Absorption (Chemical)

Description

ABSTRACT

Chemical absorption is one of the most effective methods for CO₂ separation. This chapter first explains the principle of chemical absorption. Chemical Absorption, a Preferred Option for Post-combustion Capture. Absorption methods of separation, whether chemical or physical, are broadly used in the oil and gas and chemical industries for removal of CO₂ from gas streams. Chemical absorption involves reactions between the absorbing component and the absorbed substance. Chemical absorption method takes advantage of the chemical reaction between absorbed substance (CO₂) and solvent to form a rich liquid, and then the rich liquid enters the desorption tower to heat and decompose CO₂.

TABLE OF CONTENT

TITLE PAGE

APPROVAL PAGE

DEDICATION

ACKNOWLEDGEMENT

ABSTRACT.

TABLE OF CONTENT

CHAPTER ONE

INTRODUCTION

• BACKGROUND OF THE STUDY
• OBJECTIVE OF THE STUDY
• SIGNIFICANCE OF THE STUDY
• SCOPE OF THE STUDY

CHAPTER TWO

REVIEW OF RELATED LITERATURE

• CHEMICAL ABSORPTION
• TYPES OF ABSORPTION
• DIFFERENCE BETWEEN ABSORPTION AND ADSORPTION

CHAPTER THREE

• GAS ABSORPTION
• CONCLUSION

REFERENCES

CHAPTER ONE

1.0                                       INTRODUCTION

1.1                         BACKGROUND OF THE STUDY

In chemistry, absorption is a process by which a substance incorporated in one state is transferred into another substance of a different state (e.g., gases being absorbed by a liquid or liquids being absorbed by a solid). As an industrial process, the most commonly encountered use of absorption is for the separation and/or purification of a gas mixture by the absorption of part of the mixture in a solvent.

Separations of solids, liquids and gases are required in nearly all chemical and biochemical processes. These processes often involve mass transfer between two phases, so that some components from a rich stream are selectively transferred into a lean mass separating agent (MSA). Rich streams are typically process or effluent streams that contain valuable materials or undesirable components. The MSAs, are streams employed to carry out the separation (e.g., solvents, stripping agents, adsorbents, ion exchange resins, etc.) The MSAs are used for different purposes, such as: feed preparation, product separation, product finishing, and recovery of valuable materials. Separation processes depend primarily upon differences in physical properties, which lead to different interphase mass transfer rates for the components of the mixture. Lately, industry has expressed increasing interest in separation processes involving chemical reactions, in which the reaction is used as a separation tool or the chemical reaction and physical separation are coupled in a single unit operation.

Mass transfer operations involving the diffusion of the component to be separated through a stationary phase (unidirectional mass transfer) include: gas absorption, liquid extraction, adsorption, and ion exchange. Distillation is a typical process in which the rates of mass transfer of the more and the less volatile components between phases are equal in magnitude, but opposite in direction (equimolar mass transfer). The design equations will depend on the mass transfer mechanism, and it may be expected that similar expressions will be obtained for processes such as gas absorption and liquid- liquid extraction, where unidirectional mass transfer takes place.

The two key design and operating parameters in separation processes are efficiency, which indicates how well components are separated, and capacity, which is related to the hydrodynamics of the contacting device and the overall rate at which the desired material can be processed without loss of efficiency. Column height is determined by the efficiency of the separation process, while the diameter of the column is governed by the required capacity. Phase equilibria, mass balances and design parameters are required for the reliable design of a separation process and these topics will be considered briefly.

Progress in separation processes will contribute to waste minimization by reduction and recycle of waste components, and by decreasing the energy consumption of the chemical process per unit of product. Innovations in separation processes (e.g., mass exchange networks, reactive separation processes, hybrid separations using membranes, etc.) are needed for more efficient utilization of resources. Such utilization will contribute to the ability of the chemical and biochemical industries to sustainable development.

1.2                                   AIM OF THE STUDY

The of main aim chemical absorption is for gas purification, eg, removal of air pollutants from exhaust gases; product recovery; or production of solutions of gases for various purposes. Chemical absorption is one of the most effective methods for CO₂ separation. The objectives are:

1. To give details about absorption process and clarify the differences between absorption and adsorption process.
2. To explain the process of gas absorption and the importance terms involved in it.
3. To show the importance of the operation and its application in everyday life.

1.3                               SCOPE OF THE STUDY

The scope of this seminar is on absorption. Absorption, or gas absorption, is a unit operation used in the chemical industry to separate gases by washing or scrubbing a gas mixture with a suitable liquid. One or more of the constituents of the gas mixture dissolves or is absorbed in the liquid and can thus be removed from the mixture. In some systems, this gaseous constituent forms a physical solution with the liquid or the solvent, and in other cases, it reacts with the liquid chemically.

1.4                       SIGNIFICANCE OF THE STUDY

This study will be of great benefit both to the researcher and readers of the work in that it will help them to understand the importance of absorption in chemical industries and how absorption process is been carried out.