CN111905409B - Deep dehydration method for industrial organic solvent - Google Patents
Deep dehydration method for industrial organic solvent Download PDFInfo
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Abstract
The invention discloses a deep dehydration method for an industrial organic solvent, belonging to the technical field of chemical solvent dehydration and comprising the following steps: nitrogen displacement stage-dehydration stage-regeneration stage; the air in the solvent drying system is replaced by nitrogen, so that the organic solvent is dehydrated under the protection of dry nitrogen, and the organic solvent is prevented from deteriorating; the organic solvent is cooled by the solvent cooler and then enters the molecular sieve drying tower for dehydration, and the low-temperature molecular sieve can effectively improve the dehydration efficiency; meanwhile, the dehydrated organic solvent can filter impurities such as molecular sieve fragments and the like generated in the regeneration process of the organic solvent, so that the purity of the organic solvent is ensured, and the influence on the normal operation of downstream production procedures is avoided; the regeneration temperature of the molecular sieve is maintained by means of a heat exchanger and a nitrogen heater in the molecular sieve drying tower, and the regenerated molecular sieve is continuously put into the dehydration process. The invention can realize continuous dehydration of the organic solvent, improve the dehydration efficiency and ensure the purity of the organic solvent.
Description
Technical Field
The invention belongs to the technical field of chemical solvent dewatering, and particularly relates to a deep dehydration method for an industrial organic solvent.
Background
In modern industrial production processes, anhydrous organic solvents occupy an important position. Such as Grignard reaction, reaction with active metal or reagent, electrolyte of lithium battery, etc., all need to be carried out under the condition of anhydrous organic solvent. The moisture content of the organic solvent seriously affects the industrial production and even causes safety accidents. The dehydration of the organic solvent is a crucial part of the above-mentioned production process.
At present, there are many methods for dehydrating organic solvents, such as pervaporation membrane method, chemical dehydration, azeotropic distillation method, molecular sieve dehydration method, etc. Among them, molecular sieve dehydration is a commonly used dehydration method, and is mentioned in patents CN2031833736U, CN205109102U, CN209270889U, CN204182160U, etc. As the molecular sieve absorbs the water in the organic solvent and releases the heat of adsorption, the temperature of the organic solvent is raised. Meanwhile, the organic solvent is circularly dehydrated in the molecular sieve drying tower, and the temperature of the organic solvent is also increased due to friction between the organic solvent and the molecular sieve, a pipeline and the like in the circulating process, so that the molecular sieve is increased along with the temperature increase of the organic solvent. In the later stage of solvent dehydration, the adsorption capacity of the molecular sieve is reduced along with the increase of temperature of the molecular sieve. After the molecular sieve reaches adsorption equilibrium, if the temperature continues to rise, the water adsorbed by the molecular sieve will be resolved, and the water in the organic solvent will not fall but rise.
However, these methods are suitable for dehydrating a small amount of organic solvent, and are not suitable for industrially dehydrating a large amount of solvent. When a small amount of organic solvent is dehydrated, the temperature rise in the dehydration process is small, so that the influence on the adsorption capacity of the molecular sieve is small, and the organic solvent dehydration is carried out. Particularly, in patent CN205109102U, three stages of molecular sieve drying towers are used in series, the system resistance is large, the gradient temperature rise is large, the adsorption capacity of the molecular sieve is seriously affected in the industrial dehydration process of a large amount of organic solvents, the drying period of the molecular sieve solvent is shortened, and the dehydration cost of the organic solvent is greatly increased. Especially when the organic solvent with large difference between initial moisture and final moisture is dehydrated, the molecular sieve is replaced or regenerated more frequently, so that the dehydration cost of the organic solvent is greatly increased. The invention aims to solve the problems and find a method suitable for deep dehydration of industrial organic solvents.
Disclosure of Invention
The invention aims to provide an industrialized organic solvent deep dehydration method, and aims to solve the technical problem of high cost for dehydrating a large amount of industrialized solvents by adopting a molecular sieve in the prior art.
