An in-line evaporation apparatus for unsaturated polyester synthesis

Abstract

This invention discloses an online evaporation device for unsaturated polyester synthesis, comprising a reactor connected to a vertical condenser, which in turn is connected to a horizontal condenser. The horizontal condenser is connected to a tube condenser and a wastewater collection tank via material conveying pipes. The outlet of the wastewater collection tank is connected to a circulating pump via a material conveying pipe. The outlet of the tube condenser is connected to a buffer tank of the reactor via a material conveying pipe. The buffer tank is connected to the circulating pump via a material conveying pipe. The circulating pump is connected to a heater via a material conveying pipe. The heater is connected to an evaporator via a material conveying pipe. The evaporator is connected to the circulating pump via a material conveying pipe. This invention can shorten the heating time of the unsaturated polyester synthesis reaction and significantly improve production efficiency.

Description

Technical Field

[0001] This utility model relates to the field of chemical production technology, specifically to an online evaporation device for the synthesis of unsaturated polyester. Background Technology

[0002] Unsaturated polyester resins are typically synthesized by reacting diacids and diols at 160℃-210℃ under slight negative pressure (-0-0.08 MPa) through esterification and polycondensation reactions to produce linear polymers. Polycondensation reactions (such as the synthesis of polyesters and polyamides) are equilibrium reactions, during which small molecule byproducts (such as water and alcohols) are generated, competing with the reverse reaction (such as hydrolysis). In reversible polycondensation, the residue of small molecule byproducts significantly limits the polymer molecular weight. Timely removal of byproducts can shift the reaction towards the direction of polymer formation, reducing the inhibitory effect of the reverse reaction on polymer chain growth. Continuous removal of byproducts can disrupt the equilibrium to increase the degree of polymerization.

[0003] In the synthesis of unsaturated polyester, during the effluent stage (material temperature 150-200℃), the material reaction is vigorous, resulting in a large volume of water output. To prevent alcohol runoff, the distillation head temperature needs to be controlled. This is achieved by cooling the evaporated gas using a vertical condenser, with a large amount of cooled alcohol and condensed water flowing back into the reactor, indirectly cooling the materials inside. Alternatively, the recirculated alcohol and water can be reheated, leading to energy waste. Furthermore, this process cannot quickly remove byproducts, significantly reducing the efficiency of the unsaturated polyester reaction. Utility Model Content

[0004] The technical problem this invention aims to solve is to address the shortcomings of existing technologies by providing an online evaporation device that is simple in structure, requires modification of existing equipment, and rapidly distills the water generated in the reaction vessel by not controlling the distillation head temperature of the vertical condenser. The water is then concentrated through online circulating evaporation outside the reaction vessel and pressure-returned to the vessel to participate in the reaction again. This online evaporation device increases the heating rate by 150-200℃, thereby shortening the reaction time for unsaturated polyester synthesis.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0006] An online evaporation device for unsaturated polyester synthesis includes a reactor, wherein the reactor is connected to a vertical condenser, the vertical condenser is connected to a horizontal condenser, the horizontal condenser is connected to a tube condenser and a wastewater collection tank via material conveying pipes, the outlet of the wastewater collection tank is connected to a circulating pump via a material conveying pipe, the outlet of the tube condenser is connected to a reactor buffer tank via a material conveying pipe, the reactor buffer tank is connected to a circulating pump via a material conveying pipe, the circulating pump is connected to a heater via a material conveying pipe, the heater is connected to an evaporator via a material conveying pipe, and the evaporator is connected to the circulating pump via a material conveying pipe.

[0007] Preferably, the tube condenser has a cooling water inlet and a cooling water outlet.

[0008] Preferably, the circulating pump is a peristaltic pump.

[0009] Preferably, the material conveying pipeline is equipped with a valve. More preferably, the valve is a pneumatic valve.

[0010] Preferably, the outlet of the reactor buffer tank is connected to a wastewater pipe, a vacuum pipe, and an exhaust gas pipe. More preferably, the wastewater pipe and the vacuum pipe are equipped with valves, preferably pneumatic valves.

[0011] Preferably, the heater is provided with a steam inlet, a steam outlet, and a temperature transmitter.

[0012] Preferably, the evaporator is equipped with a level gauge, a temperature transmitter, a level viewing window, an inlet connected to a heater, a top outlet connected to a reaction vessel buffer tank, and a bottom outlet connected to a circulating pump.

[0013] Preferably, the wastewater collection tank is equipped with a level gauge and a weighing module.

