PK polymerization solvent recovery system and process

Abstract

A PK polymerization solvent recovery system comprises a dehydrating tower, a heavy component removing tower and a solvent rectifying tower, an inlet is formed in the middle of the side wall of the dehydrating tower and connected with a crude solvent source, a tower top discharge port of the dehydrating tower flows back to the top of the dehydrating tower through a dehydrating tower condenser and a dehydrating tower return tank to discharge process water, and a bottom discharge port of the dehydrating tower supplies materials to the heavy component removing tower. A tower top discharge port of the heavy component removal tower is refluxed to the top of the heavy component removal tower through a heavy component removal tower condenser and a heavy component removal tower return tank, materials are supplied to the solvent rectifying tower, a tower top discharge port of the solvent rectifying tower is refluxed to the top of the solvent rectifying tower through a solvent rectifying tower condenser and a solvent rectifying tower return tank, and light components are discharged. And a tower bottom discharge port of the solvent rectifying tower is used for discharging the solvent. The device is simple in structure and convenient to operate, the solvent N-methyl pyrrolidone in the crude solvent and the residual catalyst palladium element can be effectively recycled, and the PK production cost is effectively reduced.

Description

Technical Field

[0001] The invention relates to the field of chemical industry, and in particular to a PK polymerization solvent recovery system and process. Background Art

[0002] PK is polyketone resin, a hard and dense material with a smooth, white and shiny surface. It has a high elastic modulus, high rigidity and hardness, and its specific strength and specific rigidity are close to those of metals. It also has a low friction coefficient, is wear-resistant, and has good dimensional stability. Polyketone resin can partially replace copper, zinc, aluminum, steel and other metals and is widely used in automobiles, machinery manufacturing, precision instruments, office appliances, military and other industries. Polyketone resin has the characteristics of high hardness and wear resistance, so it is widely used in the manufacture of various gears, rollers, bearings, conveyor belts, springs, cams, bolts, and various pump bodies, housings, impeller friction bearings and other mechanical equipment structural parts.

[0003] PK is a linear crystalline high molecular polymer obtained by alternating copolymerization of carbon monoxide, ethylene and propylene. During the polymerization and post-treatment steps, a large amount of crude solvent is generated, and the composition of the crude solvent is complex.

[0004] Therefore, designing a separation system that can efficiently separate this complex crude solvent to reduce production costs and enhance the competitiveness of PK products is an urgent problem to be solved by those skilled in the art. Summary of the invention

[0005] One of the purposes of the present invention is to provide a PK polymerization solvent recovery system in view of the deficiencies in the prior art, which has a simple structure and is easy to operate, and can effectively recycle the solvent N-methylpyrrolidone in the crude solvent and the residual catalyst palladium element, thereby effectively reducing the PK production cost.

[0006] The second object of the present invention is to provide a process for recovering PK polymerization solvent using the above-mentioned recovery system, which has a simple process and mild separation conditions, and can recover high-purity solvent for recycling, thereby effectively reducing the production cost of PK.

[0007] The technical scheme for achieving one of the purposes of the present invention is: a PK polymerization solvent recovery system, comprising a dehydration tower, a weight removal tower, and a solvent distillation tower, wherein an inlet is arranged in the middle of the side wall of the dehydration tower, connected to a crude solvent source, a top discharge port of the dehydration tower refluxes to the top of the dehydration tower through a dehydration tower condenser and a dehydration tower reflux tank, and discharges process water, a bottom discharge port of the dehydration tower supplies the weight removal tower, a top discharge port of the weight removal tower refluxes to the top of the weight removal tower through a weight removal tower condenser and a weight removal tower reflux tank, and supplies the solvent distillation tower, a top discharge port of the solvent distillation tower refluxes to the top of the solvent distillation tower through a solvent distillation tower condenser and a solvent distillation tower reflux tank, and discharges light components, and a bottom discharge port of the solvent distillation tower discharges the solvent to the outside.

[0008] The dehydration tower, the deweighting tower and the solvent distillation tower are respectively provided with a reboiler at the bottom.

[0009] The bottom discharge port of the deweighting tower supplies materials to the incineration process to recover the palladium element.

