Low-density oxidized polyethylene wax preparation system and preparation method

Abstract

The present invention belongs to the technical field of polymer compounds, and specifically relates to a low-density oxidized polyethylene wax preparation system and preparation method. The low-density oxidized polyethylene wax preparation system includes an oxidation reactor in which an oxidation reaction chamber, a preheating gas flow chamber and a pre-reaction chamber are arranged in parallel, a cyclone separator is arranged on the top of the pre-reaction chamber, and a plurality of overflow plates are arranged at intervals in the pre-reaction chamber, and a gas disk 2 is arranged on the overflow plate, and two adjacent overflow plates are connected by an overflow pipe; a plurality of flow partitions, a high-pressure spray gun and a gas disk 1 are arranged in sequence from top to bottom in the oxidation reaction chamber, and the bottom of the pre-reaction chamber is connected to the high-pressure spray gun through a circulation pipeline; the cyclone separator is respectively connected to an exhaust gas pipeline and a temperature controller 1, and the temperature controller 1, a blower, a temperature controller 2 and a gas disk 1 are connected in sequence, and an air supply pipeline is arranged on the pipeline between the blower and the temperature controller 1. The present invention is provided with a multi-cavity oxidation reactor, which can realize continuous reaction and make the reaction more uniform.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer compounds, and in particular relates to a system and a method for preparing low-density oxidized polyethylene wax. Background Art

[0002] Low-density oxidized polyethylene wax is an excellent new polar wax, which is made by oxidizing polyethylene wax through a special process. It has the advantages of low viscosity, high softening point, good hardness, non-toxicity, good thermal stability and low high-temperature volatility. Low-density oxidized polyethylene wax can be used to improve the plasticization degree and is suitable for products that require high-speed extrusion, good surface gloss and anti-precipitation, such as high-speed extruded PVC threading pipes, injection molding pipes and PVC profiles. In the production of PVC products, low-density oxidized polyethylene wax can improve the external lubricity and glossiness of PVC products. The excellent internal and external lubrication balance performance can reduce melt viscosity and friction heat, and improve processability and fluidity.

[0003] At present, when producing low-density oxidized polyethylene wax, intermittent production equipment is usually used for production, and oxidization is carried out by introducing oxidizing gas into the molten oxidized wax, or the molten oxidized wax is added to an autoclave and dispersed in water for oxidation.

[0004] However, there are the following problems in the above production method:

[0005] 1. The oxygen utilization rate is low and the oxidation reaction time is long. During the oxidation reaction, gas needs to be continuously introduced and tail gas will be continuously generated. The tail gas output is large and the tail gas treatment is difficult.

[0006] 2. The gas-liquid entrainment phenomenon is serious and the finished product yield is low. A large number of interception equipment such as condensers and cyclone separators are required for interception. A large amount of oxidized wax is not easy to intercept.

[0007] 3. The reaction tail gas will take away a lot of heat and cannot be recycled, resulting in energy waste.

[0008] 4. The use of the in-water reaction method will produce a large amount of wastewater, increasing the cost of wastewater treatment.

[0009] 5. The intermittent production equipment is used, with low automation, high work intensity, poor product stability and unstable quality. Summary of the invention

[0010] In view of the above deficiencies in the prior art, the technical problem to be solved by the present invention is: to provide a low-density oxidized polyethylene wax preparation system to achieve continuous production and full utilization of energy, and to improve reaction efficiency and product yield; the present invention also provides a preparation method using the low-density oxidized polyethylene wax preparation system.

[0011] The technical solution adopted by the present invention to solve its technical problem is:

[0012] The low-density oxidized polyethylene wax preparation system of the present invention comprises an oxidation reactor, wherein an oxidation reaction chamber, a preheating gas circulation chamber and a pre-reaction chamber are arranged in parallel in the oxidation reactor, the top of the oxidation reaction chamber is connected to the top of the preheating gas circulation chamber, the bottom of the preheating gas circulation chamber is connected to the bottom of the pre-reaction chamber, a cyclone separator is arranged on the top of the pre-reaction chamber, a plurality of overflow plates are arranged from top to bottom in the pre-reaction chamber, a gas disk 2 is arranged on the overflow plate, a plurality of overflow pipes are arranged in the pre-reaction chamber, two adjacent overflow plates are connected by overflow pipes, and a feed pipe is connected to the upper part of the pre-reaction chamber;

