CN212347768U - Device for synthesizing trioxymethylene by salt effect reaction rectification - Google Patents
Device for synthesizing trioxymethylene by salt effect reaction rectification Download PDFInfo
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Abstract
The utility model discloses a device for synthesizing trioxymethylene by salt effect reaction rectification, which comprises a reaction rectification tower, an extraction tower, a concentration tower, a recovery tower and the like; the utility model discloses device of synthetic trioxymethylene of salt effect reaction rectification, formaldehyde conversion rate is high, production efficiency is high, trioxymethylene product purity is high, the flow is short, the energy consumption is low, possesses popularization usability.
Description
The technical field is as follows:
the utility model relates to a device for synthesizing trioxymethylene by reactive distillation, in particular to a device for synthesizing trioxymethylene by salt effect reactive distillation.
Background art:
trioxymethylene is an important chemical raw material, and has been widely used for preparing anhydrous formaldehyde, insecticides, molding materials, adhesives, disinfectants, antibacterial agents and other products. At present, 50-65 wt% of formaldehyde aqueous solution is mainly used as a raw material in industry, acid is used as a catalyst, and trioxymethylene with higher content is obtained in a gas phase through multiple distillation of a reaction rectifying tower. The equilibrium concentration of trioxymethylene in the bottom liquid of the reactive distillation column is about 3 wt%, the relative volatility of the separated components is low, the number of the tower plates of the distillation column is large under the same separation requirement, the operation reflux ratio is high, and the investment of distillation equipment is high, the production efficiency is low, and the energy consumption is high.
The salt effect is widely applied in the fields of catalytic processes, extractive distillation, azeotropic distillation and the like. The salt effect reactive distillation integrates the advantages of salt-dissolving distillation, reactive distillation and extractive distillation, namely, the salt is dissolved in the reaction solution and recycled in operation, thereby being convenient for industrial application.
However, the research on the influence of the salt effect on the trioxymethylene synthesis process is less, and no relevant report and industrial case exist.
The utility model has the following contents:
in order to solve the technical problem, the utility model aims to provide a device for synthesizing trioxymethylene by salt effect reaction rectification, which has high formaldehyde conversion rate, high purity of trioxymethylene products, short flow, low energy consumption and high production efficiency of a reaction rectification tower.
The purpose of the utility model is implemented by the following technical scheme: a device for synthesizing trioxymethylene by salt effect reactive distillation comprises a reactive distillation column, an extraction column, a concentration column and a recovery column, wherein a feed inlet is formed in the middle of the reactive distillation column, a middle material outlet of the reactive distillation column is connected with an inlet of a pump III, a top material outlet of the reactive distillation column is connected with a material inlet of a condenser I, a material outlet of the condenser I is connected with an inlet of a reflux tank I, an outlet of the reflux tank I is connected with an inlet of a pump II, and an outlet of the pump II is respectively connected with a top reflux port of the reactive distillation column and a material inlet of the extraction column; the top material outlet of the extraction tower is connected with the material inlet of the recovery tower, the bottom of the recovery tower is provided with a trioxymethylene product discharge port, the top extractant outlet of the recovery tower is connected with the feed port of a condenser III, the discharge port of the condenser III is connected with the inlet of a reflux tank III, the outlet of the reflux tank III is connected with the inlet of a pump IV, and the outlet of the pump IV is respectively connected with the reflux port of the recovery tower and the extractant inlet of the extraction tower; the extraction raffinate phase outlet of the extraction tower is connected with the inlet of a pump III, the outlet of the pump III is connected with the feed inlet of the concentration tower, the top discharge hole of the concentration tower is connected with the inlet of a condenser II, the outlet of the condenser II is connected with the inlet of a reflux tank II, and the outlet of the reflux tank II is respectively connected with the reflux port of the concentration tower and the feed inlet of the reaction rectification tower.
Further, a bottom circulating material outlet of the reaction rectifying tower is connected with an inlet of a pump I, and an outlet of the pump I is connected with a feeding hole of the reaction rectifying tower.
Further, the number of the tower plates of the reaction rectifying tower is 25-45 layers; the number of the tower plates of the extraction tower is 5-12 layers; the number of the tower plates of the concentration tower is 20-40 layers; the number of the tower plates of the recovery tower is 30-55 layers.
