Epoxypropane purifying method

A technology of propylene oxide and purification method, applied in the direction of organic chemistry and the like, can solve the problems of low yield of propylene oxide and large loss of extractant, and achieve the effect of high extraction efficiency and good technical effect.

Active Publication Date: 2014-10-22

CHINA PETROLEUM & CHEM CORP +1

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AI-Extracted Technical Summary

Problems solved by technology

[0005] The technical problem to be solved by the present invention is that propylene oxide and extractant are entrained in the overhead stream of the extra...

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Abstract

The invention relates to an epoxypropane purifying method. The problems of low epoxypropane yield and large extractant loss due to the entrainment of epoxypropane and an extractant in the material flow from the top of an extraction distillation tower in the prior art are mainly solved. The method comprises the following steps: 1, a crude epoxypropane solution enters the extraction distillation tower to obtain a material flow 2 at the tower top and a material flow 3 at the tower bottom; 2, the material flow 3 enters a solvent recovery tower to obtain an epoxypropane product at the tower top and an extractant flow 5 at the tower bottom, and the flow 5 is divided into a flow 6 and a flow 7; 3, the material flow 2 is condensed, and the condensed flow 2 enters a phase splitter and undergoes oil and water separation to obtain an oil layer 8 and a water layer 9; 4, the oil layer 8 and the flow 6 return to the top of the extraction distillation tower; and 5, the flow 7 enters the lower portion of a water washing tower and the water layer 9 enters the upper portion of the water washing tower to obtain wastewater flow at the tower bottom and a flow 11 at the tower top, and the flow 11 enters the phase splitter. The method well solves the problems and can be used in the industrial production of epoxypropane purification.

Application Domain

Organic chemistry

Technology Topic

ChemistryPhase splitter +6

Image

Examples

Experimental program(2)

Example Embodiment

[0047] [Example 1]

[0048] The crude propylene oxide solution (stream 1) and the solvent recovery tower kettle liquid (stream 5) exchange heat to 80℃ and enter the extractive distillation tower T-101. The extractive distillation tower uses n-octane as the extractant. The flow rate ratio of reagent stream 6 to crude propylene oxide solution feed 1) is 4, and deionized water (stream 12) is sprayed into the gas phase at the top of the tower. After condensation, the oil-water separation operation is carried out in the top phase separator D-101. There are multi-layer partitions in the phaser, and the separated oil layer (stream 8) and the recovered extractant (stream 6) are mixed as the reflux of the extractive distillation column (stream 13), and the separated water layer (stream 9) enters the washing tower T -103, the theoretical plate number of T101 tower is 70, the operating pressure is controlled at 200kPa, the temperature of the tower bottom is 100°C, and the composition of the crude propylene oxide solution is shown in Table 5.

[0049] table 5

[0050] composition Content, wt water 0.008 Acetaldehyde 0.001 Methanol 0.001 Methyl formate 0.001 Propylene oxide 0.989

[0051] The still liquid of the extractive distillation tower (stream 3) mainly contains propylene oxide and extractant, enters the solvent recovery tower T-102, the top of the tower is separated to obtain the propylene oxide product (stream 4), and the tower kettle is recovered to obtain the extractant (stream 5). The number of theoretical plates of T102 tower is 30, the operating pressure is controlled at 180kPa, the extractant (stream 5) and the extractive distillation tower feed (stream 1) are cooled to 40°C through a cooler after heat exchange. The cooling liquid is divided into two parts, one part ( Stream 6) is mixed with the oil layer of the phase separator at the top of the extractive distillation tower as a reflux, and a part (stream 7) enters the water washing tower; the weight ratio of stream 6 to stream 7 is 420:1.

[0052] The water layer of the phase separator (stream 9) is fed from the upper part of the water washing tower, and the recovered extractant (stream 7) is fed from the lower part. Liquid-liquid extraction is used to recover propylene oxide and extractant in the water phase, and the oil layer at the top of the water washing tower (Stream 11) mainly contains propylene oxide and extractant, which is recycled into the phase separator D-101 of the extractive distillation tower. The water layer of the bottom of the washing tower (stream 10) mainly contains water, acetaldehyde, methanol, and methyl formate as wastewater. Processing, the composition of logistics 9 and logistics 10 are shown in Table 6.

