requirements of intelligent, automated, and unmanned operation. ② Triethylamine is a toxic, harmful, and volatile substance. The addition of solid alkali to crude triethylamine and pH value detection are all manual operations, which are labor-intensive. During the operation, triethylamine is very volatile and the environmental pollution is serious. ③ When the "oil phase" and "water phase" are separated by layers, misjudgment is prone to occur, and the operating conditions and methods are difficult to master, resulting in a small amount of alkali solution being carried in the triethylamine, affecting subsequent production.

[0003] The boiling point of triethylamine is 89.5°C, the boiling point of water is 100°C, and the difference between the two boiling points is 10.5°C, which is a small difference; triethylamine and water can form an azeotrope, the azeotropic point is 75.8°C, and the azeotropic composition is 90% triethylamine and 10% water. These characteristics of triethylamine make it impossible to use ordinary distillation process when distilling crude triethylamine to obtain refined triethylamine with a water content of less than 0.2%.

[0004] Therefore, there is an urgent need to replace the solid alkali deep dehydration process with a continuous distillation deep dehydration process to facilitate the realization of automation, intelligence and unmanned control requirements, and avoid environmental pollution caused by triethylamine leakage and the impact on the health of operators. Summary of the invention

[0005] The object of the invention is to provide a rectification method for deep dehydration of triethylamine in view of the deficiencies in the prior art.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] The present invention provides a distillation method for deep dehydration of triethylamine, comprising the following steps:

[0008] 1) crude triethylamine and sodium hydroxide solution are mixed and preliminarily dehydrated to obtain pretreated triethylamine;

[0009] 2) The pretreated triethylamine is distilled three times, and the front fraction is collected at the top of the tower after each distillation, and the remaining material is further distilled, and the tower bottom is used to obtain deeply dehydrated triethylamine after three distillations; the water content of the deeply dehydrated triethylamine is ≤0.2%.

[0010] Preferably, the mass concentration of the sodium hydroxide solution is 30-40%; the mass fraction of the sodium hydroxide solution is 5-8% of the crude triethylamine.

[0011] Preferably, the water content of crude triethylamine is 2-3%; the water content of pretreated triethylamine is 0.5-1%.

[0012] Preferably, the water content of the fore fraction collected after the first distillation is 8-10%, the water content of the fore fraction collected after the second distillation is 2-5%, and the water content of the fore fraction collected after the third distillation is 0.2-0.3%.

[0013] Preferably, the total amount of the front fraction is 5.5-6.3% of the mass of the pretreated triethylamine; and the gas phase temperature of the front fraction is ≤88°C.

[0014] Preferably, the distillation adopts a packed tower with a tower diameter of 1 to 1.4 m and a tower height of 13 to 17 m, wherein the distillation section is 3 to 5 m high and the stripping section is 3 to 5 m high; the plate spacing is 0.55 to 0.65 m.

[0015] Preferably, the number of plates of the packed tower is 8 to 12, the pretreated triethylamine is fed on the 5th to 6th plates, the reflux ratio is 1.2 to 1.7, and the flooding fraction of the 10th plate is 58.5 to 60%;

[0016] Both the rectification section and the stripping section are packed towers, and the material and packing of the packed towers are stainless steel.

[0017] As a preferred embodiment, the load of the tower bottom reboiler is 925-945 kW / h, the steam consumption is 1.55-1.75 t / h, and the heat exchange area of ​​the tower bottom reboiler is 65-85 m 2 ;

[0018] The load of the top condenser is 705-722 kW / h, the circulating cooling water consumption is 74-77 t / h, and the heat exchange area of ​​the top condenser is 45-55 m 2 ; The top condenser is cooled to 72-76°C.

[0019] Preferably, the load of the triethylamine mixed liquid cooler at the top of the tower is 72 to 85 kW / h, the circulating cooling water consumption is 13 to 14.5 t / h, the circulating cooling water temperature is 4 to 10°C, and the heat exchange area of ​​the triethylamine mixed liquid cooler at the top of the tower is 15 to 22 m 2 ; The triethylamine mixed solution at the top of the tower is cooled to 20-30°C;

[0020] The load of the triethylamine condenser at the bottom of the tower is 200-220kW / h, the circulating cooling water consumption is 35.5-37.5t / h, the circulating cooling water temperature is 4-10℃, and the heat exchange area of ​​the triethylamine condenser at the bottom of the tower is 35-45m 2 ; The triethylamine at the bottom of the tower is cooled to 20-30°C.

