Unsaturated polyester resin safe dilution system

Abstract

The utility model relates to the technical field of polyester production devices, in particular to a safe unsaturated polyester resin diluting system which comprises a diluting kettle, a stirring assembly arranged in the diluting kettle, a double-layer coil pipe spirally arranged in the diluting kettle, an unsaturated polyester discharging pipe arranged on the upper portion of the diluting kettle, a styrene discharging pipe and an air inlet pipe. A conical cap is arranged under an opening in the bottom end of the unsaturated polyester discharging pipe, a discharging space is formed between the conical cap and the opening in the bottom end of the unsaturated polyester discharging pipe, and an adjusting valve is arranged on the unsaturated polyester discharging pipe. The styrene discharging pipe is provided with an inner inserting pipe extending into the diluting kettle, and oppositely-opened through holes are formed in the inner inserting pipe at intervals in the length direction; the air inlet pipe penetrates through the upper wall of the dilution kettle, extends inwards to the bottom and is respectively connected with a nitrogen pipe and a compressed air pipe. According to the unsaturated polyester resin diluting device, the safety in the unsaturated polyester resin diluting process is improved, and the probability of accidents is reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of polyester production devices, in particular to a safety dilution system for unsaturated polyester resins. Background Technique

[0002] The production of unsaturated polyester resins mainly includes two major systems: a polymerization kettle system and a dilution kettle system. Among them, in the polymerization kettle, dibasic acids (such as fumaric acid, terephthalic acid, isophthalic acid, etc.) or dibasic anhydrides (such as phthalic anhydride, maleic anhydride, etc.) and diols (such as ethylene glycol, diethylene glycol, propylene glycol, etc.) are dehydrated and polycondensed into polyester long chains under high temperature and the action of a catalyst, which is unsaturated polyester; the dilution kettle is to mix the unsaturated polyester with vinyl monomers (mainly styrene) evenly. This stage is the dilution stage, and the product after dilution is unsaturated polyester resin.

[0003] From the actual production situation, flash explosion accidents and gelling accidents are prone to occur in the dilution stage of unsaturated polyester resin production. In the dilution stage, styrene is first injected into the dilution kettle, and then the unsaturated polyester is put into the dilution kettle to be mixed with styrene. The dilution temperature is generally maintained at 70-90°C and stirred for 2-3 hours; if the temperature is too low, it is easy to cause uneven mixing of the unsaturated polyester and styrene, resulting in a layering phenomenon; if the temperature is too high, a gelling accident is prone to occur.

[0004] Reasons for flash explosion accidents in the dilution stage: Styrene belongs to Class A flammable and explosive liquids. Its volatile gas is easy to mix with air above the dilution kettle to reach the explosion range of styrene; at the same time, during the process of injecting styrene into the dilution kettle and putting the unsaturated polyester into the dilution kettle, static electricity is easily generated. If the static electricity is not removed in time, the accumulation and discharge of static electricity are likely to provide an ignition source for the explosion of styrene gas. Moreover, since styrene gas does not contain a polymerization inhibitor, if the upper space of the dilution kettle is an oxygen-rich environment, the styrene gas without a polymerization inhibitor is easy to condense, polymerize, and adhere to the wall at the top head of the dilution kettle in the oxygen-rich environment, and the shedding of the polymer is also likely to generate a large amount of static charges. Therefore, to avoid the occurrence of flash explosion accidents, one is to avoid the styrene gas reaching the explosion range above the dilution kettle; the other is to reduce the generation of static electricity and remove the static electricity in time.

[0005] Reasons for gelation accidents during the dilution stage: There are many reasons for the gelation of unsaturated polyester resin, and the situation is relatively complex. However, there are mainly two reasons for gelation during the dilution stage. One is that the dilution temperature is relatively high or the local temperature is too high, which causes the unsaturated double bond of styrene to break to generate free radicals and quickly consume the inhibitor, resulting in gelation. The other is that the amount of inhibitor added is small or the inhibitor does not play a role in an anaerobic environment. The commonly used inhibitors in the production process of unsaturated polyester resin mainly include hydroquinone, methyl hydroquinone, and tert-butylcatechol. These three types of inhibitors are aerobic inhibitors and must play an inhibitory role in a certain dissolved oxygen environment. Therefore, to avoid gelation accidents, first, it is necessary to avoid the overall temperature and local temperature being too high during the dilution process; second, it is necessary to increase the dissolved oxygen in styrene to give full play to the inhibitory effect of the inhibitor. Utility Model Content

[0006] The technical problem to be solved by this utility model is to provide a safety dilution system for unsaturated polyester resin, which improves the safety during the dilution process of unsaturated polyester resin and reduces the probability of accidents.