In order to solve the technical problems, the technical scheme adopted by the invention is as follows:
an industrial deep dehydration method for organic solvent comprises the following steps:
s1: nitrogen replacement stage: replacing air in the solvent drying system with nitrogen;
the solvent drying system comprises a solvent storage tank, a solvent circulating pump, a solvent cooler, a molecular sieve drying tower I and a filter, wherein the molecular sieve drying tower I is filled with a molecular sieve; the solvent storage tank, the solvent circulating pump, the solvent cooler and the molecular sieve drying tower I are sequentially connected, an outlet of the molecular sieve drying tower I is connected with an inlet of a filter, and an outlet of the filter is connected with an inlet of the solvent storage tank; the top of the molecular sieve drying tower I is provided with an emptying pipe and a nitrogen inlet which is communicated with the nitrogen pipe; opening a valve on a nitrogen pipe, and replacing air in the molecular sieve drying tower I by using nitrogen;
s2: and (3) a dehydration stage: starting a solvent circulating pump, and conveying the organic solvent in the solvent storage tank into a molecular sieve drying tower I through a solvent cooler for dehydration; controlling the dehydration temperature of the organic solvent after passing through a solvent cooler to be 5-30 ℃; dehydrating the organic solvent in a molecular sieve drying tower I, refluxing the organic solvent to a solvent storage tank through a filter, and circularly dehydrating;
s3: a regeneration stage:
the solvent drying system also comprises a nitrogen heater, and an outlet of the nitrogen heater is connected with the bottom of the molecular sieve drying tower I; a heat exchanger for regenerating the molecular sieve is also arranged in the molecular sieve drying tower I; starting a nitrogen heater, inputting heated nitrogen into a molecular sieve drying tower I to regenerate the molecular sieve, heating the molecular sieve by a heat exchanger in the molecular sieve drying tower I, and controlling the regeneration temperature of the molecular sieve at 250 ℃ for 120-; and the regenerated molecular sieve drying tower I continues to dehydrate the organic solvent.
Preferably, a plurality of molecular sieve drying towers of the solvent drying system are connected in parallel, and sequentially comprise a molecular sieve drying tower I, a molecular sieve drying tower II and a molecular sieve drying tower III, and heat exchangers are arranged in the molecular sieve drying tower I, the molecular sieve drying tower II and the molecular sieve drying tower III; the dehydration stage of step S2 is divided into a first stage and a second stage,
the first stage is as follows: after the first batch of organic solvent is circularly dehydrated through the molecular sieve drying tower I, stopping the molecular sieve drying tower I when the water content of the solvent is reduced to 0.10-0.05%;
and a second stage: the first batch of organic solvent is switched to a molecular sieve drying tower II for circular dehydration, and the organic solvent is continuously circulated until the water content of the organic solvent is reduced to below 300ppm or below 30 ppm;
when the molecular sieve drying tower II in the second stage reaches dynamic balance, taking the molecular sieve drying tower II as a solvent drying container in the first stage of the second batch of organic solvent dehydration stage for continuous use, and taking the molecular sieve drying tower III as a solvent drying container in the second stage of the second batch for use; regenerating the stopped molecular sieve drying tower I through a regeneration stage for later use;
continuously dehydrating the third batch of organic solvent, taking the molecular sieve drying tower III as a first-stage solvent drying container of the third batch, and taking the regenerated molecular sieve drying tower I as a second-stage solvent drying container of the third batch; and continuously dehydrating the organic solvent in a circulating sequence in turn.
Preferably, introducing cold nitrogen into the regenerated molecular sieve drying tower I, the regenerated molecular sieve drying tower II or the regenerated molecular sieve drying tower III, and cooling to room temperature for later use; the purity of the nitrogen is more than 99.0 percent.
Preferably, the solvent drying system further comprises a condenser and a solvent recovery tank, the emptying pipe is connected with the solvent recovery tank, an air outlet of the solvent recovery tank is connected with the condenser, and an exhaust pipe of the solvent storage tank is communicated with the emptying pipe; heated nitrogen flows through the molecular sieve drying tower I and then converges in the collecting tank through the solvent recovery pipe
Preferably, the dehydration temperature in step S2 is 15-25 ℃.
Preferably, the regeneration temperature in step S3 is 150-200 ℃.
Preferably, the solvent cooler is an immersed coil cooler, and the cooling medium in the solvent cooler is cold brine.
Preferably, the heat exchangers in the molecular sieve drying tower I, the molecular sieve drying tower II and the molecular sieve drying tower III are all coil pipes connected with a heating device.