The utility model has the advantages that:
the utility model discloses can carry out high-efficient separation to the synthetic trioxymethylene reaction system of formaldehyde, improve product quality, but the energy consumption of device is reduced again simultaneously, specifically has following two aspects advantage:
(1) application of salt effect in reactive distillation process
The utility model discloses combine together salt effect and trioxymethylene's reaction rectification technology for the first time, carry out the synthetic trioxymethylene reaction of formaldehyde in the reaction rectifying column reaction section, in reaction process, salt auxiliary agent produces the salt effect to every layer of column plate or the steam-liquid phase equilibrium that the surface goes on of packing in the circulating flow, show "salt solution effect" and the "salting out effect" of trioxymethylene in having increased the liquid phase, thereby increase the relative volatility between trioxymethylene and the formaldehyde, increase the relative volatility between trioxymethylene and the water, be favorable to the separation of trioxymethylene among the liquid phase reaction system, promote the trioxymethylene to generate and go on to positive reaction direction, improve formaldehyde conversion rate. The number of the tower plates of the rectifying tower and the operation reflux ratio are reduced under the same separation requirement, so that the investment of rectifying equipment can be reduced, and the energy consumption of the rectifying operation is reduced. Meanwhile, the salt effect increases the reaction rate of trioxymethylene generation, and improves the single-pass conversion rate of formaldehyde and the production efficiency of the reactive distillation column.
(2) Recovery of formaldehyde and trioxymethylene from extraction residue
The utility model discloses set up the recovery that the condensing tower is arranged in extracting remaining phase formaldehyde and trioxymethylene, concentrated back formaldehyde solution returns the reaction rectifying column and continues to carry out the synthetic reaction, improves the conversion of formaldehyde. The problem that the formaldehyde and the trioxymethylene wastewater are independently recycled in the traditional trioxymethylene production process is solved, the total flow of the production process is shortened, and the total energy consumption of the production process is reduced.
To sum up, the utility model discloses trioxymethylene synthesizer's formaldehyde conversion rate is high, production efficiency is high, trioxymethylene product purity is high, the flow is short, the energy consumption is low, possesses the popularization usability.
Drawings
FIG. 1 is a process flow chart of a method for synthesizing trioxymethylene by salt effect reaction rectification.
FIG. 2 is a schematic diagram of a device for synthesizing trioxymethylene by salt effect reaction rectification.
FIG. 3 is a schematic diagram of an apparatus for synthesizing trioxymethylene by reactive distillation in example 2.
FIG. 4 is a process flow diagram of the method for synthesizing trioxymethylene by reactive distillation in example 7.
The device comprises a reaction rectifying tower 1, an extraction tower 2, a concentration tower 3, a recovery tower 4, a condenser I5, a reflux tank I6, a pump II 7, a condenser III 8, a reflux tank III 9, a pump IV 10, a pump III 11, a condenser II12, a reflux tank II 13 and a pump I14.
The specific implementation mode is as follows:
example 1: as shown in fig. 2, a device for synthesizing trioxymethylene by salt effect reactive distillation comprises a reactive distillation column 1, an extraction column 2, a concentration column 3 and a recovery column 4, wherein a feed inlet is arranged in the middle of the reactive distillation column 1, a middle material outlet of the reactive distillation column 1 is connected with an inlet of a pump III 11, a top material outlet of the reactive distillation column 1 is connected with a material inlet of a condenser I5, a material outlet of the condenser I5 is connected with an inlet of a reflux tank I6, an outlet of the reflux tank I6 is connected with an inlet of a pump II 7, and an outlet of the pump II 7 is respectively connected with a top reflux port of the reactive distillation column 1 and a material inlet of the extraction column 2; a top material outlet of the extraction tower 2 is connected with a material inlet of the recovery tower 4, a trioxymethylene product discharge port is arranged at the bottom of the recovery tower 4, a top extractant outlet of the recovery tower 4 is connected with a feed port of a condenser III 8, a discharge port of the condenser III 8 is connected with an inlet of a reflux tank III 9, an outlet of the reflux tank III 9 is connected with an inlet of a pump IV 10, and an outlet of the pump IV 10 is respectively connected with a reflux port of the recovery tower 4 and the extractant inlet of the extraction tower 2; an raffinate phase outlet of the extraction tower 2 is connected with an inlet of a pump III 11, an outlet of the pump III 11 is connected with a feed inlet of a concentration tower 3, a top discharge port of the concentration tower 3 is connected with an inlet of a condenser II12, an outlet of a condenser II12 is connected with an inlet of a reflux tank II 13, and an outlet of the reflux tank II 13 is respectively connected with a reflux port of the concentration tower 3 and a feed inlet of the reactive distillation tower 1; the bottom circulating material outlet of the reactive distillation column 1 is connected with the inlet of a pump I14, and the outlet of a pump I14 is connected with the feed inlet of the reactive distillation column 1.
