Synthesis device of dioctyl terephthalate

Abstract

The utility model relates to a dioctyl terephthalate synthesizing device which comprises a reaction kettle, a first nitrogen conveying pipe is arranged on the reaction kettle, and a first temperature sensor, an electric heater, a second temperature sensor, a nitrogen pressure unit, a first gas flow sensor and a first adjusting valve are arranged on the first nitrogen conveying pipe. A rectifying tower is arranged above the reaction kettle and comprises a tower body and a filler layer, a first liquid phase return pipe is arranged between the tower body and the reaction kettle, a first gas phase conveying pipe is arranged between the tower body and the reaction kettle, and a second adjusting valve, a first pressure sensor and a third temperature sensor are arranged on the first gas phase conveying pipe; and a third regulating valve is arranged on the first liquid phase return pipe. The synthesis efficiency of the dioctyl terephthalate can be improved under the condition of keeping the esterification rate of reactants. And the device is convenient to adjust and use, and has a wide market prospect.

Description

Technical Field

[0001] The utility model relates to the field of dioctyl terephthalate synthesis equipment, in particular to a dioctyl terephthalate synthesis device. Background Art

[0002] Dioctyl terephthalate, referred to as DOTP. Dioctyl terephthalate is widely used as a plasticizer in materials such as PVC. It is a product that replaces dioctyl phthalate, which has been partially banned in Europe and the United States due to its potential carcinogenic risk. In addition to being environmentally friendly, dioctyl terephthalate also has the advantages of heat resistance, cold resistance, low volatility, anti-extraction, flexibility and good electrical insulation performance. It shows excellent durability, soap water resistance and low-temperature flexibility in the products. Due to its low volatility, the use of DOTP can fully meet the temperature resistance grade requirements of wires and cables, and can be widely used in 70°C cable materials that meet the IEC standards of the International Electrotechnical Commission, and various other PVC soft products.

[0003] The mainstream process of dioctyl terephthalate is synthesized by heating terephthalic acid and isooctyl alcohol under the action of a catalyst, and its reaction principle is esterification. Since there is water in the product, the water generated during the reaction is discharged together with the vaporized isooctyl alcohol, which is conducive to the positive reaction, that is, to improve the conversion rate of dioctyl terephthalate. In the prior art, in order to promote the discharge of produced water during the synthesis of dioctyl terephthalate, the mainstream process is to use reduced pressure discharge, that is, to reduce the pressure of the gas above the reactor liquid layer. The advantage of doing so is to reduce the boiling point of water, so that the water generated during the reaction process is quickly vaporized and discharged together with the steam, so as to facilitate the positive reaction. However, from a power point of view, a lower pressure is maintained in the reactor, and the corresponding reaction temperature also needs to be reduced to keep the corresponding esterification reaction in the positive direction. The corresponding reaction temperature is low and the energy received by the reactants in the reactor is relatively low, which will increase the reaction time and affect the production efficiency. It is not beneficial to directly increase the reaction pressure by reducing the steam emission, because after the reaction pressure is increased, the water vapor produced by the esterification reaction will affect the further evaporation of water in the liquid phase of the reactor, thereby affecting the esterification rate. Therefore, while increasing the reactor pressure to improve the synthesis efficiency of dioctyl phthalate, attention should be paid to the emission of water vapor, so that the water generated during the esterification reaction is taken out in the form of gas, thereby correspondingly improving the esterification rate. There is room for improvement in this aspect to meet production needs. Summary of the invention

[0004] In view of the deficiencies in the prior art, the utility model provides a synthesis device for dioctyl terephthalate which can improve the synthesis efficiency of dioctyl terephthalate while maintaining the esterification rate of reactants, so as to overcome the defects in the prior art.

[0005] The technical scheme adopted by the utility model is as follows: a synthesis device of dioctyl terephthalate comprises a reactor, wherein the reactor is provided with an outlet end of a first nitrogen delivery pipe, the first nitrogen delivery pipe is provided with a first temperature sensor, an electric heater, a second temperature sensor, a nitrogen compressor unit, a first gas flow sensor and a first regulating valve in sequence along a direction from close to the reactor to far away from the reactor, a rectification tower is provided above the reactor, the rectification tower comprises a tower body and a packing layer provided in the tower body, a first liquid phase reflux pipe is provided between the bottom end of the tower body and the reactor, a first gas phase delivery pipe is provided between the tower body and the packing layer and the reactor, a second regulating valve, a first pressure sensor and a third temperature sensor are provided in sequence along the direction from the tower body to the reactor, and a third regulating valve is provided on the first liquid phase reflux pipe.

