For fixed bed gasifiers, like the down-draft reactor, the fuel can be fired starting from the top Top Lit or from the bottom Bottom Lit of the reactor. The remaining are ash and some char [unburned carbon]. Factors Influencing Gasification 7. The heat for pyrolization is mainly delivered by the upward-flowing producer gas and partly by radiation from the hearth zone. It depends on the fuel used to raise the temperature of the feed material before stimulating the production of the gas. Basic Design Formulae In order to achieve the desired design of the gasifier, factors such as:
The quantity of gas constituents depends upon the types of fuels and operating conditions. In this type of reactor, smooth operation of producing gas can be achieved. The only advantage in using a thicker column of biomass is that it slows down the downward movement of the combustion zone in the reactor, which can help in minimizing the erratic production of flammable gas during gasification. Senthil and Vevekanandan 42 conducted a statistical study on the effect of design and operating parameters such as bed temperature, pressure, equivalent ratio, feed rate and particle size on the performance of the gasification process of coconut shell as biomass in a continuous fixed bed updraft gasifier reactor. The moisture in biomass can remain in two forms: The biomass breaks down into a combination of solids, liquids and gasses. The heating value of producer gas usually varies from 4.
If the moisture content is excessive, the combustion process may not be self-sustaining and supplemental fuel must be used which could defeat the objective of producing energy by biomass combustion Cracking is also necessary to ensure proper combustion because complete combustion only occurs when combustible gases thoroughly mix with oxygen.
This process is crucial for the production of clean gas that is compatible with an internal combustion gzsification because tar gases condense into sticky tar that will rapidly foul the valves of an engine. With the increase in temperature, combustible gas content, gas yield, hydrogen, and heating value all increased significantly, while the tar content decreased sharply.
This refers to the inorganic, residual component in biomass, usually obtained after combustion of the biomass. First, this will provide better conversion of biomass fuel into gas. Colorado Solar Energy Research Institute, According to Mc Kendry 3most of the development work was carried out with common fuels such as coal, charcoal and wood.
During the combustion process very minor quantities of carbon monoxide, nitrogen oxides and volatile thessis compounds are generated which leave the furnace with the flue gases. Most biomass may also contain a small amount of nitrogen 2 as shown in Table 1 It was recognized that fuel properties such as surface area, size, shape as well as moisture content, volatile matter and carbon content affect gasification performance.
Biomass gasification has received tremendous attention throughout the world. The gas quality indicates gaskfication extent to which the gas is suitable for end use equipment or process and is represented by several parameters including chemical composition, tar and particulate concentration, and Lower Heating Value LHV and is dependent upon the requirements of the end use itself. Standard E provides an alternative means of measurement using microwave 4.
Factors Influencing Gasification 7. As the name suggests, volatiles are reactive.
CFD Modeling and Simulation on Hydrodynamics of CFB Biomass Gasifier using FLUENT
Wood Gas from the Suction Gasifier: The other advantage of firing from the bottom is that the total start-up time for the same height of the reactor can be extended, which cannot be done when firing the fuel from the top of the reactor.
The resulting water vapour together with water vapour formed in the combustion zone partly lead to production of hydrogen and remaining is going with producer gas However, it has one disadvantage: Tela and Abubakar M.
Karemore and Chincholhat S. Using blowers can overcome pressure in long reactors or those with thicker fuel column. So, the coconut shell is best suitable material for the above constructed updraft biomass gasifier as compare to the other two. The key to a successful design of gasifier is to understand the properties and thermal behaviour of the fuel fed into the gasifier system.
The reaction is influenced by the chemical composition of biomass fuels and the operating conditions. The heating value of producer gas usually varies from 4. AtiyehRaymond L.
Biomass materials exhibit a wide range of moisture content and since this affects its value as a fuel source, it is important that the basis be stated whenever moisture content is measured Free moisture is that above the equilibrium moisture content.
Assessment of Biomass Gasification: A Review of Basic Design Considerations
Reduction in a gasifier is accomplished by passing carbon dioxide CO 2 or water vapor H 2 O across a bed of red hot charcoal C. Biomass fuel can be fired in the stove fpuent different ways.
They evaluated various biomass energy conversion technologies and their applications to developing countries such as Nigeria.