A p-phenylenediamine refining system and method for a para-aramid device

Abstract

This invention discloses a system and method for refining p-phenylenediamine in a para-aramid fiber unit, belonging to the field of chemical technology. The p-phenylenediamine refining system of this invention includes a vacuum distillation subsystem, a high-temperature heat transfer oil subsystem, a medium-temperature heat transfer oil subsystem, and a low-temperature heat transfer oil subsystem. The vacuum distillation subsystem includes a p-phenylenediamine distillation column, a column top condenser, a p-phenylenediamine reflux tank, and a p-phenylenediamine product tank. The high-temperature heat transfer oil subsystem provides a heat source for the p-phenylenediamine refining column; the medium-temperature heat transfer oil subsystem provides a heat source for the p-phenylenediamine reflux tank and the p-phenylenediamine product tank; and the low-temperature heat transfer oil subsystem provides a cold source for the column top condenser. This invention also discloses a method for refining p-phenylenediamine in a para-aramid fiber unit using the above system. This invention not only achieves the refining of p-phenylenediamine but also significantly reduces the risk of blockage and leakage, saves energy, and improves the production capacity and economic efficiency of the unit.

Description

Technical Field

[0001] This invention belongs to the field of chemical technology, specifically relating to a system and method for refining p-phenylenediamine using a para-aramid apparatus. Background Technology

[0002] Currently, the aramid fibers that are commercially produced and applied mainly fall into two categories: meta-aramid (PMIA, 1313) and para-aramid (PPTA, 1414). Para-aramid production technology is more challenging, but the product performance is superior. The product specifications of para-aramid are directly constrained by the purity of the p-phenylenediamine feedstock. P-phenylenediamine is highly susceptible to oxidation by air. Current para-aramid production technologies suffer from problems such as high temperature differences and susceptibility to damage in traditional water coolers used in p-phenylenediamine distillation columns, posing risks of blockage and leakage, which severely restricts para-aramid production.

[0003] Therefore, providing a system and method for refining p-phenylenediamine using a para-aramid apparatus, which reduces the risk of blockage and leakage and improves the production capacity and economy of the apparatus, has become an urgent problem to be solved by those skilled in the art. Summary of the Invention

[0004] One objective of this invention is to provide a p-phenylenediamine refining system for a para-aramid fiber unit, comprising a vacuum distillation subsystem, a high-temperature heat transfer oil subsystem, a medium-temperature heat transfer oil subsystem, and a low-temperature heat transfer oil subsystem. By removing high-boiling-point substances such as p-phenylenediamine oxides through vacuum distillation, using the high-temperature heat transfer oil system as the heat source for the bottom of the p-phenylenediamine distillation column, the medium-temperature heat transfer oil system as the heat source for the p-phenylenediamine reflux tank and product tank, and the low-temperature heat transfer oil system as the cold source for the top condenser of the p-phenylenediamine distillation column, the refining of p-phenylenediamine is ultimately achieved, significantly reducing the risk of blockage and leakage.

[0005] A second objective of this invention is to provide a method for refining p-phenylenediamine using a para-aramid apparatus, which employs the aforementioned system.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: This invention discloses a p-phenylenediamine refining system for a para-aramid apparatus, comprising a vacuum distillation subsystem, a high-temperature heat transfer oil subsystem, a medium-temperature heat transfer oil subsystem, and a low-temperature heat transfer oil subsystem. The vacuum distillation subsystem includes a p-phenylenediamine distillation column, a top condenser located at the top of the p-phenylenediamine distillation column, a p-phenylenediamine reflux tank connected to the top condenser, and a p-phenylenediamine product tank connected to the p-phenylenediamine reflux tank; the p-phenylenediamine distillation column is connected to a molten p-phenylenediamine input line, a p-phenylenediamine distillation column bottom discharge conveyor line is connected to the bottom of the p-phenylenediamine distillation column, and a p-phenylenediamine product discharge conveyor line is connected to the p-phenylenediamine product tank; The high-temperature heat transfer oil subsystem is used to provide a heat source for the bottom of the p-phenylenediamine distillation column; The medium-temperature heat transfer oil subsystem is used to provide a heat source for the p-phenylenediamine reflux tank and the p-phenylenediamine product tank. The low-temperature heat transfer oil subsystem is used to provide a cold source for the tower top condenser.

[0007] In some embodiments of the present invention, the p-phenylenediamine distillation column and the top condenser are connected via a gas-p-phenylenediamine conveying line. The top condenser and the p-phenylenediamine reflux tank are connected via a p-phenylenediamine condensation conveyor line. Preferably, the p-phenylenediamine reflux tank is connected to the p-phenylenediamine distillation column via the first p-phenylenediamine discharge conveyor line, and to the p-phenylenediamine product tank via the second p-phenylenediamine discharge conveyor line; Preferably, the p-phenylenediamine refining system of the para-aramid unit also includes a distillation column vacuum unit; The vacuum unit of the distillation column is connected to the p-phenylenediamine reflux tank via a vapor phase discharge conveyor line from the reflux tank. More preferably, the vacuum unit of the distillation column is connected to a demineralized water conveying line and outputs a wastewater conveying line and an exhaust gas conveying line for the vacuum unit of the p-phenylenediamine distillation column.

[0008] In some embodiments of the present invention, the high-temperature heat transfer oil subsystem includes a high-temperature heat transfer oil electric heater and a high-temperature heat transfer oil gas-liquid separator. The high-temperature heat transfer oil electric heater is connected to the first high-temperature heat transfer oil conveying line. The high-temperature heat transfer oil electric heater is connected to the p-phenylenediamine distillation column via the high-temperature heat transfer oil supply line, which is used to send the heated high-temperature heat transfer oil into the jacket side of the p-phenylenediamine distillation column for heating. The p-phenylenediamine distillation column is connected to the high-temperature heat-conducting oil gas-liquid separator via a high-temperature heat-conducting oil return conveyor line. Preferably, the high-temperature thermal oil gas-liquid separator and the high-temperature thermal oil electric heater are connected via a second high-temperature thermal oil conveying line, which is used to send the liquid phase thermal oil after gas-liquid separation into the high-temperature thermal oil electric heater for reheating and reuse.

[0009] In some embodiments of the present invention, a high-temperature heat transfer oil shutdown cooler is also included. The high-temperature heat transfer oil shutdown cooler is connected to the first high-temperature heat transfer oil conveying line via a third high-temperature heat transfer oil conveying line, and is connected to the high-temperature heat transfer oil supply conveying line after cooling of the p-phenylenediamine distillation column.

[0010] In some embodiments of the present invention, the medium-temperature thermal oil subsystem includes a medium-temperature thermal oil electric heater and a medium-temperature thermal oil gas-liquid separator; The medium-temperature thermal oil electric heater is connected to the first medium-temperature thermal oil conveying line. The medium-temperature thermal oil electric heater is connected to the p-phenylenediamine reflux tank via the first medium-temperature thermal oil supply line, and to the p-phenylenediamine product tank via the second medium-temperature thermal oil supply line. The medium-temperature heat transfer oil gas-liquid separator is connected to the p-phenylenediamine reflux tank via the first medium-temperature heat transfer oil return line, and is connected to the p-phenylenediamine product tank via the second medium-temperature heat transfer oil return line. Preferably, the medium-temperature thermal oil gas-liquid separator and the medium-temperature thermal oil electric heater are connected via a second medium-temperature thermal oil conveying line, which is used to send the liquid phase thermal oil after gas-liquid separation into the medium-temperature thermal oil electric heater for reheating and reuse.