[0013] A plurality of flow partitions are arranged at intervals from top to bottom on the upper inner side of the oxidation reaction chamber, a high-pressure spray gun is arranged below the flow partition, the bottom of the pre-reaction chamber is connected with the high-pressure spray gun through a circulation pipeline, a gas disk 1 is arranged at the lower inner side of the oxidation reaction chamber, and a discharge port is arranged at the bottom of the oxidation reaction chamber; the cyclone separator is respectively connected with an exhaust gas pipeline and a temperature controller 1, the temperature controller 1 is connected with a blower, an air supply pipeline is arranged on the pipeline between the blower and the temperature controller 1, the blower is connected with a temperature controller 2, and the temperature controller 2 is connected with the gas disk 1.

[0014] An oxygen content measuring instrument 1 is arranged on the pipeline between the cyclone separator and the temperature controller 1, an oxygen content measuring instrument 2 is arranged on the pipeline between the blower and the temperature controller 2, and an exhaust pipeline is arranged on the pipeline between the temperature controller 2 and the gas disk 1.

[0015] A through hole is arranged in the middle of the overflow plate, and the gas disk 2 is arranged in an inverted concave shape as a whole. The gas disk 2 is arranged on the top of the through hole, and a plurality of overflow pipes are staggeredly arranged on the left and right sides of the gas disk 2 from top to bottom.

[0016] The gas disk 2 includes a horizontal disk and side disks supported on both sides of the horizontal disk. An air inlet is arranged at the center of the bottom of the horizontal disk, and a plurality of air outlets are arranged on the outer wall of the side disk; a plurality of flow partitions are staggeredly arranged on the inner wall of the oxidation reaction chamber.

[0017] A high-pressure pump is provided on the circulation pipeline.

[0018] The gas plate is arranged below the high-pressure spray gun, and the feed pipe is arranged above the overflow plate.

[0019] The preparation method of the low-density oxidized polyethylene wax preparation system of the present invention comprises the following steps:

[0020] (1) Adding a mixture of molten polyethylene wax and a catalyst into a pre-reaction chamber, the mixture of the molten polyethylene wax and the catalyst flows from top to bottom through an overflow plate, a second gas plate and an overflow pipe, and the preheated gas is bubbled from bottom to top through the second gas plate and then pre-reacts with the mixture of the molten polyethylene wax and the catalyst to obtain oxidatively excited polyethylene wax, and the remaining preheated gas is separated by a cyclone separator to obtain tail gas, which is then transported back to the oxidation reaction chamber for recycling;

[0021] (2) The oxidatively excited polyethylene wax enters the high-pressure spray gun through the circulation pipeline, and is atomized into droplets by the high-pressure spray gun and then enters the oxidation reaction chamber. The preheated oxygen-containing gas is dispersed from the gas disk and enters the oxidation reaction chamber. The oxidatively excited polyethylene wax contacts the preheated oxygen-containing gas to undergo an oxidation reaction to obtain a low-density oxidized polyethylene wax and preheated gas.

[0022] (3) The preheated gas in step (2) is transported to the pre-reaction chamber through the preheated gas flow chamber to continue pre-reacting with the mixture of molten polyethylene wax and catalyst.

[0023] In step (1), the temperature of the mixed solution of polyethylene wax and catalyst is 160-200°C.

[0024] In step (2), the average particle size of the droplets is 100-200 μm, the temperature of the preheated oxygen-containing gas is 60-150° C., and the oxygen content of the preheated oxygen-containing gas is 50-100 v%.

[0025] In step (2), the insulation temperature in the oxidation reaction chamber is 130-150° C. Under the insulation temperature condition in the oxidation reaction chamber, the temperature of the oxidation reaction can be maintained at 140-160° C. to prevent the temperature of the oxidation reaction from being too high.

[0026] Oxidized polyethylene wax accumulates continuously at the bottom of the oxidation reaction chamber, and the liquid level is maintained at 20-200 cm.

[0027] The mixed liquid of molten polyethylene wax and catalyst enters the pre-reaction chamber from the upper part of the pre-reaction chamber and flows to the bottom of the pre-reaction chamber after passing through gas disk 2, overflow pipe and overflow plate. After the preheated gas enters the pre-reaction chamber, it is dispersed and bubbled from bottom to top through gas disk 2. The preheated gas is evenly mixed with the molten polyethylene wax on the overflow plate, and the polyethylene wax is excited by high-temperature oxidation.

