Vortex reactor

Thermochemical Liquefaction. Most of the research done since 1970 on the direct thermochemical Hquefaction of biomass has been concentrated on the use of various pyrolytic techniques for the production of Hquid fuels and fuel components (96,112,125,166,167). Some of the techniques investigated are entrained-flow pyrolysis, vacuum pyrolysis, rapid and flash pyrolysis, ultrafast pyrolysis in vortex reactors, fluid-bed pyrolysis, low temperature pyrolysis at long reaction times, and updraft fixed-bed pyrolysis. Other research has been done to develop low cost, upgrading methods to convert the complex mixtures formed on pyrolysis of biomass to high quaHty transportation fuels, and to study Hquefaction at high pressures via solvolysis, steam—water treatment, catalytic hydrotreatment, and noncatalytic and catalytic treatment in aqueous systems. 

Ultrafast pyrolysis in the vortex reactor is capable of pyrolyzing biomass at high heat-transfer rates on the reactor wall by ablation and has been... 

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. 

This chapter describes the initial results of converting waste sawdust into phenolics through fast pyrolysis employing a vortex reactor and a very fast heat transfer to depolymerize biomass into monomeric and oligomeric components. The pyrolysis method and the chemical fractionation employed to isolate the phenolic-rich fraction used in the subsequent adhesive gel testing are described. Results of an economic evaluation of the process are presented as well as the characterization of the phenolic-rich material. A novolak and a resol were successfully prepared with these compounds. 

Fractionation of Pyrolysis Oils. Pyrolysis oil obtained from the vortex reactor was fractionated according to the scheme shown in Figure 3. Whole oil (1 kg) was dissolved in ethyl acetate (EA) on a 1 1 (w/w) basis. The oil was then vacuum filtered through filter paper to remove fine char. Upon standing, the EA/pyrolysis oil separated into two phases-an organic rich, EA-soluble phase and an EA-insoluble phase. Most of the water formed during pyrolysis is contained in the EA-insoluble phase. The EA-soluble portion of the oil was washed with water (2 x 75 mL) to remove the remaining water-soluble derived products. 

Much of the pioneering work on ablative pyrolysis reactors was performed by CNRS at Nancy where extensive basic research has been carried out onto the relationships between pressure, motion and tenperature (23). NREL developed an ablative vortex reactor (see Figure 6 and (14)), in which the biomass is accelerated to supersonic velocities to derive high tangential pressures inside a heated cylinder. Unreacted particles are recycled and the vapours and char fmes leave the reactor axially for collection. Liquid yields of 60 65%wt. on dry feed basis are typically obtained. 

Diebold JP, Czernik S, Scahill JW, Philips SD and Feik CJ. Hot-gas filtration to remove char from pyrolysis vapours produced in the vortex reactor at NREL , in Milne, TA, editor. Biomass I Tolysis Oil Properties and Combustion Meeting, NREL, 1994, p. 90-108. 

Contactors in which gas is dispersed into the liquid phase Plate columns (including control cycle reactors) Mechanically agitated reactors (principally stirred tanks) Bubble columns Packed bubble columns Sectionalized bubble columns Two-phase horizontal contactors Cocurrent pipeline reactors Coiled reactors Plunging jet reactors, ejectors Vortex reactors... 

Taylor Vortex Reactor (TVR) Suspended Karpel et al., 1997 Sczechowski et al., 1995a. 

FIGURE 2.2. Taylor vortex reactor in operation (Reprinted from Chem. Eng. Sci.., 50(20), J.G. Sczechowski, C.A. Koval and R.D. Noble, A taylor vortex reactor for heterogeneous photocatalysis, pp. 3163-3173, Copyright 1995, with permission from Elsevier)... 

Diebold, J.P. Scahill, J.W. "Production of primary pyrolysis oils in a vortex reactor." In This Volume. 

Production of Primaiy Pyrolysis Oils in a Vortex Reactor... 

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. 

Figure 2. Vortex Reactor Schematic. (Reproduced with permission from ref. 19. Copyright 1985 Solar Energy Research Institute.)...

As noted above, the primary vapors are cracking significantly even at 500°C and a residence time of half a second. If the recycle loop of the vortex reactor is removed, the yield of permanent gases is about 4%, based on the reacted feed. The initial gases, which are formed under these conditions, are... 

The concept of supplying heat through the wall of a vortex reactor to drive endothermic processes is in its early development. The scale-up potential of this concept depends upon the angular... 

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