Separation system and method for preparing acetaldehyde product from ethanol

Abstract

The invention discloses a separation system for preparing acetaldehyde products from ethanol, which comprises a reactor and an ethanol absorption tower, the reactor is connected with the bottom side wall of the ethanol absorption tower, and the tower top of the ethanol absorption tower is sequentially connected with a compressor, a first cooler and a first gas-liquid separation tank; a tower bottom outlet of the ethanol absorption tower is connected with an acetaldehyde rectifying tower through a booster pump, the tower top of the acetaldehyde rectifying tower is sequentially connected with a second cooler, a second gas-liquid separation tank and a reflux pump, and the reflux pump is further connected with the side wall of the top of the acetaldehyde rectifying tower; the tower bottom of the acetaldehyde rectifying tower is respectively connected with the top side wall of the ethanol absorption tower and the inlet of the reactor; and the tower bottom of the acetaldehyde rectifying tower is also provided with an ethanol outlet. Meanwhile, the invention also discloses a method for preparing an acetaldehyde product by separating ethanol by using the system. By adding the ethanol absorption tower, the main product acetaldehyde, the by-product hydrogen and the unreacted ethanol can be efficiently separated, the separation precision is high, and the utilization efficiency of raw materials is high.

Description

technical field [0001] The invention belongs to the field of separation of acetaldehyde products from ethanol, and in particular relates to a separation system and method for acetaldehyde products from ethanol. Background technique [0002] Acetaldehyde is an important organic chemical intermediate and is a direct derivative of ethanol, which can be used to produce acetic acid, acetate, pentaerythritol, crotonaldehyde, trichloroacetaldehyde, glyoxal, vinyl acetate and pyridine compounds, etc. It has a wide range of uses in the fields of pesticides, medicine, food and feed additives. [0003] At present, the industrial production routes of acetaldehyde in the world mainly include the following: ethylene oxidation method, acetylene hydration method, and ethanol method. Among them, the ethanol method is further divided into ethanol oxidation method and ethanol catalytic dehydrogenation method. The ethanol oxidation method is that ethanol vapor is mixed with air on a silver wir...

AI Technical Summary

Problems solved by technology

However, due to the low pressure or even negative pressure of the reaction, when the reaction product gas is cooled to 40°C, it becomes a gas-liquid two-phase, and it is difficult to directly pressurize the gas-liquid two-phase, so a rectification tower directly connected to the reaction product is also under negative pressure. Or low pressure, which leads to a very low temperature at the top of the first rectification tower, reaching about -20°C, which requires adding a chilled water system, and consumes a lot of cooling capacity

In addition, the top products separated by the first rectification tower are mainly acetaldehyde and hydrogen. Since acetaldehyde has a relatively low boiling point, which is 20.8°C under normal pressure, the separation of acetaldehyde and hydrogen is relatively difficult. It is necessary to use an absorption process (such as water as an absorbent) to absorb the acetaldehyde in it, and then carry out rectification to obtain the acetaldehyde product. The process is relatively complicated

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