Biomass oxygen content

Hydrothermolysis is a specific process developed by Shell for producing an oil-like material, called bio-erude, with a low oxygen content. The process is so called because it involves treatment of the biomass with water at temperatures of 200-330 °C and pressures over 30 bar. Although the proeess is not yet economical it may well be so in the near future as crude oil prices eontinue to rise. 

Detoxification methods, pesticide content of fish, environmental analytical and monitoring techniques. (4 Utilization of biomass, drinking water quality, organic contaminants in lakes and rivers, and effect of deforestation on carbon dioxide and oxygen content of air. 

With biomass as feedstock, completely new strategies are needed to reduce the oxygen content and the degree of functionalization in biomass to reach the levels of common fuels. Alternatively, the fuel basis can be switched to fuels more similar to the oxygen-rich biomass (e.g. bioethanol). 

These points hold only partially for the production of chemicals from biomass. The smallest part of bulk chemicals consists of unfunctionalized hydrocarbons. Nevertheless, the oxygen content of biomass has to be reduced to the level needed for typical bulk chemicals. Therefore, strategies are strongly needed [7]. 

Important biomass fuel properties for thermochemical conversion processes are reported as proximate and ultimate analyses. The proximate and ultimate analyses for selected biomass feedstocks are presented in Table 33.5. For comparison, the analyses from two selected coal samples are also presented. Biomass generally has a lower energy density than coal, oils, and natural gas it also has higher oxygen content. The higher volatiles and oxygen content of biomass translate into a higher reactivity compared to traditional fossil fuels. In terms of thermochemical conversions, this means that less severe process conditions (lower temperature and shorter residence time) are required for bio-... 

Biomass and coal have fundamentally different fuel properties that can lead to benefits or deterrents to co-firing. For instance, biomass is a more volatile fuel than coal and has higher oxygen content. Coal, on the other hand, has more fixed carbon than biomass. Wood fuels tend to contain very little ash (on the order of 1% ash or less) and consequently increasing the ratio of wood in biomass/coal blends can reduce the amount of ash that needs to be disposed. A negative aspect of biomass is that it can contain more chlorine than coal. This is particularly true for some grasses, straws, and other agricultural residues. 

Figure 7 shows CoE plotted against air oxygen concentration to the gasifier, for a system with an RFSG and a band conveyor dryer. The biomass feed rate is 1.5 dt/h, the pre-dryer biomass moisture content 75% and the biomass cost 630/dt. 

Similar results are seen at other feed rates, pre-dryer biomass moisture contents and biomass costs. If the RFSG has to operate with oxygen-enriched air however, its superiority in CoE is rapidly eroded. For an oxygen concentration of 0.28 the difference in CoE is negligible for an oxygen concentration above 0.28 the UGETC is usually superior. 

Endpoint Oxygen content, algal densities, microbial activity, respiratory activity, biomass, protozoan population... 

---