[0006] Preferably, the top of the tower body is provided with an inlet end of a second gas phase delivery pipe, the outlet end of the second gas phase delivery pipe is provided with an inlet end of a heat source channel of a heat exchanger, the outlet end of the heat source channel of the heat exchanger is connected with the inlet end of a cyclone separator, the liquid phase outlet end of the cyclone separator is connected with the top of a phase separator, a wastewater discharge pipe is provided at the bottom end of the phase separator, a fourth regulating valve is provided on the wastewater discharge pipe, the middle part of the phase separator is provided with an inlet end of a second liquid phase reflux pipe, a fifth regulating valve is provided on the second liquid phase reflux pipe, the outlet end of the second liquid phase reflux pipe is connected with the inlet end of a U-shaped liquid seal pipe, and the outlet end of the U-shaped liquid seal pipe is connected to the tower body above the packing layer.

[0007] Preferably, the second gas phase transport pipe is provided with a sixth regulating valve, a second pressure sensor and a fourth temperature sensor in sequence along a direction from close to the heat exchanger to far away from the heat exchanger.

[0008] Preferably, an observation window is provided on the phase separator, and the observation window adopts a plate-like structure made of transparent material.

[0009] Preferably, a tail gas delivery pipe is provided on the gas phase outlet end of the cyclone separator, a seventh regulating valve is provided on the tail gas delivery pipe, a buffer tank is provided on the inlet end of the first nitrogen delivery pipe, a second nitrogen delivery pipe is provided on the buffer tank, an eighth regulating valve is provided on the second nitrogen delivery pipe, a tail gas reflux pipe is provided between the tail gas delivery pipe between the seventh regulating valve and the cyclone separator and the buffer tank, and a ninth regulating valve and a second gas flow sensor are provided on the tail gas reflux pipe.

[0010] Preferably, an online chromatograph is provided on the tail gas delivery pipe between the tail gas reflux pipe and the cyclone separator, and a third pressure sensor and a safety valve are provided on the top of the buffer tank.

[0011] Preferably, liquid level sensors are respectively provided on the tower body below the packing layer and on the reactor.

[0012] The utility model has the following beneficial effects: firstly, the utility model utilizes nitrogen as an inert gas to be transported to the reactor, thereby increasing the gas pressure in the upper layer of the reactor; at the same time, water generated by esterification is vaporized in the form of water vapor and the vaporized isooctyl alcohol steam is transported to the distillation tower together with the nitrogen flow for further separation; the isooctyl alcohol liquefied in the distillation tower is refluxed into the reactor again as a raw material to react with terephthalic acid again.

[0013] Secondly, an online chromatograph is arranged on the tail gas delivery pipe between the tail gas reflux pipe and the cyclone separator in the utility model, and the installation of the online chromatograph facilitates the feedback of the component parameters of the medium delivered through the tail gas reflux pipe.

[0014] Finally, a third pressure sensor and a safety valve are arranged on the top of the buffer tank of the utility model; installing the third pressure sensor facilitates feedback of pressure parameters, and installing the safety valve facilitates pressure relief of the buffer tank, thereby protecting the safety of the use of the buffer tank.

[0015] The utility model has the advantages of simple structure, convenient operation, ingenious design, greatly improved work efficiency, good social and economic benefits, and is a product that is easy to promote and use. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a structural schematic diagram of the utility model. DETAILED DESCRIPTION

[0017] like Figure 1 As shown, a synthesis device of dioctyl terephthalate comprises a reactor 1, wherein the reactor 1 is provided with an outlet end of a first nitrogen delivery pipe 2, wherein the first nitrogen delivery pipe 2 is provided with a first temperature sensor 3, an electric heater 4, a second temperature sensor 5, a nitrogen compressor unit 6, a first gas flow sensor 7 and a first regulating valve 8 in sequence along a direction from close to the reactor 1 to far away from the reactor 1, wherein a rectifying tower is provided above the reactor 1, wherein the rectifying tower comprises a tower body 9 and a packing layer 10 arranged in the tower body 9, wherein a first liquid phase reflux pipe 11 is provided between the bottom end of the tower body 9 and the reactor 1, wherein a first gas phase delivery pipe 12 is provided between the tower body 9 and the packing layer 10 and the reactor 1, wherein a second regulating valve 13, a first pressure sensor 14 and a third temperature sensor 15 are provided in sequence along a direction from the tower body 9 to the reactor 1, and a third regulating valve 16 is provided on the first liquid phase reflux pipe 11. Liquid level sensors 41 are respectively provided on the tower body 9 below the packing layer 10 and on the reactor 1, so as to facilitate the feedback of liquid level parameters.

