Design of Biomass Gasifiers - Biomass Gasification, Pyrolysis and Torrefaction - page 249

Chapter 8

Design of Biomass Gasifiers

8.1 INTRODUCTION
A gasification plant includes the gasifier reactor as well as its auxiliary or
support equipment. So, the design of a gasification plant would involve
design of individual units like:

Gasifier reactor
Biomass-handling system
Biomass-feeding system
Gas-cleanup system
Ash or solid residue-removal system

This chapter deals with the design of the gasifier reactor alone.
Chapter 12 discusses the design of the handling and feeding systems. Gas-
cleaning systems are briefly discussed in Chapter 6.
As with most process plant equipment, the design of a gasifier is gener-
ally done in the following three major phases:

Phase 1. Process design and preliminary sizing.
Phase 2. Optimization of design.
Phase 3. Detailed mechanical design.

For cost estimation and/or for submission of initial bids, most manufacturers
use the first step of sizing the gasifier. The second step is considered only for a
confirmed project—that is, when an order is placed and the manufacturer is ready
for the final stage of detailed mechanical or manufacturing design. The detailed
mechanical design begins after the design is optimized and actual manufacturing
is to begin.
This chapter mainly concerns the first phase and, briefly, the second
phase (design optimization). To set the ground for design methodologies, a
short description of different gasifier types is presented, followed by a dis-
cussion of design considerations and design methodologies.

8.1.1 Gasifier Types
Gasifiers are classified mainly on the basis of their gas

solid contacting
mode and gasifying medium. Based on the gas solid contacting mode,