Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Pyrolysis, slow char yields

Table 4.3 Comparison of Slow and Rapid Pyrolysis Char Yield and Density at 800°C to 1000°C... Table 4.3 Comparison of Slow and Rapid Pyrolysis Char Yield and Density at 800°C to 1000°C...
Pyrolysis of biomass is divided into slow pyrolysis, which is well known to produce charcoal, for example, fast pyrolysis, which produces a high yield of liquid biofuels and other chemicals (Bridgwater, 2000) and flash pyrolysis. Slow pyrolysis (or carbonisation) requires low temperatures and very long residence time. In the carbonisation process the amount of char is maximised. [Pg.163]

In pyrolysis the wood material is heated rapidly to about 500 °C at which temperature the wood decomposes to a maximum amount of liquid product. At lower temperatures more char is formed and less liquid and gas, and at higher tenperatures the energy requirements are higher without producing noticeably more liquid. The pyrolysis process is carried out in a fluidised bed where milled material is fed into the bed and the product stream is condensed at temperatures between 30 and 60 °C. The char is usually separated before the condenser and used as fuel - along with the gas -to provide heat to the fluidised bed. The fluidised bed may be bubbling or circulating. In both cases a fast pyrolysis is obtained in contrast to slow pyrolysis which usually yields lower amounts of liquids. [Pg.868]

Liquid yields of 35-50% on dry feed are typically obtained with higher char yields than fast pyrolysis systems. Conversely, the liquid yields are higher than in slow pyrolysis technologies because of fast removal of vapours from the reaction zone,... [Pg.986]

Pyrolysis of biomass, as well as pyrolysis of Salix viminalis wood, yields volatile products besides the mentioned solid product—active carbon (Figure 5). Figure 5 doc-mnents that the proportions between basic products of biomass heat-treatment depend on process dynamics. High speed pyrolysis prefers the formation of non-condensable gases while slow carbonizations increase the share of soUd product (char or active carbon). [Pg.106]

Slow pyrolysis of biomass operates at relatively low heating rates (0. l-2°C/s) and longer solid and vapor residence time (2-30 min) to favor biochar yield (Nanda et al., 2014b). Slow pyrolysis operates at temperature lower than that of fast pyrolysis, t q)ically 400 10°C and has a gas residence time usually > 5 s. Slow pyrolysis is similar to carbonization (for low temperatures and long residence times). During conventional pyrolysis, biomass is slowly devolatilized facilitating the formation of chars and some tars as the main products. This process yields different range of products with their properties dependent on temperature, inert gas flow rate and residence time. [Pg.348]

Given the specifics of the fast pyrolysis process in terms of feedstock requirements and process conditions, ie, fast heating and short residence time in reactor, it can be expected to yield biochar with a different set of properties compared to other conversion processes, such as slow pyrolysis or gasification. The short residence time can lead to incomplete charring of the biomass particle, as observed by Bruun et al. (2011,2012). This in turn leads to lower environmental stability of biochar, and therefore lower carbon sequestration potential. This is the case even when the biomass conversion during pyrolysis is apparently complete, as reported in Brewer et al. (2009). These authors observed lower stability of fast pyrolysis biochar, assessed based on fixed carbon content and aromaticity, compared to slow pyrolysis and gasification biochar produced from the same feedstock. [Pg.659]


See other pages where Pyrolysis, slow char yields is mentioned: [Pg.149]    [Pg.226]    [Pg.233]    [Pg.559]    [Pg.308]    [Pg.114]    [Pg.114]    [Pg.331]    [Pg.351]    [Pg.352]    [Pg.887]    [Pg.272]    [Pg.287]    [Pg.374]    [Pg.609]    [Pg.1117]    [Pg.233]    [Pg.42]    [Pg.345]    [Pg.350]    [Pg.352]    [Pg.363]    [Pg.548]    [Pg.658]   
See also in sourсe #XX -- [ Pg.233 ]




SEARCH



Char yields

Charring

Chars

Slow pyrolysis

© 2024 chempedia.info