What is fixed bed gasifier?
Fixed bed gasifiers, which consist of a fixed bed of biomass through which the oxidation medium flows in updraft or downdraft configuration, are simple and reliable designs and can be used to gasify wet biomass economically on a small scale for CHP applications (Wang et al., 2008).
What are gasifiers explain any two?
Gasifier equipment is generally classified as upward draft, downward draft and cross draft gasifiers, based on the direction of air/oxygen flow in the equipment. Gasification processes can be categorized into three groups: entrained flow, fluidised bed and moving bed (sometimes called, somewhat erroneously, fixed bed).
What is downdraft gasifier?
The downdraft gasifiers or cocurrent gasifiers are the most common type of gasifiers. In cocurrent gasifiers, biomass feedstock is fed from the top while air is passed downwards and producer gas leaves from the bottom of the gasifier. A clean mixture of combustible gases in the exit stream is obtained.
What is the use of gasifier?
Most gasifiers in commercial operation today are used for the production of heat, rather than fuel for internal combustion engines, because of the less stringent requirements for gas heating value and tar content.
What is updraft fixed bed gasifier?
The updraft fixed bed (“counter-current”) gasifier consists of a fixed bed of carbonaceous fuel (e.g. coal or biomass) through which the “gasification agent” (steam, oxygen and/or air) flows in counter-current configuration. The ash is either removed dry or as a slag.
What are the advantages and disadvantages of downdraft fixed bed gasifier?
Advantage of the downdraft fixed-bed gasifier is that the tars are cracked down in the oxidation zone, thus the producer gas has lower tar content compared to other types of gasifiers.
What are multistage fixed bed gasifiers?
Multistage fixed bed gasifiers have become a reference since the 2000s owing to their potential for producing a syngas with very low tar content. The concept of staged fixed bed gasifiers relies on the decoupling of biomass pyrolysis, fuel gases combustion, and char gasification, by using two separated reactor vessels.
What happens to the Tar in an updraft gasifier?
The tar can be recycled to the reactor. The updraft gasifier consists of a top fed fuel bed through which the “gasification agent” (steam, oxygen and/or air) flows in from the bottom and exits through the top as gas.