[0011] In some embodiments of the present invention, the low-temperature heat transfer oil subsystem includes a low-temperature heat transfer oil air cooler, which is connected to a first low-temperature heat transfer oil conveying line. The low-temperature heat transfer oil air cooler is connected to the top condenser of the tower via a low-temperature heat transfer oil supply line, and is used to send the cooled low-temperature heat transfer oil into the top condenser of the tower as a cold source. The condenser at the top of the tower is connected to a low-temperature heat transfer oil return line, which is connected to a low-temperature heat transfer oil air cooler to cool the low-temperature heat transfer oil again after heat exchange. Preferably, a second low-temperature heat transfer oil return line is connected to the low-temperature heat transfer oil return line, and the second low-temperature heat transfer oil return line is connected to the medium-temperature heat transfer oil gas-liquid separator.

[0012] In some embodiments of the present invention, the p-phenylenediamine refining system of the para-aramid device further includes a heat transfer oil expansion tank, which is connected to a medium-temperature heat transfer oil gas-liquid separator via a medium-temperature heat transfer oil gas-liquid separator gas phase discharge conveying line, and to a high-temperature heat transfer oil gas-liquid separator via a high-temperature heat transfer oil gas-liquid separator gas phase discharge conveying line. Preferably, it also includes a heat transfer oil tail gas condenser, and the heat transfer oil expansion tank is connected to the heat transfer oil tail gas condenser via the heat transfer oil expansion tank gas phase discharge conveyor line. More preferably, the heat transfer oil tail gas condenser is connected to a heat transfer oil tail gas condenser gas phase discharge line and a heat transfer oil tail gas condenser condensate discharge conveying line, and the heat transfer oil tail gas condenser condensate discharge conveying line is connected to the heat transfer oil expansion tank.

[0013] In some embodiments of the present invention, the p-phenylenediamine refining system of the para-aramid apparatus further includes a heat transfer oil storage tank, which is connected to a fresh heat transfer oil delivery line. The heat transfer oil storage tank and the high-temperature heat transfer oil electric heater are connected via the first high-temperature heat transfer oil delivery line. It is connected to the medium-temperature thermal oil electric heater via the first medium-temperature thermal oil delivery line. It is connected to the low-temperature heat transfer oil air cooler via the first low-temperature heat transfer oil delivery line. Preferably, the thermal oil expansion tank is connected to the thermal oil storage tank via the thermal oil expansion tank overflow discharge conveyor line.

[0014] The present invention discloses a method for refining p-phenylenediamine using a para-aramid apparatus, which employs the aforementioned para-aramid apparatus p-phenylenediamine refining system.

[0015] In some embodiments of the present invention, the method for refining p-phenylenediamine using the p-aramid apparatus includes the following steps: removing high-boiling substances such as p-phenylenediamine oxides by vacuum distillation of p-phenylenediamine. A high-temperature heat transfer oil subsystem is used to provide a heat source for the bottom of the p-phenylenediamine distillation column, a medium-temperature heat transfer oil system is used as the heat source for the p-phenylenediamine reflux tank and product tank, and a low-temperature heat transfer oil system is used as the cold source for the top condenser of the p-phenylenediamine distillation column.

[0016] Compared with the prior art, the present invention has the following beneficial effects: This invention is scientifically designed and ingeniously conceived. It employs a vacuum distillation-high-low temperature heat transfer oil system. High-boiling-point substances such as p-phenylenediamine oxides are removed through vacuum distillation of p-phenylenediamine. The high-temperature heat transfer oil system serves as the heat source for the bottom of the p-phenylenediamine distillation column, the medium-temperature heat transfer oil system serves as the heat source for the p-phenylenediamine reflux tank and product tank, and the low-temperature heat transfer oil system serves as the cold source for the top condenser of the p-phenylenediamine distillation column. Ultimately, this invention achieves the purification of p-phenylenediamine and significantly reduces the risk of blockage and leakage.

[0017] This invention employs a vacuum distillation process, which minimizes the consumption of materials and nitrogen in the equipment, saves energy, and significantly improves the production capacity and economic efficiency of the equipment. Attached Figure Description

[0018] Appendix Figure 1 This is a schematic diagram of the system of the present invention.

[0019] Appendix Figure 2 This is a process flow diagram of Embodiment 7 of the present invention.

[0020] The names corresponding to the reference numerals in the attached figures are: a-p-phenylenediamine distillation column, b-high temperature thermal oil electric heater, c-medium temperature thermal oil electric heater, d-low temperature thermal oil air cooler, e-thermal oil tail gas condenser, f-high temperature thermal oil shutdown cooler, g-top condenser, h-p-phenylenediamine reflux tank, i-p-phenylenediamine product tank, j-thermal oil storage tank, k-thermal oil expansion tank, l-medium temperature thermal oil gas-liquid separator, m-high temperature thermal oil gas-liquid separator, n-p-phenylenediamine product transfer pump, o-p-phenylenediamine distillation column bottom transfer pump, p-medium temperature thermal oil circulation pump, q-high temperature thermal oil circulation pump, r-low temperature thermal oil circulation pump, s-fresh thermal oil replenishment pump, t-distillation column vacuum unit.

[0021] 101 - Molten p-phenylenediamine input line; 102 - p-phenylenediamine distillation column reboiler discharge conveyor line; 103 - p-phenylenediamine product discharge conveyor line; 104 - Gas phase p-phenylenediamine conveyor line; 105 - Condensed p-phenylenediamine conveyor line; 106 - p-phenylenediamine first discharge conveyor line; 107 - p-phenylenediamine second discharge conveyor line; 108 - Reflux tank gas phase discharge conveyor line; 109 - Demineralized water conveyor line; 110 - p-phenylenediamine 111-Wastewater conveying line for vacuum unit of distillation column; 112-Waste gas conveying line for vacuum unit of p-phenylenediamine distillation column; 113-First high-temperature heat transfer oil conveying line; 114-High-temperature heat transfer oil loading conveying line; 115-Second high-temperature heat transfer oil conveying line; 116-Third high-temperature heat transfer oil conveying line; 117-Cooled high-temperature heat transfer oil loading conveying line; 118-First medium-temperature heat transfer oil conveying line; 119-First medium-temperature heat transfer oil loading conveying line; 120-Second medium-temperature heat transfer oil loading conveying line; 121-First medium-temperature heat transfer oil return conveying line; 122-Second medium-temperature heat transfer oil return conveying line; 123-Second medium-temperature heat transfer oil conveying line; 124-First low-temperature heat transfer oil conveying line; 125-Low-temperature heat transfer oil loading conveying line; 126-Low-temperature heat transfer oil return conveying line; 127-Second low-temperature heat transfer oil return conveying line; 12... 8-Medium-temperature thermal oil gas-liquid separator gas phase discharge conveying line; 129-High-temperature thermal oil gas-liquid separator gas phase discharge conveying line; 130-Temperature thermal oil expansion tank gas phase discharge conveying line; 131-Temperature thermal oil tail gas condenser gas phase discharge line; 132-Temperature thermal oil tail gas condenser condensate discharge conveying line; 133-Fresh thermal oil conveying line; 134-Temperature thermal oil expansion tank overflow discharge conveying line; 135-Temperature thermal oil storage tank discharge line. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0023] Example 1 As attached Figure 1 As shown, this embodiment discloses a p-phenylenediamine refining system for a para-aramid apparatus, including a vacuum distillation subsystem, a high-temperature heat transfer oil subsystem, a medium-temperature heat transfer oil subsystem, and a low-temperature heat transfer oil subsystem. The reduced pressure distillation subsystem includes a p-phenylenediamine distillation column a, a top condenser g located at the top of the p-phenylenediamine distillation column, a p-phenylenediamine reflux tank h connected to the top condenser g, and a p-phenylenediamine product tank i connected to the p-phenylenediamine reflux tank h; the p-phenylenediamine distillation column a is connected to a molten p-phenylenediamine input line 101, the bottom of the p-phenylenediamine distillation column a is connected to a p-phenylenediamine distillation column bottom discharge conveyor line 102, and the p-phenylenediamine product tank i is connected to a p-phenylenediamine product discharge conveyor line 103; The high-temperature heat transfer oil subsystem is used to provide a heat source for the bottom of the p-phenylenediamine distillation column a; the medium-temperature heat transfer oil subsystem is used to provide a heat source for the p-phenylenediamine reflux tank h and the p-phenylenediamine product tank i; and the low-temperature heat transfer oil subsystem is used to provide a cold source for the column top condenser g.

