Primary pyrolysis oils

Fast pyrolysis of pine sawdust in a small vortex reactor operating at 10 to 20 kg/h and 480 to 520 °C produces high yields of primary pyrolysis oils (over 55% by weight on a dry basis). The vortex reactor transmits very high heat fluxes to the sawdust, causing primarily depolymerization of the constituent polymers into monomers and oligomers. A preliminary scheme separates the raw oils into a carbohydrate-derived aqueous fraction and a phenolic-rich ethyl acetate (EA) soluble fraction. The EA fraction is washed with water and with aqueous sodium bicarbonate to remove acids yielding 20% to 25% of the feed as phenols and neutrals (P/N) in the EA solution. 

Diebold J.P., Power A.J. (1988) Engineering Aspects of the Vortex Pyrolysis Reactor to Produce Primary Pyrolysis Oil Vapours for use in Resins and Adhesives. In Research in Thermochemical Biomass Conversion, (Ed. by A.V. Bridgwater J.L. Kuesler), pp, 609-628, Elsevier Applied Science Publishers, London and New York. 

Dieboid, J. Scahill, J. (1988) Production of primary pyrolysis oils in a vortex... 

DIEBOLD SCAHILL Production of Primary Pyrolysis Oils... 

Process development of the use of hydrogen as a radical quenching agent for the primary pyrolysis was conducted (37). This process was carried out in a fluidized-bed reactor at pressures from 3.7 to 6.9 MPa (540—1000 psi), and a temperature of 566°C. The pyrolysis reactor was designed to minimize vapor residence time in order to prevent cracking of coal volatiles, thus maximizing yield of tars. Average residence times for gas and soHds were quoted as 25 seconds and 5—10 rninutes. A typical yield stmcture for hydropyrolysis of a subbiturninous coal at 6.9 MPa (1000 psi) total pressure was char 38.4, oil... 

Heavy fuel oil Primary bioliquids (pyrolysis oil, hydrothermal liquefaction oil)... 

The quality of the product is of primary importance in developing a recycling technology converting plastics into fuels by pyrolysis. Today the characterization of a liquid fuel from any sources is obviously based on the qualification methods and standards of fuels from mineral oil. The properties of the pyrolysis-derived fuels from plastics are expected to be similar to conventional fuels (energy content, viscosity, density, octane and cetane number, flash-point, etc.). However, in addition to the familiar ranking values it is necessary to know more about the chemical composition of the plastic pyrolysis oil, because of the peculiarities as follows ... 

Table 6 Typical emission values for different oil grades at nominal fuel power of 4 MW. Combustion conditions total output 3.4 - 3.S MW, conq)res ed air used as atomisation medium of pyrolysis oil, oil tenqierature 48 - 58 "C, regulation of primary air 50%, regulation of secondary swirl S =0.7, primary air swirler 60°. Particles had been measured during a longer-term test cycle.

It s easy to say that the key to commercial implementation of biomass pyrolysis for tar production will be the identification of economically competitive technology for the production of higher-valued products. As the primary virtues of pyrolysis oils are those attributable to petroleum (liquid fuels and, under some pyrolytic conditionsi also olefins), it can be assumed that pyrolysis can become an avenue to petroleum-type products from renewable biomass. Is biomass pyrolysis, coupled with oil upgrading, the renewable route to petroleum Pyrolysis, after all, allows for the production of biomass-derived fuels in efficient-to-use petroleum forms. 

A vortex tube has certain advantages as a chemical reactor, especially if the reactions are endothermic, the reaction pathways are temperature dependent, and the products are temperature sensitive. With low temperature differences, the vortex reactor can transmit enormous heat fluxes to a process stream containing entrained solids. This reactor is ideally suited for the production of pyrolysis oils from biomass at low pressures and residence times to produce about 10 wt % char, 13% water, 7% gas, and 70% oxygenated primary oil vapors based on mass balances. This product distribution was verified by carbon, hydrogen, and oxygen elemental balances. The oil production appears to form by fragmenting all of the major constituents of the biomass. 

Vacuum pyrolysis Oil phase P.C.II. Primary Condensing Unit... 

High catalyst to biomass ratios are necessary to ensure all of the primary pyrolysis vapors are adsorbed on the catalyst surface. Otherwise the catalyst in the reaction zone can become deactivated before aU the primary pyrolysis vapors are reformed by the catalyst, resulting in the produced bio-oU being a mixture of catalytic pyrolysis oil and noncatalytic pyrolysis oil. This can also be the case for short vapor residence times that prevent sufficient contact time for the reactions on the catalyst surface to take place. The catalyst to biomass ratio can be expressed as the weight hourly space velocity (WHSV, h ), which is defined as the ratio of the mass flow rate of feed (g/h) to the mass of catalyst in the reactor (g). This is one of the most important parameters in... 

A breakdown of the mixed xylene supply sources in the United States is summarized in Table 1 (1). As shown in Table 1, the primary source of xylenes in the United States is catalytic reformate. In 1992, over 90% of the isolated xylenes in the United States were derived from this source. Approximately 9% of the recovered xylenes is produced via toluene disproportionation (TDP). In the United States, only negligible amounts of the xylenes are recovered from pyrolysis gasoline and coke oven light oil. In other parts of the world, pyrolysis gasoline is a more important source of xylenes. 

The primary sources of toluene and xylenes are reformates from catalytic reforming units, gasoline from catcracking, and pyrolysis gasoline from steam reforming of naphtha and gas oils. As mentioned earlier, solvent extraction is used to separate these aromatics from the reformate mixture. 

An olefin plant that uses liquid feeds requires an additional pyrolysis furnace, an effluent quench exchanger, and a primary fractionator for fuel oil separation. 

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