Rectification Column Description

Contents

Introduction

Diagram Description

Process calculation

Hydraulic calculation

Constructive calculation

Mechanical calculation

Safety precautions

Conclusion

List of used literature

Introduction

In chemical technology, mass transfer processes characterized by the transition of one or more substances from one phase to another are widespread and important. By transferring one or more components from phase to phase, both heterogeneous and homogeneous systems (gas mixtures, liquid solutions, etc.) can be separated, and most often mass transfer processes are used to separate homogeneous systems.

One of the most common methods for separating liquid homogeneous mixtures consisting of two or more components is distillation (distillation and rectification).

Simple distillation is a process of flash evaporation of a liquid mixture and condensation of the resulting vapors. Simple distillation is only applicable to the separation of mixtures whose volatility varies considerably.

A much more complete separation of liquid mixtures into components is achieved by rectification.

Rectification is a process of multiple partial liquid evaporation and vapor condensation. The process is carried out by contacting streams of steam and liquid at different temperatures, and is usually carried out in column apparatuses.

Rectification has been known since the beginning of the 19th century as one of the most important technological processes mainly in the alcohol and oil industries. Currently, rectification is increasingly used in a wide variety of fields of chemical technology, where the isolation of components in pure form is very important (in the production of organic synthesis, isotopes, polymers, etc.).

Distillation processes are carried out periodically or continuously.

The rectification process takes place at the phase interface, so the devices must provide a developed contact surface between liquid and gas .

According to the method of forming this surface, rectifiers can be conditionally divided into the following groups: 1) surface and film; 2) nozzle; 3) bubbling (poppet); 4) spraying.

Plate distillation columns have been widely used in industry. Currently, a variety of tray designs are used. By the method of draining liquid from the tray, they can be divided: 1) trays with drain devices; 2) trays without drain devices.

Trays with drain devices include: sieve, cap, valve and ballast, plate.

In a tray without drains, gas and liquid pass through the same holes or slots. On the tray, simultaneously with the interaction of liquid and gas by bubbling, part of the liquid flows to the lower tray - the "failure" of the liquid. Therefore, plates of this type are usually called failure. These include hole, lattice, tubular and wavy plates.

The choice of the particular type of tray depends on many factors, for example, the hydraulic resistance of the tray, the range of stable operation, efficiency, liquid and gas capacity, etc.

As contact devices, nozzles are also used, which can be divided into regular and irregular ones. The irregular nozzle is used in mass exchange processes under pressure or under shallow vacuum conditions and has significant advantages over the regular production, transportation and installation technology. This type of nozzle includes: Rashig rings, Palya rings, saddle rings, etc.

Sieve trays have low resistance, high efficiency and intensity, require low metal consumption and ease of installation.

Cap trays have a fairly large area of ​ ​ work, great efficiency and ensure the ease of starting and stopping the device.

Valve trays have a large area of ​ ​ stable operation, a small splash, require a small distance between the trays, and have a high intensity and efficiency.

The initial mixture is supplied to the storage tank E1, which is necessary for uniform power supply of the rectification column of RK. By pump H1, the mixture is supplied to the feed tray in RK, passing through heat exchanger - preheater P. In the preheater of the initial mixture, the mixture is heated to boiling temperature, due to the supply of heating steam to the tube space. The initial mixture entering the boiler at boiling temperature flows down the trays to the lower part of the column. At each stage (tray), liquid flowing down and vapors rising up the column interact, while a high-boiling component (HC) condenses from the vapors, and a low-boiling component (HC) evaporates from the liquid. As a result of this interaction, almost pure NC leaves the top of the column at each stage, and VK is removed from the bottom of the column. The vapors in the cube are obtained by evaporating the bottom liquid in the heat exchanger - reboiler K. The vapors withdrawn from the upper part of the column are sent to the heat exchanger - condenser D. Due to the supply of cooling water to the pipe space, the vapors are condensed and withdrawn from the apparatus at the condensation temperature. Further, the condensate stream is divided into two parts: reflux and distillate. Reflux refers to part of the condensate returning to the top of the column for irrigation. Distillate is a finished product (target), which is first cooled in a heat exchanger - refrigerator X2, and then supplied to a storage tank E3. Distillate is pumped by H4 pump to consumer. The bottom residue (VC) is removed from the cube and sent to the heat exchanger-cooler X1, after which it is accumulated in the tank E2, from where it is pumped by the pump H3 to the consumer.

The rectification plant is a complex controlled facility, so it includes a large number of instruments and automation, a warning and alarm system, as well as interlocks.

Conclusion

According to the task, the plate distillation column was calculated and designed. The plate is sieve, which has the following advantages: high efficiency, a large area of ​ ​ sustainable work, work on contaminated media. The diameter of the column is 1200mm, the number of trays is 14 pcs in total, the height of the poppet part of the column is 9.5 m.

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