[0018] In order to improve the utilization efficiency of isooctyl alcohol, the top of the tower body 9 described in the present product is provided with the inlet end of the second gas phase delivery pipe 17, the outlet end of the second gas phase delivery pipe 17 is provided with the inlet end of the heat source channel of the heat exchanger 18, the outlet end of the heat source channel of the heat exchanger 18 is connected with the inlet end of the cyclone separator 19, the liquid phase outlet end of the cyclone separator 19 is connected with the top of the phase separator 20, the bottom end of the phase separator 20 is provided with a wastewater discharge pipe 21, the wastewater discharge pipe 21 is provided with a fourth regulating valve 22, the middle part of the phase separator 20 is provided with the inlet end of the second liquid phase reflux pipe 23, the second liquid phase reflux pipe 23 is provided with a fifth regulating valve 24, the outlet end of the second liquid phase reflux pipe 23 is connected with the inlet end of the U-shaped liquid seal pipe 25, and the outlet end of the U-shaped liquid seal pipe 25 is connected to the tower body 9 above the packing layer 10; thereby facilitating the reflux of liquefied isooctyl alcohol. Furthermore, the phase separator 20 is provided with an observation window 29, and the observation window 29 is a plate-shaped structure made of a transparent material. The observation window 29 is installed to facilitate feedback of the stratification position of the water phase and the isooctyl alcohol phase, and the fourth regulating valve 22 is adjusted to increase or reduce the drainage volume, so as to facilitate the reflux of the isooctyl alcohol phase to the distillation tower.

[0019] The second gas phase transport pipe 17 is provided with a sixth regulating valve 26, a second pressure sensor 27 and a fourth temperature sensor 28 in sequence along the direction from close to the heat exchanger 18 to away from the heat exchanger 18, so as to facilitate the parameters fed back by the second pressure sensor 27 and the parameters fed back by the fourth temperature sensor 28.

[0020] Since a large amount of nitrogen is required during the reaction process, a tail gas delivery pipe 30 is provided on the gas phase outlet end of the cyclone separator 19 described in this product, and a seventh regulating valve 31 is provided on the tail gas delivery pipe 30, a buffer tank 32 is provided on the inlet end of the first nitrogen delivery pipe 2, and a second nitrogen delivery pipe 33 is provided on the buffer tank 32, and an eighth regulating valve 34 is provided on the second nitrogen delivery pipe 33, and a tail gas reflux pipe 35 is provided between the tail gas delivery pipe 30 between the seventh regulating valve 31 and the cyclone separator 19 and the buffer tank 32, and a ninth regulating valve 36 and a second gas flow sensor 37 are provided on the tail gas reflux pipe 35; part of the tail gas delivered through the tail gas delivery pipe 30 is refluxed through the tail gas reflux pipe 35 to reduce the consumption of nitrogen. Furthermore, since non-condensable gas is produced during the reaction process, the non-condensable gas part is a combustible gas, and the increase in the concentration of combustible gas in the exhaust gas will further increase the difficulty of exhaust gas treatment; at the same time, the impurity content in the nitrogen delivered to the reactor 1 should also be maintained within an appropriate range. Therefore, this product is provided with an online chromatograph 38 on the exhaust gas delivery pipe 30 between the exhaust gas reflux pipe 35 and the cyclone separator 19, and a third pressure sensor 39 and a safety valve 40 are provided on the top of the buffer tank 32.

[0021] The usage of this product is as follows: Figure 1 As shown, the following steps are included: S1, adding terephthalic acid, isooctyl alcohol and corresponding catalyst into the reactor 1 in proportion and heating the reactor 1. At the same time, the second nitrogen delivery pipe 33 receives the nitrogen delivered by the air separation and distillation device and delivers it to the buffer tank 32, and then enters the first nitrogen delivery pipe 2, and is compressed by the nitrogen compressor unit 6 after the flow rate is fed back by the first gas flow sensor 7. The temperature parameters after compression by the nitrogen compressor unit 6 are fed back by the second temperature sensor 5, and then sent to the electric heater 4 for further heating and sent to the reactor 1 after the parameters are fed back by the first temperature sensor 3, so as to increase the pressure of the reactor 1 and serve as a means of auxiliary heating, and then adjust the opening of the second regulating valve 13 again so that the first pressure sensor 14 is always maintained within the preset pressure range, and the water vapor and isooctyl alcohol vapor generated by terephthalic acid and isooctyl alcohol in the esterification reaction process are transported outward together with the nitrogen flow transported outward from the first gas phase delivery pipe 12.