[0024] Example 2 As attached Figure 1 As shown, this embodiment discloses a p-phenylenediamine refining system for a para-aramid apparatus, including a vacuum distillation subsystem, a high-temperature heat transfer oil subsystem, a medium-temperature heat transfer oil subsystem, and a low-temperature heat transfer oil subsystem. The reduced pressure distillation subsystem includes a p-phenylenediamine distillation column a, a top condenser g located at the top of the p-phenylenediamine distillation column, a p-phenylenediamine reflux tank h connected to the top condenser g, and a p-phenylenediamine product tank i connected to the p-phenylenediamine reflux tank h; the p-phenylenediamine distillation column a is connected to a molten p-phenylenediamine input line 101, the bottom of the p-phenylenediamine distillation column a is connected to a p-phenylenediamine distillation column bottom discharge conveyor line 102, and the p-phenylenediamine product tank i is connected to a p-phenylenediamine product discharge conveyor line 103; The high-temperature heat transfer oil subsystem is used to provide a heat source for the bottom of the p-phenylenediamine distillation column a; the medium-temperature heat transfer oil subsystem is used to provide a heat source for the p-phenylenediamine reflux tank h and the p-phenylenediamine product tank i; and the low-temperature heat transfer oil subsystem is used to provide a cold source for the column top condenser g.

[0025] The p-phenylenediamine distillation column a is connected to the top condenser g via a gas-p-phenylenediamine conveying line 104. The top condenser g is connected to the p-phenylenediamine reflux tank h via a condensing p-phenylenediamine conveying line 105. The p-phenylenediamine reflux tank h is connected to the p-phenylenediamine distillation column a via the first p-phenylenediamine discharge conveying line 106 and to the p-phenylenediamine product tank i via the second p-phenylenediamine discharge conveying line 107.

[0026] The p-phenylenediamine refining system of the para-aramid unit also includes a distillation column vacuum unit t; the distillation column vacuum unit t is connected to the p-phenylenediamine reflux tank h via a reflux tank gas phase discharge conveyor line 108; the distillation column vacuum unit t is connected to a demineralized water conveyor line 109, and is connected to a p-phenylenediamine distillation column vacuum unit wastewater conveyor line 110 and a p-phenylenediamine distillation column vacuum unit exhaust gas conveyor line 111.

[0027] This embodiment 2 provides a more optimized technical solution for the vacuum distillation subsystem based on embodiment 1. Specifically, it discloses that the p-phenylenediamine distillation column a is connected to the top condenser g via a gas-phase p-phenylenediamine conveying line 104, and to the p-phenylenediamine reflux tank h via a condensing p-phenylenediamine conveying line 105; the p-phenylenediamine reflux tank h is connected to the p-phenylenediamine distillation column a via a first p-phenylenediamine discharge conveying line 106, and to the p-phenylenediamine product tank i via a second p-phenylenediamine discharge conveying line 107; the p-phenylenediamine refining system of the p-aramid unit also includes a distillation column vacuum unit t; the distillation column vacuum unit t is connected to the p-phenylenediamine reflux tank h via a reflux tank gas-phase discharge conveying line 108; the distillation column vacuum unit t is connected to a demineralized water conveying line 109, and outputs a p-phenylenediamine distillation column vacuum unit wastewater conveying line 110 and a p-phenylenediamine distillation column vacuum unit waste gas conveying line 111.

[0028] Example 3 As attached Figure 1 As shown, this embodiment discloses a p-phenylenediamine refining system for a para-aramid apparatus, including a vacuum distillation subsystem, a high-temperature heat transfer oil subsystem, a medium-temperature heat transfer oil subsystem, and a low-temperature heat transfer oil subsystem. The reduced pressure distillation subsystem includes a p-phenylenediamine distillation column a, a top condenser g located at the top of the p-phenylenediamine distillation column, a p-phenylenediamine reflux tank h connected to the top condenser g, and a p-phenylenediamine product tank i connected to the p-phenylenediamine reflux tank h; the p-phenylenediamine distillation column a is connected to a molten p-phenylenediamine input line 101, the bottom of the p-phenylenediamine distillation column a is connected to a p-phenylenediamine distillation column bottom discharge conveyor line 102, and the p-phenylenediamine product tank i is connected to a p-phenylenediamine product discharge conveyor line 103; The high-temperature heat transfer oil subsystem is used to provide a heat source for the bottom of the p-phenylenediamine distillation column a; the medium-temperature heat transfer oil subsystem is used to provide a heat source for the p-phenylenediamine reflux tank h and the p-phenylenediamine product tank i; and the low-temperature heat transfer oil subsystem is used to provide a cold source for the column top condenser g.

[0029] The p-phenylenediamine distillation column a is connected to the top condenser g via a gas-p-phenylenediamine conveying line 104. The top condenser g is connected to the p-phenylenediamine reflux tank h via a condensing p-phenylenediamine conveying line 105. The p-phenylenediamine reflux tank h is connected to the p-phenylenediamine distillation column a via a first p-phenylenediamine discharge conveying line 106 and to the p-phenylenediamine product tank i via a second p-phenylenediamine discharge conveying line 107. The p-phenylenediamine refining system of the para-aramid unit also includes a distillation column vacuum unit t; the distillation column vacuum unit t is connected to the p-phenylenediamine reflux tank h via a reflux tank gas phase discharge conveyor line 108; the distillation column vacuum unit t is connected to a demineralized water conveyor line 109, and is connected to a p-phenylenediamine distillation column vacuum unit wastewater conveyor line 110 and a p-phenylenediamine distillation column vacuum unit exhaust gas conveyor line 111.

[0030] The high-temperature heat transfer oil subsystem includes a high-temperature heat transfer oil electric heater b and a high-temperature heat transfer oil gas-liquid separator m.

[0031] The high-temperature heat transfer oil electric heater b is connected to the first high-temperature heat transfer oil conveying line 112. The high-temperature heat transfer oil electric heater b is connected to the p-phenylenediamine distillation column a via the high-temperature heat transfer oil supply line 113, which is used to send the heated high-temperature heat transfer oil into the jacket side of the p-phenylenediamine distillation column a for heating. The p-phenylenediamine distillation column a is connected to the high-temperature heat-conducting oil gas-liquid separator m via a high-temperature heat-conducting oil return conveyor line 114. The high-temperature heat transfer oil gas-liquid separator m is connected to the high-temperature heat transfer oil electric heater b via the second high-temperature heat transfer oil conveying line 115, and is used to send the liquid phase heat transfer oil after gas-liquid separation into the high-temperature heat transfer oil electric heater b for reheating and reuse.

[0032] The para-aramid unit's p-phenylenediamine refining system also includes a high-temperature heat transfer oil shutdown cooler f, which is connected to the first high-temperature heat transfer oil conveying line 112 via the third high-temperature heat transfer oil conveying line 116, and to the high-temperature heat transfer oil supply conveying line 117 after cooling the p-phenylenediamine distillation column a.

