Gas Treating

Absorption Theory and Practice

Dag Eimer

• Publisher: Wiley
• Year: 2014
• Print ISBN: 9781118877739
• eBook ISBN: 9781118877623
• Edition: 1
• Topic: Physical Sciences
• Subtopic: Energy

Gas Treating: Absorption Theory and Practice provides an introduction to the treatment of natural gas, synthesis gas and flue gas, addressing why it is necessary and the challenges involved. The book concentrates in particular on the absorption–desorption process and mass transfer coupled with chemical reaction.

Following a general introduction to gas treatment, the chemistry of CO2, H2S and amine systems is described, and selected topics from physical chemistry with relevance to gas treating are presented. Thereafter the absorption process is discussed in detail, column hardware is explained and the traditional mass transfer model mechanisms are presented together with mass transfer correlations. This is followed by the central point of the text in which mass transfer is combined with chemical reaction, highlighting the associated possibilities and problems. Experimental techniques, data analysis and modelling are covered, and the book concludes with a discussion on various process elements which are important in the absorption–desorption process, but are often neglected in its treatment. These include heat exchange, solution management, process flowsheet variations, choice of materials and degradation of absorbents. The text is rounded off with an overview of the current state of research in this field and a discussion of real-world applications.

This book is a practical introduction to gas treating for practicing process engineers and chemical engineers working on purification technologies and gas treatment, in particular, those working on CO2 abatement processes, as well as post-graduate students in process engineering, chemical engineering and chemistry.

Chapter 1
Introduction

Gas treating is featured in many process plants in many contexts. There are almost always unwanted components that need to be removed from a gas stream. These components may need to be removed for a number of reasons like:

• Contamination of product
• Catalyst poison
• Reaction by-product
• Corrosion
• Dew point, unwanted condensation downstream
• Environmental considerations.

The challenges are many, and they occur when dealing with natural gas, synthesis gas, air and latterly, the challenge associated with CO₂ abatement. Different settings, seemingly different challenges, but for the chemical engineer there is a common denominator as shall become clear by the end of this book.

No matter what the application is, and no matter what the treatment needs are, cost effective solutions are always targeted. Having said that, it must be remembered that operational costs and any lost production are also factors included in this equation. There is always competition and the operator with the best profit margin will be better off in the longer term.

1.1 Definitions

Natural gas is the gas produced from hydrocarbon reservoirs. Some fields are gas fields producing nothing but natural gas, but natural gas is also produced as so-called associated gas where the gas comes from the reservoir along with the oil. The composition of natural gas varies, but is dominated by the presence of methane. It may be contaminated by CO₂ and H₂S, and there may be more or less of ethane and heavier hydrocarbons.

Most natural gas is transported to its point of use by pipeline, but there are markets that are too far away from the natural gas source. Japan is a case, and is served by liquefied natural gas, LNG, that is shipped in on gas tankers. LNG is mostly methane, it is made to be liquid at atmospheric pressure and requires a temperature down towards 111 K. The low temperature requires that higher boiling components must be removed in order not to precipitate, and water, CO₂ and H₂S must naturally be removed in order not to freeze out in the condensation process and thus block the flow channels.

Natural gas liquids, or NGLs, is a term that is used to describe the hydrocarbon condensate separated from natural gas on cooling. It is essentially ethane and heavier. In the case of NGL there is no particular refinement of the product such that there can be a tail of heavier hydrocarbons. This is different from liquefied petroleum gas, LPG, which is a tailored product that is mainly ethane and propane and may also contain a little butane, but nothing heavier.

Natural gas may also be referred to as lean or rich. A rich gas implies that there are significant amounts of ethane and heavier components that may be recovered for extra value. If a gas is lean, no such condensate would be economical to recover and the gas is sold for fuel.

Next there is synthesised gas, often referred to as syngas. This is gas that has been synthetically manufactured. Often natural gas has been the raw material, but it could also be produced as part of the activity in an oil refinery although this is more likely r...

Table of contents

• Cover
• Title Page
• Copyright
• Dedication
• Preface
• Online Supplementary Material
• List of Abbreviations
• Nomenclature List
• Chapter 1: Introduction
• Chapter 2: Gas Treating in General
• Chapter 3: Rate of Mass Transfer
• Chapter 4: Chemistry in Acid Gas Treating
• Chapter 5: Physical Chemistry Topics
• Chapter 6: Diffusion
• Chapter 7: Absorption Column Mass Transfer Analysis
• Chapter 8: Column Hardware
• Chapter 9: Rotating Packed Beds
• Chapter 10: Mass Transfer Models
• Chapter 11: Correlations for Mass Transfer Coefficients
• Chapter 12: Chemistry and Mass Transfer
• Chapter 13: Selective Absorption of H2S
• Chapter 14: Gas Dehydration
• Chapter 15: Experimental Techniques
• Chapter 16: Absorption Equilibria
• Chapter 17: Desorption
• Chapter 18: Heat Exchangers
• Chapter 19: Solution Management
• Chapter 20: Absorption–Desorption Cycle
• Chapter 21: Degradation
• Chapter 22: Materials, Corrosion, Inhibitors
• Chapter 23: Technological Fronts
• Chapter 24: Flue Gas Treating
• Chapter 25: Natural Gas Treating (and Syngas)
• Chapter 26: Treating in Various Situations
• Index
• End User License Agreement