The number of the trays of the reactive distillation column 1 is 25-45 layers, and the number of the trays is 25 layers in the embodiment; the number of the extraction tower 2 is 5-12 layers, 5 layers in this example; the number of the trays of the concentration tower 3 is 20-40 layers, and the number of the trays is 20 layers in the embodiment; the number of trays in the recovery column 4 was 30 to 55, and in this example, 30.
Example 2: a device for synthesizing trioxymethylene by reactive distillation is different from embodiment 1 in that no concentration tower is provided, and comprises a reactive distillation tower 1, an extraction tower 2 and a recovery tower 4, as shown in figure 3, a feed inlet is arranged in the middle of the reactive distillation tower 1, a top material outlet of the reactive distillation tower 1 is connected with a material inlet of a condenser I5, a material outlet of the condenser I5 is connected with an inlet of a reflux tank I6, an outlet of the reflux tank I6 is connected with an inlet of a pump II 7, and an outlet of the pump II 7 is respectively connected with a top reflux port of the reactive distillation tower 1 and a material inlet of the extraction tower 2; a top material outlet of the extraction tower 2 is connected with a material inlet of the recovery tower 4, a trioxymethylene product discharge port is arranged at the bottom of the recovery tower 4, a top extractant outlet of the recovery tower 4 is connected with a feed port of a condenser III 8, a discharge port of the condenser III 8 is connected with an inlet of a reflux tank III 9, an outlet of the reflux tank III 9 is connected with an inlet of a pump IV 10, and an outlet of the pump IV 10 is respectively connected with a reflux port of the recovery tower 4 and the extractant inlet of the extraction tower 2; the bottom circulating material outlet of the reactive distillation column 1 is connected with the inlet of a pump I14, and the outlet of a pump I14 is connected with the feed inlet of the reactive distillation column 1.
The number of the trays of the reactive distillation column 1 is 25-45 layers, and the number of the trays is 25 layers in the embodiment; the number of the extraction tower 2 is 5-12 layers, 5 layers in this example; the number of the trays of the concentration tower 3 is 20-40 layers, and the number of the trays is 20 layers in the embodiment; the number of trays in the recovery column 4 was 30 to 55, and in this example, 30.
Example 3: as shown in figure 1, the method for synthesizing trioxymethylene by rectifying the salt effect reaction by using the device of the embodiment 1 comprises the following steps: (1) rectifying to obtain trioxymethylene synthetic liquid; (2) extracting the trioxymethylene synthetic liquid to obtain an extract phase rich in trioxymethylene and a raffinate phase rich in water and formaldehyde; (3) concentrating the raffinate phase to recover a formaldehyde solution; (4) separating and recovering the extractant from the extraction phase to obtain a trioxymethylene product; wherein,
(1) and (3) performing reactive distillation to generate trioxymethylene synthetic fluid: adding a formaldehyde solution, a catalyst and a salt auxiliary agent into a reaction rectifying tower through a feed inlet arranged in the middle of the reaction rectifying tower, wherein the concentration of the fed formaldehyde solution is 65 wt%; the concentration of the catalyst sulfuric acid in the kettle liquid is 10 wt%; the salt auxiliary agent is potassium sulfate; the concentration of the salt auxiliary agent in the kettle liquid is 10 wt%. The formaldehyde solution, the catalyst and the salt auxiliary agent are subjected to a reaction for synthesizing trioxymethylene from formaldehyde in the process of flowing from top to bottom, the operation temperature at the top of the reactive distillation tower is 92 ℃, the operation temperature at the bottom of the reactive distillation tower is 100 ℃, and the operation pressure of the reactive distillation tower is 0.1 MPa; materials at the bottom of the reactive distillation tower are conveyed to a feed inlet of the reactive distillation tower through a circulating pump I, so that salt auxiliary agents in circulating flow generate a salt effect; discharging noncondensable light component methyl formate in a product at the top of the reactive distillation tower from the top of the reflux tank; the condensed trioxymethylene synthetic liquid in the tower top product mainly comprises trioxymethylene, formaldehyde and water, wherein the trioxymethylene synthetic liquid partially refluxes, the reflux ratio is 3, and part of the triformol synthetic liquid is used as the feeding material of the extraction tower.
