Rectification Column Project for Separation of Binary Methanol Water Mixture

Contents

Introduction

1 Material Settlement

1.1 List of permissible restrictions

1.2 Calculation of column capacity by feed mixture, distillate and bottoms

1.3 Calculation of the minimum reflux number

1.4 Construction of working lines at different values of reflux excess factor

1.5 Determination of working reflux number

1.6 Calculation of average liquid mass flow rate for upper and lower parts of the column

1.7 Calculation of average mass flow rate of steam for the upper and lower parts of the column

2 Process calculation

2.1 Steam velocity and column diameter

2.2 Column height

2.3 Hydraulic resistance of column trays

3 Thermal calculation

4 Structural and mechanical calculation

4.1 Calculation of connectors and flange

4.1.1 Connector for initial mixture injection

4.1.2 Nozzle for reflux injection

4.1.3 Nozzle for discharge of bottoms

4.1.4 Nozzle for distillate vapour discharge

4.1.5 Nozzle for inlet of bottoms mixture vapour

4.2 Calculation of shell thickness

4.3 Calculation of bottom and cover thickness

4.4 Approximate weight of the apparatus

5 Calculation of thermal insulation

Conclusion

List of sources used

Introduction

Rectification is a heat and mass exchange process used to separate liquid mixtures whose components differ in boiling points.

The process is carried out when contacting streams of steam and liquid, which have different compositions and temperatures: steam has a higher temperature than the liquid coming into contact with it.

As a result of this interaction, at a sufficiently long contact time, steam and liquid can reach an equilibrium state, i.e., the temperatures of the streams will become the same, with their compositions being bound by equilibrium equations. Such a flow interaction scheme is known as a "theoretical tray" or "theoretical contact stage."

Under real conditions, the equilibrium of the vapor and liquid streams leaving the contact zone may not be achieved, so that these streams will have different temperatures, and their compositions will be determined not only by equilibrium equations, but also by more complex dependencies.

The rectification process can be carried out in periodic and continuous schemes.

During periodic rectification, the mixture is divided into separate components (or fractions boiling in a certain temperature range) by sequentially selecting them at process operating parameters varying over time.

Rectification according to a continuous scheme makes it possible to simultaneously obtain two or more products under stationary process conditions.

Rectification process is carried out in rectification columns. To create a vapor flow, heat is supplied to the lower part of the column, and a liquid flow (reflux, reflux) is created by removing heat from the upper part of the column, condensing the corresponding amount of vapor.

The portion of the column serving to isolate low boiling point components (LC) is called concentration or strengthening, the other portion in which the high boiling point components (HC) are isolated is called exhaustive or stripping. Between these main parts of the column there is a raw material inlet (feed tray, feed section, evacuation space).

Structural and Mechanical Calculation

The task of structural and mechanical calculation is to determine the necessary geometric dimensions of individual parts and assemblies that determine the structure of the column, its mechanical strength and geometric dimensions.

Conclusion

In this course work, the rectification plant was calculated for the separation of the binary mixture methanol - water according to the given parameters of productivity, the content of the light boiling component in the initial mixture was determined :

• Type of TCB trays with a column diameter of 1600 mm;

• amount of distillate and bottoms;

• heat consumption for heating and evaporation of the mixture;

• main dimensions of the rectification unit, number of trays.

The insulation of the column was calculated, its thickness is 7 mm (sovelite was chosen as the insulation), and a hydraulic calculation of the column was also made.

Rectification column is installed on cylindrical support (type II as per ATK 24.200.0490).

The process is monitored by resistance thermometers and pressure gauges.