Method for preparing ethylene through ethanol dehydration

Abstract

The invention relates to a method for preparing ethylene through ethanol dehydration, and mainly solves the problems that the loss of ethanol and the chemical oxygen demand (COD) value of wastewater are high in a production process flow for preparing the ethylene through ethanol dehydration in the prior art. The problems are better solved by adopting the technical scheme that the method for preparing the ethylene through ethanol dehydration comprises the following steps that: an ethanol raw material with the weight content of between 5 and 99.99 percent at the temperature of between 25 and 100 DEG C enters the upper part of a gas stripping column, recovered ethanol with the weight content of between 1 and 10 percent enters the middle part of the gas stripping column, the vaporization separation is realized in the gas stripping column, pure ethanol steam which is obtained from the top of the gas stripping column enters an ethanol dehydration reaction system, and kettle liquid in the gas stripping column is continuously discharged out of the system. The method can be used for the industrial production of the ethylene through ethanol dehydration.

Description

technical field

[0001] The invention relates to a method for the process of producing ethylene by ethanol dehydration. Background technique

[0002] Ethylene is a very important petrochemical raw material, and its bulk downstream products mainly include polyethylene, ethylene oxide, ethylene glycol, polyvinyl chloride, styrene, vinyl acetate, etc.

[0003] The production process of the existing ethanol catalytic dehydration ethylene production process (Gu Zhihua, the current situation and prospect of ethanol ethylene technology [J] Chemical Progress, 2006, 25 (8): 847-851) is: the raw material ethanol passes through the preheater, After the evaporator is heated, it is completely vaporized and sent to the ethanol dehydration reaction system for reaction. The reaction products (including reaction products ethylene, water, unreacted ethanol, etc.) from the dehydration reaction system are sent to water washing, water alkali washing, etc. to remove impurities, and then compressed...

Examples

Embodiment 1

[0017] use figure 1 In the process flow shown, the stripping column is a plate column with a theoretical plate number of 50 and an operating pressure of 0.6MPa(G). Raw material ethanol 2350kg / h, wherein ethanol 1997.5kg / h, water 352.5kg / h, ethanol content 85% (wt%). Raw ethanol is fed from the top of the stripping tower. Ethanol 66.08kg / h, water 1932kg / h in the recovered mixed solution, the feeding position is at the 8th theoretical plate from the top of the stripping tower. The steam discharged from the top of the stripping tower is sent to the dehydration reaction system, wherein the ethanol content is 93.8% (wt%). The ethanol in the water discharged from the bottom of the stripping tower contains 0.05% (wt%), and the COD value in the waste water can be less than 300ppm.

Embodiment 2

[0019] use figure 1 In the process flow shown, the stripping tower is a plate tower with a theoretical plate number of 30 and an operating gauge pressure of 0.9 MPaG. Raw material ethanol 2350kg / h, wherein ethanol 2210kg / h, water 140kg / h, ethanol content 94% (wt%). Raw ethanol is fed from the top of the stripping tower. In the recovered mixed solution, ethanol is 76.25kg / h, water is 1725kg / h, and the feeding position is at the 21st theoretical plate from the top of the stripping tower. The ethanol vapor discharged from the top of the stripping tower is sent to the dehydration reaction system, wherein the ethanol content is 98% (wt%). The ethanol content in the water discharged from the bottom of the stripping tower is 0.1% (wt%), and the COD value in the waste water is less than 500ppm.

Embodiment 3

[0021] use figure 1 In the process flow shown, the stripping tower is a plate tower with a theoretical plate number of 10 and an operating gauge pressure of 4MPaG. Raw material ethanol 2350kg / h, wherein ethanol 1739kg / h, water 611kg / h, ethanol content 74% (wt%). Raw ethanol is fed from the top of the stripping tower. In the recovered mixed solution, ethanol is 46.25kg / h, water is 1725kg / h, and the feeding position is at the 21st theoretical plate from the top of the stripping tower. The ethanol vapor discharged from the top of the stripping tower is sent to the dehydration reaction system, wherein the ethanol content is 90% (wt%). The ethanol content in the water discharged from the bottom of the stripping tower is 0.08% (wt%), and the COD value in the waste water is less than 400ppm.

technical field

[0001] The invention relates to a method for the process of producing ethylene by ethanol dehydration. Background technique

[0002] Ethylene is a very important petrochemical raw material, and its bulk downstream products mainly include polyethylene, ethylene oxide, ethylene glycol, polyvinyl chloride, styrene, vinyl acetate, etc.

[0003] The production process of the existing ethanol catalytic dehydration ethylene production process (Gu Zhihua, the current situation and prospect of ethanol ethylene technology [J] Chemical Progress, 2006, 25 (8): 847-851) is: the raw material ethanol passes through the preheater, After the evaporator is heated, it is completely vaporized and sent to the ethanol dehydration reaction system for reaction. The reaction products (including reaction products ethylene, water, unreacted ethanol, etc.) from the dehydration reaction system are sent to water washing, water alkali washing, etc. to remove impurities, and then compressed...

Examples

Embodiment 1

[0017] use figure 1 In the process flow shown, the stripping column is a plate column with a theoretical plate number of 50 and an operating pressure of 0.6MPa(G). Raw material ethanol 2350kg / h, wherein ethanol 1997.5kg / h, water 352.5kg / h, ethanol content 85% (wt%). Raw ethanol is fed from the top of the stripping tower. Ethanol 66.08kg / h, water 1932kg / h in the recovered mixed solution, the feeding position is at the 8th theoretical plate from the top of the stripping tower. The steam discharged from the top of the stripping tower is sent to the dehydration reaction system, wherein the ethanol content is 93.8% (wt%). The ethanol in the water discharged from the bottom of the stripping tower contains 0.05% (wt%), and the COD value in the waste water can be less than 300ppm.

Embodiment 2

[0019] use figure 1 In the process flow shown, the stripping tower is a plate tower with a theoretical plate number of 30 and an operating gauge pressure of 0.9 MPaG. Raw material ethanol 2350kg / h, wherein ethanol 2210kg / h, water 140kg / h, ethanol content 94% (wt%). Raw ethanol is fed from the top of the stripping tower. In the recovered mixed solution, ethanol is 76.25kg / h, water is 1725kg / h, and the feeding position is at the 21st theoretical plate from the top of the stripping tower. The ethanol vapor discharged from the top of the stripping tower is sent to the dehydration reaction system, wherein the ethanol content is 98% (wt%). The ethanol content in the water discharged from the bottom of the stripping tower is 0.1% (wt%), and the COD value in the waste water is less than 500ppm.

Embodiment 3

[0021] use figure 1 In the process flow shown, the stripping tower is a plate tower with a theoretical plate number of 10 and an operating gauge pressure of 4MPaG. Raw material ethanol 2350kg / h, wherein ethanol 1739kg / h, water 611kg / h, ethanol content 74% (wt%). Raw ethanol is fed from the top of the stripping tower. In the recovered mixed solution, ethanol is 46.25kg / h, water is 1725kg / h, and the feeding position is at the 21st theoretical plate from the top of the stripping tower. The ethanol vapor discharged from the top of the stripping tower is sent to the dehydration reaction system, wherein the ethanol content is 90% (wt%). The ethanol content in the water discharged from the bottom of the stripping tower is 0.08% (wt%), and the COD value in the waste water is less than 400ppm.

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