[0021] The beneficial effects of the present invention include:

[0022] 1) The present invention adopts a method combining chemical dehydration and distillation to purify crude triethylamine; in the distillation process, the characteristic of triethylamine and water being azeotropic at 75.8°C (azeotropic composition: 90% triethylamine, 10% water) is utilized, water can be removed from the top fraction, and the water content of triethylamine in the bottom material is controlled to be lower than 0.2%, so as to meet the requirements of recycling of glyphosate and the requirements of low water content of triethylamine in other processes; compared with the solid alkali dehydration method, the method of the present invention can be environmentally friendly, and compared with the direct distillation method, the heat loss is small and the cost is low; and continuous intelligent operation can be realized.

[0023] 2) The whole process of the distillation method of the present invention does not require the addition of solid materials, and the whole process is carried out in a closed system in a continuous, intelligent and automated manner, which will not affect the health of the workers and will not pollute the environment. DETAILED DESCRIPTION

[0024] The present invention provides a distillation method for deep dehydration of triethylamine, comprising the following steps:

[0025] 1) crude triethylamine and sodium hydroxide solution are mixed and preliminarily dehydrated to obtain pretreated triethylamine;

[0026] 2) The pretreated triethylamine is distilled three times, and the front fraction is collected at the top of the tower after each distillation, and the remaining material is further distilled, and the tower bottom is used to obtain deeply dehydrated triethylamine after three distillations; the water content of the deeply dehydrated triethylamine is ≤0.2%.

[0027] In the present invention, the mass concentration of the sodium hydroxide solution is preferably 30-40%, more preferably 33-36%, more preferably 35%; the mass fraction of the sodium hydroxide solution is preferably 5-8%, more preferably 6-7% of the crude triethylamine.

[0028] In the present invention, the water content of crude triethylamine is preferably 2-3%, more preferably 2.3-2.7%, and more preferably 2.5%; the water content of pretreated triethylamine is preferably 0.5-1%, more preferably 0.6-0.9%, and more preferably 0.7-0.8%.

[0029] The dehydration load of the initial dehydration is to a triethylamine water content of 0.5%. The triethylamine water content below 0.5% cannot be removed by adding liquid alkali.

[0030] In the present invention, the water content of the fore fraction collected after the first distillation is preferably 8-10%, more preferably 9%, the water content of the fore fraction collected after the second distillation is preferably 2-5%, more preferably 3-4%, and the water content of the fore fraction collected after the third distillation is preferably 0.2-0.3%, more preferably 0.25%.

[0031] In the present invention, the total amount of the front fraction is preferably 5.5-6.3% of the mass of the pretreated triethylamine, more preferably 5.8-6.1%, and more preferably 6%; the gas phase temperature of the front fraction is preferably ≤88°C.

[0032] In actual production, the packed tower needs to consider the following requirements: a) large production capacity: at a large gas (vapor) liquid flow rate, a large amount of mist entrainment, liquid interception or liquid flooding will not occur, which will disrupt normal operation; b) stable operation and high flexibility: when the gas (vapor) liquid load of the tower equipment fluctuates greatly, it can still operate stably at a high mass transfer efficiency, and the tower equipment should ensure long-term stable operation; c) small resistance to fluid flow, that is, small pressure drop of the fluid through the tower equipment, which will greatly save power consumption in production and reduce normal operating costs; d) simple structure, small material consumption, easy manufacturing and installation, which can reduce investment costs in the infrastructure process; e) the material should be corrosion-resistant, the tower structure should not be easily blocked, and it should be convenient to operate, adjust and overhaul. Combined with the load amplification and operation flexibility in actual production, the tower diameter and tower height of the present invention are designed.