[0028] The oxygen-containing gas is transported by a blower, and after being preheated, the oxygen-containing gas is continuously introduced into the gas disk 1 and dispersed into the oxidation reaction chamber from bottom to top. The oxidatively excited polyethylene wax is atomized by a high-pressure spray gun and fully contacts with the preheated oxygen-containing gas for oxidation reaction to obtain oxidized polyethylene wax. The molten oxidized polyethylene wax accumulates at the bottom of the oxidation reaction chamber and is fully mixed with the bubbles generated by the gas disk 1 for oxidation, thereby improving the oxidation uniformity. Finally, the low-density oxidized polyethylene wax is discharged from the discharge port at the bottom of the oxidation reaction chamber.

[0029] After the oxidation reaction, the preheated gas passes through the preheating gas flow chamber and enters the prereaction chamber for high-temperature oxidation excitation of the polyethylene wax. The preheating gas flow chamber can intercept most of the wax entrained in the gas and liquid. When the preheated gas passes through the preheating gas flow chamber, the carried liquid is left at the bottom of the preheating gas flow chamber and mixed with the oxidatively excited polyethylene wax, and then transported back to the oxidation reaction chamber together. The remaining preheated gas in the prereaction chamber is separated by a cyclone separator, and the exhaust gas produced is transported back to the oxidation reaction chamber through a blower.

[0030] The entire reaction process is implemented in a closed cycle, which improves the oxygen utilization rate; when production is stopped, the residual exhaust gas can be sent to the exhaust gas treatment facility, and the longer the continuous production time, the lower the exhaust gas output rate, which greatly reduces the exhaust gas treatment cost.

[0031] The beneficial effects of the present invention are as follows:

[0032] The present invention is provided with a multi-cavity oxidation reactor, which can realize continuous reaction and make the reaction more uniform; the preheating gas can timely bring out the oxidation reaction heat in the oxidation reaction chamber to ensure the temperature stability in the oxidation reaction chamber; the preheating gas flow cavity can make the preheating gas enter the pre-reaction chamber for pre-reaction, the preheating gas can be fully utilized, and the purpose of saving energy is achieved.

[0033] The molten polyethylene wax at the top of the pre-reaction chamber can dissolve and intercept low-molecular-weight oxidized polyethylene wax. The remaining preheated gas includes smoke gas, which can be precipitated from the molten polyethylene wax. The cyclone separator at the top of the pre-reaction chamber can intercept the liquid in the pre-reaction chamber, which can effectively prevent the phenomenon of liquid entrainment in the exhaust gas. The exhaust gas is circulated back to the oxidation reaction chamber for full reaction, which can improve the utilization rate of oxygen in the oxygen-containing gas and reduce the exhaust gas emissions by more than 80%. Increasing the oxygen content of the oxygen-containing gas can achieve a larger amount of exhaust gas recycling, thereby significantly reducing exhaust gas emissions and improving product yields.

[0034] The baffle in the oxidation reaction chamber can intercept some droplets in the preheated gas, the high-pressure spray gun can disperse the oxidatively excited polyethylene wax into fine droplets, the gas disk 1 can evenly disperse the preheated oxygen-containing gas into tiny bubbles, the oxidatively excited polyethylene wax and the preheated oxygen-containing gas can be fully in contact, and the circulation pipeline can continuously transport the polyethylene wax to the oxidation reaction chamber; the coordinated arrangement of the baffle, the gas disk 1 and the high-pressure spray gun improves the oxidation reaction efficiency and increases the yield of the oxidized polyethylene wax to more than 97%.

[0035] As the temperature of the preheated oxygen-containing gas increases, the temperature of the mixed liquid of polyethylene wax and catalyst increases, the insulation temperature in the oxidation reaction chamber increases, the oxygen content of the preheated oxygen-containing gas increases, the particle size of the atomized droplets becomes finer, and the liquid level in the oxidation reaction chamber increases, the polyethylene wax and oxygen can be more fully contacted, and the acid value of the obtained oxidized polyethylene wax product also increases accordingly. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a schematic diagram of the structure of the present invention;

[0037] Figure 2 It is a schematic diagram of the structure of the gas disk 2 in the present invention;

[0038] In the figure: 1. oxidation reactor; 2. feed pipe; 3. overflow plate; 4. gas disk 2; 5. cyclone separator; 6. overflow pipe; 7. high-pressure spray gun; 8. circulation pipe; 9. gas disk 1; 10. discharge port; 11. flow partition; 12. exhaust pipe; 13. tail gas pipe; 14. temperature controller 1; 15. blower; 16. air supply pipe; 17. temperature controller 2; 18. oxygen content meter 1; 19. oxygen content meter 2; 20. high-pressure pump; 101. oxidation reaction chamber; 102. preheating gas flow chamber; 103. pre-reaction chamber; 401. air inlet; 402. air outlet. DETAILED DESCRIPTION

[0039] The present invention is further described below with reference to the embodiments.