[0007] The safety dilution system for unsaturated polyester resin described in this utility model includes a dilution kettle. A stirring assembly is provided inside the dilution kettle. A double-layer coil pipe is spirally arranged inside the dilution kettle. An unsaturated polyester feeding pipe, a styrene feeding pipe, and an air inlet pipe are provided at the upper part of the dilution kettle. A cone cap is provided directly below the bottom opening of the unsaturated polyester feeding pipe. A feeding space is provided between the cone cap and the bottom opening of the unsaturated polyester feeding pipe. A regulating valve is provided on the unsaturated polyester feeding pipe. The styrene feeding pipe is provided with an inner insertion pipe extending into the interior of the dilution kettle. Opposite through holes are arranged at intervals along the length direction of the inner insertion pipe, and the through holes are round holes. The air inlet pipe passes through the upper wall of the dilution kettle and extends inward to the bottom of the dilution kettle. The air inlet pipe is respectively connected to a nitrogen gas pipe and a compressed air pipe.

[0008] Preferably, the stirring assembly includes a stirring shaft, the stirring shaft is connected to the output end of the motor, and blades are provided on the stirring shaft.

[0009] Preferably, the blades are turbine blades.

[0010] Preferably, the upper end of the stirring shaft is connected to the motor through a reducer, and the lower end of the stirring shaft is connected to the dilution kettle through a bottom bearing.

[0011] Preferably, the cone cap is connected to the unsaturated polyester feeding pipe through a round steel.

[0012] Preferably, ear-type supports are provided on both sides of the dilution kettle. Static electricity grounding plates are provided on the ear-type supports. The ear-type supports and the dilution kettle, as well as the static electricity grounding plates and the ear-type supports, are all connected by welding.

[0013] Preferably, a nitrogen gas flow meter and a nitrogen gas flow control valve are electrically connected to the nitrogen gas pipe, and an air flow meter and an air flow control valve are electrically connected to the compressed air pipe.

[0014] Preferably, an inner coil support is provided in the dilution kettle, and the coil is connected to the inner coil support through a guard plate.

[0015] Preferably, the water inlet at the lower end of the coil is connected to the circulating water supply pipe, and the water outlet at the upper end of the coil is connected to the circulating water return pipe.

[0016] Compared with the prior art, the beneficial effects of the present utility model are as follows:

[0017] 1. Through the stirring assembly, the circulating water cooling system of the double-layer coil, and the cone cap at the bottom of the unsaturated polyester discharge pipe, the dilution temperature in the dilution stage can be effectively controlled.

[0018] The double-layer coil with a spiral upward shape can increase the cooling area, enhance the cooling effect, and has no right-angle turns, reducing the resistance of the circulating water. It can effectively control the temperature in the dilution stage of unsaturated polyester and prevent overheating.

[0019] When the unsaturated polyester is fed into the discharge pipe, the cone cap provided at the bottom end of the pipe orifice causes the unsaturated polyester to disperse around after passing through the barrier of the cone cap and enter the dilution kettle from the discharge space, increasing the contact area between the high-temperature unsaturated polyester and styrene, and avoiding the direct contact between a large flow of unsaturated polyester and styrene, which may cause local overheating.

[0020] 2. The styrene discharge pipe is provided with an inner inserted pipe, which can effectively reduce the feeding drop of styrene during the initial feeding and reduce the generation of static charges. When the styrene feeding liquid level exceeds the bottom of the styrene discharge pipe, the styrene feeding becomes a sub-surface feeding method, which can more effectively prevent the generation of static charges. At the same time, the inner inserted pipe is provided with through holes that are spaced along the length direction and are split, avoiding the styrene in the pipeline not participating in the dilution cycle, thereby affecting the product quality.

[0021] 3. It is fixed on the steel structure frame through an ear-type support, and an electrostatic grounding plate is welded on the ear-type support. The electrostatic grounding plate is then connected to the electrostatic grounding network to form a path for conducting static charges, effectively conducting static charges.

[0022] 4. From the perspective of safety in avoiding flash explosion accidents, an oxygen-deficient environment should be formed inside the dilution kettle to prevent the styrene gas from forming an explosive atmosphere. From the perspective of avoiding gelation accidents, the dissolved oxygen in styrene should be increased to give full play to the inhibiting effect of the inhibitor. Therefore, an air inlet pipe is arranged to extend to the bottom of the dilution kettle and is connected to the nitrogen pipe and the compressed air pipe at the same time. The nitrogen pipe and the compressed air pipe are each equipped with corresponding flow meters and flow regulating valves, so that nitrogen and compressed air are fed into the dilution kettle according to a certain flow ratio. Under the rotational dispersion action of the unsaturated polyester resin, nitrogen and air are fully dissolved in the unsaturated polyester resin liquid, and at the same time, an oxygen-deficient environment is formed in the upper space of the dilution kettle; this not only achieves the purpose of activating the catalyst but also prevents the styrene gas in the upper space from reaching the explosion range. Brief Description of the Drawings

[0023] Figure 1 is a schematic structural diagram of the safety dilution system for unsaturated polyester resin of the present utility model;

[0024] Figure 2 is a schematic structural diagram of the unsaturated polyester discharging pipe;

[0025] Figure 3 is a schematic structural diagram of the inner coil support and the guard plate.