[0010] The feed inlet of the deweighting tower and the feed inlet of the solvent distillation tower are both located in the middle of the side wall.

[0011] The technical solution for achieving the second object of the present invention is: a process for recovering the PK polymerization solvent using any of the above-mentioned recovery systems comprises the following steps:

[0012] 1) The crude solvent discharged from the PK polymerization process and the PK post-treatment process is sent to the dehydration tower after converging;

[0013] 2) Control the top temperature of the dehydration tower to 105°C, the bottom temperature to 206°C, normal pressure, and the reflux ratio to 1:1.5;

[0014] 3) The bottom liquid of the dehydration tower is sent to the deweighting tower, and the top temperature of the deweighting tower is controlled to be 155°C, the bottom temperature is 182°C, the vacuum degree is 1500mmHg, and the reflux ratio is 1:2.5;

[0015] 4) The top condensate of the deweighting tower is sent to the solvent distillation tower, and the top temperature of the solvent distillation tower is controlled to be 115°C, the bottom temperature is 202°C, the pressure is normal, the reflux ratio is 1:1, and the bottom liquid is discharged for solvent recovery.

[0016] Step 1) The crude solvent of the confluence contains N-methylpyrrolidone, palladium acetate catalyst, PK polymer and desalted water.

[0017] Step 3) The bottom liquid of the deweighting tower is sent to an incineration process to recover the palladium element.

[0018] Step 3) The top of the de-weighting tower reflux tank of the de-weighting tower is connected to a negative pressure source.

[0019] The above technical solution has the following beneficial effects:

[0020] 1. The PK polymerization solvent recovery system of the present invention includes a dehydration tower, a deweighting tower, and a solvent distillation tower, wherein the dehydration tower is used to remove desalted water in the crude solvent, the deweighting tower is used to remove PK polymers and palladium acetate catalysts in the crude solvent, and the solvent distillation tower is used to purify the purity of the solvent to meet the needs of recycling. An inlet is arranged in the middle of the side wall of the dehydration tower, which is connected to the crude solvent source. The top discharge port of the dehydration tower is refluxed to the top of the dehydration tower through the dehydration tower condenser and the dehydration tower reflux tank, and the process water is discharged to avoid the escape of the target product and improve the yield of the target product. The bottom discharge port of the dehydration tower is for the deweighting tower material, and the top discharge port of the deweighting tower is refluxed to the top of the deweighting tower through the deweighting tower condenser and the deweighting tower reflux tank, and the solvent distillation tower is fed. The heavy components in the materials sent to the deweighting tower, including PK polymers and catalysts, are retained in the deweighting tower, and the palladium element therein can be recovered after spraying and incineration treatment, thereby reducing the catalyst loss. The top discharge port of the solvent distillation tower is refluxed to the top of the solvent distillation tower through the solvent distillation tower condenser and the solvent distillation tower reflux tank, and the light components are discharged externally. The bottom discharge port of the solvent distillation tower discharges the solvent externally, and the target product is recovered and reused as a polymerization solvent, thereby reducing the production cost of PK.

[0021] 2. The feed inlet of the deweighting tower and the feed inlet of the solvent distillation tower are both located in the middle of the tower. The advantages of feeding in the middle of the tower are:

[0022] 1) Improve separation efficiency: Middle feeding can make the raw materials evenly distributed in the tower, fully utilize the tower plates, and thus improve separation efficiency. Compared with top or bottom feeding, middle feeding can more effectively utilize the space in the tower, so that the raw materials can be better separated in the tower;

[0023] 2) Optimize resource utilization: Middle feeding helps reduce dead zones and short circuits in the tower, allowing the raw materials to be more fully contacted and exchanged in the tower. This can not only improve product quality, but also reduce energy and material consumption, thereby achieving optimal resource utilization;

[0024] 3) Reduce energy consumption: Middle feeding can reduce the reflux ratio, because the feed position is in the middle of the tower, which can reduce the reflux volume at the top of the tower, thereby reducing energy consumption;

[0025] 4) Improve product quality: Middle feeding can better control product quality. By adjusting the feeding position, the composition of the feed can be made closer to the composition of each layer of the tower, thereby improving the purity and yield of the product.