Adopt the produced beneficial effect of above-mentioned technical scheme to lie in: compared with the prior art, the method has the advantages that the air in the solvent drying system is replaced by the nitrogen, so that the organic solvent is dehydrated under the protection of dry nitrogen, and the organic solvent is prevented from deteriorating; the organic solvent is cooled by the solvent cooler and then enters the molecular sieve drying tower for dehydration, and the adsorption capacity of the molecular sieve can be maintained in the optimal state at low temperature, so that the dehydration efficiency is effectively improved; meanwhile, the dehydrated organic solvent can filter impurities such as molecular sieve fragments and the like generated in the regeneration process of the organic solvent, so that the purity of the organic solvent is ensured, and the influence on the normal operation of downstream production procedures is avoided; the regeneration temperature of the molecular sieve is maintained by means of a heat exchanger and a nitrogen heater in the molecular sieve drying tower, and the regenerated molecular sieve is continuously put into a dehydration process. The invention can realize continuous dehydration of the organic solvent, improve the dehydration efficiency and ensure the purity of the organic solvent.
Drawings
The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.
FIG. 1 is a schematic flow diagram of a solvent drying system in an embodiment of the present invention;
in the figure: 1-solvent storage tank; 2-a solvent circulation pump; 3-a solvent cooler; 4-molecular sieve drying tower I; 5-molecular sieve drying tower II; 6-molecular sieve drying tower III; 7-a nitrogen heater; 8-a condenser; 9-a solvent recovery tank; 10-a filter; 11-emptying the pipe; a 12-nitrogen gas pipe; 13-exhaust pipe.
Detailed Description
The technical solutions in the embodiments of the present invention are clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
An industrial deep dehydration method for organic solvent comprises the following steps:
s1: nitrogen replacement stage: replacing air in the solvent drying system with nitrogen;
the solvent drying system comprises a solvent storage tank 1, a solvent circulating pump 2, a solvent cooler 3, a molecular sieve drying tower and a filter 10, wherein the molecular sieve drying tower is filled with a molecular sieve; the solvent storage tank 1, the solvent circulating pump 2, the solvent cooler 3 and the molecular sieve drying tower are sequentially connected, an outlet of the molecular sieve drying tower is connected with an inlet of a filter 10, and an outlet of the filter 10 is connected with an inlet of the solvent storage tank 1; the top of the molecular sieve drying tower is provided with an emptying pipe 11 and a nitrogen inlet which is communicated with a nitrogen pipe 12; opening a valve on the nitrogen pipe 12, and replacing air in the molecular sieve drying tower by using nitrogen; the nitrogen pipe can be inserted into the bottom of the molecular sieve drying tower, and the nitrogen replaces the air in the molecular sieve drying tower from bottom to top.
S2: and (3) a dehydration stage: starting a solvent circulating pump 2, and conveying the organic solvent in the solvent storage tank 1 to a molecular sieve drying tower through a solvent cooler 3 for dehydration; the dehydration temperature of the organic solvent after passing through the solvent cooler 3 is controlled at 5-30 ℃, preferably 15-25 ℃, and the dehydration effect is optimal; organic solvent is dehydrated by a molecular sieve drying tower, then reflows to a solvent storage tank 1 through a filter 10, and is circularly dehydrated. The solvent cooler 3 is an immersion coil cooler, and the cooling medium in the solvent cooler 3 is cold brine.
In view of the fact that at a certain temperature, the water absorbed by the molecular sieve and the water of the organic solvent have a dynamic balance. When the molecular sieve absorbs a certain amount of water and does not reach the maximum adsorption capacity, the water content of the organic solvent is increased to destroy the dynamic balance, so that the molecular sieve can continuously absorb the water. The invention accordingly proceeds with the organic solvent dehydration stage in two stages.