[0026] In the figure: 1. Dilution kettle; 2. Coil; 3. Unsaturated polyester discharging pipe; 4. Styrene discharging pipe; 5. Air inlet pipe; 6. Cone cap; 7. Discharging space; 8. Inner inserting pipe; 9. Through hole; 10. Nitrogen pipe; 11. Compressed air pipe; 12. Stirring shaft; 13. Motor; 14. Blade; 15. Reducer; 16. Bottom bearing; 17. Round steel; 18. Ear support; 19. Static electricity grounding plate; 20. Nitrogen flow meter; 21. Nitrogen flow control valve; 22. Air flow meter; 23. Air flow control valve; 24. Inner coil support; 25. Guard plate; 26. Circulating water supply pipe; 27. Circulating water return pipe; 28. Control valve. Detailed Embodiment

[0027] The present utility model will be clearly and completely described below in conjunction with the accompanying drawings.

[0028] As Figure 1 shown, the safety dilution system for unsaturated polyester resin includes a dilution kettle 1. A stirring assembly is arranged inside the dilution kettle 1. The stirring assembly includes a stirring shaft 12. The stirring shaft 12 is connected to the output end of a motor 13. Blades 14 are arranged on the stirring shaft 12. The blades 14 are turbine-type blades. There are 4 sections of blades 14 arranged on the stirring shaft 12 from top to bottom, which strengthens the forced stirring power from top to bottom of the dilution kettle, avoids poor circulation in the dead corner area, and avoids local overheating of the temperature during the dilution stage of unsaturated polyester.

[0029] Inside the dilution kettle 1, a double-layer coil pipe 2 is spirally arranged. This form of coil pipe 2 increases the cooling area, enhances the cooling effect, and has no right-angle turns, reducing the resistance of the circulating water. It can effectively control the temperature during the dilution stage of unsaturated polyester and prevent overheating. The lower water inlet of the coil pipe 2 is connected to the circulating water supply pipe 26, and the upper water outlet of the coil pipe 2 is connected to the circulating water return pipe 27.

[0030] At the upper part of the dilution kettle 1, there are an unsaturated polyester discharge pipe 3, a styrene discharge pipe 4, and an inlet pipe 5. Right below the bottom opening of the unsaturated polyester discharge pipe 3, there is a cone cap 6. Between the cone cap 6 and the bottom opening of the unsaturated polyester discharge pipe 3, there is a discharge space 7. When the unsaturated polyester is fed into the unsaturated polyester discharge pipe 3, the cone cap 6 arranged at the bottom pipe orifice thereof causes the unsaturated polyester to disperse around after passing through the barrier of the cone cap 6 and enter the dilution kettle 1 from the discharge space 7, increasing the contact area between the high-temperature unsaturated polyester and styrene and avoiding the direct contact of a large flow of unsaturated polyester and styrene, which may cause local overheating.

[0031] A regulating valve 28 is provided on the unsaturated polyester discharge pipe 3. By adjusting the discharge speed of the unsaturated polyester, the purpose of controlling the temperature inside the kettle can also be achieved.

[0032] The above measures can all effectively control the dilution temperature during the dilution stage.

[0033] The styrene discharge pipe 4 is provided with an inner insertion pipe 8 extending into the interior of the dilution kettle 1. Along the length direction of the inner insertion pipe 8, there are oppositely opened through holes 9 at intervals. The through holes 9 are round holes, and the diameter of the through holes 9 is 18 mm. The styrene discharge pipe 4 is provided with an inner insertion pipe 8, which effectively reduces the feeding drop of styrene during the initial feeding and reduces the generation of static charges. When the styrene feeding liquid level exceeds the bottom of the styrene discharge pipe 4, the styrene feeding becomes a feeding method under the liquid surface, which more effectively prevents the generation of static charges. At the same time, the oppositely opened through holes 9 are arranged at intervals along the length direction of the inner insertion pipe 8, avoiding the styrene in the pipeline not participating in the dilution cycle and thus affecting the product quality.

[0034] On both sides of the dilution kettle 1, there are lug supports 18, and on the lug supports 18, there are static grounding plates 19. The lug supports 18 are fixed on the steel structure frame. The static grounding plates 19 are welded on the lug supports 18, and the static grounding plates 19 are then connected to the static grounding network to form a path for conducting static charges and effectively conduct static charges.

