Project of periodic rectification plant for separation of binary mixture of formic acid - acetic acid

Contents

CONTENTS

INTRODUCTION

1 Literary overview

1.1Rectification Process Severity

1.2 Classification of rectification plants by periodicity

1.3 Classification of rectifiers by internal device

1.3.1 Cap Fractionation Columns

1.3.2 Packing Distillation Columns

1.3.3 Tray Distillation Columns

1.5 Types of rectifier tray devices

1.6 Output

2 Physicochemical properties of substances involved in the rectification process

2.1 Physicochemical properties of formic acid

2.2 Physical and chemical properties of acetic acid

3 Physicochemical bases of rectification process

4 Main and auxiliary equipment design and operation principle

5 Description of the process diagram

6 Design part

6.1 Material balance of distillation column

6.2 Thermal calculation of rectification column

6.3 Rectification Column Design

6.4 Mechanical calculation of rectification column

6.5 Selection of auxiliary equipment

7 Occupational safety

8 Environmental protection

Conclusion

List of sources

APPROVED

At the meeting of the Department "Biochemistry, Agribusiness and Ecology"

Protocol No. 1 of 28 August 2014

Director of the Department of __________________ Proskurin L. I.

Task

for course design

by discipline Basis of design and equipment of enterprises

to student Tanabaev Oral Sarsenbaevich

KHTOV402 groups

Task topic: Project of periodic rectification plant for separation of binary mixture of formic acid - acetic acid

Input: Capacity F = 18500 kg; Duration of the operation _ a = 3 hours; The content of the volatile component in the mixture is xf = 40% (mol); Component content in distillate chr = 85% (mol); Component content in the bottom residue xw = 5% (mol).

When performing a course project on the specified topic, the following shall be presented:

1. Explanatory Note

contains the following sections:

Introduction

1 Literary overview

2 Physicochemical properties of substances involved in the process

3 Physical and chemical foundations of the process

4 Main and auxiliary equipment design and operation principle

5 Description of the process diagram

6 Design part

6.1 Material Balance

6.2 Heat Balance

6.3 Structural calculation of the main unit

6.4 Mechanical calculation of the main unit

6.5 Selection of auxiliary equipment

7 Occupational safety

8 Environmental protection

Conclusion

List of sources used

2. Graphic part.

1 The technological scheme - 1 sheet A1;

2 A device general view - 1 sheet A1.

Date of assignment issue September 3, 2014

Deadline for assignment delivery on December 10, 2014

Head of course design: senior lecturer PariychukO.

______________________ signature date "___" ___________________ 2014

Introduction

Rectification is a process of multiple evaporation and condensation, during which the initial mixture is divided into two or more components, and the vapor phase is saturated with a low-volatile (low-boiling) component, and the liquid part of the mixture is saturated with a heavy-volatile (high-boiling) component.

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. Rectification is currently being applied worldwide in a wide variety of chemical technologies, where the release of pure components is very important. These include: organic synthesis, the production of isotopes, polymers, semiconductors and various other substances of high purity.

The field of application of rectification in industry is expanding every year, and this method can today be considered as one of the most economical methods of separating liquid solutions.

Rectification is used to purify not only liquid preparations. The use of rectification to separate liquefied gases (oxygen, nitrogen, inert gases, etc.) is well known.

In recent years, many solids that evaporate relatively easily have been purified by rectification. Successfully purified aluminum chloride from iron, sulfur from selenium.

The relevance of the course project is that rectification plants are widely used in industry to obtain substances of high purity, to separate all or partially soluble mixtures in each other.

The purpose of this project is to design a periodic rectification plant to separate the liquid mixture formic acid-acetic acid.

The objectives of the course project are:

- to consider the existing rectification methods, design of rectification columns;

- to consider physicochemical bases of rectification process;

- to consider physicochemical properties of substances involved in the process;

- develop a process diagram of the rectification process;

- calculate the material and thermal balance of the distillation column;

- perform structural and mechanical calculation of rectification column;

- consider environmental and safety measures.

Literary review

Essence of rectification process

Currently, distillation and rectification are widespread in chemical technology and are used to obtain a variety of products in pure form, as well as to separate gas mixtures after their liquefaction.

Distillation is usually used to separate the mixture of liquids. The distillation separation is based on different boiling points of the individual substances in the mixture. Thus, if the mixture consists of two components, the lower boiling component (low boiling component) is vaporized during evaporation and the higher boiling component (high boiling component) remains in the liquid state. The resulting vapors condense to form a so-called distillate, and the unspoiled liquid is called a residue. Thus, as a result of distillation, the low boiling component is transferred to distillate and the high boiling component to residue.

The described process, called simple distillation, does not allow the complete separation of the components of the mixture to be obtained in pure form. Both components are volatile and therefore both go into pairs, albeit to varying degrees. Therefore, the vapors formed in the distillation are not a pure low boiling component, since it evaporates more than the high boiling component due to its greater volatility, the vapors are enriched with the low boiling component compared to its content in the initial mixture. Thus, in the distillate, the content of the low boiling component is higher than in the starting mixture, and in the residue, on the contrary, the content of the low boiling component is lower than in the starting mixture.