The method comprises the following steps that a plurality of molecular sieve drying towers of a solvent drying system are designed to be connected in parallel, and sequentially comprise a molecular sieve drying tower I4, a molecular sieve drying tower II5 and a molecular sieve drying tower III6, heat exchangers are arranged in the molecular sieve drying tower I4, the molecular sieve drying tower II5 and the molecular sieve drying tower III6, and the molecular sieve drying tower I4, the molecular sieve drying tower II5 and the molecular sieve drying tower III6 are connected in parallel; the dehydration stage is divided into a first stage and a second stage,
the first stage is as follows: after the first batch of organic solvent is circularly dehydrated through the molecular sieve drying tower I4, stopping the molecular sieve drying tower I4 when the water content of the solvent is reduced to 0.10-0.05%;
and a second stage: switching the first batch of organic solvent to a molecular sieve drying tower II5 for circular dehydration, and continuously circulating until the water content of the organic solvent is reduced to below 300ppm or below 30 ppm;
when the molecular sieve drying tower II5 in the second stage reaches dynamic balance, taking the molecular sieve drying tower II5 as a solvent drying container in the first stage of the second batch of organic solvent dehydration stage for continuous use, and taking the molecular sieve drying tower III6 as a solvent drying container in the second stage of the second batch for use; regenerating the stopped molecular sieve drying tower I4 through a regeneration stage for later use;
continuing to dehydrate the third batch of organic solvent, taking a molecular sieve drying tower III6 as a first-stage solvent drying container of the third batch, and taking a regenerated molecular sieve drying tower I4 as a second-stage solvent drying container of the third batch; and continuously dehydrating the organic solvent in a circulating sequence in turn.
S3: a regeneration stage:
the solvent drying system also comprises a nitrogen heater 7, and the outlet of the nitrogen heater 7 is connected in parallel with the bottom of the molecular sieve drying tower I4 through a preheated nitrogen pipe respectively; a heat exchanger for regenerating the molecular sieve is arranged in the molecular sieve drying tower I4; starting a nitrogen heater 7, inputting heated nitrogen into the molecular sieve drying tower I4 to regenerate the molecular sieve, heating the molecular sieve by a heat exchanger in the molecular sieve drying tower I4, and controlling the regeneration temperature of the molecular sieve at 250 ℃; preferably 150 ℃ and 200 ℃, and the regeneration effect of the molecular sieve is optimal.
The regeneration process of the molecular sieve drying tower II5 and the molecular sieve drying tower III6 is the same as that of the molecular sieve drying tower I4. Introducing cold nitrogen into the regenerated molecular sieve drying tower I4, the regenerated molecular sieve drying tower II5 or the regenerated molecular sieve drying tower III6, and cooling to room temperature for later use; wherein the purity of the nitrogen is more than 99.0 percent.
The heat exchangers in the molecular sieve drying tower I4, the molecular sieve drying tower II5 and the molecular sieve drying tower III6 are all coil pipes connected with a heating device, and the molecular sieves are filled around the coil pipes. The regeneration temperature of the molecular sieve can be rapidly increased by the structure. The molecular sieve regeneration mode is on-line regeneration, and a heat source is provided for molecular sieve regeneration through a built-in coil heat exchanger, so that the molecular sieve regeneration temperature is controlled to be 120-250 ℃. The nitrogen is heated to 120-250 ℃ by a nitrogen preheater and enters a molecular sieve drying tower to be regenerated, and the water and the organic solvent adsorbed by the molecular sieve are blown off and regenerated. The method has the advantages that the factors such as the regeneration effect of the molecular sieve, the consumption of the molecular sieve regeneration heat source, the consumption of the organic solvent recovery refrigerant and the like are balanced, the regeneration temperature of the molecular sieve is preferably controlled to be 200 ℃ plus 150 ℃, and the effect is best when the temperature of the preheated nitrogen is controlled to be 200 ℃ plus 150 ℃.
In view of the high initial water content of the organic solvent, the water content of the organic solvent is reduced to 0.10-0.05% in the first stage of the dehydration stage; then the water content of the organic solvent is reduced to below 300ppm, even below 30ppm in the second stage. And the molecular sieve drying tower I4, the molecular sieve drying tower II5 and the molecular sieve drying tower III6 are used as molecular sieve containers in the first stage and the second stage in turn for dehydration. And when the molecular sieve adsorption of the second-stage molecular sieve drying tower reaches dynamic balance, the second-stage molecular sieve drying tower is used as the first-stage molecular sieve drying tower for continuous use, and the replaced molecular sieve or regenerated molecular sieve drying tower is used as the second-stage drying tower. Thereby realizing the cyclic dehydration of the organic solvent.
