What are fixed bed gasifiers?

The fixed bed gasifier has a bed of solid fuel particles through which the gasifying media and gas move either up or down. It is the simplest type of gasifier consisting of usually a cylindrical space for fuel feeding unit, an ash removal unit and a gas exit.

What are gasifiers and their types?

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. It should be noted that there are types of gasifier equipment which are different from types of gasification processes.

What is a downdraft gasifier?

A downdraft gasifier is the typical configuration used for bioenergy production. This well-established technology allows the production of syngas with low tar, due to the syngas passes through the combustion zone at high temperature and the subsequent dimensioning which in turn leads to the thermal cracking of tars.

What is downdraft gasifier?

What is difference between updraft and downdraft gasifier?

In downdraft gasifiers, both fuel and the gas move downward. In updraft gasifiers, fuel moves downward and gas upward. In co-current gasifiers, the fuel and gas move in the same direction, usually downward (downdraft gasifiers), but the movement can also be upward.

How does a downdraft gasifier work?

In downdraft gasifier the fuel slowly moves down by gravity. During this downward movement, the fuel reacts with air, which is supplied by the suction of a blower or an engine and is converted into combustible producer gas in a complex series of oxidation, reduction, and pyrolysis reactions [3].

What are the advantages of downdraft gasifier?

1.3 Downdraft Gasifier

Advantages	Disadvantages
Simple and consolidated process	Need of biomass with small size (1–3 cm)
Low tar content	Difficult to scaling up
	High probability of bridging phenomena
	High probability of clinkering phenomena

Downdraft Gasifier. A downdraft gasifier is a gasification reactor with four distinct zones: (a) upper drying zone, (b) upper-middle pyrolysis section, (c) lower-middle oxidation zone, and (d) lower reduction zone. A schematic of a downdraft gasifier is given in Figure 8.3. Figure 8.3. Schematic of a downdraft gasifier.

What is a cross-draft fixed bed gasifier?

In the cross-draft fixed-bed gasifiers, the gasification agent is introduced from one side of the reactor and exits from the other side. This last one gasifier is mainly used for charcoal gasification, due to the very high temperatures reached.

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 staged fixed bed gasifiers?

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. This separation enables a better control of the pyrolysis and gasification stages, affording the possibility of independently optimizing each stage.