Wood pyrolysis liquids

Spince B. Zhurinsh A. Zandersons J. (1998) Chemical analysis of wood pyrolysis liquid products. Latvian Chemical Journal, 3, 92-5. (in Latvian)... 

Chen, N.Y. Walsh, D.E. Koenig, L.R. "Fluidized bed upgrading of wood pyrolysis liquids and related compounds." In This Volume. 

Fluidized-Bed Upgrading of Wood Pyrolysis Liquids and Related Compounds... 

When processing wood pyrolysis liquids, the two pyrolysis product liquid layers were homogenized (EHI of the blend was 0.32) by high speed mixing and fed immediately to the fluid bed catalytic reactor. When co-processed with methanol, the two pyrolysis liquid layers were dissolved in the methanol to provide a mixture having an apparent EHI of 1.2-1.3. 

CHEN ET AL. FluuUzed-Bed Upgrading cf Wood Pyrolysis Liquids... 

When processed in the presence of methanol, wood pyrolysis liquids exhibited synergisms and selectivity shifts similar to those discussed above for the model... 

Figure 2 shows the products obtained in a scheme in which direct upgrading of the wood pyrolysis liquids over ZSM-5 occurs in parallel with upgrading of methanol obtained from synthesis gas derived from gasification of the pyrolysis char. In Figure 3, the methanol is mixed with the pyrolysis liquids prior to co-processing over ZSM-5. Approximately 40 lbs. of methanol per 100 lbs. of dry wood feed is potentially available from the char and pyrolysis gas products. 

Hydrocarbon yields can be increased significantly when wood pyrolysis liquids are coprocessed with methanol over ZSM-5 catalyst vs separate processing of the two streams over the same catalyst. Thus, coprocessing pyrolysis liquids with methanol produced from char gasification is one means of producing hydrocarbon fuels from wood. Results obtained in this study provide a basis for comparison with other processing schemes such as wood gasification followed by either Fischer-Tropsch synthesis or methanol synthesis plus Mobil s MT6 process. 

Since reaction of wood with acetic anhydride leads to the formation of acetic acid by-product, which must be removed from the wood, there has been some interest in the use of ketene gas for acetylation (Figure 4.4a). Ketene, for reaction with wood, is produced by pyrolysis of diketene. Provided that the wood contains no moisture, no acetic acid by-product is produced. However, ketene presents handling problems it is very toxic and explosive, and it also has a tendency to dimerize. A comprehensive series of studies of ketene-based acetylation has been performed in Latvia and this work has been reviewed by Morozovs etal. (2003). Hardwoods have been found to be more reactive to ketene than softwoods and the optimal temperature for reaction has been determined as 47 °C. Application of vacuum and treatment of wood with ammonia solution has been used to remove the excess ketene. The reaction of wood with liquid diketene was also studied, with a WPG of 35 % being obtained after reaction for 3 hours at 52 °C. 

Catalytie synthesis from CO and Hj Natural gas Petroleum gas Distillation of liquid from eoal pyrolysis Catalytic synthesis from CO and Hj Distillation of liquid from wood pyrolysis Gaseous products from biomass gasification Synthetic gas from biomass and coal... 

For many centuries, wood slow-pyrolysis liquids were a major source of chemicals such... 

A Comparison of Using Wood Pellets and Fast Pyrolysis Liquid Industrially for Heat Production within Stockholm... 

ABSTRACT Wood pellets and tall oil pitch are currently used as renewable fuel for district heating in the Stockholm Metropolitan Area, Pyrolysis liquid, another biofuel, is also a potential substitute for petroleum fuel oil. A technical, economic, and envi ronmental assessment for the whole utilisation chain from forest residues to heat has been carried out,... 

Preliminary results indicate that pyrolysis liquid may compete with wood pellets in heat production. The assessment from raw material to hot water and flue gases yields a small preference to pyrolysis liquid. However, this requires utilisation of the by-product steam in production stage. Otherwise pellet manufacture seems slightly more advantageous since the energy efficiency of pyrolysis is lower. 