(2) Extracting the trioxymethylene synthetic liquid to obtain an extract phase rich in trioxymethylene and a raffinate phase rich in water and formaldehyde: feeding a trioxymethylene synthetic solution produced at the top of the reactive distillation tower from a material inlet of the extraction tower, and feeding a circulating extractant and a supplementary fresh extractant from an extractant inlet of the extraction tower; the mass ratio of the extractant benzene to the feeding amount of the trioxymethylene synthetic liquid is 1: 1; the extractant is composed of the circulating extractant and the fresh supplementary extractant. Carrying out countercurrent extraction operation in the extraction tower, wherein the operation temperature at the top of the extraction tower is 70 ℃, the operation temperature at the bottom of the extraction tower is 70 ℃, and the operation pressure of the extraction tower is 0.1 MPa; the extraction phase rich in trioxymethylene obtained by extraction is output from the top of the extraction tower and is used as the feed of a recovery tower; the obtained raffinate rich in water and formaldehyde is produced from the bottom of the extraction tower to a concentration tower, and the trioxymethylene content in the raffinate is lower than 0.2 wt%.
(3) Concentrating raffinate phase to recover formaldehyde solution: feeding raffinate phase produced at the bottom of the extraction tower from the middle part of the concentration tower, and performing pressurized concentration operation of formaldehyde in the concentration tower; the operation temperature of the top of the concentration tower is 151 ℃, the operation temperature of the bottom of the concentration tower is 159 ℃, and the operation pressure of the concentration tower is 0.6 MPa; refluxing the concentrated formaldehyde solution at the top of the column with reflux ratio of 2.5; part of the formaldehyde solution returns to the reactive distillation tower from a feed inlet of the reactive distillation tower, the trioxymethylene synthesis reaction is continued, and the concentration of the concentrated formaldehyde solution distilled from the tower top is 57 wt%; the bottom of the concentration tower produces waste water with formaldehyde content lower than 0.15 wt%.
(4) Separating and recovering the extractant from the extraction phase to obtain a trioxymethylene product: an extract phase produced at the top of the extraction tower is fed from a material inlet of a recovery tower, and an extractant and trioxymethylene are separated in the recovery tower; the operation temperature of the top of the recovery tower is 80 ℃, the operation temperature of the bottom of the recovery tower is 120 ℃, and the operation pressure of the recovery tower is 0.1 MPa; the overhead extractant of the recovery tower partially refluxes, and the reflux ratio is 2.0; part of the extractant is used as a circulating extractant and returns to the extraction tower from an extractant inlet of the extraction tower; the bottom of the recovery tower produces trioxymethylene product with purity of 99.9 wt%.