To achieve the most complete separation of components, a more complex type of distillation is used - rectification. Rectification consists in countercurrent interaction of vapors formed during distillation with liquid obtained during condensation of vapors [4 ].

In other words, rectification can be interpreted as a combination of multiple distillation and multiple partial condensation processes with countercurrent contact of vapor and liquid streams. In such a distillation process, it is possible to use the vapor condensation heat to evaporate the liquid in each said operation by directly contacting the condensing vapor and boiling liquid phases.

In the process of rectification, the heat supplied from outside is spent only in the reboiler - at the bottom of the column once to partially evaporate the liquid mixture to obtain the initial steam flow in the heating device in the lower part of the rectification apparatus. Heat of vapour condensation is also removed only in condensing device - in upper part of rectifier [12].

Various mixtures of substances are subjected to rectification. Depending on the mutual solubility of the components, the following types of double mixtures are distinguished:

Mixtures of mutually soluble liquids, that is, such liquids that are soluble in each other in any relation. These mixtures, in turn, are divided into three groups:

a) mixtures of liquids in which the coupling forces between the molecules of both components are the same as between the molecules of each of the components (ideal mixtures);

b) mixtures with positive deviations from Raoul's law, in which the adhesion forces between molecules of low-boiling and high-boiling components are less than between molecules of each of the components;

c) mixtures with negative deviations from Raoul's law, in which the adhesion forces between molecules of low-boiling and high-boiling components are greater than between molecules of each of the components.

Mixtures of liquids insoluble in each other.

Mixtures of partially soluble liquids [4].

Rectification is carried out in column-type apparatus - rectification columns.

The diffusion process of liquid separation by rectification is possible provided that the boiling points of the liquids are different. To perform diffusion, vapors and liquids must contact each other as best as possible, moving in the distillation column towards each other: liquid under its own weight from top to bottom, vapors from bottom to top.

From the properties of the equilibrium system, it is known that when non-equilibrium steam and liquid phases are contacted, the system tends to an equilibrium state as a result of mass exchange and heat exchange between these phases. Therefore, in order for the rectification to proceed, it is necessary that the contacting liquid and vapors at the same pressure are not equilibrium. In other words, it is necessary that the temperature of the liquid be lower than the vapor temperature.

To ensure effective phase contact, the distillation columns are provided with internal devices. Depending on the design of these devices, continuous (in packing columns) and stepped (in poppet columns) phase contact [3] is carried out.

Classification of rectifiers by internal device

Distillation columns differ mainly in the design of an internal device for distributing liquid and steam phases. Interaction of liquid and steam is carried out in columns by bubbling steam through a layer of liquid on trays or by surface contact of steam and liquid on a nozzle or on the surface of liquid flowing with a thin film [2].

Rectifiers use three main types of columns:

1) cap

2) mesh

3) nozzle

Rectifier designs have also been developed in which the separation process is intensified by centrifugal force (centrifugal rectifiers).

Types of rectifier tray devices

According to the shape and design of the devices providing dispersion and distribution of steam in the column, the trays are divided into:

Cap;

Bandless;

Valve;

Tubular.

Conclusion

In this course project, a poppet column is used as standard equipment for the designed distillation plant to separate the binary mixture of formic acid - acetic acid, since it minimizes gas slipping due to the formation of large bubbles and channels. At the same time, thermal conditions can be controlled quite clearly by installing heat exchangers on trays. In addition, the poppet column meets the general requirements: cost, high intensity. The use of sieve trays compared to others is that they provide a better interaction of steam with liquid than on trays with caps. Also, the advantages of sieve trays are the simplicity of the device, the high efficiency and the speed of emptying from the liquid in case of an emergency.

Conclusion

In the course design, a rectification plant of continuous action of the poppet type was calculated to separate the binary mixture of formic acid - acetic acid.

The literature review considers the types of distillation columns and process flow charts. It was concluded that for the designed distillation plant, a poppet column is used to separate the binary mixture of formic acid - acetic acid, since it minimizes gas slipping due to the formation of large bubbles and channels. The advantages of using sieve trays are to ensure a better interaction of steam with liquid than on trays with hoods, simplicity of the device, high efficiency and speed of emptying from liquid in case of an emergency

In the technological part of the course design, the characteristics of the raw materials and the finished product, the physicochemical properties of the substances involved in the rectification process and the physicochemical foundations of the rectification process are considered, a process diagram of the rectification process has been developed.

The following types of works were performed in the calculation part: calculation of material balance of the rectification column, calculation of thermal balance of the rectification column, structural calculation of the rectification column, mechanical calculation of the rectification column.

Also, in the sections "Labor Protection" and "Environmental Protection," a number of measures were considered for environmental protection and basic safety rules for the operation and maintenance of rectification plants.

Thus, the goal set in the course project has been achieved.