[0040] Example 1

[0041] like Figure 1-2 As shown, the low-density oxidized polyethylene wax preparation system includes an oxidation reactor 1, in which an oxidation reaction chamber 101, a preheating gas circulation chamber 102 and a pre-reaction chamber 103 are arranged in parallel, the top of the oxidation reaction chamber 101 is connected to the top of the preheating gas circulation chamber 102, the bottom of the preheating gas circulation chamber 102 is connected to the bottom of the pre-reaction chamber 103, a cyclone separator 5 is arranged on the top of the pre-reaction chamber 103, a plurality of overflow plates 3 are arranged from top to bottom in the pre-reaction chamber 103, a gas disk 2 4 is arranged on the overflow plate 3, a plurality of overflow pipes 6 are arranged in the pre-reaction chamber 103, two adjacent overflow plates 3 are connected by the overflow pipe 6, and the upper part of the pre-reaction chamber 103 is connected to the feed pipeline 2;

[0042] A plurality of flow partitions 11 are arranged at intervals from top to bottom on the upper inner side of the oxidation reaction chamber 101, a high-pressure spray gun 7 is arranged below the flow partition 11, the bottom of the pre-reaction chamber 103 is connected to the high-pressure spray gun 7 through a circulation pipe 8, a gas disk 9 is arranged at the lower inner side of the oxidation reaction chamber 101, and a discharge port 10 is arranged at the bottom of the oxidation reaction chamber 101; the cyclone separator 5 is respectively connected to the exhaust gas pipeline 13 and the temperature controller 14, the temperature controller 14 is connected to the blower 15, and an air supply pipeline 16 is arranged on the pipeline between the blower 15 and the temperature controller 14, the blower 15 is connected to the temperature controller 2 17, and the temperature controller 2 17 is connected to the gas disk 9.

[0043] An oxygen content meter 18 is provided on the pipeline between the cyclone separator 5 and the temperature controller 14, an oxygen content meter 19 is provided on the pipeline between the blower 15 and the temperature controller 17, and an exhaust pipeline 12 is provided on the pipeline between the temperature controller 17 and the gas disk 9.

[0044] A through hole is arranged in the middle of the overflow plate 3, and the gas disk 2 4 is arranged in an inverted concave shape as a whole. The gas disk 2 4 is arranged on the top of the through hole, and a plurality of overflow pipes 6 are staggeredly arranged on the left and right sides of the gas disk 2 4 from top to bottom.

[0045] The gas plate 2 4 includes a horizontal plate and side plates supported on both sides of the horizontal plate. An air inlet 401 is arranged at the center of the bottom of the horizontal plate, and a plurality of air outlets 402 are arranged on the outer wall of the side plate; a plurality of flow partitions 11 are staggeredly arranged on the inner wall of the oxidation reaction chamber 101.

[0046] A high-pressure pump 20 is provided on the circulation pipeline 8 .

[0047] The gas plate 9 is arranged below the high-pressure spray gun 7, and the feed pipe 2 is arranged above the overflow plate 3.

[0048] The preparation method using the low-density oxidized polyethylene wax preparation system comprises the following steps:

[0049] (1) A mixture of molten polyethylene wax and a catalyst at a temperature of 200° C. is added to the pre-reaction chamber 103 through the feed pipe 2. The mixture of molten polyethylene wax and the catalyst flows from top to bottom through the overflow plate 3, the gas plate 2 4 and the overflow pipe 6. The preheated gas enters the pre-reaction chamber 103 and is bubbled from bottom to top through the gas plate 2 4. The mixture is then mixed with the molten polyethylene wax on the overflow plate 3 for pre-reaction to obtain oxidatively excited polyethylene wax. The remaining preheated gas is separated by the cyclone separator 5 to obtain tail gas. The tail gas is tested for oxygen content by an oxygen content meter 18 and the temperature is adjusted by a temperature controller 14. Then, oxygen-containing gas is added through the gas supply pipe 16 according to the required oxygen content and transported through the blower 15. After the oxygen content of the oxygen-containing gas meets the conditions after being tested by the oxygen content meter 2 19, the temperature of the oxygen-containing gas is adjusted to 130° C. by the temperature controller 2 17. The preheated oxygen-containing gas is transported to the oxidation reaction chamber 101 for recycling.