Example 4: as shown in figure 1, the method for synthesizing trioxymethylene by rectifying the salt effect reaction by using the device of the embodiment 1 comprises the following steps: (1) rectifying to obtain trioxymethylene synthetic liquid; (2) extracting the trioxymethylene synthetic liquid to obtain an extract phase rich in trioxymethylene and a raffinate phase rich in water and formaldehyde; (3) concentrating the raffinate phase to recover a formaldehyde solution; (4) separating and recovering the extractant from the extraction phase to obtain a trioxymethylene product; wherein,
(1) and (3) performing reactive distillation to generate trioxymethylene synthetic fluid: adding a formaldehyde solution, a catalyst and a salt auxiliary agent into a reaction rectifying tower through a feed inlet arranged in the middle of the reaction rectifying tower, wherein the concentration of the fed formaldehyde solution is 50 wt%; the concentration of the catalyst sulfuric acid in the kettle liquid is 8 wt%; the salt auxiliary agent is sodium sulfate; the concentration of the salt auxiliary agent in the kettle liquid is 2 wt%. The formaldehyde solution, the catalyst and the salt auxiliary agent are subjected to a reaction for synthesizing trioxymethylene from formaldehyde in the process of flowing from top to bottom, the operation temperature of the top of the reactive distillation tower is 120 ℃, the operation temperature of the bottom of the reactive distillation tower is 128 ℃, and the operation pressure of the reactive distillation tower is 0.3 MPa; materials at the bottom of the reactive distillation tower are conveyed to a feed inlet of the reactive distillation tower through a circulating pump I, so that salt auxiliary agents in circulating flow generate a salt effect; discharging noncondensable light component methyl formate in a product at the top of the reactive distillation tower from the top of the reflux tank; the condensed trioxymethylene synthetic liquid in the tower top product mainly comprises trioxymethylene, formaldehyde and water, wherein the trioxymethylene synthetic liquid partially refluxes, the reflux ratio is 1.0, and part of the condensed trioxymethylene synthetic liquid is used as the feeding material of the extraction tower.
(2) Extracting the trioxymethylene synthetic liquid to obtain an extract phase rich in trioxymethylene and a raffinate phase rich in water and formaldehyde: feeding a trioxymethylene synthetic solution produced at the top of the reactive distillation tower from a material inlet of the extraction tower, and feeding a circulating extractant and a supplementary fresh extractant from an extractant inlet of the extraction tower; the mass ratio of the benzene as the extracting agent to the feeding amount of the trioxymethylene synthetic liquid is 0.6: 1; the extractant consists of a circulating extractant and a fresh supplementary extractant. Carrying out countercurrent extraction operation in the extraction tower, wherein the operation temperature at the top of the extraction tower is 90 ℃, the operation temperature at the bottom of the extraction tower is 90 ℃, and the operation pressure of the extraction tower is 0.3 MPa; the extraction phase rich in trioxymethylene obtained by extraction is output from the top of the extraction tower and is used as the feed of a recovery tower; the obtained raffinate rich in water and formaldehyde is produced from the bottom of the extraction tower to a concentration tower, and the trioxymethylene content in the raffinate is lower than 0.5 wt%.
(3) Concentrating raffinate phase to recover formaldehyde solution: feeding raffinate phase produced at the bottom of the extraction tower from the middle part of the concentration tower, and performing pressurized concentration operation of formaldehyde in the concentration tower; the operation temperature of the top of the concentration tower is 136 ℃, the operation temperature of the bottom of the concentration tower is 145 ℃, and the operation pressure of the concentration tower is 0.4 MPa; refluxing the concentrated formaldehyde solution at the top of the column with reflux ratio of 4.0; part of the formaldehyde solution returns to the reactive distillation tower from a feed inlet of the reactive distillation tower, the trioxymethylene synthesis reaction is continued, and the concentration of the concentrated formaldehyde solution distilled from the tower top is 53 wt%; the bottom of the concentration tower produces waste water with formaldehyde content lower than 0.2 wt%.
(4) Separating and recovering the extractant from the extraction phase to obtain a trioxymethylene product: an extract phase produced at the top of the extraction tower is fed from a material inlet of a recovery tower, and an extractant and trioxymethylene are separated in the recovery tower; the operation temperature of the top of the recovery tower is 120 ℃, the operation temperature of the bottom of the recovery tower is 157 ℃, and the operation pressure of the recovery tower is 0.3 MPa; the overhead extractant of the recovery tower partially refluxes, and the reflux ratio is 4.0; part of the extractant is used as a circulating extractant and returns to the extraction tower from an extractant inlet of the extraction tower; the bottom of the recovery tower produces trioxymethylene product with purity of 99.9 wt%.