[0022] S2, the nitrogen flow carries water vapor and isooctyl alcohol vapor into the tower body 9 to form an ascending airflow in the tower body 9. The ascending airflow is gradually cooled due to heat exchange with the outside atmosphere during the ascending process of the tower body 9. The role of the packing layer 10 here is to provide corresponding flow resistance to reduce the rising speed of the ascending airflow, so that there is enough time for heat exchange with the outside atmosphere; the high-boiling point substance in the ascending airflow, that is, isooctyl alcohol, is first liquefied to form a descending liquid flow and enters the tower body 9 ascending airflow for heat exchange again, and the water component in the descending airflow is gradually evaporated, and finally a relatively pure isooctyl alcohol liquid is formed at the bottom of the tower body 9, and a nitrogen flow containing a large amount of water vapor and a small amount of isooctyl alcohol vapor is formed at the top of the tower body 9 and transported outward through the second gas phase conveying pipe 17; the pressure parameter of the tower body 9 is fed back by the second pressure sensor 27; and the temperature of the nitrogen flow containing a large amount of water vapor and a small amount of isooctyl alcohol vapor transported outward from the second gas phase conveying pipe 17 should be maintained, and the temperature parameter of the nitrogen flow is fed back by the fourth temperature sensor 28.

[0023] S3, the nitrogen gas flow containing a large amount of water vapor and a small amount of isooctyl alcohol vapor is transported to the heat source channel of the heat exchanger 18 through the outlet end of the second gas phase delivery pipe 17 and continuously transported to the medium of the cold source channel of the heat exchanger 18 for heat exchange; when the nitrogen gas containing a large amount of water vapor and a small amount of isooctyl alcohol vapor is discharged from the heat source channel of the heat exchanger 18, the water vapor component and the isooctyl alcohol component in the nitrogen gas flow containing a large amount of water vapor and a small amount of isooctyl alcohol vapor are liquefied to form a liquid-containing nitrogen gas flow, the liquid-containing nitrogen gas flow is sent to the cyclone separator 19 for gas-liquid separation, and the liquid phase part of the liquid-containing nitrogen gas flow is sent to the phase separator 20 for static stratification; and the gas phase part of the liquid-containing nitrogen gas flow is transported outward through the tail gas delivery pipe 30.

[0024] S4, the phase separator 20 continuously receives the liquid discharged from the liquid phase outlet end of the cyclone separator 19, and the liquid level in the phase separator 20 continuously rises. The liquid in the phase separator 20 is divided into three layers, the top layer is the isooctyl alcohol phase, the middle layer is the mixed phase of isooctyl alcohol and water, and the bottom layer is the water phase. The heights of the three layers of liquid are fed back through the observation window 29. The discharge amount of the water phase is adjusted by adjusting the opening of the fourth regulating valve 22, so that the top layer of the isooctyl alcohol phase is adjusted to the preset position, and the sixth regulating valve 26 is opened. The isooctyl alcohol phase then flows back to the tower body 9 through the second liquid phase reflux pipe 23 and the U-shaped liquid seal pipe 25 in turn to form a part of the descending liquid flow. The tail gas delivery pipe 30 continuously receives the gas phase part of the liquid-containing nitrogen gas flow discharged outward from the gas phase outlet end of the cyclone separator 19 to form tail gas. The tail gas contains a large amount of nitrogen and a small amount of non-condensable gas. As the phthalic acid and isooctyl alcohol increase in the esterification reaction process, the proportion of the non-condensable gas gradually increases. The component parameters in the tail gas are divided into two parts after being fed back by the online chromatograph 38. The first part is sent to the tail gas treatment equipment through the outlet end of the tail gas delivery pipe 30; the second part is delivered to the buffer tank 32 again through the tail gas reflux pipe 35 and mixed with the nitrogen delivered through the second nitrogen delivery pipe 33, and then delivered to the first nitrogen delivery pipe 2 together. The amount of gas delivered to the buffer tank 32 again through the tail gas reflux pipe 35 is fed back through the second gas flow sensor 37.

[0025] Through this embodiment, nitrogen is used as an inert gas to be transported to the reactor 1, thereby increasing the gas pressure in the upper layer of the reactor 1. At the same time, the water generated by esterification is vaporized in the form of water vapor and the vaporized isooctyl alcohol vapor is transported to the distillation tower together with the nitrogen flow for further separation. The isooctyl alcohol liquefied in the distillation tower is refluxed into the reactor 1 again as a raw material to react with terephthalic acid again.