[0033] In the present invention, the pretreated triethylamine is distilled three times in three towers, and after the first distillation, the fore fraction is collected at the tower top, and alkali liquor is added to the collected fore fraction, and the pH value of the mixed solution is adjusted to 8 and then separated to obtain a water layer and a triethylamine layer with a water content of 2%, and the triethylamine is mixed with a sodium hydroxide solution for preliminary dehydration to obtain the pretreated triethylamine (with a water content of 0.5-1%), and the pretreated triethylamine enters the first tower again, and the tower bottom liquid enters the second tower for the second distillation; after the second distillation, the fore fraction is collected at the tower top, and alkali liquor is added to the collected fore fraction for preliminary dehydration to obtain the pretreated triethylamine (with a water content of 0.5-1%), and the pretreated triethylamine enters the first tower again, and the tower bottom liquid enters the third tower for the third distillation; after the third distillation, the fore fraction is collected at the tower top, and the collected fore fraction enters the feed tank of the first tower; after the third distillation, deeply dehydrated triethylamine is obtained in the tower bottom.

[0034] In the present invention, a packed tower is used for distillation, and the tower diameter is preferably 1-1.4 m, more preferably 1.1-1.3 m, and more preferably 1.2 m. The tower height is preferably 13-17 m, more preferably 14.5-15.5 m, and more preferably 15.05-15.3 m. Among them, the distillation section height is preferably 3-5 m, more preferably 3.8-4.3 m, and more preferably 4.05 m, and the stripping section height is preferably 3-5 m, more preferably 3.8-4.2 m, and more preferably 4-4.1 m; the plate spacing is preferably 0.55-0.65 m, more preferably 0.58-0.62 m, and more preferably 0.6 m.

[0035] In the present invention, the number of plates of the packed tower is preferably 8 to 12, more preferably 10, the pretreated triethylamine is fed on the 5th to 6th plates, the reflux ratio is preferably 1.2 to 1.7, more preferably 1.5, and the flooding fraction on the 10th plate is preferably 58.5 to 60%, more preferably 59 to 59.6%, and more preferably 59.3 to 59.4%;

[0036] Both the rectifying section and the stripping section are packed towers, and the material and packing of the packed towers are preferably stainless steel, and more preferably 304 stainless steel.

[0037] The material and filler of the packed tower of the present invention can reduce the cost.

[0038] In the present invention, the load of the bottom reboiler is preferably 925 to 945 kW / h, more preferably 935 to 941 kW / h, and more preferably 938 kW / h. The steam consumption is preferably 1.55 to 1.75 t / h, more preferably 1.65 to 1.7 t / h, and more preferably 1.68 t / h. The heat exchange area of ​​the bottom reboiler is preferably 65 to 85 m 2 , more preferably 70 to 80 m 2 , preferably 73m 2 ;

[0039] The load of the top condenser is preferably 705 to 722 kW / h, more preferably 712 to 718 kW / h, and more preferably 714 to 716 kW / h. The circulating cooling water consumption is preferably 74 to 77 t / h, and more preferably 75.5 to 76 t / h. The heat exchange area of ​​the top condenser is preferably 45 to 55 m 2 , more preferably 47 to 50 m 2 , preferably 48m 2 The top condenser is preferably cooled to 72-76°C, more preferably to 73-75°C, and even more preferably to 74°C.

[0040] In the present invention, the load of the triethylamine mixed liquid cooler at the top of the tower is preferably 72 to 85 kW / h, more preferably 75 to 80 kW / h, more preferably 82 to 83 kW / h, the circulating cooling water consumption is preferably 13 to 14.5 t / h, more preferably 13.5 to 13.9 t / h, more preferably 13.7 to 13.8 t / h, the temperature of the circulating cooling water is preferably 4 to 10°C, more preferably 6 to 8°C, more preferably 7°C, and the heat exchange area of ​​the triethylamine mixed liquid cooler at the top of the tower is preferably 15 to 22 m 2 , more preferably 17 to 20 m 2 , more preferably 18 to 19 m 2 The triethylamine mixture at the top of the tower is preferably cooled to 20 to 30°C, more preferably 24 to 25°C;