Example 5: as shown in figure 1, the method for synthesizing trioxymethylene by rectifying the salt effect reaction by using the device of the embodiment 1 comprises the following steps: (1) rectifying to obtain trioxymethylene synthetic liquid; (2) extracting the trioxymethylene synthetic liquid to obtain an extract phase rich in trioxymethylene and a raffinate phase rich in water and formaldehyde; (3) concentrating the raffinate phase to recover a formaldehyde solution; (4) separating and recovering the extractant from the extraction phase to obtain a trioxymethylene product; wherein,
(1) and (3) performing reactive distillation to generate trioxymethylene synthetic fluid: adding a formaldehyde solution, a catalyst and a salt auxiliary agent into a reaction rectifying tower through a feed inlet arranged in the middle of the reaction rectifying tower, wherein the concentration of the fed formaldehyde solution is 60 wt%; the concentration of the catalyst sulfuric acid in the kettle liquid is 12 wt%; the salt auxiliary agent is magnesium sulfate; the concentration of the salt auxiliary agent in the kettle liquid is 8 wt%. The formaldehyde solution, the catalyst and the salt auxiliary agent are subjected to a reaction for synthesizing trioxymethylene from formaldehyde in the process of flowing from top to bottom, the operation temperature of the top of the reactive distillation tower is 110 ℃, the operation temperature of the bottom of the reactive distillation tower is 117 ℃, and the operation pressure of the reactive distillation tower is 0.2 MPa; materials at the bottom of the reactive distillation tower are conveyed to a feed inlet of the reactive distillation tower through a circulating pump I, so that salt auxiliary agents in circulating flow generate a salt effect; discharging noncondensable light component methyl formate in a product at the top of the reactive distillation tower from the top of the reflux tank; the condensed trioxymethylene synthetic liquid in the tower top product mainly comprises trioxymethylene, formaldehyde and water, wherein the trioxymethylene synthetic liquid partially refluxes, the reflux ratio is 2.0, and part of the condensed trioxymethylene synthetic liquid is used as the feeding material of the extraction tower.
(2) Extracting the trioxymethylene synthetic liquid to obtain an extract phase rich in trioxymethylene and a raffinate phase rich in water and formaldehyde: feeding a trioxymethylene synthetic solution produced at the top of the reactive distillation tower from a material inlet of the extraction tower, and feeding a circulating extractant and a supplementary fresh extractant from an extractant inlet of the extraction tower; the mass ratio of the benzene as the extracting agent to the feeding amount of the trioxymethylene synthetic liquid is 0.8: 1; the extractant consists of a circulating extractant and a fresh supplementary extractant. Carrying out countercurrent extraction operation in the extraction tower, wherein the operation temperature at the top of the extraction tower is 80 ℃, the operation temperature at the bottom of the extraction tower is 80 ℃, and the operation pressure of the extraction tower is 0.2 MPa; the extraction phase rich in trioxymethylene obtained by extraction is output from the top of the extraction tower and is used as the feed of a recovery tower; the obtained raffinate rich in water and formaldehyde is produced from the bottom of the extraction tower to a concentration tower, and the trioxymethylene content in the raffinate is lower than 0.3 wt%.
(3) Concentrating raffinate phase to recover formaldehyde solution: feeding raffinate phase produced at the bottom of the extraction tower from the middle part of the concentration tower, and performing pressurized concentration operation of formaldehyde in the concentration tower; the operation temperature of the top of the concentration tower is 143 ℃, the operation temperature of the bottom of the concentration tower is 153 ℃, and the operation pressure of the concentration tower is 0.5 MPa; refluxing the concentrated formaldehyde solution at the top of the column with reflux ratio of 3.0; part of the formaldehyde solution returns to the reactive distillation tower from a feed inlet of the reactive distillation tower, the trioxymethylene synthesis reaction is continued, and the concentration of the concentrated formaldehyde solution distilled from the tower top is 57 wt%; the bottom of the concentration tower produces waste water with formaldehyde content lower than 0.18 wt%.
(4) Separating and recovering the extractant from the extraction phase to obtain a trioxymethylene product: an extract phase produced at the top of the extraction tower is fed from a material inlet of a recovery tower, and an extractant and trioxymethylene are separated in the recovery tower; the operation temperature of the top of the recovery tower is 104 ℃, the operation temperature of the bottom of the recovery tower is 143 ℃, and the operation pressure of the recovery tower is 0.2 MPa; the overhead extractant of the recovery tower partially refluxes, and the reflux ratio is 3.0; part of the extractant is used as a circulating extractant and returns to the extraction tower from an extractant inlet of the extraction tower; the bottom of the recovery tower produces trioxymethylene product with purity of 99.9 wt%.
