Hot Gas Cleaning
Hot gas cleanup has been traditionally used in the removal of particulate matter and tar with the goal of minimizing maintenance of syngas combustion equipment. In this technique high temperature gas is cleaned directly at the neck of the gasifier. This is a highly efficient and reliable method. Many common gas cleaning technologies have been applied to hot gas particulate cleanup, most of which are based upon one or more of the following physical principles: inertial separation, barrier filtration, and electrostatic interaction. A summary of hot gas cleaning technologies that can be used in particulate removal in biomass-derived syngas is shown in Table 11.4.
|
Device |
Collection efficiency (%) |
Pressure drop (kPa) |
Flow capacity (m3 s1 m2) |
Energy required |
|
Cyclones |
||||
|
Conventional |
Low (~ 90) |
Moderate to high (7.5-27.5) |
Very high |
Low |
|
Enhanced |
(>90-95) |
Moderate to high |
Very high |
Moderate to high |
|
Granular filters |
||||
|
Fixed |
Good (>99) |
Moderate (6-10) |
High (0.15-0.2) |
High |
|
Moving |
— |
Moderate |
High |
Moderate to high |
|
Rigid barrier filters |
||||
|
Ceramic candle |
Excellent (>99.5) |
Moderate to high (5-25) |
Moderate to high (0.03-0.07) |
Moderate |
|
Cross-flow |
— |
Low to moderate (2.5e7.5) |
Moderate to high (0.03-0.07) |
Low to Moderate |
|
Ceramic tube |
— |
Moderate (8-12.5) |
Moderate to high (0.03-0.05) |
Moderate |
|
Metallic |
— |
Moderate to high |
Moderate to high |
Moderate |
|
Electrostatic precipitators |
— |
Very low (0.3-0.6) |
Low to moderate (0.01-0.03) |
Moderate to high |
|
Table 11.4 A summary of hot gas particulate removal technologies [1,23]. |
|
398 Handbook of Cellulosic Ethanol |
Biomass Pyrolysis and Gasifier Designs 399