The following is the process analysis of distillation tower, extraction distillation, and reactive distillation:

        1. Distillation Tower Process

        The distillation tower is the main equipment for implementing distillation operations, and its process mainly includes the following aspects:

        1. Operating principle:

        Distillation is a distillation method that uses reflux to achieve high-purity separation of liquid mixtures.

        The heat source of the distillation tower is controlled by controlling the heating amount of the tower kettle, the cold source at the top of the tower is controlled by controlling the reflux temperature and reflux rate, and the quality of the product is controlled by the corresponding relationship between temperature and pressure composition.

        2. Tower structure:

        The distillation tower consists of a tower body, a tray, a condenser at the top of the tower, and a reboiler at the bottom of the tower.

        The tray is the core part of the distillation tower, used to achieve contact and mass transfer between gas and liquid phases.

        3. Process flow:

        After preheating, the raw material liquid is sent into the distillation tower, where it merges with the reflux liquid descending from the upper part of the tower on the feed plate, overflows plate by plate, and finally flows into the bottom reboiler of the tower.

        On each layer, the reflux liquid comes into contact with the rising vapor to carry out the process of heat and mass transfer.

        The vapor at the top of the tower enters the condenser and is completely condensed. Some of the condensed liquid is sent back to the top of the tower as reflux liquid, while the rest is sent out as the top product (distillate) after being cooled.

        The liquid at the bottom of the tower vaporizes, producing rising vapor that passes through each layer of tray in sequence, and is finally taken out as the bottom product (kettle liquid).

        2、 Extraction Distillation Process

        Extraction distillation is a special distillation method mainly used to separate solutions with little difference in boiling point (volatility) of each component. The process characteristics are as follows:

        1. Principle:

        Add a third component (called an extractant or solvent) to the raw material liquid to change the relative volatility between the original components and achieve separation. The extractant does not form an azeotrope with any component in the raw material liquid, and its boiling point is higher than that of each component in the raw material liquid.

        two Process flow:

        The raw materials and extraction solvents are added to the tower in a certain proportion, and there exists an optimal reflux ratio.

        The solvent inlet is located above the raw material inlet to maintain a high solvent concentration on most of the trays in the tower.

        After the solvent and heavy components are extracted from the bottom of the tower, they are sent to the solvent recovery unit. Generally, the heavy components are distilled from the solvent using a distillation tower and sent back to the extraction distillation tower for recycling.

        3. Application Example:

        When separating butadiene from the C4 fraction of hydrocarbon cracking gas, the extraction distillation method is used. Acetonitrile is added as an extractant to the C4 fraction, which can increase the relative volatility between components and enable the separation of butadiene, butane, and butene with similar boiling points by distillation.

        3、 Reactive Distillation Process

        Reactive distillation is the process of separating the product by distillation while carrying out a reaction. The process characteristics are as follows:

        one Principle:

        Distillation methods accompanied by chemical reactions, some use distillation to promote reactions, while others use reactions to promote distillation.

        By continuously removing the products of the reaction through distillation, the conversion rate and yield of the reaction can be improved.

        two Process flow:

        Send the reactants into the distillation tower for chemical reactions and distillation operations.

        The products or intermediate products generated by the reaction are promptly separated by distillation method.

        The separated product can be extracted as either the top or bottom product.

        three Application Example:

        Esterification reaction is a reversible reaction. When this reaction is carried out in a distillation tower, chemical reaction is carried out while distillation is carried out, and the resulting esters and water are separated in a timely manner. This can keep the reaction moving towards esterification, improving the selectivity and conversion rate of the reaction.

        Distillation tower, extraction distillation, and reactive distillation are all important chemical separation technologies, each with its own characteristics in terms of principles, process flow, and applications. In practical applications, it is necessary to select appropriate separation methods based on specific separation requirements and process conditions.