[0014] Preferably, the vertical condenser is provided with a Pall ring packing layer, a tube condenser, and a temperature transmitter. More preferably, the cooling water used in the vertical condenser is 0-10°C.

[0015] Preferably, the inlet of the tube condenser is connected to the evaporator, the outlet is connected to the reactor buffer tank, and it is provided with a cooling water inlet and a cooling water outlet.

[0016] Preferably, the reactor buffer tank is equipped with a level gauge and a pressure transmitter, and has multiple outlets that are respectively connected to a wastewater pipeline, a vacuum pipeline, an exhaust gas pipeline, and a tube condenser.

[0017] This invention's apparatus, during the effluent stage of the unsaturated polyester production synthesis process (material temperature 150-200℃), does not control the distillation head temperature of the vertical condenser. It rapidly distills the wastewater generated in the reaction vessel, concentrates it through online circulating evaporation, and then pressurizes it back into the vessel to participate in the subsequent reaction process. By not controlling the vertical condenser head temperature, rapidly distilling, concentrating online, and then pressurizing it back into the vessel to participate in the reaction, this process increases the heating rate (150-200℃) and reaction rate, thereby effectively shortening the unsaturated polyester polycondensation reaction time and improving production efficiency. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the online evaporation device for unsaturated polyester synthesis according to this utility model.

[0019] In the diagram: 1-Reaction vessel, 2-Bottom valve, 3-Reaction vessel buffer tank, 4-Wastewater collection tank, 5-Circulation pump.

[0020] 6-Vertical condenser, 7-Shell tube condenser, 8-Horizontal condenser, 9-Heater, 10-Evaporator, 11-Temperature transmitter, 12-Level gauge, 13-Weighing module, 14-Exhaust gas pipeline, 15-Pneumatic valve, 16-Cooling water inlet, 22-Cooling water outlet, 17-Steam outlet, 21-Steam inlet, 18-Stirring mechanism, 19-Material conveying pipeline, 20-Wastewater pipeline, 23-Vacuum pipeline. Detailed Implementation

[0021] The technical solution of this utility model will be described in detail below with reference to specific embodiments and accompanying drawings. However, it should be noted that the protection scope of this utility model is not limited to the following embodiments.

[0022] Reference Figure 1 The diagram shows a schematic representation of the online evaporation apparatus for unsaturated polyester synthesis according to this invention.

[0023] like Figure 1 As shown, the online evaporation device for unsaturated polyester synthesis of this utility model includes a reactor 1. The reactor 1 has a stirring mechanism for stirring the materials in the reactor 1 to ensure uniform mixing and thorough reaction. A bottom valve may be installed at the bottom of the reactor 1, and a circulating pump 5 is connected to the reactor 1 via a circulating material conveying pipe 19 and a valve (such as a pneumatic valve). The reactor is preferably an atmospheric pressure vessel made of stainless steel.

[0024] The reactor 1 is connected to the vertical condenser 6, which is connected to the horizontal condenser 8. The horizontal condenser 8 is connected to the tube condenser 7 and the wastewater collection tank 4 via the material conveying pipe 19. The outlet of the wastewater collection tank 4 is connected to the circulating pump 5 via the material conveying pipe 19. The outlet of the tube condenser 7 is connected to the reactor buffer tank 3 via the material conveying pipe 19. The reactor buffer tank 3 is connected to the circulating pump 5 via the material conveying pipe 19. The circulating pump 5 is connected to the heater 9 via the material conveying pipe 19. The heater 9 is connected to the evaporator 10 via the material conveying pipe 19. The evaporator 10 is connected to the circulating pump 5 via the material conveying pipe 19.

[0025] In a preferred embodiment, the vertical condenser 6 is provided with a Pall ring packing layer, a tube condenser, and a temperature transmitter. More preferably, the cooling water used in the vertical condenser 6 is 0-10°C.

[0026] In a preferred embodiment, the inlet of the tube condenser 7 is connected to the evaporator 10, the outlet is connected to the reactor buffer tank 3, and it has a cooling water inlet 16 and a cooling water outlet 22.

[0027] In a preferred embodiment, the circulating pump 5 may be a peristaltic pump, and a sampling port may be provided at the pump inlet, but it is not limited thereto.

[0028] In a preferred embodiment, valves may be provided on the material conveying pipeline 19 used to connect the horizontal condenser 8 to the shell-and-tube condenser 7, the horizontal condenser 8 to the wastewater collection tank 4, the wastewater collection tank 4 to the circulating pump 5, the evaporator 10 to the circulating pump 5, the reactor 1 to the circulating pump 5, the circulating pump 5 to the heater 9, and the reactor buffer tank 3 to the circulating pump 5, to control the flow and conveying of materials. Preferably, the valves are pneumatic valves.