[0026] 5) Adapt to changes in raw material composition: In terms of design, the distillation tower is usually equipped with multiple feed ports, and the position of the feed ports can be adjusted according to changes in the raw material composition.

[0027] In a de-weighting tower, the feed port is located in the middle to better separate the heavy components, reduce the accumulation of heavy components at the top of the tower, and ensure the quality of the top product. In a solvent distillation tower, the middle feed can better control the recovery of the solvent and the purity of the product, and improve the overall separation efficiency.

[0028] 3. The solvent recovery process of the present invention combines the crude solvent and sequentially sends it to the dehydration tower, the deweighting tower, and the solvent distillation tower. The sequential dehydration tower, the deweighting tower, and the solvent distillation tower in the NMP recovery system each have the advantages of efficient dehydration, removal of light components, and distillation purification, which together ensure the high purity and quality of NMP.

[0029] The dehydration tower effectively removes water from NMP waste liquid to ensure the purity of the solvent. This multi-stage treatment method improves the efficiency of dehydration and reduces the burden of subsequent processing steps.

[0030] The design of the first dehydration tower makes the entire treatment process easy to control, capable of steadily removing water and ensuring the quality and purity of NMP.

[0031] The de-weighting tower is mainly used to remove light components in NMP waste liquid, such as low-boiling impurities. The light components can be effectively removed by decompression operation, thereby improving the purity of NMP. The de-weighting tower can significantly improve the purity of NMP to meet the needs of electronic grade or other high-demand applications.

[0032] The solvent is further purified through the solvent distillation tower to remove residual impurities and ensure the quality of the final product. The design of the distillation tower makes the purity of NMP meet the standard. The distillation process of the solvent distillation tower can ensure the high purity of NMP to meet the needs of polymerization.

[0033] The applicant's test results show that the recovery rate of the crude solvent of the present invention is 98.96% and the purity is 99.0%.

[0034] Further description is given below in conjunction with the accompanying drawings and specific implementation methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a connection schematic diagram of the recovery system of the present invention.

[0036] In the accompanying drawings, 1 is a dehydration tower, 11 is a dehydration tower condenser, 12 is a dehydration tower reflux tank, 2 is a deweighting tower, 21 is a deweighting tower condenser, 22 is a deweighting tower reflux tank, 3 is a solvent distillation tower, 31 is a solvent distillation tower condenser, and 32 is a solvent distillation tower reflux tank. DETAILED DESCRIPTION

[0037] Example 1

[0038] See also Figure 1The PK polymerization solvent recovery system includes a dehydration tower 1, a deweighting tower 2, and a solvent distillation tower 3. An inlet is arranged in the middle of the side wall of the dehydration tower 1, which is connected to a crude solvent source. The top discharge port of the dehydration tower 1 refluxes to the top of the dehydration tower through a dehydration tower condenser 11 and a dehydration tower reflux tank 12, and the process water is discharged. The bottom discharge port of the dehydration tower 1 supplies the deweighting tower 2. Obviously, a reboiler is arranged at the bottom of the dehydration tower, and a production pump is arranged downstream of the dehydration tower reflux tank. The top discharge port of the de-weighting tower 2 refluxes to the top of the de-weighting tower through the de-weighting tower condenser 21 and the de-weighting tower reflux tank 22, and feeds the solvent distillation tower. The de-weighting tower reflux tank 22 is connected to the negative pressure source. Specifically, the feed port of the de-weighting tower is arranged in the middle of the side wall of the de-weighting tower, and the bottom discharge port of the de-weighting tower 2 feeds the incineration process to recover the palladium element. Obviously, the bottom of the de-weighting tower is equipped with a reboiler, and the downstream of the de-weighting tower reflux tank is provided with an extraction pump. The top discharge port of the solvent distillation tower 3 refluxes to the top of the solvent distillation tower through the solvent distillation tower condenser 31 and the solvent distillation tower reflux tank 32, and discharges the light components. The bottom discharge port of the solvent distillation tower 3 discharges the solvent to the outside. Specifically, the feed port of the solvent distillation tower is arranged in the middle of the side wall of the solvent distillation tower. Obviously, the bottom of the solvent distillation tower is equipped with a reboiler, and the downstream of the solvent distillation tower reflux tank is provided with an extraction pump.