[0053] Table 6

[0054]

[0055] It can be seen from Table 6 that after liquid-liquid extraction, the propylene oxide content in the wastewater is reduced by 86.5%, and the extractant content is reduced by 93.75%.

[0056] From the top of the solvent recovery tower, a polymerization grade propylene oxide product (stream 4) with a purity of more than 99.99wt% is obtained. The composition of the propylene oxide product is shown in Table 7, and the recovery rate of propylene oxide is 99.75%.

[0057] Table 7

[0058] composition Content, wt Propylene oxide 0.9999 water 2 ppm Aldehyde (calculated as propionaldehyde) 2 ppm Methanol 2 ppm Methyl formate 3 ppm

Example Embodiment

[0059] [Example 2]

[0060] The crude propylene oxide solution (stream 1) and the solvent recovery tower kettle liquid (stream 3) exchange heat to 70°C and enter the extractive distillation tower T-101. The extractive distillation tower uses n-heptane as the extractant. The flow rate ratio of reagent stream 6 to crude propylene oxide solution feed 1) is 5:1, and medium-pressure steam (stream 12) is sprayed into the gas phase at the top of the tower. After condensation, the oil-water separation operation is carried out in the top phase separator D-101 , There are multiple baffles in the phase separator, the separated oil layer (stream 8) and the recovered extractant (stream 6) are mixed as the reflux of the extractive distillation column (stream 13), and the separated water layer (stream 9) enters the water washing Column T-103, T101 column has 75 theoretical plates, operating pressure is controlled at 200kPa, tower bottom temperature is 95°C, and the composition of crude propylene oxide solution is shown in Table 8.

[0061] Table 8

[0062] composition Content, wt water 0.008 Acetaldehyde 0.001 Methanol 0.001 Methyl formate 0.001 Propylene oxide 0.989

[0063] The still liquid of the extractive distillation tower (stream 3) mainly contains propylene oxide and extractant, enters the solvent recovery tower T-102, the top of the tower is separated to obtain the propylene oxide product (stream 4), and the tower kettle is recovered to obtain the extractant (stream 5). The number of theoretical plates of T102 tower is 30, the operating pressure is controlled at 180kPa, the extractant (stream 5) and the extractive distillation tower feed (stream 1) are cooled to 40°C through a cooler after heat exchange. The cooling liquid is divided into two parts, one part ( Stream 6) is mixed with the oil layer of the phase separator at the top of the extractive distillation tower as a reflux, and a part (stream 7) enters the water washing tower; the weight ratio of stream 6 to stream 7 is 495:1.

[0064] The water layer of the phase separator (stream 9) is fed from the upper part of the water washing tower, and the recovered extractant (stream 7) is fed from the lower part. Liquid-liquid extraction is used to recover propylene oxide and extractant in the water phase, and the oil layer at the top of the water washing tower (Stream 11) mainly contains propylene oxide and extractant, which is recycled into the phase separator D-101 of the extractive distillation tower. The water layer of the bottom of the washing tower (stream 10) mainly contains water, acetaldehyde, methanol, and methyl formate as wastewater. Processing, the composition of logistics 9 and logistics 10 are shown in Table 9.

[0065]

[0066] Table 9

[0067]

[0068] It can be seen from Table 9 that after liquid-liquid extraction, the propylene oxide content in the wastewater is reduced by 93.2%, and the extractant content is reduced by 96.6%.

[0069] From the top of the solvent recovery tower, a polymerization grade propylene oxide product (stream 4) with a purity of more than 99.99wt% is obtained. The composition of the propylene oxide product is shown in Table 10, and the recovery rate of propylene oxide is 99.70%.

[0070] Table 10

[0071] composition Content, wt Propylene oxide 0.9999 water 1 ppm Aldehyde (calculated as propionaldehyde) 1 ppm Methanol 1 ppm Methyl formate 2 ppm

[0072] It can be seen from the above that the implementation of the present invention can separate and obtain qualified polymer grade propylene oxide products in an economical and convenient way.

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the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine

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