[0033] This embodiment 3 provides a more optimized technical solution for the high-temperature heat transfer oil subsystem based on embodiment 2. Specifically, the high-temperature heat transfer oil subsystem includes a high-temperature heat transfer oil electric heater b and a high-temperature heat transfer oil gas-liquid separator m. The high-temperature heat transfer oil electric heater b is connected to a first high-temperature heat transfer oil conveying line 112, and is connected to the p-phenylenediamine distillation column a via a high-temperature heat transfer oil supply conveying line 113. The p-phenylenediamine distillation column a is connected to the high-temperature heat transfer oil gas-liquid separator m via a high-temperature heat transfer oil return conveying line 114, and the high-temperature heat transfer oil gas-liquid separator m is connected to the high-temperature heat transfer oil electric heater b via a second high-temperature heat transfer oil conveying line 115. The p-phenylenediamine refining system of the p-aramid unit also includes a high-temperature heat transfer oil shutdown cooler f. The high-temperature heat transfer oil shutdown cooler f is connected to the first high-temperature heat transfer oil conveying line 112 via a third high-temperature heat transfer oil conveying line 116, and is connected to the high-temperature heat transfer oil supply conveying line 117 after cooling of the p-phenylenediamine distillation column a.

[0034] Example 4 As attached Figure 1As shown, this embodiment discloses a p-phenylenediamine refining system for a para-aramid apparatus, including a vacuum distillation subsystem, a high-temperature heat transfer oil subsystem, a medium-temperature heat transfer oil subsystem, and a low-temperature heat transfer oil subsystem. The reduced pressure distillation subsystem includes a p-phenylenediamine distillation column a, a top condenser g located at the top of the p-phenylenediamine distillation column, a p-phenylenediamine reflux tank h connected to the top condenser g, and a p-phenylenediamine product tank i connected to the p-phenylenediamine reflux tank h; the p-phenylenediamine distillation column a is connected to a molten p-phenylenediamine input line 101, the bottom of the p-phenylenediamine distillation column a is connected to a p-phenylenediamine distillation column bottom discharge conveyor line 102, and the p-phenylenediamine product tank i is connected to a p-phenylenediamine product discharge conveyor line 103; The high-temperature heat transfer oil subsystem is used to provide a heat source for the bottom of the p-phenylenediamine distillation column a; the medium-temperature heat transfer oil subsystem is used to provide a heat source for the p-phenylenediamine reflux tank h and the p-phenylenediamine product tank i; and the low-temperature heat transfer oil subsystem is used to provide a cold source for the column top condenser g.

[0035] The p-phenylenediamine distillation column a is connected to the top condenser g via a gas-p-phenylenediamine conveying line 104, and the top condenser g is connected to the p-phenylenediamine reflux tank h via a condensed p-phenylenediamine conveying line 105. The p-phenylenediamine reflux tank h is connected to the p-phenylenediamine distillation column a via the first p-phenylenediamine discharge conveyor line 106, and is connected to the p-phenylenediamine product tank i via the second p-phenylenediamine discharge conveyor line 107; The p-phenylenediamine refining system of the para-aramid unit also includes a distillation column vacuum unit t; the distillation column vacuum unit t is connected to the p-phenylenediamine reflux tank h via a reflux tank gas phase discharge conveyor line 108; the distillation column vacuum unit t is connected to a demineralized water conveyor line 109, and is connected to a p-phenylenediamine distillation column vacuum unit wastewater conveyor line 110 and a p-phenylenediamine distillation column vacuum unit exhaust gas conveyor line 111.

[0036] The high-temperature heat transfer oil subsystem includes a high-temperature heat transfer oil electric heater b and a high-temperature heat transfer oil gas-liquid separator m.

[0037] The high-temperature heat transfer oil electric heater b is connected to the first high-temperature heat transfer oil conveying line 112. The high-temperature heat transfer oil electric heater b is connected to the p-phenylenediamine distillation column a via the high-temperature heat transfer oil supply line 113, which is used to send the heated high-temperature heat transfer oil into the jacket side of the p-phenylenediamine distillation column a for heating. The p-phenylenediamine distillation column a is connected to the high-temperature heat-conducting oil gas-liquid separator m via a high-temperature heat-conducting oil return conveyor line 114. The high-temperature heat transfer oil gas-liquid separator m is connected to the high-temperature heat transfer oil electric heater b via the second high-temperature heat transfer oil conveying line 115, and is used to send the liquid phase heat transfer oil after gas-liquid separation into the high-temperature heat transfer oil electric heater b for reheating and reuse.

[0038] The para-aramid unit's p-phenylenediamine refining system also includes a high-temperature heat transfer oil shutdown cooler f, which is connected to the first high-temperature heat transfer oil conveying line 112 via the third high-temperature heat transfer oil conveying line 116, and to the high-temperature heat transfer oil supply conveying line 117 after cooling the p-phenylenediamine distillation column a.

[0039] The medium-temperature thermal oil subsystem includes a medium-temperature thermal oil electric heater c and a medium-temperature thermal oil gas-liquid separator l. The medium-temperature thermal oil electric heater c is connected to a first medium-temperature thermal oil conveying line 118. The medium-temperature thermal oil electric heater c is connected to the p-phenylenediamine reflux tank h via a first medium-temperature thermal oil supply line 119, and to the p-phenylenediamine product tank i via a second medium-temperature thermal oil supply line 120. The medium-temperature thermal oil gas-liquid separator l is connected to the p-phenylenediamine reflux tank h via a first medium-temperature thermal oil return line 121, and to the p-phenylenediamine product tank i via a second medium-temperature thermal oil return line 122. The medium-temperature thermal oil gas-liquid separator l is connected to the medium-temperature thermal oil electric heater c via a second medium-temperature thermal oil conveying line 123, which is used to send the liquid phase thermal oil after gas-liquid separation into the medium-temperature thermal oil electric heater c for reheating and reuse.

[0040] This embodiment 4 provides a more preferred technical solution for the medium-temperature thermal oil subsystem based on embodiment 3. Specifically, the medium-temperature thermal oil subsystem includes a medium-temperature thermal oil electric heater c and a medium-temperature thermal oil gas-liquid separator l; the medium-temperature thermal oil electric heater c is connected to a first medium-temperature thermal oil conveying line 118, and the medium-temperature thermal oil electric heater c is connected to the p-phenylenediamine reflux tank h via a first medium-temperature thermal oil supply conveying line 119, and to the p-phenylenediamine product tank i via a second medium-temperature thermal oil supply conveying line 120. The medium-temperature thermal oil gas-liquid separator l is connected to the p-phenylenediamine reflux tank h via a first medium-temperature thermal oil return conveying line 121, and to the p-phenylenediamine product tank i via a second medium-temperature thermal oil return conveying line 122; the medium-temperature thermal oil gas-liquid separator l is connected to the medium-temperature thermal oil electric heater c via a second medium-temperature thermal oil conveying line 123.

[0041] Example 5 As attached Figure 1 As shown, this embodiment discloses a p-phenylenediamine refining system for a para-aramid apparatus, including a vacuum distillation subsystem, a high-temperature heat transfer oil subsystem, a medium-temperature heat transfer oil subsystem, and a low-temperature heat transfer oil subsystem. The reduced pressure distillation subsystem includes a p-phenylenediamine distillation column a, a top condenser g located at the top of the p-phenylenediamine distillation column, a p-phenylenediamine reflux tank h connected to the top condenser g, and a p-phenylenediamine product tank i connected to the p-phenylenediamine reflux tank h; the p-phenylenediamine distillation column a is connected to a molten p-phenylenediamine input line 101, the bottom of the p-phenylenediamine distillation column a is connected to a p-phenylenediamine distillation column bottom discharge conveyor line 102, and the p-phenylenediamine product tank i is connected to a p-phenylenediamine product discharge conveyor line 103; The high-temperature heat transfer oil subsystem is used to provide a heat source for the bottom of the p-phenylenediamine distillation column a; the medium-temperature heat transfer oil subsystem is used to provide a heat source for the p-phenylenediamine reflux tank h and the p-phenylenediamine product tank i; and the low-temperature heat transfer oil subsystem is used to provide a cold source for the column top condenser g.