[0041] The load of the triethylamine condenser at the bottom of the tower is preferably 200 to 220 kW / h, more preferably 205 to 215 kW / h, more preferably 210 to 211.4 kW / h, the circulating cooling water consumption is preferably 35.5 to 37.5 t / h, more preferably 36 to 37 t / h, more preferably 36.5 to 36.6 t / h, the temperature of the circulating cooling water is preferably 4 to 10°C, more preferably 6 to 8°C, more preferably 7°C, and the heat exchange area of ​​the triethylamine condenser at the bottom of the tower is preferably 35 to 45 m 2 , more preferably 37 to 40 m 2 , more preferably 38 to 39 m 2 The triethylamine at the bottom of the tower is preferably cooled to 20 to 30°C, more preferably 24 to 25°C.

[0042] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0043] In the embodiment, the mass concentration of the NaOH solution is 35%.

[0044] Example 1

[0045] NaOH solution is added to crude triethylamine with a water content of 2% (the added NaOH solution is 7% of the mass fraction of the crude triethylamine), and preliminary dehydration is carried out at 50° C. to obtain triethylamine with a water content of 0.5%.

[0046] Triethylamine with a water content of 0.5% is distilled in a packed tower with a tower diameter of 1.2m, a tower height of 15.05m (including a distillation section of 4.05m and a stripping section of 4m), a plate spacing of 0.6m, an opening rate of 10%, 10 plates in the packed tower, and triethylamine with a water content of 0.5% is fed on the 5th plate. The reflux ratio is 1.5, and the liquid flooding fraction of the 10th plate is 59.3%. Both the distillation section and the stripping section are packed towers, and the material and packing of the packed tower are both 304 stainless steel.

[0047] The load of the tower bottom reboiler is 938kW / h, the steam consumption is 1.7t / h, and the heat exchange area of ​​the tower bottom reboiler is 75m 2 The load of the top condenser is 716kW / h, the circulating cooling water consumption is 76t / h, and the heat exchange area of ​​the top condenser is 50m 2 , the top condenser is cooled to 74℃; the top triethylamine mixed liquid needs to be cooled to 25℃, the load of the top triethylamine mixed liquid cooler is 80kW / h, the circulating cooling water consumption (7℃ cooling water) is 13.9t / h, and the heat exchange area of ​​the top triethylamine mixed liquid cooler is 20m 2 The triethylamine at the bottom of the tower needs to be cooled to 25°C. The load of the triethylamine condenser at the bottom of the tower is 211.4kW / h, the circulating cooling water consumption (cooling water at 7°C) is 36.8t / h, and the heat exchange area of ​​the triethylamine condenser at the bottom of the tower is 40m 2 .

[0048] 9 tons / hour of triethylamine with a water content of 0.5% is distilled three times in three towers. After the first distillation, the first fore fraction (the water content of the fore fraction is 9%) with a gas phase temperature lower than 88° C. is collected at the top of the tower. NaOH solution is added to the collected fore fraction, and the pH value of the mixed solution is adjusted to 8, and then separated to obtain a water layer and a triethylamine layer (the water content of the triethylamine is 2%). The triethylamine is mixed with the NaOH solution for preliminary dehydration to obtain pretreated triethylamine (the water content is 0.5%). The pretreated triethylamine enters the first tower again, and the bottom material enters the second tower for the second distillation. The method comprises the following steps: performing a second distillation; collecting a second fore fraction (the water content of the fore fraction is 3%) with a gas phase temperature lower than 88° C. at the top of the tower after the second distillation, adding a NaOH solution to the collected fore fraction for preliminary dehydration to obtain pretreated triethylamine (the water content is 0.5%), and then the pretreated triethylamine enters the first tower, and the tower bottom material enters the third tower for a third distillation, and after the third distillation, collecting a third fore fraction (the water content of the fore fraction is 0.25%) with a gas phase temperature lower than 88° C. at the top of the tower, and the collected fore fraction enters the feed tank of the first tower, and the tower bottom obtains deeply dehydrated triethylamine.