[0035] The inlet pipe 5 passes through the upper wall of the dilution kettle 1 and extends inward to the bottom of the dilution kettle 1. The inlet pipe 5 is respectively connected to a nitrogen pipe 10 and a compressed air pipe 11. On the nitrogen pipe 10, there are an electrically connected nitrogen flowmeter 20 and a nitrogen flow control valve 21. On the compressed air pipe 11, there are an electrically connected air flowmeter 22 and an air flow control valve 23. Nitrogen and compressed air are fed into the dilution kettle 1 according to a certain flow ratio. Generally, the ratio of nitrogen to air is controlled at 27:3 (flow ratio, unit Nm 3 / h), under the rotational dispersion of unsaturated polyester resin, nitrogen and air are fully dissolved in the unsaturated polyester resin liquid, and at the same time, an oxygen-deficient environment is formed in the upper space of the dilution kettle 1; it not only achieves the purpose of activating the catalyst but also prevents the styrene gas in the upper space from reaching the explosion range.

[0036] As Figure 2 shown, the cone cap 6 is connected to the unsaturated polyester discharge pipe 3 through the round steel 17.

[0037] As Figure 3 shown, an inner coil support 24 is provided in the dilution kettle 1, and the coil 2 is connected to the inner coil support 24 through the guard plate 25.

[0038] The upper end of the stirring shaft 12 is connected to the motor 13 through the reducer 15, and the lower end of the stirring shaft 12 is connected to the dilution kettle 1 through the bottom bearing 16.

Claims

1. A safe dilution system for unsaturated polyester resin, comprising a dilution kettle (1), wherein a stirring assembly is provided in the dilution kettle (1), characterized in that: A double-layer coil (2) is spirally arranged inside the dilution kettle (1). An unsaturated polyester discharge pipe (3), a styrene discharge pipe (4) and an air inlet pipe (5) are arranged on the upper part of the dilution kettle (1). A cone cap (6) is arranged just below the bottom opening of the unsaturated polyester discharge pipe (3). A discharge space (7) is arranged between the cone cap (6) and the bottom opening of the unsaturated polyester discharge pipe (3). The styrene discharge pipe (4) is provided with an inner insert pipe (8) extending into the interior of the dilution kettle (1). The inner insert pipe (8) is provided with through holes (9) that are opened at intervals along the length direction. The air inlet pipe (5) passes through the upper wall of the dilution kettle (1) and extends inward to the bottom of the dilution kettle (1). The air inlet pipe (5) is connected to a nitrogen pipe (10) and a compressed air pipe (11) respectively.

2. The unsaturated polyester resin safe dilution system according to claim 1, characterized in that: The stirring assembly comprises a stirring shaft (12), the stirring shaft (12) being connected to the output end of a motor (13), and a paddle (14) being provided on the stirring shaft (12).

3. The unsaturated polyester resin safe dilution system according to claim 2, characterized in that: The blade (14) is a turbine blade.

4. The unsaturated polyester resin safe dilution system according to claim 2, characterized in that: The upper end of the stirring shaft (12) is connected to the motor (13) via a reducer (15), and the lower end of the stirring shaft (12) is connected to the dilution kettle (1) via a bottom bearing (16).

5. The unsaturated polyester resin safe dilution system according to claim 1, characterized in that: The cone cap (6) is connected to the unsaturated polyester discharge pipe (3) via a round steel (17).

6. The unsaturated polyester resin safe dilution system according to claim 1, characterized in that: The unsaturated polyester discharge pipe (3) is provided with a regulating valve (28).

7. The unsaturated polyester resin safe dilution system according to claim 1, characterized in that: Ear-type supports (18) are provided on both sides of the dilution kettle (1), and electrostatic grounding plates (19) are provided on the ear-type supports (18).

8. The unsaturated polyester resin safe dilution system according to claim 1, characterized in that: The nitrogen pipe (10) is provided with a nitrogen flow meter (20) and a nitrogen flow control valve (21) which are electrically connected, and the compressed air pipe (11) is provided with an air flow meter (22) and an air flow control valve (23) which are electrically connected.

9. The unsaturated polyester resin safe dilution system according to claim 1, characterized in that: An inner coil support (24) is provided in the dilution kettle (1), and the coil (2) is connected to the inner coil support (24) via a guard plate (25).

10. The unsaturated polyester resin safe dilution system according to claim 1, characterized in that: The water inlet at the lower end of the coil (2) is connected to the circulating water supply pipe (26), and the water outlet at the upper end of the coil (2) is connected to the circulating water return pipe (27).

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