[0042] The p-phenylenediamine distillation column a is connected to the top condenser g via a gas-p-phenylenediamine conveying line 104. The top condenser g is connected to the p-phenylenediamine reflux tank h via a condensing p-phenylenediamine conveying line 105. The p-phenylenediamine reflux tank h is connected to the p-phenylenediamine distillation column a via the first p-phenylenediamine discharge conveying line 106 and to the p-phenylenediamine product tank i via the second p-phenylenediamine discharge conveying line 107.

[0043] The p-phenylenediamine refining system of the para-aramid unit also includes a distillation column vacuum unit t; the distillation column vacuum unit t is connected to the p-phenylenediamine reflux tank h via a reflux tank gas phase discharge conveyor line 108; the distillation column vacuum unit t is connected to a demineralized water conveyor line 109, and is connected to a p-phenylenediamine distillation column vacuum unit wastewater conveyor line 110 and a p-phenylenediamine distillation column vacuum unit exhaust gas conveyor line 111.

[0044] The high-temperature heat transfer oil subsystem includes a high-temperature heat transfer oil electric heater b and a high-temperature heat transfer oil gas-liquid separator m.

[0045] The high-temperature heat transfer oil electric heater b is connected to the first high-temperature heat transfer oil conveying line 112. The high-temperature heat transfer oil electric heater b is connected to the p-phenylenediamine distillation column a via the high-temperature heat transfer oil supply line 113, which is used to send the heated high-temperature heat transfer oil into the jacket side of the p-phenylenediamine distillation column a for heating. The p-phenylenediamine distillation column a is connected to the high-temperature heat-conducting oil gas-liquid separator m via a high-temperature heat-conducting oil return conveyor line 114. The high-temperature heat transfer oil gas-liquid separator m is connected to the high-temperature heat transfer oil electric heater b via the second high-temperature heat transfer oil conveying line 115, and is used to send the liquid phase heat transfer oil after gas-liquid separation into the high-temperature heat transfer oil electric heater b for reheating and reuse.

[0046] The para-aramid unit's p-phenylenediamine refining system also includes a high-temperature heat transfer oil shutdown cooler f, which is connected to the first high-temperature heat transfer oil conveying line 112 via the third high-temperature heat transfer oil conveying line 116, and to the high-temperature heat transfer oil supply conveying line 117 after cooling the p-phenylenediamine distillation column a.

[0047] The medium-temperature thermal oil subsystem includes a medium-temperature thermal oil electric heater c and a medium-temperature thermal oil gas-liquid separator l; the medium-temperature thermal oil electric heater c is connected to a first medium-temperature thermal oil conveying line 118, the medium-temperature thermal oil electric heater c is connected to the p-phenylenediamine reflux tank h via a first medium-temperature thermal oil supply line 119, and is connected to the p-phenylenediamine product tank i via a second medium-temperature thermal oil supply line 120; the medium-temperature thermal oil gas-liquid separator l is connected to the p-phenylenediamine reflux tank h via a first medium-temperature thermal oil return line 121, and is connected to the p-phenylenediamine product tank i via a second medium-temperature thermal oil return line 122.

[0048] The medium-temperature thermal oil gas-liquid separator l is connected to the medium-temperature thermal oil electric heater c via the second medium-temperature thermal oil conveying line 123, and is used to send the liquid phase thermal oil after gas-liquid separation into the medium-temperature thermal oil electric heater c for reheating and reuse.

[0049] The low-temperature heat transfer oil subsystem includes a low-temperature heat transfer oil air cooler d, which is connected to a first low-temperature heat transfer oil conveying line 124. The low-temperature heat transfer oil air cooler d is connected to the top condenser g via a low-temperature heat transfer oil supply line 125, and is used to send the cooled low-temperature heat transfer oil into the top condenser g as a cold source. The tower top condenser g is connected to a low-temperature heat transfer oil return line 126, which is connected to the low-temperature heat transfer oil air cooler d to cool the low-temperature heat transfer oil after heat exchange. The low-temperature heat transfer oil return conveying line 126 is connected to a second low-temperature heat transfer oil return conveying line 127, which is connected to the medium-temperature heat transfer oil gas-liquid separator 1.

[0050] This embodiment 5 provides a more preferred technical solution for the low-temperature heat transfer subsystem based on embodiment 4. Specifically, the low-temperature heat transfer oil subsystem includes a low-temperature heat transfer oil air cooler d, which is connected to a first low-temperature heat transfer oil conveying line 124. The low-temperature heat transfer oil air cooler d is connected to the top condenser g via a low-temperature heat transfer oil inlet conveying line 125, which is used to send the cooled low-temperature heat transfer oil into the top condenser g as a cold source. The top condenser g is connected to a low-temperature heat transfer oil return conveying line 126, which is connected to the low-temperature heat transfer oil air cooler d. The low-temperature heat transfer oil return conveying line 126 is connected to a second low-temperature heat transfer oil return conveying line 127, which is connected to a medium-temperature heat transfer oil gas-liquid separator l.

[0051] Example 6 As attached Figure 1 As shown, this embodiment discloses a p-phenylenediamine refining system for a para-aramid apparatus, including a vacuum distillation subsystem, a high-temperature heat transfer oil subsystem, a medium-temperature heat transfer oil subsystem, and a low-temperature heat transfer oil subsystem. The reduced pressure distillation subsystem includes a p-phenylenediamine distillation column a, a top condenser g located at the top of the p-phenylenediamine distillation column, a p-phenylenediamine reflux tank h connected to the top condenser g, and a p-phenylenediamine product tank i connected to the p-phenylenediamine reflux tank h; the p-phenylenediamine distillation column a is connected to a molten p-phenylenediamine input line 101, the bottom of the p-phenylenediamine distillation column a is connected to a p-phenylenediamine distillation column bottom discharge conveyor line 102, and the p-phenylenediamine product tank i is connected to a p-phenylenediamine product discharge conveyor line 103; The high-temperature heat transfer oil subsystem is used to provide a heat source for the bottom of the p-phenylenediamine distillation column a; the medium-temperature heat transfer oil subsystem is used to provide a heat source for the p-phenylenediamine reflux tank h and the p-phenylenediamine product tank i; and the low-temperature heat transfer oil subsystem is used to provide a cold source for the column top condenser g.

[0052] The p-phenylenediamine distillation column a is connected to the top condenser g via a gas-p-phenylenediamine conveying line 104. The top condenser g is connected to the p-phenylenediamine reflux tank h via a condensing p-phenylenediamine conveying line 105. The p-phenylenediamine reflux tank h is connected to the p-phenylenediamine distillation column a via the first p-phenylenediamine discharge conveying line 106 and to the p-phenylenediamine product tank i via the second p-phenylenediamine discharge conveying line 107.

[0053] The p-phenylenediamine refining system of the para-aramid unit also includes a distillation column vacuum unit t; the distillation column vacuum unit t is connected to the p-phenylenediamine reflux tank h via a reflux tank gas phase discharge conveyor line 108; the distillation column vacuum unit t is connected to a demineralized water conveyor line 109, and is connected to a p-phenylenediamine distillation column vacuum unit wastewater conveyor line 110 and a p-phenylenediamine distillation column vacuum unit exhaust gas conveyor line 111.