[0026] The embodiments described above are only preferred embodiments of the present invention and are not intended to limit the scope of implementation of the present invention. Therefore, any equivalent changes or modifications made based on the structures, features and principles described in the patent scope of the present invention should be included in the patent application scope of the present invention.

Claims

1. A synthesis device for dioctyl terephthalate, characterized in that: The invention comprises a reactor (1), wherein the reactor (1) is provided with an outlet end of a first nitrogen delivery pipe (2), and the first nitrogen delivery pipe (2) is provided with a first temperature sensor (3), an electric heater (4), a second temperature sensor (5), a nitrogen compressor unit (6), a first gas flow sensor (7) and a first regulating valve (8) in sequence along a direction from close to the reactor (1) to far away from the reactor (1). A distillation tower is provided above the reactor (1), and the distillation tower comprises a tower body (9) and a packing layer (10) provided in the tower body (9). 0), a first liquid phase reflux pipe (11) is arranged between the bottom end of the tower body (9) and the reactor (1), a first gas phase delivery pipe (12) is arranged between the bottom end of the tower body (9) and the tower body (9) between the packing layer (10) and the reactor (1), a second regulating valve (13), a first pressure sensor (14) and a third temperature sensor (15) are arranged in sequence on the first gas phase delivery pipe (12) along the direction from the tower body (9) to the reactor (1), and a third regulating valve (16) is arranged on the first liquid phase reflux pipe (11).

2. The synthesis device of dioctyl terephthalate according to claim 1, characterized in that: The top end of the tower body (9) is provided with an inlet end of a second gas phase delivery pipe (17), the outlet end of the second gas phase delivery pipe (17) is provided with an inlet end of a heat source channel of a heat exchanger (18), the outlet end of the heat source channel of the heat exchanger (18) is connected to an inlet end of a cyclone separator (19), the liquid phase outlet end of the cyclone separator (19) is connected to a top end of a phase separator (20), and a wastewater discharge pipe (20) is provided at a bottom end of the phase separator (20). 21), a fourth regulating valve (22) is provided on the wastewater discharge pipe (21), an inlet end of a second liquid phase reflux pipe (23) is provided on the middle part of the phase separator (20), a fifth regulating valve (24) is provided on the second liquid phase reflux pipe (23), an outlet end of the second liquid phase reflux pipe (23) is connected to an inlet end of a U-shaped liquid seal pipe (25), and an outlet end of the U-shaped liquid seal pipe (25) is connected to a tower body (9) above the packing layer (10).

3. The synthesis device of dioctyl terephthalate according to claim 2, characterized in that: The second gas phase transport pipe (17) is provided with a sixth regulating valve (26), a second pressure sensor (27) and a fourth temperature sensor (28) in sequence along a direction from close to the heat exchanger (18) to far away from the heat exchanger (18).

4. The synthesis device of dioctyl terephthalate according to claim 2, characterized in that: An observation window (29) is provided on the phase separator (20), and the observation window (29) is a plate-shaped structure made of a transparent material.

5. The synthesis device of dioctyl terephthalate according to claim 2, characterized in that: A tail gas delivery pipe (30) is provided at the gas phase outlet end of the cyclone separator (19), a seventh regulating valve (31) is provided on the tail gas delivery pipe (30), a buffer tank (32) is provided at the inlet end of the first nitrogen delivery pipe (2), a second nitrogen delivery pipe (33) is provided on the buffer tank (32), an eighth regulating valve (34) is provided on the second nitrogen delivery pipe (33), a tail gas return pipe (35) is provided between the tail gas delivery pipe (30) between the seventh regulating valve (31) and the cyclone separator (19) and the buffer tank (32), and a ninth regulating valve (36) and a second gas flow sensor (37) are provided on the tail gas return pipe (35).

6. The synthesis device of dioctyl terephthalate according to claim 5, characterized in that: An online chromatograph (38) is provided on the exhaust gas delivery pipe (30) between the exhaust gas return pipe (35) and the cyclone separator (19), and a third pressure sensor (39) and a safety valve (40) are provided on the top of the buffer tank (32).

7. The synthesis device of dioctyl terephthalate according to claim 1, characterized in that: Liquid level sensors (41) are respectively arranged on the tower body (9) below the packing layer (10) and on the reaction kettle (1).

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