Further optimize above-mentioned technical scheme, as shown in fig. 1, solvent drying system still includes condenser 8 and solvent recovery jar 9, and the evacuation pipe 11 of molecular sieve drying tower I4, molecular sieve drying tower II5 and molecular sieve drying tower III6 all links to each other with solvent recovery jar 9, the gas outlet of solvent recovery jar 9 links to each other with condenser 8, and the blast pipe 13 and the evacuation pipe 11 intercommunication of solvent storage tank 1 simultaneously. By adopting the structure, organic solvent gas generated in the regeneration processes of the solvent storage tank, the molecular sieve drying tower I4, the molecular sieve drying tower II5 and the molecular sieve drying tower III6 can be converged to the solvent recovery tank to be collected, and the solvent discharged from the solvent recovery tank is cooled by the condenser and then condensed into liquid which flows back to the solvent recovery tank to recover the organic solvent.
The following examples are provided to illustrate the dehydration of organic solvents.
Example 1: according to the process flow shown in figure 1, 5000L of organic solvent is filled in a solvent storage tank 1, the initial water content of the solvent is 0.60-0.50%, the inner diameters of a molecular sieve drying tower I4, a molecular sieve drying tower II5 and a molecular sieve drying tower III6 are all 500mm, the filling height of the molecular sieve is 5000mm, and the solvent circulation amount is 30m3/h。
A. The solvent cooler is not communicated with a refrigerant, and the circulating solvent is not cooled. The organic solvent is circulated only through the molecular sieve drying tower 4. This is compared with the dehydration process with the addition of the refrigerant.
After the first 5000L of organic solvent circulates for 90min, the water content of the organic solvent is reduced to 0.011 percent, and the temperature is 32 ℃;
after the second 5000L of organic solvent circulates for 90min, the water content of the organic solvent is reduced to 0.018 percent, and the temperature is 38 ℃;
circulating 5000L of organic solvent in the third batch for 90min, and reducing water content of the organic solvent to 0.024% at 43 deg.C;
after 5000L of organic solvent in the fourth batch circulates for 90min, the water content of the organic solvent is reduced to 0.031%, and the temperature is 46 ℃.
B. And introducing a cooling medium into the solvent cooler for cooling the circulating solvent, controlling the temperature to be 20-25 ℃ during circulation, leading the organic solvent to pass through a molecular sieve drying tower I4 used in the A example, reducing the water content of the solvent to be less than 0.10%, and then reducing the water content to meet the process requirement through a molecular sieve drying tower II 5.
Circulating a first 5000L of organic solvent in a molecular sieve drying tower I4 used in the A case for 90min to reduce the water content of the organic solvent to 0.024%; and then the organic solvent is circulated for 45min by a molecular sieve drying tower II5, and the water content of the organic solvent is reduced to 0.001 percent.
Circulating a second 5000L of organic solvent in a molecular sieve drying tower I4 used in the A case for 90min to reduce the water content of the organic solvent to 0.030%; and then the organic solvent is circulated for 45min by a molecular sieve drying tower II5, and the water content of the organic solvent is reduced to 0.004 percent.
Circulating 5000L of organic solvent in the third batch through a molecular sieve drying tower I4 used in the A case for 90min, and reducing the water content of the organic solvent to 0.035%; and then the mixture is circulated for 45min by a molecular sieve drying tower II5, and the water content of the organic solvent is reduced to 0.009%.
Circulating 5000L of organic solvent in a fourth batch through a molecular sieve drying tower I4 used in the A case for 90min, and reducing the water content of the organic solvent to 0.038%; and then the organic solvent is circulated for 45min by a molecular sieve drying tower II5, and the water content of the organic solvent is reduced to 0.013%.
Circulating a fifth 5000L of organic solvent in a molecular sieve drying tower I4 used in the example a for 90min, and reducing the water content of the organic solvent to 0.042%; and then the organic solvent is circulated for 45min by a molecular sieve drying tower II5, and the water content of the organic solvent is reduced to 0.019 percent.
Circulating a sixth batch of 5000L of organic solvent in a molecular sieve drying tower I4 used in the A example for 90min, and reducing the water content of the organic solvent to 0.051%; then the mixture is circulated for 45min by a molecular sieve drying tower II5, and the water content of the organic solvent is reduced to 0.022 percent.
Circulating a seventh batch of 5000L of organic solvent in a molecular sieve drying tower I4 used in the A example for 90min, and reducing the water content of the organic solvent to 0.062%; and then circulating for 45min by a molecular sieve drying tower II5, and reducing the water content of the organic solvent to 0.024%.