[0049] The total amount of the front fraction in this embodiment is 6% of the mass of the triethylamine before rectification; the bottom liquid accounts for 94% of the total amount, and the water content of the triethylamine in the bottom liquid is 0.19%. The triethylamine obtained in this embodiment can be fully reused in glyphosate production, and the yield can reach 82%.

[0050] Example 2

[0051] NaOH solution is added to crude triethylamine with a water content of 2.5% (the added NaOH solution is 6% of the mass fraction of the crude triethylamine), and preliminary dehydration is carried out at 45° C. to obtain triethylamine with a water content of 0.7%.

[0052] Triethylamine with a water content of 0.7% is distilled in a packed tower with a tower diameter of 1.3m, a tower height of 14.8m (including a distillation section of 3.9m and a stripping section of 3.7m), a plate spacing of 0.6m, an opening rate of 10%, 12 plates in the packed tower, triethylamine with a water content of 0.7% is fed on the 6th plate, the reflux ratio is 1.4, and the liquid flooding fraction of the 10th plate is 59.4%; both the distillation section and the stripping section are packed towers, and the material and packing of the packed tower are both 304 stainless steel.

[0053] The load of the tower bottom reboiler is 930kW / h, the steam consumption is 1.68t / h, and the heat exchange area of ​​the tower bottom reboiler is 73m 2 The load of the top condenser is 712kW / h, the circulating cooling water consumption is 75.5t / h, and the heat exchange area of ​​the top condenser is 48m 2 , the top condenser is cooled to 74℃; the top triethylamine mixed liquid needs to be cooled to 25℃, the load of the top triethylamine mixed liquid cooler is 75kW / h, the circulating cooling water consumption (5℃ cooling water) is 13.7t / h, and the heat exchange area of ​​the top triethylamine mixed liquid cooler is 18m 2 The triethylamine at the bottom of the tower needs to be cooled to 23°C. The load of the triethylamine condenser at the bottom of the tower is 206kW / h. The circulating cooling water consumption (cooling water at 5°C) is 36.6t / h. The heat exchange area of ​​the triethylamine condenser at the bottom of the tower is 39m 2 .

[0054] 8.5 tons / hour of triethylamine with a water content of 0.7% was distilled three times in three towers. After the first distillation, the first fore fraction (the water content of the fore fraction was 8%) with a gas phase temperature lower than 88° C. was collected at the top of the tower. NaOH solution was added to the collected fore fraction, and the pH value of the mixed solution was adjusted to 8, and then separated to obtain a water layer and a triethylamine layer (the water content of the triethylamine was 2%). The triethylamine was mixed with the NaOH solution for preliminary dehydration to obtain pretreated triethylamine (the water content was 0.7%). The pretreated triethylamine was then fed into the first tower, and the bottom material was fed into the second tower for the second distillation. The method comprises the following steps: performing a second distillation; collecting a second fore fraction (the water content of the fore fraction is 3.5%) with a gas phase temperature lower than 88° C. at the top of the tower after the second distillation, adding a NaOH solution to the collected fore fraction for preliminary dehydration to obtain pretreated triethylamine (the water content is 0.7%), and then the pretreated triethylamine enters the first tower, and the tower bottom material enters the third tower for a third distillation, and after the third distillation, collecting a third fore fraction (the water content of the fore fraction is 0.2%) with a gas phase temperature lower than 88° C. at the top of the tower, and the collected fore fraction enters the feed tank of the first tower, and the tower bottom obtains deeply dehydrated triethylamine.

[0055] The total amount of the front fraction in this embodiment is 5.8% of the mass of the triethylamine before rectification; the bottom liquid accounts for 94.2% of the total amount, and the water content of the triethylamine in the bottom liquid is 0.19%. The triethylamine obtained in this embodiment can be fully reused in glyphosate production, and the yield can reach 85%.

[0056] Comparative Example 1 Direct distillation method

[0057] Crude triethylamine with a water content of 2% is distilled in a packed tower and fully refluxed until the gas phase temperature at the top of the tower is 75.4°C, and the azeotropic fraction begins to evaporate; as the azeotropic fraction evaporates, the boiling point gradually increases, and the positive fraction is collected when the gas phase temperature rises to 88°C.