[0054] The high-temperature heat transfer oil subsystem includes a high-temperature heat transfer oil electric heater b and a high-temperature heat transfer oil gas-liquid separator m.

[0055] The high-temperature heat transfer oil electric heater b is connected to the first high-temperature heat transfer oil conveying line 112. The high-temperature heat transfer oil electric heater b is connected to the p-phenylenediamine distillation column a via the high-temperature heat transfer oil supply line 113, which is used to send the heated high-temperature heat transfer oil into the jacket side of the p-phenylenediamine distillation column a for heating. The p-phenylenediamine distillation column a is connected to the high-temperature heat transfer oil gas-liquid separator m via the high-temperature heat transfer oil return line 114.

[0056] The high-temperature heat transfer oil gas-liquid separator m is connected to the high-temperature heat transfer oil electric heater b via the second high-temperature heat transfer oil conveying line 115, and is used to send the liquid phase heat transfer oil after gas-liquid separation into the high-temperature heat transfer oil electric heater b for reheating and reuse.

[0057] The para-aramid unit's p-phenylenediamine refining system also includes a high-temperature heat transfer oil shutdown cooler f, which is connected to the first high-temperature heat transfer oil conveying line 112 via the third high-temperature heat transfer oil conveying line 116, and to the high-temperature heat transfer oil supply conveying line 117 after cooling the p-phenylenediamine distillation column a.

[0058] The medium-temperature thermal oil subsystem includes a medium-temperature thermal oil electric heater c and a medium-temperature thermal oil gas-liquid separator l. The medium-temperature thermal oil electric heater c is connected to a first medium-temperature thermal oil conveying line 118. The medium-temperature thermal oil electric heater c is connected to the p-phenylenediamine reflux tank h via a first medium-temperature thermal oil supply line 119, and to the p-phenylenediamine product tank i via a second medium-temperature thermal oil supply line 120. The medium-temperature thermal oil gas-liquid separator l is connected to the p-phenylenediamine reflux tank h via a first medium-temperature thermal oil return line 121, and to the p-phenylenediamine product tank i via a second medium-temperature thermal oil return line 122.

[0059] The medium-temperature thermal oil gas-liquid separator l is connected to the medium-temperature thermal oil electric heater c via the second medium-temperature thermal oil conveying line 123, and is used to send the liquid phase thermal oil after gas-liquid separation into the medium-temperature thermal oil electric heater c for reheating and reuse.

[0060] The low-temperature heat transfer oil subsystem includes a low-temperature heat transfer oil air cooler d, which is connected to a first low-temperature heat transfer oil conveying line 124. The low-temperature heat transfer oil air cooler d is connected to the top condenser g via a low-temperature heat transfer oil supply line 125, and is used to send the cooled low-temperature heat transfer oil into the top condenser g as a cold source. The tower top condenser g is connected to a low-temperature heat transfer oil return line 126, which is connected to the low-temperature heat transfer oil air cooler d to cool the low-temperature heat transfer oil after heat exchange. The low-temperature heat transfer oil return conveying line 126 is connected to a second low-temperature heat transfer oil return conveying line 127, which is connected to the medium-temperature heat transfer oil gas-liquid separator 1.

[0061] The para-aramid unit's p-phenylenediamine refining system also includes a heat transfer oil expansion tank k, a heat transfer oil tail gas condenser e, and a heat transfer oil storage tank j.

[0062] The thermal oil expansion tank k is connected to the medium-temperature thermal oil gas-liquid separator l via the medium-temperature thermal oil gas-liquid separator gas phase discharge conveying line 128, and to the high-temperature thermal oil gas-liquid separator m via the high-temperature thermal oil gas-liquid separator gas phase discharge conveying line 129; the thermal oil expansion tank k is connected to the thermal oil tail gas condenser e via the thermal oil expansion tank gas phase discharge conveying line 130, and is connected to the thermal oil storage tank j via the thermal oil expansion tank overflow discharge conveying line 134.

[0063] The heat transfer oil tail gas condenser e is connected to a heat transfer oil tail gas condenser gas phase discharge line 131 and a heat transfer oil tail gas condenser condensate discharge conveying line 132, and the heat transfer oil tail gas condenser condensate discharge conveying line 132 is connected to the heat transfer oil expansion tank k.

[0064] The heat transfer oil storage tank j is connected to a fresh heat transfer oil conveying line 133 and a heat transfer oil storage tank discharge line 135 is connected to the first high temperature heat transfer oil conveying line 112, the first medium temperature heat transfer oil conveying line 118 and the first low temperature heat transfer oil conveying line 124 respectively.

[0065] A p-phenylenediamine product conveying pump n is installed on the p-phenylenediamine product discharge conveying line 103; a p-phenylenediamine distillation column bottom conveying pump o is installed on the p-phenylenediamine distillation column bottom conveying line 102; a medium-temperature heat transfer oil circulation pump p is installed on the first medium-temperature heat transfer oil conveying line 118; a high-temperature heat transfer oil circulation pump q is installed on the first high-temperature heat transfer oil conveying line 112; a low-temperature heat transfer oil circulation pump r is installed on the first low-temperature heat transfer oil conveying line 124; and a fresh heat transfer oil replenishment pump s is installed on the heat transfer oil storage tank discharge line 135.

[0066] This embodiment 6 provides a more preferred technical solution based on embodiment 5. Specifically, the para-aramid device's p-phenylenediamine refining system further includes a heat transfer oil expansion tank k, a heat transfer oil tail gas condenser e, and a heat transfer oil storage tank j, and defines the connection relationships between the heat transfer oil expansion tank k, the heat transfer oil tail gas condenser e, and the heat transfer oil storage tank j, as well as the connection relationships with the high-temperature heat transfer oil subsystem, the medium-temperature heat transfer oil subsystem, and the low-temperature heat transfer oil subsystem.

[0067] Example 7 As attached Figure 1 and 2As shown, this embodiment discloses a method for refining p-phenylenediamine using a para-aramid apparatus, employing the para-aramid apparatus p-phenylenediamine refining system of Example 6. The method includes the following steps: removing high-boiling-point substances such as p-phenylenediamine oxides through vacuum distillation; using a high-temperature heat transfer oil subsystem to provide a heat source for the bottom of the p-phenylenediamine distillation column; using a medium-temperature heat transfer oil system as a heat tracing source for the p-phenylenediamine reflux tank and product tank; and using a low-temperature heat transfer oil system as a cold source for the top condenser of the p-phenylenediamine distillation column. The specific process is as follows: Molten p-phenylenediamine stream 1 (6813.6 kg / batch) from the PPDA storage tank outside the boundary enters the bottom of p-phenylenediamine distillation column a. The vapor stream 2 from the top of the p-phenylenediamine distillation column enters the hot side of the top condenser g of the p-phenylenediamine distillation column for total condensation. After total condensation, stream 3 (1701.7 kg / h) enters the p-phenylenediamine reflux tank h. The discharge stream 4 from the p-phenylenediamine reflux tank splits into two streams: reflux stream 5 and outflow stream 6. Reflux stream 5 enters the top of p-phenylenediamine distillation column a, while outflow stream 6 (6806.8 kg / batch) enters the p-phenylenediamine product tank i. The discharge stream 7 (6806.8 kg / batch) from the p-phenylenediamine product tank enters the p-phenylenediamine product transfer pump n, and after pressurization, the p-phenylenediamine product stream (6806.8 kg / batch) is sent to the downstream polymerization reaction unit.

[0068] The gaseous discharge stream 9 from the p-phenylenediamine reflux tank enters the vacuum unit t of the p-phenylenediamine distillation tower. The demineralized water stream 11 is used as working fluid to replenish the p-phenylenediamine distillation tower vacuum unit t. The wastewater stream 12 from the p-phenylenediamine distillation tower vacuum unit is sent to the sewage treatment plant outside the boundary for treatment. The exhaust gas stream 10 from the p-phenylenediamine distillation tower vacuum unit is sent to the scrubbing system for treatment and then discharged at high altitude.