[0050] (2) The oxidatively excited polyethylene wax enters the circulation pipe 8 from the bottom of the pre-reaction chamber 103, and is then pumped into the high-pressure spray gun 7 by the high-pressure pump 20. The oxidatively excited polyethylene wax is atomized into fine droplets with an average particle size of 100 μm by the high-pressure spray gun 7 and then enters the oxidation reaction chamber 101. The preheated oxygen-containing gas with a temperature of 130° C. and an oxygen concentration of 100 v% is dispersed from the gas disk 9 into the oxidation reaction chamber 101, and is fully contacted with the oxidatively excited polyethylene wax to undergo an oxidation reaction. The insulation temperature in the oxidation reaction chamber is 130° C. The oxidized polyethylene wax accumulates at the bottom of the oxidation reaction chamber 101 until the liquid level is maintained at a dynamic equilibrium height of 100 cm. The accumulated oxidized polyethylene wax is fully mixed with the bubbles generated by the gas disk 9 to react, thereby obtaining a low-density oxidized polyethylene wax with an acid value of 25 and preheated gas. The obtained low-density oxidized polyethylene wax is discharged from the discharge port 10 and transported to the molding process. When the production is stopped, the residual tail gas is transported to the tail gas treatment facility through the tail gas pipeline 13 for treatment. The final product yield is 98%, and the tail gas emission is reduced by 94%.

[0051] (3) The preheated gas in step (2) enters the preheated gas circulation chamber 102 through the flow partition 11, and the carried liquid is left at the bottom of the preheated gas circulation chamber 102 and mixed with the oxidized polyethylene wax at the bottom of the pre-reaction chamber 103, and then transported back to the oxidation reaction chamber 101; after entering the pre-reaction chamber 103, the preheated gas continues to pre-react with the mixed liquid of the molten polyethylene wax and the catalyst.

[0052] Example 2

[0053] The low-density oxidized polyethylene wax preparation system used in this embodiment is the same as that in Example 1.

[0054] The preparation method using the low-density oxidized polyethylene wax preparation system comprises the following steps:

[0055] (1) A mixture of molten polyethylene wax and a catalyst at a temperature of 180° C. is added to the pre-reaction chamber 103 through the feed pipe 2. The mixture of molten polyethylene wax and the catalyst flows from top to bottom through the overflow plate 3, the gas plate 2 4 and the overflow pipe 6. The preheated gas enters the pre-reaction chamber 103 and is bubbled from bottom to top through the gas plate 2 4. The mixture is then mixed evenly with the molten polyethylene wax on the overflow plate 3 for pre-reaction to obtain oxidatively excited polyethylene wax. The remaining preheated gas is separated by the cyclone separator 5 to obtain tail gas. The tail gas is tested for oxygen content by an oxygen content meter 18 and the temperature is adjusted by a temperature controller 14. Then, oxygen-containing gas is added through an air supply pipe 16 according to the required oxygen content and transported by a blower 15. After the oxygen content of the oxygen-containing gas meets the conditions after being tested by an oxygen content meter 19, the temperature of the oxygen-containing gas is adjusted to 100° C. by a temperature controller 2 17. The preheated oxygen-containing gas is transported to the oxidation reaction chamber 101 for recycling.

[0056] (2) The oxidatively excited polyethylene wax enters the circulation pipe 8 from the bottom of the pre-reaction chamber 103, and is then pumped into the high-pressure spray gun 7 by the high-pressure pump 20. The oxidatively excited polyethylene wax is atomized into fine droplets with an average particle size of 150 μm by the high-pressure spray gun 7 and then enters the oxidation reaction chamber 101. The preheated oxygen-containing gas with a temperature of 100°C and an oxygen concentration of 100v% is dispersed from the gas disk 9 into the oxidation reaction chamber 101, and is fully contacted with the oxidatively excited polyethylene wax to undergo oxidation reaction. The insulation temperature in the oxidation reaction chamber is 140°C, and the oxygen concentration is 100v%. The oxidized polyethylene wax accumulates at the bottom of the oxidation reaction chamber 101 until the liquid level is maintained at a dynamic equilibrium height of 50 cm. The accumulated oxidized polyethylene wax is fully mixed with the bubbles generated by the gas disk 9 to react, thereby obtaining a low-density oxidized polyethylene wax with an acid value of 15 and preheated gas. The obtained low-density oxidized polyethylene wax is discharged from the discharge port 10 and transported to the molding process. When the production is stopped, the residual tail gas is transported to the tail gas treatment facility through the tail gas pipeline 13 for treatment. The final product yield is 98.5%, and the tail gas emission is reduced by 95%.

