Steam of wood

On ammonia treatment, the gross swelling behavior and changes in the strength and the structure of wood are very similar to those observed during and after steaming of wood with water vapor. The changes described below refer to wood saturated with ammonia. 

Table 19. Product Gases from Steam Gasification of Wood...

Turpentine Oil. The world s largest-volume essential oil, turpentine [8006-64-2] is produced ia many parts of the world. Various species of piaes and balsamiferous woods are used, and several different methods are appHed to obtain the oils. Types of turpentines include dry-distiUed wood turpentine from dry distillation of the chopped woods and roots of pines steam-distilled wood turpentine which is steam-distilled from pine wood or from solvent extracts of the wood and sulfate turpentine, which is a by-product of the production of sulfate ceUulose. From a perfumery standpoint, steam-distilled wood turpentine is the only important turpentine oil. It is rectified to yield pine oil, yellow or white as well as wood spirits of turpentine. Steam-distilled turpentine oil is a water-white mobile Hquid with a refreshing warm-balsamic odor. American turpentine oil contains 25—35% P-pinene (22) and about 50% a-pinene (44). European and East Indian turpentines are rich in a-pinene (44) withHtfle P-pinene (22), and thus are exceUent raw materials... 

Bois de Rose. Bois de rose oil is obtained by steam distillation of wood chips from South American rosewood trees, Aniba rosaeodora. The tree, a wild evergreen, grows mainly in the Amazon basin. The oil is used as obtained in perfumery for its sweet, woody-floral odor and as a source of linalool [78-70-6] (3), which it contains to the extent of 70%. Linalool distilled from bois de rose oil is also used directly in perfumery and for conversion to esters, eg, the acetate (1). 

By-Products. There are three stages within the pulping operation at which wood-derived chemicals can be recovered as by-products. Turpentine is obtained from the reHef of gases after an initial steaming of chips in the digester. Better yields of turpentine are obtained from batch digesters than from continuous systems. Pines and firs give the best yields. Turpentine is composed principally of unsaturated bicycHc hydrocarbons, of which ca 90% are a- and P-pinenes and 5—12% other terpenes. 

While the rotary dryer shown is commonly used for grains and minerals, this system has been successfully applied to fluid-bed diying of plastic pellets, air-hft diying of wood fibers, and spray drying of milk solids. The air may be steam-heated as shown or heated By direct combustion of fuel, provided that a representative measurement of inlet air temperature can be made. If it cannot, then evaporative load can be inferred from a measurement of fuel flow, replacing AT in the set point calculation. 

Braun-saLz, n, any of certain brown dyes. -schliff, m. (Paper) steamed mechanical wood pulp, brown wood pulp, braunschwarz, a, brown-black, very dark brown. 

Wood was the easiest fuel to use in early steam locomotives, but it was soon realized that the logistics of wood fuel were limiting. Steam engines were developed that could burn coal, peat, or (later) oil where those fuels were more abundant. For intercity railroads (especially in the Americas, Asia, Australia, and Africa), coal remained the fuel of choice for one hundred years. Despite impressive technology development, steam locomotives never could achieve thermal efficiencies greater than about 6 to 8 percent. 

The direct combustion of wood and other plant matter has been a primary energy source in the past. Any type of biomass can be burned to produce heat or steam to turn a generator or perform mechanical work. Direct combustion is used in large power plants that produce up to 400 megawatts. Most direct combustion systems can use any type of biomass as long as the moisture content is less than 60%. Wood and wood residues are commonly used along with a number of other agricultural residues. 

Mills that process rice may also generate process heat, that can be used for direct heating, steam generation, mechanical power or electrical power. For every five tons of rice milled, one ton of husks with an energy content equivalent to one ton of wood is left as residue. A rice mill in Louisiana has satisfied all its power needs since 1984 from an on-site rice-husk power plant. The plant sells surplus energy to the local utility. 

The inherent heterogeneity of the material leads to variations in the responses of wood to thermal modification. The rate of transfer of heat into the interior of the wood is of paramount importance in order to ensure that there is a constant temperature throughout the sample. The thermal conductivity of dry wood is low and the heating method employed must ensure that the treatment is as even as possible. Heat transfer into the interior may be improved by the use of steam-heating. Heat transfer is a very significant factor in the treatment of timber of larger dimensions. 

Samples of wood of various species were steam-treated at 150 °C, or oven-heated in air at 150°C, for various time periods and attack by the termite species C. formosanus or R. speratus determined (Doi etal., 1997, 1999). Steam heat treatment had the effect of encouraging attack upon the treated wood specimens, whereas dry heat treatment had little effect except for heat-treated Japanese larch with R. speratus. 

ThermoWood is produced by a heat-treatment process in the presence of steam, and is thus a hygrothermal treatment. The steam acts as a blanket to limit the oxidative degradation of wood, and there are also additional reactions occurring as a result of the presence... 

The Perdure process has been commercialized by PCI Industries Inc., based in Quebec. The Perdure process involves the drying and then subsequent heating of wood at temperatures ranging from 200 °C to 230 °C in a steam atmosphere. The company produces two kilns for thermal modification, the PC5 (of 8.75 m capacity) and the PC6 (of 10.5 m capacity). Process costs are of the order of 100 Euros per m. ... 

Dwianto, W., Tanaka, F., Inoue, M. and Norimoto, M. (1996). Crystallinity changes of wood by heat or steam treatment. Wood Research, 83, 47-49. 

Ito, Y., Tanahashi, M., Shigematsu, M. and Shinoda, Y. (1998a). Compressive-molding of wood by high-pressure steam-treatment. Part 2. Mechanism of permanent fixation. Holzforschung, 52(2), 217-221. 

MacLean, J.D. (1953). Effect of steaming on the strength properties of wood. Proceedings of the American Wood Preservers Association, 49, 88-112. 

Shimizu, K., Sudo, H. and Fijii, T. (1989). Total utilisation of wood components by steam explosion pre-treatment. In Wood Processing and Utilization, Kennedy, J.F., Phillips, G.O. and Williams, P.A. (Eds.). Ellis Harwood, Chichester, UK, pp. 407 12. 

Biorefinery includes fractionation for separation of primary refinery products. The fractionation refers to the conversion of wood into its constituent components (cellulose, hemicelluloses and lignin). Processes include steam explosion, aqueous separation and hot water systems. Commercial products of biomass fractionation include levulinic acid, xylitol and alcohols. Figure 3.3 shows the fractionation of wood and chemicals from wood. 

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