[0069] The feed stream 13 from the bottom of the p-phenylenediamine distillation column enters the p-phenylenediamine distillation column bottom transfer pump o, and after being pressurized, the liquid stream 14 from the bottom of the p-phenylenediamine distillation column is sent to the waste liquid buffer tank outside the boundary for storage.

[0070] Fresh heat transfer oil from outside the boundary area flows into the heat transfer oil storage tank j (stream 15), and then flows out of the heat transfer oil storage tank (stream 16) into the fresh heat transfer oil replenishment pump s (stream s). It then splits into three streams: fresh heat transfer oil replenishment pump outlet stream one (stream 17), fresh heat transfer oil replenishment pump outlet stream two (stream 18), and fresh heat transfer oil replenishment pump outlet stream three (stream 19). Fresh heat transfer oil replenishment pump outlet stream one (stream 17) enters the low-temperature heat transfer oil circulation pump r for heat transfer oil replenishment; fresh heat transfer oil replenishment pump outlet stream two (stream 18) enters the medium-temperature heat transfer oil circulation pump p for heat transfer oil replenishment; and fresh heat transfer oil replenishment pump outlet stream three (stream 19) enters the high-temperature heat transfer oil circulation pump q for heat transfer oil replenishment.

[0071] High-temperature heat transfer oil stream 20 enters the high-temperature heat transfer oil circulation pump q. The discharge stream 21 of the high-temperature heat transfer oil circulation pump splits into two streams, namely stream one 22 and stream two 24. Stream one 22 enters the high-temperature heat transfer oil electric heater b for heating. After heating, the high-temperature heat transfer oil feed stream 23 enters the jacket side of the p-phenylenediamine distillation column a for heating. Stream two 24 enters the high-temperature heat transfer oil shutdown cooler f for cooling. After cooling, the high-temperature heat transfer oil feed stream 25 enters the jacket side of the p-phenylenediamine distillation column a for shutdown cooling. The high-temperature heat transfer oil return stream 26 enters the high-temperature heat transfer oil gas-liquid separator m for gas-liquid separation. The gas phase discharge stream 27 of the high-temperature heat transfer oil gas-liquid separator enters the heat transfer oil expansion tank k. The liquid phase discharge stream 28 of the high-temperature heat transfer oil gas-liquid separator mixes with the fresh heat transfer oil replenishment pump discharge stream 19 to form a high-temperature heat transfer oil stream 20, which enters the high-temperature heat transfer oil circulation pump q. The medium-temperature thermal oil stream 29 is formed by the convergence of the fresh thermal oil replenishment pump discharge stream 2 18 and the liquid phase discharge stream 37 from the medium-temperature thermal oil gas-liquid separator, and enters the medium-temperature thermal oil circulation pump p. The discharge stream 30 from the medium-temperature thermal oil circulation pump enters the medium-temperature thermal oil electric heater c for heating. After heating, the medium-temperature thermal oil upper stream 31 splits into two streams, namely stream three 32 and stream four 33. Stream three 32 enters the jacket side of the p-phenylenediamine reflux tank h for heating, and stream four 33 enters the jacket side of the p-phenylenediamine product tank i for heating.

[0072] Medium-temperature thermal oil return stream 1 (34), medium-temperature thermal oil return stream 2 (35), and stream 5 (44) enter the medium-temperature thermal oil gas-liquid separator l for gas-liquid separation. The gas phase discharge stream 36 from the medium-temperature thermal oil gas-liquid separator enters the thermal oil expansion tank k. The liquid phase discharge stream 37 from the medium-temperature thermal oil gas-liquid separator mixes with the fresh thermal oil replenishment pump discharge stream 2 (18) to form medium-temperature thermal oil stream 29, which enters the medium-temperature thermal oil circulation pump p. The gas phase discharge stream 38 from the thermal oil expansion tank enters the thermal oil tail gas condenser e for condensation. The condensate discharge stream 40 from the thermal oil tail gas condenser returns to the thermal oil expansion tank k. After condensation in the thermal oil tail gas condenser, the gas phase discharge stream 39 is vented at its highest point. The overflow discharge stream 41 from the thermal oil expansion tank enters the thermal oil storage tank j. The low-temperature heat transfer oil stream 42 enters the low-temperature heat transfer oil circulation pump r. The discharge stream 43 of the low-temperature heat transfer oil circulation pump splits into two streams, namely stream five 44 and stream six 45. Stream five 44 enters the medium-temperature heat transfer oil gas-liquid separator l for gas-liquid separation, while stream six 45 enters the low-temperature heat transfer oil air cooler d for cooling. After cooling, the low-temperature heat transfer oil feed stream 46 enters the cold side of the top condenser g of the p-phenylenediamine distillation column. After heating, the heat transfer oil return stream 47 mixes with the fresh heat transfer oil makeup pump discharge stream -17 to form the low-temperature heat transfer oil stream 42, which then enters the low-temperature heat transfer oil circulation pump r.

[0073] In this embodiment, the operating pressure of the p-phenylenediamine distillation column a is 6~15 kPaA, and the operating temperature is 180~190℃; high-temperature heat transfer oil is used for heating and distillation. Low-temperature heat transfer oil is used for cooling the p-phenylenediamine, and it is stored after cooling. Medium-temperature heat transfer oil is used for storage and heating to prevent crystallization and blockage.

[0074] This invention improves the quality of p-phenylenediamine distillation through liquid feed and vacuum distillation. Simultaneously, the fully enclosed operation reduces the risk of high-temperature oxidation and saves on circulating water, electricity, and nitrogen consumption for purging. This significantly improves the economics of the plant. Each ton of p-phenylenediamine product saves 8.7 kWh of electricity, 0.75 tons of water, and 6.6 Nm³ of high-purity nitrogen. 3 / ton of p-phenylenediamine.

[0075] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A p-phenylenediamine purification system for a para-aramid device, characterized by, It includes a vacuum distillation subsystem, a high-temperature heat transfer oil subsystem, a medium-temperature heat transfer oil subsystem, and a low-temperature heat transfer oil subsystem; The vacuum distillation subsystem includes a p-phenylenediamine distillation column (a), a top condenser (g) located at the top of the p-phenylenediamine distillation column, a p-phenylenediamine reflux tank (h) connected to the top condenser (g), and a p-phenylenediamine product tank (i) connected to the p-phenylenediamine reflux tank (h); the p-phenylenediamine distillation column (a) is connected to a molten p-phenylenediamine input line (101), the bottom of the p-phenylenediamine distillation column (a) is connected to a p-phenylenediamine distillation column bottom discharge conveyor line (102), and the p-phenylenediamine product tank (i) is connected to a p-phenylenediamine product discharge conveyor line (103); The high-temperature heat transfer oil subsystem is used to provide a heat source for the bottom of the p-phenylenediamine distillation column (a); The medium-temperature heat transfer oil subsystem is used to provide a heat source for the p-phenylenediamine reflux tank (h) and the p-phenylenediamine product tank (i); The low-temperature heat transfer oil subsystem is used to provide a cold source for the top condenser (g).

2. The p-phenylenediamine purification system of claim 1, wherein The p-phenylenediamine distillation column (a) and the top condenser (g) are connected via a gas-p-phenylenediamine delivery line (104). The top condenser (g) and the p-phenylenediamine reflux tank (h) are connected via a p-phenylenediamine condensation conveyor line (105).