[0057] (3) The preheated gas in step (2) enters the preheated gas circulation chamber 102 through the flow partition 11, and the carried liquid is left at the bottom of the preheated gas circulation chamber 102 and mixed with the oxidized polyethylene wax at the bottom of the pre-reaction chamber 103, and then transported back to the oxidation reaction chamber 101; after entering the pre-reaction chamber 103, the preheated gas continues to pre-react with the mixed liquid of the molten polyethylene wax and the catalyst.

[0058] Example 3

[0059] The low-density oxidized polyethylene wax preparation system used in this embodiment is the same as that in Example 1.

[0060] The preparation method using the low-density oxidized polyethylene wax preparation system comprises the following steps:

[0061] (1) A mixture of molten polyethylene wax and a catalyst at a temperature of 160° C. is added to the pre-reaction chamber 103 through the feed pipe 2. The mixture of molten polyethylene wax and the catalyst flows from top to bottom through the overflow plate 3, the gas plate 2 4 and the overflow pipe 6. The preheated gas enters the pre-reaction chamber 103 and is bubbled from bottom to top through the gas plate 2 4. The mixture is then mixed with the molten polyethylene wax on the overflow plate 3 for pre-reaction to obtain oxidatively excited polyethylene wax. The remaining preheated gas is separated by the cyclone separator 5 to obtain tail gas. The tail gas is tested for oxygen content by an oxygen content meter 18 and the temperature is adjusted by a temperature controller 14. Then, oxygen-containing gas is added through an air supply pipe 16 according to the required oxygen content and transported through a blower 15. After the oxygen content of the oxygen-containing gas meets the requirements after being tested by an oxygen content meter 19, the temperature of the oxygen-containing gas is adjusted to 60° C. by a temperature controller 17. The preheated oxygen-containing gas is transported to the oxidation reaction chamber 101 for recycling.

[0062] (2) The oxidatively excited polyethylene wax enters the circulation pipe 8 from the bottom of the pre-reaction chamber 103, and is then pumped into the high-pressure spray gun 7 by the high-pressure pump 20. The oxidatively excited polyethylene wax is atomized into fine droplets with an average particle size of 200 μm by the high-pressure spray gun 7 and then enters the oxidation reaction chamber 101. The preheated oxygen-containing gas with a temperature of 60° C. and an oxygen concentration of 100 v% is dispersed from the gas disk 9 into the oxidation reaction chamber 101, and is fully contacted with the oxidatively excited polyethylene wax to undergo oxidation reaction. The insulation temperature in the oxidation reaction chamber is 150° C. Oxidized polyethylene wax accumulates at the bottom of the oxidation reaction chamber 101 until the liquid level is maintained at a dynamic equilibrium height of 20 cm. The accumulated oxidized polyethylene wax is fully mixed with the bubbles generated by the gas disk 9 to react, thereby obtaining a low-density oxidized polyethylene wax with an acid value of 7 and preheated gas. The obtained low-density oxidized polyethylene wax is discharged from the discharge port 10 and transported to the molding process. When the production is stopped, the residual tail gas is transported to the tail gas treatment facility through the tail gas pipeline 13 for treatment. The final product yield is 99%, and the tail gas emission is reduced by 95%.

[0063] (3) The preheated gas in step (2) enters the preheated gas circulation chamber 102 through the flow partition 11, and the carried liquid is left at the bottom of the preheated gas circulation chamber 102 and mixed with the oxidized polyethylene wax at the bottom of the pre-reaction chamber 103, and then transported back to the oxidation reaction chamber 101; after entering the pre-reaction chamber 103, the preheated gas continues to pre-react with the mixed liquid of the molten polyethylene wax and the catalyst.