Example 6: as shown in figure 1, the method for synthesizing trioxymethylene by rectifying and reacting salt effect by using the device in the embodiment 1 is different from the embodiment 3 in that no salt auxiliary agent is added, and the other steps are the same as the embodiment 3.
Example 7: as shown in fig. 3 and 4, the method for synthesizing trioxymethylene by performing reactive distillation using the apparatus of example 2 is different from example 3 in that: no salt additive is added, and meanwhile, no raffinate phase is concentrated to recover the formaldehyde solution;
the method specifically comprises the following steps: (1) rectifying to obtain trioxymethylene synthetic liquid; (2) extracting the trioxymethylene synthetic liquid to obtain an extract phase rich in trioxymethylene and a raffinate phase rich in water and formaldehyde; (3) separating and recovering the extractant from the extraction phase to obtain a trioxymethylene product; wherein,
(1) and (3) performing reactive distillation to generate trioxymethylene synthetic fluid: adding a formaldehyde solution and a catalyst into a reactive distillation column through a feed inlet arranged in the middle of the reactive distillation column, wherein the concentration of the fed formaldehyde solution is 65 wt%; the concentration of the catalyst sulfuric acid in the kettle liquid is 10 wt%. The formaldehyde solution and the catalyst are subjected to a reaction for synthesizing trioxymethylene from formaldehyde in the process of flowing from top to bottom, the operation temperature of the top of the reactive rectifying tower is 92 ℃, the operation temperature of the bottom of the reactive rectifying tower is 100 ℃, and the operation pressure of the reactive rectifying tower is 0.1 MPa; discharging noncondensable light component methyl formate in a product at the top of the reactive distillation tower from the top of the reflux tank; the condensed trioxymethylene synthetic liquid in the tower top product mainly comprises trioxymethylene, formaldehyde and water, wherein the trioxymethylene synthetic liquid partially refluxes, the reflux ratio is 3, and part of the triformol synthetic liquid is used as the feeding material of the extraction tower.
(2) Extracting the trioxymethylene synthetic liquid to obtain an extract phase rich in trioxymethylene and a raffinate phase rich in water and formaldehyde: feeding a trioxymethylene synthetic solution produced at the top of the reactive distillation tower from a material inlet of the extraction tower, and feeding a circulating extractant and a supplementary fresh extractant from an extractant inlet of the extraction tower; the mass ratio of the extractant benzene to the feeding amount of the trioxymethylene synthetic liquid is 1: 1; the extractant is composed of the circulating extractant and the fresh supplementary extractant. Carrying out countercurrent extraction operation in the extraction tower, wherein the operation temperature at the top of the extraction tower is 70 ℃, the operation temperature at the bottom of the extraction tower is 70 ℃, and the operation pressure of the extraction tower is 0.1 MPa; the extraction phase rich in trioxymethylene obtained by extraction is output from the top of the extraction tower and is used as the feed of a recovery tower; collecting and uniformly treating the obtained raffinate rich in water and formaldehyde.
(3) Separating and recovering the extractant from the extraction phase to obtain a trioxymethylene product: an extract phase produced at the top of the extraction tower is fed from a material inlet of a recovery tower, and an extractant and trioxymethylene are separated in the recovery tower; the operation temperature of the top of the recovery tower is 80 ℃, the operation temperature of the bottom of the recovery tower is 120 ℃, and the operation pressure of the recovery tower is 0.1 MPa; the overhead extractant of the recovery tower partially refluxes, and the reflux ratio is 2.0; part of the extractant is used as a circulating extractant and returns to the extraction tower from an extractant inlet of the extraction tower; the bottom of the recovery tower produces trioxymethylene product with purity of 99.9 wt%.