[0029] In a preferred embodiment, the reactor buffer tank 3 may be equipped with a level gauge and a pressure transmitter, and has multiple outlets connected to a wastewater pipe 20, a vacuum pipe 23, an exhaust gas pipe 14, and a tube condenser 7, respectively. Valves, preferably pneumatic valves, may be installed on the wastewater pipe 20 and the vacuum pipe 23.

[0030] In a preferred embodiment, the heater 9 is connected to the circulating pump 5 and the evaporator 10, and is equipped with a steam inlet 21, a steam outlet 17, and a temperature transmitter 11, which facilitates the control of the heating temperature and ensures that the wastewater evaporator reaches the required process temperature. A steam regulating valve may also be installed on the steam pipe of the heater 9, and a drain valve may be installed on its drain pipe. Preferably, the heater 9 is made of stainless steel, has a 2.5 m² shell-side and tube-side, withstands a pressure of 0.6 MPa, and is heat-resistant to temperatures above 200°C.

[0031] In a preferred embodiment, the evaporator 10 is equipped with a level gauge 12, a temperature transmitter 11, and a level viewing window. The inlet is connected to a heater, the top outlet is connected to a reaction vessel buffer tank, and the bottom outlet is connected to a circulating pump. The evaporator 10 may also have an internal tray structure for gas-liquid separation.

[0032] The wastewater evaporator flows through material pipe 19, then through circulation pump 5, and then through heater 9 and evaporator 10 for cyclic evaporation. A vacuum pipe 23 (connected to a vacuum pump, not shown in the figure) creates negative pressure throughout the system. After switching valves, the concentrated liquid from the evaporation process is returned to reactor 1 via circulation pump 5. The evaporated wastewater flows through material pipe 19 to the tube condenser 7, is collected in reactor buffer tank 3, and is discharged to the wastewater treatment system via wastewater pipe 20 after evaporation is complete.

[0033] In a preferred embodiment, the wastewater collection tank 4 may be equipped with a level gauge 12 and a weighing module 13 to facilitate the measurement of wastewater volume. Furthermore, the wastewater collection tank 4 may also be equipped with a temperature transmitter, a bottom outlet connected to a circulation pump 5, a bottom outlet connected to a wastewater pipe, a top exhaust port connected to an exhaust gas pipe 14 for connection to an exhaust gas treatment system, and a top vacuum pipe connected to a vacuum system.

[0034] The process for synthesizing unsaturated polyester using the above-mentioned online evaporation device includes the following steps:

[0035] 1) After the reactants are added to reactor 1, the temperature is raised and nitrogen gas is introduced into the reactor as a protective gas.

[0036] 2) When the temperature of the material in reactor 1 rises to 150°C, start stirring, turn off the cooling water of vertical condenser 6, do not control the distillation head temperature of vertical condenser 6, and turn on the cooling water of horizontal condenser 8.

[0037] 3) The temperature of the evaporated wastewater from the reactor exiting the horizontal condenser 8 is controlled at 70-80℃ and collected in the wastewater collection tank 4. The weight is measured by the weighing module 13 and the level gauge 12.

[0038] 4) When the wastewater volume in the wastewater tank reaches 150kg, open the bottom valve 2 of the wastewater collection tank 4 and start the circulation pump 5 to transport the wastewater to the heater 7; after all the wastewater in the wastewater collection tank 4 has been pumped out, close the bottom valve 2 of the wastewater collection tank 7.

[0039] 5) Turn on 0.4MPa steam to heat heater 9 to 80±2℃.

[0040] 6) Open vacuum pipe 23 and control the vacuum level between -0.06 and +0.07 MPa.

[0041] 7) Maintain the conditions of steps 5) and 6) to allow the wastewater to circulate and evaporate between the heater 9, evaporator 10, and circulating pump 5. The reactor 1 will continue to produce wastewater to the wastewater collection tank 4. Controlled by valves on the pipeline, the wastewater in the wastewater collection tank 4 is periodically pumped to the heater 9 to replenish the amount of evaporated wastewater.

[0042] 8) The evaporation time is expected to be 1.5 hours. For conventional products, when the reaction temperature is 195-200℃, the COD of the wastewater concentrate is greater than 50W. When the evaporation reaches the set parameters, the concentrate from the evaporator 10 is sent back to the reactor 1 for production by switching valves. The evaporated wastewater is cooled by the condenser 7 and then sent to the reactor buffer tank 3.