Circulating 5000L of organic solvent in an eighth batch through a molecular sieve drying tower I4 used in the A example for 90min, and reducing the water content of the organic solvent to 0.083%; and then the organic solvent is circulated for 45min by a molecular sieve drying tower II5, and the water content of the organic solvent is reduced to 0.027 percent.
The ninth batch of 5000L of organic solvent passes through a molecular sieve drying tower I4 used in the A example, and after circulating for 90min, the moisture of the organic solvent is reduced to 0.095%; and then circulating for 45min by a molecular sieve drying tower II5, and reducing the water content of the organic solvent to 0.029%.
Comparing A, B the two examples can lead to the following conclusions:
the circulating organic solvent in the A case is not controlled in temperature, only one molecular sieve drying tower I4 is used for circularly dehydrating to process four batches of solvents, the temperature of the solvents is raised to 46 ℃, and the final moisture of the solvents can only be reduced to 0.031%.
In the B case, the temperature of the organic solvent is controlled circularly, and the solvent is dehydrated in advance by using the used molecular sieve drying tower I4 in the A case, and then is dehydrated circularly by using the molecular sieve drying tower II 5. Example B treats 9 batches of solvent with a final water content of 0.029% and no more than 0.030% (300ppm), and is within the process requirements. The utilization rate of the molecular sieve is improved, and the dehydration cost of the organic solvent is greatly reduced.
Meanwhile, in the case B, the solvent moisture content of the originally used molecular sieve drying tower I4 in the case A could not be reduced to 300ppm (0.030%) or less after the solvent was circulated for 90min, while in the case B, the solvent moisture content could be reduced to 240ppm (0.024%) instead by controlling the circulating solvent temperature. Therefore, the utilization rate of the molecular sieve can be effectively improved by controlling the circulation temperature of the solvent.
Example 2: according to the process flow shown in the attached figure 1, 5000L of organic solvent is injected into a solvent tank 1, the initial water content of the solvent is 0.60-0.50%, the inner diameters of a molecular sieve drying tower I4, a molecular sieve drying tower II5 and a molecular sieve drying tower III6 are all 500mm, the filling height of the molecular sieve is 5000mm, and the circulation volume of the organic solvent is 30m 3/h.
Example B in example 1 molecular sieve drying column ii5 was used as the first stage dehydration column. Molecular sieve drying column III6 was used as the second stage dehydration column, operating as in example B, to cyclically dehydrate 11 batches of organic solvent, with a final water content of 0.027% for batch 11. Meanwhile, heated nitrogen is introduced into the molecular sieve drying tower I4 for stripping and regeneration. Controlling the temperature of nitrogen entering a molecular sieve drying tower I4 at 190-.
And (3) taking the molecular sieve drying tower III6 as a first-stage drying tower, and taking the regenerated molecular sieve drying tower I4 as a second-stage drying tower to dehydrate the solvent. The organic solvent dehydration results are shown in table 1.
TABLE 1
| Batches of | Molecular sieve drying tower after moisture (%) | Molecular sieve drying tower after moisture (%) |
| 1 | 0.033 | 0.004 |
| 2 | 0.037 | 0.007 |
| 3 | 0.045 | 0.011 |
| 4 | 0.051 | 0.013 |
| 5 | 0.055 | 0.016 |
| 6 | 0.058 | 0.021 |
| 7 | 0.060 | 0.023 |
| 8 | 0.064 | 0.024 |
| 9 | 0.073 | 0.027 |
| 10 | 0.082 | 0.029 |
Example 3: in example 2, the molecular sieve drying column I4 was used as the first stage drying column, and the molecular sieve drying column II5 was regenerated under the following conditions and used as the second stage regenerating drying column.
Regeneration conditions of the molecular sieve drying tower II 5: after nitrogen preheating, the temperature is as follows: 120 ℃ to 130 ℃; controlling the temperature in a molecular sieve drying tower II 5: 120 ℃ to 130 ℃; the nitrogen is heated by a nitrogen heater and then is introduced into a molecular sieve drying tower II5, hot nitrogen is used for blowing off and regenerating for 32 hours, and then cold nitrogen is introduced for cooling for 3 hours.