[0064] Example 4

[0065] The low-density oxidized polyethylene wax preparation system used in this embodiment is the same as that in Example 1.

[0066] The preparation method using the low-density oxidized polyethylene wax preparation system comprises the following steps:

[0067] (1) A mixture of molten polyethylene wax and a catalyst at a temperature of 200° C. is added to the pre-reaction chamber 103 through the feed pipe 2. The mixture of molten polyethylene wax and the catalyst flows from top to bottom through the overflow plate 3, the gas plate 24 and the overflow pipe 6. The preheated gas enters the pre-reaction chamber 103 and is bubbled from bottom to top through the gas plate 24. The mixture is then mixed with the molten polyethylene wax on the overflow plate 3 for pre-reaction to obtain oxidatively excited polyethylene wax. The remaining preheated gas is separated by the cyclone separator 5 to obtain tail gas. The tail gas is tested for oxygen content by an oxygen content meter 18 and the temperature is adjusted by a temperature controller 14. Then, oxygen-containing gas is added through an air supply pipe 16 according to the required oxygen content and transported through a blower 15. After the oxygen content of the oxygen-containing gas meets the conditions after being tested by an oxygen content meter 19, the temperature of the oxygen-containing gas is adjusted to 150° C. by a temperature controller 2 17. The preheated oxygen-containing gas is transported to the oxidation reaction chamber 101 for recycling.

[0068] (2) The oxidatively excited polyethylene wax enters the circulation pipe 8 from the bottom of the pre-reaction chamber 103, and is then pumped into the high-pressure spray gun 7 by the high-pressure pump 20. The oxidatively excited polyethylene wax is atomized into fine droplets with an average particle size of 100 μm by the high-pressure spray gun 7 and then enters the oxidation reaction chamber 101. The preheated oxygen-containing gas with a temperature of 150°C and an oxygen concentration of 50v% is dispersed from the gas disk 9 into the oxidation reaction chamber 101, and is fully contacted with the oxidatively excited polyethylene wax for oxidation reaction. The insulation temperature in the oxidation reaction chamber is 140°C, and the oxygen concentration is 50v%. The oxidized polyethylene wax accumulates at the bottom of the oxidation reaction chamber 101 until the liquid level is maintained at a dynamic equilibrium height of 200 cm. The accumulated oxidized polyethylene wax is fully mixed with the bubbles generated by the gas disk 9 to react, thereby obtaining a low-density oxidized polyethylene wax with an acid value of 25 and preheated gas. The obtained low-density oxidized polyethylene wax is discharged from the discharge port 10 and transported to the molding process. When the production is stopped, the residual tail gas is transported to the tail gas treatment facility through the tail gas pipeline 13 for treatment. The final product yield is 97%, and the tail gas emission is reduced by 80%.

[0069] (3) The preheated gas in step (2) enters the preheated gas circulation chamber 102 through the flow partition 11, and the carried liquid is left at the bottom of the preheated gas circulation chamber 102 and mixed with the oxidized polyethylene wax at the bottom of the pre-reaction chamber 103, and then transported back to the oxidation reaction chamber 101; after entering the pre-reaction chamber 103, the preheated gas continues to pre-react with the mixed liquid of the molten polyethylene wax and the catalyst.

Claims

1. A system for preparing low-density oxidized polyethylene wax, comprising an oxidation reactor (1), characterized in that: An oxidation reaction chamber (101), a preheating gas circulation chamber (102) and a pre-reaction chamber (103) are arranged in parallel in the oxidation reactor (1); the top of the oxidation reaction chamber (101) is connected to the top of the preheating gas circulation chamber (102); the bottom of the preheating gas circulation chamber (102) is connected to the bottom of the pre-reaction chamber (103); a cyclone separator (5) is arranged at the top of the pre-reaction chamber (103); a plurality of overflow plates (3) are arranged at intervals from top to bottom in the pre-reaction chamber (103); a gas disk 2 (4) is arranged on the overflow plate (3); a plurality of overflow pipes (6) are arranged in the pre-reaction chamber (103); two adjacent overflow plates (3) are connected via the overflow pipe (6); and a feed pipe (2) is connected to the upper part of the pre-reaction chamber (103); A plurality of flow partitions (11) are arranged at intervals from top to bottom on the inner upper part of the oxidation reaction chamber (101); a high-pressure spray gun (7) is arranged below the flow partition (11); the bottom of the pre-reaction chamber (103) is connected to the high-pressure spray gun (7) through a circulation pipeline (8); a gas disk (9) is arranged on the inner lower part of the oxidation reaction chamber (101); and a discharge port (10) is arranged on the bottom of the oxidation reaction chamber (101); the cyclone separator (5) is respectively connected to an exhaust gas pipeline (13) and a temperature controller (14); the temperature controller (14) is connected to a blower (15); an air supply pipeline (16) is arranged on the pipeline between the blower (15) and the temperature controller (14); the blower (15) is connected to a temperature controller (17); and the temperature controller (17) is connected to the gas disk (9).