A pyrolysis plant does not yet exist and for this unit the costs are estimated from previous evaluations [9, 10] and prestudies of proposed units. The pretreatment of the raw material - milling and drying - is the same or very similar to wood fuel manufacture and pyrolysis liquid manufacture in pellet production about 10 - 15% moisture content is accepted whereas pyrolysis preferably should have a feed of <10% moisture. Hence, the conq)arison of production costs basically can be reduced to the actual pellet production vs. the pyrolysis process. For the general cost level, however, the receiving and pretreatment are evaluated as well. 

The cost evaluations for the total use of wood pellets and pyrolysis liquid may be summarised according to Table 1. Cost breakdown is shown in Figure 4. The total cost of using wood fuel as pellets in a 3 MW boiler for district heating is about 33 USD per MWh. The corresponding cost of pyrolysis liquid is estimated a little lower (=30 USD/MWh). 

Cost item Wood fuel (pellets) Pyrolysis liquid Tall oil pitch... 

The difference between the costs of using wood pellets and the tentative costs of using pyrolysis liquid is some 10%, which in general is well within the accuracy that can be expected, Thefore, no significant difference exists between these alternatives. 

Thirdly, cheaper raw materials may appear. This will not affect the relation much, since the raw material share of the production costs is about the same. It might be easier to handle low-value raw materials in the pyrolysis as this includes a chemical breakdown of the material. Pelletising is to some extent sensitive to the structure of the wood. On the other hand, experiences have shown large variations in pyrolysis liquid depending on raw material. 

The overall conclusion is that pyrolysis liquid may be produced and fired at the same cost level as pellets from wood. At present though, development work on pyrolysis liquid has to secure an acceptable and even quality of the upgraded wood fuel as far as that of pellets. 

Pyrolysis liquid is referred to by many names including pyrolysis oil, bio-oil, bio-crude-oil, bio-fiiel-oil, wood liquids, wood oil, liquid smoke, wood distillates, pyroligneous tar, pyroligneous acid, and liquid wood. The crude pyrolysis liquid is dark brovyn and approximates to biomass in elemental composition. It is conqsosed of a very complex mixture of oxygenated hydrocarbons with an appreciable proportion of water from both the original moisture and reaction product. Solid char and dissolved alkali metals from ash (34) may also be present. 

Meier D, Andersens B, Irbe L Tshirkova J, Faix O, Preliminary study of fungicide and sorption effects of fast pyrolysis liquids used as wood preservative , These proceedings... 

A significant problem remains the relatively high solids (char) content in the pyrolysis liquids, due to the fiagmentation of char and wood fines in the harsh environment which are subsequently entrained in the gaseous stream, an inherent characteristic encountered in all CFB reactor systems, (ineffective solids recovery system). 

Preliminary Study on Fungicide and Sorption Effects of Fast Pyrolysis Liquids Used as Wood Preservative... 

In wood pyrolysis, it is known that several parameters influence the yield of pyrolytic oil and its composition. Among these parameters, wood composition, heating rate, pressure, moisture content, presence of catalyst, particle size and combined effects of these variables are known to be important. The thermal degradation of wood starts with free water evaporation. This endothermic process takes place at 120 to 150 C, followed by several exothermic reactions at 200 to 250°C, 280 to 320 C, and around 400 C, corresponding to the thermal degradation of hemicelluloses, cellulose, and lignin respectively. In addition to the extractives, the biomass pyrolytic liquid product represents a proportional combination of pyrolysates from cellulose, hemicelluloses. 

Laboratory (4) and Process Development Unit (5,6) studies originally conducted at the Universite de Sherbrooke, and now conducted jointly with the private industry at Universite Laval, province of Quebec, have led to the conclusion that thermal decomposition under reduced pressure is an attractive approach for the conversion of biomass into chemicals and fuels products. The process uses a multiple-hearth furnace for wood pyrolysis. This approach is characterized by a low pressure and a short residence time of the vapor products in the rciactor. When compared with conventional, atmospheric pressure carbonization, vacuum pyrolysis has the potential to significantly enhance the yields of organic liquid products with respect to solid and gaseous products. The pyrolysis oils (biooils) obtained from this process can be deoxygenated into transportation fuels upon further upgrading (7). Specialty as well as commodity (Pakdel, H. Roy, C. Biomass, in press) chemicals can also be extracted from the pyrolysis oil product. 

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