According to the process flow shown in the attached figure 1, 5000L of organic solvent is filled in a solvent storage tank 1, the initial moisture of the organic solvent is between 0.60 and 0.50 percent, the inner diameters of a molecular sieve drying tower I4, a molecular sieve drying tower II5 and a molecular sieve drying tower III6 are all 500mm, the filling height of a molecular sieve is 5000mm, and the circulation volume of the organic solvent is 30m 3/h. The solvent dehydration results are shown in table 2:
TABLE 2
| Batches of | Molecular sieve drying tower after moisture (%) | Molecular sieve drying tower after moisture (%) |
| 1 | 0.034 | 0.005 |
| 2 | 0.036 | 0.006 |
| 3 | 0.041 | 0.009 |
| 4 | 0.046 | 0.011 |
| 5 | 0.054 | 0.014 |
| 6 | 0.059 | 0.020 |
| 7 | 0.064 | 0.024 |
| 8 | 0.067 | 0.026 |
| 9 | 0.075 | 0.028 |
| 10 | 0.085 | 0.030 |
Example 4: in example 3, the molecular sieve drying column II5 was used as the first stage drying column, and the molecular sieve drying column III6 was regenerated under the following conditions and used as the second stage regenerating drying column.
Regeneration conditions of the molecular sieve drying tower III6 are as follows: after nitrogen preheating, temperature: 240 ℃ and 250 ℃; controlling the temperature in a molecular sieve drying tower II 5: 240 ℃ and 250 ℃; hot nitrogen gas is blown off for regeneration for 16h, and cold nitrogen gas is cooled for 5 h.
According to the process flow shown in the attached figure 1, 5000L of organic solvent is filled in a solvent storage tank 1, the initial moisture of the organic solvent is between 0.60 and 0.50 percent, the inner diameters of a molecular sieve drying tower I4, a molecular sieve drying tower II5 and a molecular sieve drying tower III6 are all 500mm, the filling height of a molecular sieve is 5000mm, and the circulation volume of the organic solvent is 30m 3/h. The organic solvent dehydration results are shown in table 3:
TABLE 3
| Batches of | Moisture content (%)% after first stage molecular sieve drying tower | Molecular sieve drying tower after moisture (%) |
| 1 | 0.035 | 0.003 |
| 2 | 0.039 | 0.005 |
| 3 | 0.044 | 0.007 |
| 4 | 0.049 | 0.010 |
| 5 | 0.052 | 0.013 |
| 6 | 0.057 | 0.018 |
| 7 | 0.060 | 0.021 |
| 8 | 0.065 | 0.024 |
| 9 | 0.076 | 0.026 |
| 10 | 0.084 | 0.028 |
| 11 | 0.091 | 0.029 |
In the description above, numerous specific details are set forth in order to provide a thorough understanding of the present invention, but the present invention may be practiced in other ways than those specifically described and will be readily apparent to those of ordinary skill in the art without departing from the spirit of the present invention, and thus the present invention is not limited to the specific embodiments disclosed above.
Claims (7)
1. An industrialized organic solvent deep dehydration method is characterized in that,
the method comprises the following steps:
s1: nitrogen replacement stage: replacing air in the solvent drying system with nitrogen; the solvent drying system comprises a solvent storage tank, a solvent circulating pump, a solvent cooler, a molecular sieve drying tower and a filter, wherein the molecular sieve drying tower is filled with a molecular sieve; the solvent storage tank, the solvent circulating pump, the solvent cooler and the molecular sieve drying tower are sequentially connected, an outlet of the molecular sieve drying tower is connected with an inlet of a filter, and an outlet of the filter is connected with an inlet of the solvent storage tank; the top of the molecular sieve drying tower is provided with an emptying pipe and a nitrogen inlet which is communicated with a nitrogen pipe; opening a valve on a nitrogen pipe, replacing air in the molecular sieve drying tower by using nitrogen, inserting the nitrogen pipe downwards into the bottom of the molecular sieve drying tower, and replacing the air in the molecular sieve drying tower by the nitrogen from bottom to top;
s2: and (3) a dehydration stage: starting a solvent circulating pump, and conveying the organic solvent in the solvent storage tank into a molecular sieve drying tower through a solvent cooler for dehydration; the dehydration temperature of the organic solvent after passing through a solvent cooler is controlled at 5-30 ℃; dehydrating the organic solvent in a molecular sieve drying tower, refluxing the organic solvent to a solvent storage tank through a filter, and circularly dehydrating; the initial moisture content of the organic solvent is between 0.60 and 0.50 percent;
