Biomass Gasification, Pyrolysis and Torrefaction

Practical Design and Theory

Prabir Basu

• Publisher: Academic Press
• Year: 2018
• ISBN:
  9780128130407
• Edition: 3
• Topic: Tecnologia e ingegneria
• Subtopic: Risorse energetiche rinnovabili

Biomass Gasification, Pyrolysis and Torrefaction, Third Edition, is enhanced with a new topic on processing and cleaning of product gas of gasification and a brief introduction to biomaterials, making it a versatile resource that not only explains the basic principles of energy conversion systems, but also provides valuable insight into the design of a complete biomass conversion systems. With a dedicated focus on the design, analysis and operational aspects of biomass gasification, pyrolysis and torrefaction, this edition offers comprehensive coverage of biomass in its gas, liquid or solid states in a single accessible source.

The author provides many worked design problems, step-by-step design procedures and real data on commercially operating systems. Although the book carries the name 'biomass', the bulk of its content is also applicable to non-biomass fuels like coal, petcoke, municipal solid waste and others. This book will help engineers, scientists and operating personnel of biomass gasification, pyrolysis or torrefaction plants, gain better comprehension of the basics of biomass conversion.

Biomass Gasification, Pyrolysis and Torrefaction, Third Edition, is enhanced with a new topic on processing and cleaning of product gas of gasification and brief introduction to biomaterials making it a versatile resource that not only explains the basic principles of energy conversion systems, but also provides valuable insight into the design of a complete biomass conversion systems. With a dedicated focus on the design, analysis, and operational aspects of biomass gasification, pyrolysis, and torrefaction, this edition of the book offers comprehensive coverage of biomass in its gas, liquid, or solid states in a single easy-to-access source. The author provides many worked out design problems, step-by-step design procedures and real data on commercially operating systems. Although the book carries the name 'biomass', the bulk of its content is also applicable to non-biomass fuels like, coal, petcoke, municipal solid waste and others. This book will allow professionals, such as engineers, scientists, and operating personnel of biomass gasification, pyrolysis or torrefaction plants, to gain a better comprehension of the basics of biomass conversion.

• Features updates with the most recent research and technology
• Expanded to include a new chapter on syngas purification
• Contains step-by-step process flow diagrams, design data, conversion charts and numerical examples with solutions
• Provides available research results in an easy-to-use design methodology
• Examines the economic aspects of biomass conversion

Chapter 1

Introduction

Abstract

Biomass appears to be the face of renewable green energy today. It had a prominent role in the pre-industrial age but lost that with the advent of coal, and now its share in the energy mix rising. Biomass, though used primarily for energy conversion has many other uses because one can produce almost everything that is currently produced from coal and oil. This chapter explains the benefits of biomass could bring to society and industry. A brief description of different thermochemical conversion means ranging from combustion to chemical production is presented. It includes a summary of major chemical reactions in different conversion processes. Special mention is made for the reduction in carbon emission through carbon capture and storage, co-firing and the new option of biochar production and biomass burial.

Keywords

benefits

carbon-neutral

combustion

comparison

conversion reactions

gasification

history

thermochemical processes and biomass products

The quest for renewable sustainable energy sources has given biomass a prominence it had lost during the industrial revolution after the discovery of coal. The share of biomass in meeting current world's primary energy mix is at a modest level of 24% in 2016, but given the rising concern about global warming and sustainability, this share is likely to rise to 30% by 2020 (IEA, 2017). The most common use of biomass for energy is direct combustion, followed by gasification, carbonization, and pyrolysis. The production of transportation fuel from biomass through pyrolysis, trans-esterification, fermentation, and gasification-based synthesis is also gaining commercial importance. Carbonization that produces charcoal from biomass was widely practiced for extraction of iron from iron ore in ancient India and China (∼4000 BCE). Charcoal is still being used in many parts of the world as a smokeless fuel as well as a medium for filtration of water or gas. Torrefaction, a relatively new biomass conversion option, is also attracting much attention especially in its near term application in cofiring biomass in coal-fired power plants, carbon sequestration in ground, and possibly for replacement of coke in metallurgy.

This monograph deals primarily with three major thermochemical conversions—gasification, pyrolysis, and torrefaction—which produce gas, liquid, and solids respectively from biomass.

Gasification is a chemical process that converts carbonaceous materials such as biomass into useful convenient gaseous fuels or chemical feedstock. Pyrolysis, partial oxidation, and hydrogenation are related processes. Combustion also converts carbonaceous materials into product gases but with some important differences. For example, the product gas of combustion does not have any useful heating value, but the product gas from gasification does. Gasification packs energy into chemical bonds in the product while combustion releases it. Gasification takes place in reducing (oxygen-deficient) environments requiring heat, whereas combustion takes place in an oxidizing environment releasing heat.

The purpose of gasification or pyrolysis is not just energy conversion; production of chemical feedstock is also an important application. Nowadays, gasification is not restricted to solid hydrocarbons. Its feedstock includes liquid or even gases to produce more useful fuels. For example, steam reforming of natural gas (methane) is widely used in production of hydrogen.

Torrefaction (Chapter 4) is gaining prominence due to its attractive use in cofiring biomass (Chapter 10) in existing coal-fired power plants. Pyrolysis (Chapter 5), the pioneering technique behind the production of the first transportable clean liquid fuel kerosene, produces liquid fuels from biomass. In recent times, gasification of heavy oil residues into syngas has gained popularity for the production of lighter hydrocarbons. In fact, many large gasification plants are now dedicated to the production of chemical feedstock from coal or other hydrocarbons. Hydrogenation, or hydrogasification, which involves adding hydrogen to the feed to produce fuel with a higher hydrogen-to-carbon (H/C) ratio, is also gaining popularity. Supercritical gasification (Chapter 9), a new option for gasification of very wet biomass, also has much potential.

This chapter introduces the above biomass conversion processes with a short description of the historical developments of gasification, its motivation, and its products. It also gives a brief introduction to the chemical reactions that are involved in important biomass conversion processes.

1.1 Biomass and Its Products

Biomass is formed from living species such as plants and animals—that is, anything that is now alive or was alive a short time ago. It is formed as soon as a seed sprouts or an organism is born. Unlike fossil fuels, biomass does not take millions of years to develop. Plants use sunlight through photosynthesis to metabolize atmospheric carbon dioxide and water to grow. Animals in turn grow by taking in food from biomass. Unlike fossil fuels, biomass can reprodu...