[0039] The main equipment specifications of the solvent recovery system are as follows:

[0040] Device Name Specifications (50,000 tons / year PK) quantity Material Dehydration tower DN=2500,H=42000 1 S30408 Dehydration tower reboiler <![CDATA[A=473m 2 ]]> 1 S30408 Dehydration tower condenser <![CDATA[A=676m 2 ]]> 1 S30408 Dehydration tower reflux tank <![CDATA[V=10m 3 ]]> 1 S30408 Dehydration tower water extraction pump Q=19t / h,P=3.2MPa(G) 2 S30408 Dehydration tower bottom pump Q=53t / h,H=45m 2 S30408 Deweighting tower DN=2500, H=35000 1 S30408 De-weighting tower reboiler <![CDATA[A=261m 2 ]]> 1 S30408 De-weighting tower condenser <![CDATA[A=373m 2 ]]> 1 S30408 De-weighting tower reflux tank <![CDATA[V=17m 3 ]]> 1 S30408 Degravity tower heavy component pump Q=0.4t / h H=30m 2 S30408 Degravity tower production pump Q=53t / h H=45m 2 S30408 Solvent distillation tower DN=1500,H=30000 1 S30408 Solvent distillation tower reboiler <![CDATA[A=15m 2 ]]> 1 S30408 Solvent distillation tower condenser <![CDATA[A=30m 2 ]]> 1 S30408 Solvent distillation tower reflux tank <![CDATA[V=1.5m 3 ]]> 1 S30408 Solvent distillation tower light component pump Q=0.5t / h H=30m 2 S30408 Solvent distillation tower solvent pump Q=53t / h P=4.2MPa(G) 2 S30408 total 24

[0041] Example 2

[0042] The process of recovering the PK polymerization solvent using the recovery system of Example 1 comprises the following steps:

[0043] 1) The crude solvent from the post-treatment unit (temperature is 80°C, flow rate is 2.597 t / h after flow adjustment) is combined with the crude solvent from the polymerization unit (temperature is 80°C, flow rate is 71.19 t / h after flow adjustment) (temperature is 80°C, flow rate is 73.789 t / h) and enters the middle part of the dehydration tower.

[0044] 2) The dehydration tower is a normal pressure tower, with a top temperature of 105°C, a bottom temperature of 206°C, a saturated steam pressure of 2.5MPA(G) in the dehydration tower reboiler, and a reflux ratio of 1:1.5. The water vapor at the top of the dehydration tower is 31.5t / h, which is condensed by the dehydration tower condenser. After condensation, the process water is refluxed to the dehydration tower through the dehydration tower reflux tank and the dehydration tower reflux pump at 12.6t / h. 18.9t / h is extracted and combined with a small amount of supplementary desalted water for recycling. The solvent at the bottom of the dehydration tower is 52.3t / h, which is pumped into the middle of the deweight removal tower through the dehydration tower bottom pump.

[0045] 3) The de-weighting tower is operated under vacuum, with a vacuum degree of 1500 mmHg, a tower top temperature of 155°C, a tower bottom temperature of 182°C, a de-weighting tower reboiler saturated steam pressure of 2.5 MPA (G), and a de-weighting tower reflux ratio of 1:2.5. The de-weighting tower top gas is 51.95 t / h, which is condensed by the de-weighting tower condenser. After condensation, the solvent is refluxed to the de-weighting tower at 20.76 t / h through the de-weighting tower reflux tank and the de-weighting tower reflux pump, and 51.9 t / h is sent to the solvent distillation tower. The heavy component at the bottom of the de-weighting tower is 0.358 t / h, which is sent to the outside of the device boundary for incineration through the de-weighting tower heavy component pump to recover precious palladium metal. The gas at the top of the de-weighting tower reflux tank is connected to the vacuum system.