[0043] 9) Depending on the product's process temperature, small-scale evaporation and alcohol recovery can be carried out multiple times.

[0044] 10) The online evaporation step is now complete. Continue heating the material in the reactor to continue the reaction.

[0045] 11) The reaction material temperature is kept at 208℃ (maximum temperature not exceeding 210℃). The polyester acid value and cone viscosity are tested according to the process requirements to meet the process requirements: for example, polyester acid value 55~60mgKOH / g, cone viscosity 2.6~3.8P.

[0046] 12) Evacuate a vacuum, with the vacuum level not exceeding -0.085 MPa;

[0047] 13) Evacuate the system until the process parameters are met: polyester acid value 30-34 mgKOH / g, cone-plate viscosity 7-11 P. The reaction is then complete.

[0048] Experimental data:

[0049] The product was synthesized using 6-ton reactors of phthalic LY-191C unsaturated polyester resin (approximately 8 tons of finished resin per reactor). The online wastewater evaporation, wastewater recovery volume, alcohol recovery volume after evaporation, recovery rate, and reaction time were tested.

[0050] The raw material components for synthesizing phthalic LY-191C unsaturated polyester resin are as follows:

[0051] Phthalic anhydride: 1150 kg

[0052] maleic anhydride: 2000 kg

[0053] Diethylene glycol: 2455kg

[0054] Ethylene glycol: 360kg

[0055] Hydroquinone: 200g

[0056] Experimental batch: Phthalic LY-191C unsaturated polyester resin was synthesized using the online evaporation device of this invention and the above process.

[0057] Regular batch: Synthesized phthalic LY-191C unsaturated polyester resin using conventional production equipment (excluding online evaporation equipment).

[0058] The test results are recorded in Table 1 below:

[0059]

[0060] The experimental results in the table above show that, through online wastewater evaporation, the reaction time for synthesizing phthalic LY-191C unsaturated polyester resin is shortened by 20% (the conventional reaction time for producing LY-191C unsaturated polyester resin is 11.5 hours). This indicates that the apparatus of this invention can significantly shorten the reaction time for synthesizing unsaturated polyester resin, improve production efficiency, and save production costs.

Claims

1. An online evaporation apparatus for the synthesis of unsaturated polyesters, comprising a reaction vessel, characterized in that: The reactor is connected to a vertical condenser, which is connected to a horizontal condenser. The horizontal condenser is connected to a tube condenser and a wastewater collection tank via material conveying pipes. The outlet of the wastewater collection tank is connected to a circulating pump via a material conveying pipe. The outlet of the tube condenser is connected to a reactor buffer tank via a material conveying pipe. The reactor buffer tank is connected to a circulating pump via a material conveying pipe. The circulating pump is connected to a heater via a material conveying pipe. The heater is connected to an evaporator via a material conveying pipe. The evaporator is connected to the circulating pump via a material conveying pipe.

2. The online evaporation apparatus according to claim 1, characterized in that: The vertical condenser is equipped with a Pall ring packing layer, a tube condenser, and a temperature transmitter.

3. The online evaporation apparatus according to claim 1, characterized in that: The material conveying pipeline is equipped with valves.

4. The online evaporation apparatus according to claim 1, characterized in that: The outlet of the reactor buffer tank is connected to a wastewater pipeline, a vacuum pipeline, and an exhaust gas pipeline.

5. The online evaporation apparatus according to claim 1, characterized in that: The heater is equipped with a steam inlet, a steam outlet, and a temperature transmitter.

6. The online evaporation apparatus according to claim 1, characterized in that: The evaporator is equipped with a level gauge, a temperature transmitter, and a level viewing window. The inlet is connected to a heater, the top outlet is connected to a reaction vessel buffer tank, and the bottom outlet is connected to a circulating pump.

7. The online evaporation apparatus according to claim 1, characterized in that: The wastewater collection tank is equipped with a level gauge and a weighing module.

8. The online evaporation apparatus according to claim 1, characterized in that: The tube condenser is connected to the evaporator at its inlet and to the buffer tank of the reaction vessel at its outlet, and is equipped with a cooling water inlet and a cooling water outlet.

9. The online evaporation apparatus according to claim 1, characterized in that: The reactor buffer tank is equipped with a level gauge and a pressure transmitter, and has multiple outlets that are respectively connected to wastewater pipelines, vacuum pipelines, exhaust gas pipelines, and tube condensers.

Images