3. The p-phenylenediamine purification system of claim 1, wherein The p-phenylenediamine reflux tank (h) is connected to the p-phenylenediamine distillation column (a) via the first p-phenylenediamine discharge conveyor line (106), and to the p-phenylenediamine product tank (i) via the second p-phenylenediamine discharge conveyor line (107).

4. The p-phenylenediamine purification system of claim 1, wherein, The para-aramid unit's p-phenylenediamine refining system also includes a distillation column vacuum unit (t). The distillation column vacuum unit (t) is connected to the p-phenylenediamine reflux tank (h) via the reflux tank gas phase discharge conveyor line (108).

5. The p-phenylenediamine purification system of claim 4, wherein The distillation column vacuum unit (t) is connected to a demineralized water conveying line (109) and connected to a p-phenylenediamine distillation column vacuum unit wastewater conveying line (110) and a p-phenylenediamine distillation column vacuum unit exhaust gas conveying line (111).

6. The p-phenylenediamine purification system of claim 1, wherein The high-temperature heat transfer oil subsystem includes a high-temperature heat transfer oil electric heater (b) and a high-temperature heat transfer oil gas-liquid separator (m). The high-temperature heat transfer oil electric heater (b) is connected to the first high-temperature heat transfer oil conveying line (112). The high-temperature heat transfer oil electric heater (b) is connected to the p-phenylenediamine distillation column (a) via the high-temperature heat transfer oil supply line (113) to send the heated high-temperature heat transfer oil into the jacket side of the p-phenylenediamine distillation column (a) for heating. The p-phenylenediamine distillation column (a) is connected to the high-temperature heat-conducting oil gas-liquid separator (m) via a high-temperature heat-conducting oil return line (114).

7. The p-phenylenediamine purification system of claim 6, wherein the system further comprises a first column and a second column. The high-temperature heat transfer oil gas-liquid separator (m) and the high-temperature heat transfer oil electric heater (b) are connected via the second high-temperature heat transfer oil conveying line (115) to send the liquid phase heat transfer oil after gas-liquid separation into the high-temperature heat transfer oil electric heater (b) for reheating and use.

8. The p-phenylenediamine purification system of claim 6, wherein, It also includes a high-temperature heat transfer oil shutdown cooler (f), which is connected to the first high-temperature heat transfer oil conveying line (112) via the third high-temperature heat transfer oil conveying line (116) and to the high-temperature heat transfer oil supply conveying line (117) after cooling of the p-phenylenediamine distillation column (a).

9. The p-phenylenediamine purification system of claim 6, wherein, The medium-temperature thermal oil subsystem includes a medium-temperature thermal oil electric heater (c) and a medium-temperature thermal oil gas-liquid separator (l). The medium-temperature thermal oil electric heater (c) is connected to a first medium-temperature thermal oil conveying line (118). The medium-temperature thermal oil electric heater (c) is connected to the p-phenylenediamine reflux tank (h) via a first medium-temperature thermal oil supply conveying line (119), and to the p-phenylenediamine product tank (i) via a second medium-temperature thermal oil supply conveying line (120). The medium-temperature thermal oil gas-liquid separator (l) is connected to the p-phenylenediamine reflux tank (h) via a first medium-temperature thermal oil return conveyor line (121), and to the p-phenylenediamine product tank (i) via a second medium-temperature thermal oil return conveyor line (122).

10. The p-phenylenediamine purification system of claim 9, wherein, The medium-temperature thermal oil gas-liquid separator (l) is connected to the medium-temperature thermal oil electric heater (c) via the second medium-temperature thermal oil conveying line (123) to send the liquid phase thermal oil after gas-liquid separation into the medium-temperature thermal oil electric heater (c) for reheating and use.

11. The p-phenylenediamine purification system of claim 9, wherein, The low-temperature heat transfer oil subsystem includes a low-temperature heat transfer oil air cooler (d), which is connected to a first low-temperature heat transfer oil conveying line (124). The low-temperature heat transfer oil air cooler (d) is connected to the top condenser (g) via a low-temperature heat transfer oil supply line (125) to send the cooled low-temperature heat transfer oil into the top condenser (g) as a cold source. The tower top condenser (g) is connected to a low-temperature heat transfer oil return line (126), which is connected to a low-temperature heat transfer oil air cooler (d) to cool the low-temperature heat transfer oil after heat exchange.

12. The p-phenylenediamine purification system of claim 11, wherein, The low-temperature heat transfer oil return line (126) is connected to a second low-temperature heat transfer oil return line (127), which is connected to the medium-temperature heat transfer oil gas-liquid separator (l).

13. The p-phenylenediamine refining system for a para-aramid apparatus according to claim 9, characterized in that, It also includes a thermal oil expansion tank (k), which is connected to the medium-temperature thermal oil gas-liquid separator (l) via the medium-temperature thermal oil gas-liquid separator gas phase discharge conveying line (128), and to the high-temperature thermal oil gas-liquid separator (m) via the high-temperature thermal oil gas-liquid separator gas phase discharge conveying line (129).

14. The p-phenylenediamine purification system of claim 13, wherein, It also includes a heat transfer oil tail gas condenser (e), and the heat transfer oil expansion tank (k) is connected to the heat transfer oil tail gas condenser (e) via the heat transfer oil expansion tank gas phase discharge conveyor line (130).

15. The p-phenylenediamine purification system of claim 14, wherein, The heat transfer oil tail gas condenser (e) is connected to a heat transfer oil tail gas condenser gas phase discharge line (131) and a heat transfer oil tail gas condenser condensate discharge conveying line (132), and the heat transfer oil tail gas condenser condensate discharge conveying line (132) is connected to the heat transfer oil expansion tank (k).

16. The p-phenylenediamine purification system of claim 13, wherein, It also includes a heat transfer oil storage tank (j), which is connected to a fresh heat transfer oil delivery line (133). The heat transfer oil storage tank (j) and the high-temperature heat transfer oil electric heater (b) are connected via the first high-temperature heat transfer oil conveying line (112). It is connected to the medium-temperature thermal oil electric heater (c) via the first medium-temperature thermal oil conveying line (118). It is connected to the low-temperature heat transfer oil air cooler (d) via the first low-temperature heat transfer oil delivery line (124).

17. A p-phenylenediamine purification system for a para-aramid device according to claim 16, wherein, The thermal oil expansion tank (k) is connected to the thermal oil storage tank (j) via the thermal oil expansion tank overflow conveyor line (134).

18. A method for purifying p-phenylenediamine using a para-aramid apparatus, characterized in that, The method employs the para-aramid apparatus according to any one of claims 1-17 to refine phenylenediamine; the method comprises the following steps: Molten p-phenylenediamine stream (1) from the PPDA storage tank outside the boundary enters the bottom of the p-phenylenediamine distillation column (a). The vapor stream (2) from the top of the p-phenylenediamine distillation column enters the hot side of the top condenser (g) to complete total condensation. After total condensation, the stream (3) enters the p-phenylenediamine reflux tank (h). The p-phenylenediamine reflux tank discharge stream (4) is divided into two streams: reflux stream (5) and discharge stream (6). The reflux stream (5) enters the top of the p-phenylenediamine distillation column (a), and the discharge stream (6) enters the p-phenylenediamine product tank (i). After heating, the high-temperature heat transfer oil stream (23) enters the jacket side of the p-phenylenediamine distillation column (a) for heating; After heating, the medium-temperature heat transfer oil stream (31) splits into two streams, namely stream three (32) and stream four (33); stream three (32) enters the jacket side of the p-phenylenediamine reflux tank (h) for heat tracing, and stream four (33) enters the jacket side of the p-phenylenediamine product tank (i) for heat tracing. After the distillation column is cooled, the low-temperature heat transfer oil stream (46) enters the cold side of the top condenser (g).

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