Straw feedstocks

Feedstock Straw + kaolin pelletised Straw + MgO Straw + pelletised kaolin Straw + MgO... 

From the ash samples, cross-sections were prepared and analysed by SEM. In the analysis, particle sizes and their chemical con osition were deteimined. In the analysis of chemical composition, the following elements were measured Si, Al, Fe, Ca, Mg, K, Na, Ti, P, S, Cl, (Mn), The summary results of this SEM analysis are shown in Figure 4. The con osition measured for particles was conpared with the chemical composition of ash of the feedstock straw (also indicated in Figure 4). According to the results, the most abundant substance in bottom ash was silicon, the amount of which was locally much higher than that of straw ash. The potassium content was quite equal from particle to particle. 

Fig. 4 The composition measured for particles of bottom, 2nd cyclone ash and hot filter dust samples taken irom a CFB test run of wheat straw. For comparison, the chemical composition of ash of feedstock straw is shown as red bars at the right ends of the diagrams (note for better visualisation, the array of the graphs in bottom ash diagram deviates from that of the other diagrams).

The Biolig process of the research center Karlsruhe FZK, Germany. Here, flash pyrolysis, with emphasis on straw as feedstock, is tested to produce a bio-oil-char slurry. The pyrolysis reactor compares to the ER reactor (Lurgi-Ruhrgas) by which sand as heat carrier is mixed and transported together with biomass in a double (twin) screw feeder. A novel unit is constructed with a biomass processing capacity of 12 t/day. 

A source of fly ash particulates is the mineral matter in the biomass feedstock. As material is gasified, the inorganic matter from the feedstock may be either retained in the gasifier bed or entrained in the product gas and swept out from the reactor. The mineral concentrations in clean wood are typically 1 to 2%, and herbaceous crops may contain up to 10% or more. Crop residues such as straw or rice hulls typically contain 15 to 20% inorganic material. Mineral matter... 

A pilot plant using residual straw as feedstock to produce ethanol is in operation by Iogen in Ottawa, Canada. The plant can produce up to 3000 m3 of ethanol annually (Iogen, 2005). 

Figure 15.15. Biomass hydrogen infrastructure design, using rice straw as feedstock for hydrogen production (Parker, 2007).

The next generation of biofuel processes should differ from the first in (a) utilizing the whole plant as a feedstock and (b) the use of non-food perennial crops (woody biomass and tall grasses) and lignocellulosic residues and wastes (woodchips from forest thinning and harvest residues, surplus straw from agriculture). 

It should be pointed out that the raw materials for VAM and its related polymers (i.e. ethylene and acetic acid) are produced from fossil resources, mainly crude oil. It is possible to completely substitute the feedstock for these raw materials and switch to ethanol, which can be produced from renewable resources like sugar cane, com, or preferably straw and other non-food parts of plants. Having that in mind, the whole production of PVAc, that nowadays is based on traditional fossil resources, could be switched to a renewable, sustainable and C02-neutral production process based on bioethanol, as shown in Fig. 3. If the vinyl acetate circle can be closed by the important steps of biodegradation or hydrolysis and biodegradation of vinyl ester-based polymers back to carbon dioxide, then a tmly sustainable material circle can be established. 

Ukraine has good prospects to revive highly efficient agriculture, which is able to satisfy domestic needs in foodstuff and feedstock and also produce products for export. The big part of the territory is steppe. It is characterized by low atmospheric precipitation, frequent draughts, and other unfavorable phenomena. Due to that yields of the main crops are not stable. Potential yield of straw and stems may come to 35 mill t/year. Demand of agriculture is 13 mill t of straw a year, the surplus - about 20 mill t/year that is equivalent to 82 TWh - can be used for other purposes including energy production. 

Present collection costs are 1.5-2 times the delivered cost target— 35/ dt, including 20/acre or more net income for the farmer. Bulk collection is likely needed, because baling adds cost, 15/dt, and no value. One-pass harvest can lower the delivered feedstock cost to < 20/dt within a 15- to 20-mi radius. Prototypes for one-pass harvest of straw and stover are under development, adapting existing equipment. Many variations are possible, but until a better market definition is available, a new design is probably limited to paper studies. 

Recent studies have proven ethanol to be an ideal liquid fuel for transportation and renewable lignocellulosic biomass to be an attractive feedstock for ethanol fuel production by fermentation (1,2). The major fermentable sugars from hydrolysis of lignocellulosic biomass, such as rice and wheat straw, sugarcane bagasse, corn stover, corn fiber, softwood, hardwood, and grasses, are D-glucose and D-xylose except that softwood... 

The first step will be to separate the seed from the straw (collection will obviously occur simultaneously, to minimise energy use and labour cost). The seeds may then be processed to produce starch and a wide variety of products, including ethanol and bioplastics (e.g. polylactic acid). The straw can be processed to products via various conversion processes, as described above for a lignocellulosic feedstock biorefinery. 

In principle, most types of biomass can be used as a raw material in the pyrolysis process [14]. Most of the research has been carried out using different wood as feedstock, although more than 100 different types of biomass have been tested [14]. Besides wood, these materials include forest residues, such as bark black liquor and agricultural residues such as straw, olive pits, and nut shells [12, 14], Additionally, pure biological polymers cellulose (linear polymer of D-glucose units), hemicellulose (heteropolymers of different hexoses and pentoses), and lignin (heteropolymer of p-coumaryl alcohol, coniferyl alcohol, and sinapyl alcohol [19]) - have been tested as raw materials in the pyrolysis. 

Historically, pricing had been the biggest barrier to biodegradable polymer market development. However, growing volumes of production and the development of new technology should further allow bio-based resin makers to reduce costs. Using materials such as corn stover, wheat straw and rice straw, which remain in fields after crops are harvested, as resin feedstock, could also increase productivity and economic performance. 

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