[0058] The front fraction of this comparative example accounts for 35% of the total amount of crude triethylamine, and the water content of the front fraction is 6%; the positive fraction accounts for 60% of the total amount, and the water content is 0.2%; although the distillation process is feasible, the front fraction has a large amount, the heat loss is large, and it is not economically cost-effective.

[0059] The method of the present invention is significantly superior to the direct distillation method. Compared with the direct distillation method, the heat loss is small, the cost is low, and continuous intelligent operation can be achieved.

[0060] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A distillation method for deep dehydration of triethylamine, characterized in that: The following steps are included: 1) crude triethylamine and sodium hydroxide solution are mixed and preliminarily dehydrated to obtain pretreated triethylamine; 2) The pretreated triethylamine is distilled three times, and the front fraction is collected at the top of the tower after each distillation, and the remaining material is further distilled, and the tower bottom is used to obtain deeply dehydrated triethylamine after three distillations; the water content of the deeply dehydrated triethylamine is ≤0.2%.

2. The rectification method for the deep dehydration of triethylamine according to claim 1, wherein: The mass concentration of the sodium hydroxide solution is 30-40%; the mass fraction of the sodium hydroxide solution is 5-8% of the crude triethylamine.

3. The rectification method for the deep dehydration of triethylamine according to claim 1 or 2, characterized in that: The water content of crude triethylamine is 2-3%; the water content of pretreated triethylamine is 0.5-1%.

4. The rectification method for the deep dehydration of triethylamine according to claim 3, characterized in that: The water content of the fore fraction collected after the first distillation is 8-10%, the water content of the fore fraction collected after the second distillation is 2-5%, and the water content of the fore fraction collected after the third distillation is 0.2-0.3%.

5. The rectification method for the deep dehydration of triethylamine according to claim 3, characterized in that: The total amount of the front fraction is 5.5-6.3% of the mass of the pretreated triethylamine; and the gas phase temperature of the front fraction is ≤88°C.

6. The rectification method for deep dehydration of triethylamine according to claim 4 or 5, characterized in that: The distillation adopts a packed tower with a tower diameter of 1 to 1.4m and a tower height of 13 to 17m, of which the distillation section is 3 to 5m high and the stripping section is 3 to 5m high; the plate spacing is 0.55 to 0.65m.

7. The rectification method for deep dehydration of triethylamine according to claim 6, characterized in that: The number of plates of the packed tower is 8 to 12, the pretreated triethylamine is fed on the 5th to 6th plates, the reflux ratio is 1.2 to 1.7, and the flooding fraction of the 10th plate is 58.5 to 60%; Both the rectification section and the stripping section are packed towers, and the material and packing of the packed towers are stainless steel.

8. The rectification method for deep dehydration of triethylamine according to claim 6, characterized in that: The load of the tower bottom reboiler is 925~945kW / h, the steam consumption is 1.55~1.75t / h, and the heat exchange area of ​​the tower bottom reboiler is 65~85m 2 ; The load of the top condenser is 705-722 kW / h, the circulating cooling water consumption is 74-77 t / h, and the heat exchange area of ​​the top condenser is 45-55 m 2 ; The top condenser is cooled to 72-76°C.

9. The rectification method for deep dehydration of triethylamine according to claim 8, characterized in that: The load of the triethylamine mixed liquid cooler at the top of the tower is 72-85kW / h, the circulating cooling water consumption is 13-14.5t / h, the circulating cooling water temperature is 4-10℃, and the heat exchange area of ​​the triethylamine mixed liquid cooler at the top of the tower is 15-22m 2 ; The triethylamine mixed solution at the top of the tower is cooled to 20-30°C; The load of the triethylamine condenser at the bottom of the tower is 200-220kW / h, the circulating cooling water consumption is 35.5-37.5t / h, the circulating cooling water temperature is 4-10℃, and the heat exchange area of ​​the triethylamine condenser at the bottom of the tower is 35-45m 2 ; The triethylamine at the bottom of the tower is cooled to 20-30°C.