Examples 3-7 comparative experiments on total formaldehyde conversion, trioxymethylene yield, single pass conversion of formaldehyde, trioxymethylene product purity, and energy consumption, the experimental results are given in the following table:
as can be seen from the data in the table above, in example 3, (1) the reaction rectifying tower has high salt concentration and obvious salt effect, and can significantly improve the formaldehyde conversion rate and the trioxymethylene yield; (2) the operation temperature and pressure of the reaction rectifying tower and the recovery tower are low, and the corresponding energy consumption is low; (3) although the operating pressure of the concentration tower is high, the concentration of the concentrated formaldehyde is high, which is beneficial to the rapid proceeding of the synthesis reaction in the reactive distillation tower, thereby improving the conversion rate of the formaldehyde. For the above 3 reasons, the conversion of formaldehyde and the yield of trioxymethylene are higher in example 3 than in other examples, and the energy consumption is lower than in other examples.
Examples 4 and 5 have a reduced salt concentration in the reactive distillation column compared to example 3, and it is necessary to increase the operating temperature and pressure of the reactive distillation column and the recovery column, resulting in an increase in energy consumption.
Compared with the example 3, the example 6 has no salt auxiliary agent and has no salt effect rectification effect, so that the conversion per pass of the formaldehyde in the reactive rectification tower and the yield of the trioxymethylene are lower, and the load and the energy consumption of the concentration tower are increased.
Example 7 compared with example 3, example 7 has low conversion per pass of formaldehyde in the reactive distillation column due to no addition of salt promoter and no formaldehyde concentration device, and the conversion per pass is the total conversion, thus resulting in low trioxymethylene yield. The energy consumption of example 7 is higher than the other examples in comparison with the energy consumption per ton of product.
The above description is only a preferred embodiment of the present invention, and should not be taken as limiting the invention, and any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (3)
1. The device for synthesizing trioxymethylene by salt effect reactive distillation is characterized by comprising a reactive distillation column, an extraction column, a concentration column and a recovery column, wherein a feed inlet is formed in the middle of the reactive distillation column, a material outlet in the middle of the reactive distillation column is connected with an inlet of a pump III, a material outlet at the top of the reactive distillation column is connected with a material inlet of a condenser I, a material outlet of the condenser I is connected with an inlet of a reflux tank I, an outlet of the reflux tank I is connected with an inlet of a pump II, and an outlet of the pump II is respectively connected with a reflux port at the top of the reactive distillation column and a material inlet of the extraction column; the top material outlet of the extraction tower is connected with the material inlet of the recovery tower, the bottom of the recovery tower is provided with a trioxymethylene product discharge port, the top extractant outlet of the recovery tower is connected with the feed port of a condenser III, the discharge port of the condenser III is connected with the inlet of a reflux tank III, the outlet of the reflux tank III is connected with the inlet of a pump IV, and the outlet of the pump IV is respectively connected with the reflux port of the recovery tower and the extractant inlet of the extraction tower; the extraction raffinate phase outlet of the extraction tower is connected with the inlet of a pump III, the outlet of the pump III is connected with the feed inlet of the concentration tower, the top discharge hole of the concentration tower is connected with the inlet of a condenser II, the outlet of the condenser II is connected with the inlet of a reflux tank II, and the outlet of the reflux tank II is respectively connected with the reflux port of the concentration tower and the feed inlet of the reaction rectification tower.
2. The device for synthesizing trioxymethylene by salt effect reaction rectification according to claim 1, wherein the bottom circulating material outlet of the reaction rectification column is connected with the inlet of a pump I, and the outlet of the pump I is connected with the feed inlet of the reaction rectification column.
3. The device for synthesizing trioxymethylene by salt effect reactive distillation according to claim 1 or 2, wherein the number of the reaction distillation tower plates is 25-45; the number of the tower plates of the extraction tower is 5-12 layers; the number of the tower plates of the concentration tower is 20-40 layers; the number of the tower plates of the recovery tower is 30-55 layers.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN112237749A (en) * | 2020-06-11 | 2021-01-19 | 鄂尔多斯应用技术学院 | Device and method for synthesizing trioxymethylene by rectifying through salt effect reaction |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112237749A (en) * | 2020-06-11 | 2021-01-19 | 鄂尔多斯应用技术学院 | Device and method for synthesizing trioxymethylene by rectifying through salt effect reaction |
| CN112237749B (en) * | 2020-06-11 | 2024-07-12 | 鄂尔多斯应用技术学院 | Device and method for synthesizing trioxymethylene through salt effect reaction rectification |
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