2. The low-density oxidized polyethylene wax preparation system according to claim 1, characterized in that: An oxygen content measuring instrument 1 (18) is provided on the pipeline between the cyclone separator (5) and the temperature controller 1 (14), an oxygen content measuring instrument 2 (19) is provided on the pipeline between the blower (15) and the temperature controller 2 (17), and an exhaust pipeline (12) is provided on the pipeline between the temperature controller 2 (17) and the gas disk 1 (9).

3. The system for preparing low-density oxidized polyethylene wax according to claim 1, characterized in that: A through hole is provided in the middle of the overflow plate (3), the gas disc 2 (4) is arranged in an inverted concave shape as a whole, the gas disc 2 (4) is arranged at the top of the through hole, and a plurality of overflow pipes (6) are arranged alternately on the left and right sides of the gas disc 2 (4) from top to bottom.

4. The system for preparing low-density oxidized polyethylene wax according to claim 3, characterized in that: The gas disk 2 (4) comprises a horizontal disk and side disks supported on both sides of the horizontal disk. An air inlet (401) is arranged at the center of the bottom of the horizontal disk, and a plurality of air outlets (402) are arranged on the outer wall of the side disk. A plurality of flow partitions (11) are arranged alternately on the inner wall of the oxidation reaction chamber (101).

5. The system for preparing low-density oxidized polyethylene wax according to claim 1, characterized in that: A high-pressure pump (20) is provided on the circulation pipeline (8).

6. The system for preparing low-density oxidized polyethylene wax according to claim 1, characterized in that: The gas plate 1 (9) is arranged below the high-pressure spray gun (7), and the feed pipe (2) is arranged above the overflow plate (3).

7. A method for preparing a low-density oxidized polyethylene wax using the system for preparing the low-density oxidized polyethylene wax according to any one of claims 1 to 6, characterized in that: The following steps are involved: (1) adding a mixture of molten polyethylene wax and a catalyst into a pre-reaction chamber (103), the mixture of molten polyethylene wax and the catalyst flows from top to bottom through an overflow plate (3), a second gas plate (4) and an overflow pipe (6), and preheating gas is bubbled from bottom to top through the second gas plate (4) to pre-react with the mixture of molten polyethylene wax and the catalyst to obtain oxidatively excited polyethylene wax, and the remaining preheating gas is separated by a cyclone separator (5) to obtain tail gas, which is then transported back to the oxidation reaction chamber (101) for recycling; (2) The oxidatively excited polyethylene wax enters the high-pressure spray gun (7) through the circulation pipe (8), and is atomized into liquid droplets by the high-pressure spray gun (7) and enters the oxidation reaction chamber (101). The preheated oxygen-containing gas is dispersed from the gas disk (9) and enters the oxidation reaction chamber (101). The oxidatively excited polyethylene wax contacts the preheated oxygen-containing gas to undergo an oxidation reaction, thereby obtaining a low-density oxidized polyethylene wax and a preheated gas. (3) The preheated gas in step (2) is transported to the pre-reaction chamber (103) through the preheated gas flow chamber (102) to continue pre-reacting with the mixed liquid of molten polyethylene wax and catalyst.

8. The method for preparing the low-density oxidized polyethylene wax according to claim 7, characterized in that: In step (1), the temperature of the mixed solution of polyethylene wax and catalyst is 160-200°C.

9. The preparation method using a low-density oxidized polyethylene wax preparation system according to claim 7, characterized in that: In step (2), the average particle size of the droplets is 100-200 μm, the temperature of the preheated oxygen-containing gas is 60-150° C., and the oxygen content of the preheated oxygen-containing gas is 50-100 v%.

10. The preparation method using a low-density oxidized polyethylene wax preparation system according to claim 7, characterized in that: In step (2), the insulation temperature in the oxidation reaction chamber (101) is 130-150°C.

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