[0046] 4) The solvent distillation tower is a normal pressure tower, with a top temperature of 115°C, a bottom temperature of 202°C, a saturated steam pressure of 2.5MPA(G) in the solvent distillation tower reboiler, and a reflux ratio of 1:1. The top gas of the solvent distillation tower is 0.9t / h, which is condensed by the solvent distillation tower condenser. After condensation, the solvent is refluxed to the solvent distillation tower through the solvent distillation tower reflux tank and the solvent distillation tower reflux pump at 0.45t / h, and 0.45t / h is sent to the light component tank group outside the boundary area. The solvent recovered at the bottom of the solvent distillation tower is 51.5t / h, which is sent to the polymerization unit through the solvent distillation tower solvent pump.

[0047] 5) The solvent loss in the post-processing unit is 0.0156 t / h, the NMP carryover from the bottom of the deweighting tower in the solvent recovery unit is 0.26 t / h, and the NMP carryover from the top of the solvent distillation tower is 0.259 t / h. The total NMP loss of the three items is 0.5346 t / h. Based on the solvent circulation rate of 51.5 t / h, the solvent recovery rate is 98.96%.

[0048] The material flow of each equipment is as follows:

[0049]

[0050]

[0051] The operation control indicators of each equipment are as follows:

[0052]

[0053]

Claims

1. A PK polymerization solvent recovery system, characterized in that: It comprises a dehydration tower (1), a weight removal tower (2), and a solvent distillation tower (3). An inlet is arranged in the middle of the side wall of the dehydration tower (1), which is connected to a crude solvent source. The top discharge port of the dehydration tower (1) refluxes to the top of the dehydration tower through a dehydration tower condenser (11) and a dehydration tower reflux tank (12), and discharges process water to the outside. The bottom discharge port of the dehydration tower (1) supplies material to a deweighting tower (2). The top discharge port of the de-weighting tower (2) is refluxed to the top of the de-weighting tower through the de-weighting tower condenser (21) and the de-weighting tower reflux tank (22) to supply the solvent distillation tower. The de-weighting tower reflux tank (22) is connected to a negative pressure source. The top discharge port of the solvent distillation tower (3) refluxes to the top of the solvent distillation tower through the solvent distillation tower condenser (31) and the solvent distillation tower reflux tank (32) to discharge light components to the outside, and the bottom discharge port of the solvent distillation tower (3) discharges the solvent to the outside.

2. The PK polymerization solvent recovery system according to claim 1, characterized in that: The dehydration tower (1), the deweighting tower (2) and the solvent distillation tower (3) are respectively provided with a reboiler at the bottom.

3. The PK polymerization solvent recovery system according to claim 1, characterized in that: The bottom discharge port of the deweighting tower (2) supplies materials to the incineration process to recover the palladium element.

4. The PK polymerization solvent recovery system according to claim 1, characterized in that: The feed inlet of the deweighting tower (2) and the feed inlet of the solvent distillation tower (3) are both located in the middle of the side wall.

5. A process for recovering a PK polymerization solvent using any recovery system according to any one of claims 1 to 4, characterized in that: The following steps are involved: 1) The crude solvent discharged from the PK polymerization process and the PK post-treatment process is sent to the dehydration tower after confluence; 2) Control the top temperature of the dehydration tower to 105°C, the bottom temperature to 206°C, normal pressure, and the reflux ratio to 1:1.5; 3) The bottom liquid of the dehydration tower is sent to the dehydration tower, and the top temperature of the dehydration tower is controlled to be 155°C, the bottom temperature is 182°C, the vacuum degree is 1500mmHg, and the reflux ratio is 1:2.5; 4) The top condensate of the deweighting tower is sent to the solvent distillation tower, and the top temperature of the solvent distillation tower is controlled to be 115°C, the bottom temperature is 202°C, the pressure is normal, the reflux ratio is 1:1, and the bottom liquid is discharged for solvent recovery.

6. The process according to claim 5, characterized in that Step 1) The crude solvent of the confluence contains N-methylpyrrolidone, palladium acetate catalyst, PK polymer and desalted water.

7. The process according to claim 5, characterized in that Step 3) The bottom liquid of the deweighting tower is sent to an incineration process to recover the palladium element.

8. The process according to claim 5, characterized in that Step 3) The top of the de-weighting tower reflux tank of the de-weighting tower is connected to a negative pressure source.

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