s3: a regeneration stage: the solvent drying system also comprises a nitrogen heater, and an outlet of the nitrogen heater is connected with the bottom of the molecular sieve drying tower; a heat exchanger for regenerating the molecular sieve is also arranged in the molecular sieve drying tower; starting a nitrogen heater, inputting the heated nitrogen into a molecular sieve drying tower to regenerate the molecular sieve, heating the molecular sieve by a heat exchanger in the molecular sieve drying tower at the same time, and controlling the regeneration temperature of the molecular sieve at 250 ℃ of 120-; introducing cold nitrogen into the regenerated molecular sieve drying tower, cooling to room temperature, and continuously dehydrating the organic solvent;
the solvent drying system comprises a solvent drying system, a solvent drying system and a solvent drying system, wherein a plurality of molecular sieve drying towers of the solvent drying system are connected in parallel and sequentially comprise a molecular sieve drying tower I, a molecular sieve drying tower II and a molecular sieve drying tower III, and heat exchangers are arranged in the molecular sieve drying tower I, the molecular sieve drying tower II and the molecular sieve drying tower III;
the dehydration stage of step S2 is divided into a first stage and a second stage,
the first stage is as follows: after the first batch of organic solvent is circularly dehydrated through the molecular sieve drying tower I, stopping the molecular sieve drying tower I when the water content of the solvent is reduced to 0.10-0.05%;
and a second stage: switching the first batch of organic solvent to a molecular sieve drying tower II for circular dehydration, and continuously circulating until the water content of the organic solvent is reduced to below 300ppm or below 30 ppm;
when the molecular sieve drying tower II in the second stage reaches dynamic balance, taking the molecular sieve drying tower II as a solvent drying container in the first stage of the second batch of organic solvent dehydration stage for continuous use, and taking the molecular sieve drying tower III as a solvent drying container in the second stage of the second batch for use; regenerating the stopped molecular sieve drying tower I through a regeneration stage for later use;
continuously dehydrating the third batch of organic solvent, taking the molecular sieve drying tower III as a first-stage solvent drying container of the third batch, and taking the regenerated molecular sieve drying tower I as a second-stage solvent drying container of the third batch; and continuously dehydrating the organic solvent in a circulating sequence in turn.
2. The industrial organic solvent deep dehydration method according to claim 1 characterized by:
introducing cold nitrogen into the regenerated molecular sieve drying tower I, the regenerated molecular sieve drying tower II or the regenerated molecular sieve drying tower III, and cooling to room temperature for later use; the purity of the nitrogen is more than 99.0 percent.
3. The industrial deep dehydration method for organic solvents according to claim 1, characterized by comprising:
the solvent drying system further comprises a condenser and a solvent recovery tank, the emptying pipe is connected with the solvent recovery tank, the gas outlet of the solvent recovery tank is connected with the condenser, and the exhaust pipe of the solvent storage tank is communicated with the emptying pipe.
4. The industrial organic solvent deep dehydration method according to claim 1 characterized by:
in step S2, the dehydration temperature is 15-25 ℃.
5. The industrial organic solvent deep dehydration method according to claim 1 characterized by:
the regeneration temperature in step S3 is 150-200 ℃.
6. The industrial organic solvent deep dehydration method according to claim 1 characterized by:
and the heat exchangers in the molecular sieve drying tower I, the molecular sieve drying tower II and the molecular sieve drying tower III are all coil pipes connected with a heating device.
7. The industrial deep dehydration method of organic solvent according to any of claims 1 to 6, characterized by:
the solvent cooler is an immersed coil cooler, and the cooling medium in the solvent cooler is cold brine.
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| CN112479797B (en) * | 2020-11-30 | 2023-03-07 | 安徽泽升科技有限公司 | Preparation method of ultra-dry organic solvent |
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| CN113274763A (en) * | 2021-06-08 | 2021-08-20 | 清华大学深圳国际研究生院 | Method and device for concentrating graphene oxide dispersion liquid |
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| CN114887354A (en) * | 2022-05-26 | 2022-08-12 | 上海淳然环境工程有限公司 | Solvent dehydration device and process based on adsorption coupling of molecular sieve membrane and molecular sieve |
| CN115121035B (en) * | 2022-06-21 | 2024-04-12 | 永华化学股份有限公司 | Method for preparing ultra-dry reagent by using ISEP system |
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