Entrained flow

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. 

There are essentially three types of coal gasifiers moving-bed or countercurrent reactors fluidized-bed or back-mixed reactors and entrained-flow or plug-flow reactors. The three types are shown schematically in Eigure 2. 

Dow Goal Gasification Process. The Dow coal gasification process (Destec) is a two-stage, slurry feed, entrained-flow, slagging gasifier. 

The principal advance ia technology for SASOL I relative to the German Fischer-Tropsch plants was the development of a fluidized-bed reactor/regenerator system designed by M. W. Kellogg for the synthesis reaction. The reactor consists of an entrained-flow reactor ia series with a fluidized-bed regenerator (Fig. 14). Each fluidized-bed reactor processes 80,000 m /h of feed at a temperature of 320 to 330°C and 2.2 MPa (22 atm), and produces approximately 300 m (2000 barrels) per day of Hquid hydrocarbon product with a catalyst circulation rate of over 6000 t/h (49). 

J. P. Knapp and M. F. Doherty, "Minimum Entrainer Flows for Extractive Distillation. A Bifurcation Theoretic Approach," submitted to AIChE J. (1993). 

Continuous Cylindrical Surface The continuous surface shown in Fig. 6-48b is apphcable, for example, for a wire drawn through a stagnant fluid (Sakiadis, AIChE ]., 7, 26-28, 221-225, 467-472 [1961]). The critical-length Reynolds number for transition is Re = 200,000. The laminar boundary laver thickness, total drag, and entrainment flow rate may be obtained from Fig. 6-49 the drag and entrainment rate are obtained from the momentum area 0 and displacement area A evaluated at x = L. 

This entrained flow rate is normally many times the original flow race and it is the total flow rate that the receiving opening must be designed to exhaust. At the same time the entrained air must be available to both sides of the jet,... 

Nq is strongly dependent on the flow regime, Reynolds Number, N e, and installation geometi y of the impeller. The flow from an impeller is only that produced by the impeller and does not include the entrained flow, which can be a major part of the total motion flow from the impeller. The entrained flow refers to fluid set in motion by the turbulence of the impeller output stream [27]. To compare different impellers, it is important to define the t -pe of flows being considered. 

Combustion of coal may take place in conventional fixed beds using lump coal and in which temperatures up to 1 300°C may be reached by entrained flow in which pulverised coal is injected into the combustion zone with the air, reaching temperatures up to 1 500°C or in the more recently developed systems of fluidised-bed combustion, again using pulverised coal but with... 

The Texaeo Gasifieation proeess is a eontinuous, entrained flow, pressurised, non-eatalytie partial oxidation process in whieh earbonaeeous solids, liquids or gases reaet with oxygen. Gasification breaks the polymer ehains and eonverts the hydroearbons to their simplest forms. A detailed description is given of the proeess and its eommereial applieation. The proeess is a eommereially... 

The FCC process is used worldwide in more than 300 installations, of which about 175 are in North America and 70 in Europe. Figure 9.10 shows the principle of an FCC unit. The preheated heavy feed (flash distillate and residue) is injected at the bottom of the riser reactor and mixed with the catalyst, which comes from the regeneration section. Table 9.5 gives a typical product distribution for the FCC process. Cracking occurs in the entrained-flow riser reactor, where hydrocarbons and catalyst have a typical residence time of a few seconds only. This, however, is long enough for the catalyst to become entirely covered by coke. While the products leave the reactor at the top, the catalyst flows into the regeneration section, where the coke is burned off in air at 1000 K. 

Autothermal entrained-flow (EF) gasification, operated in a slagging or nonslagging mode... 

The company Noell in Germany, currently owned by Future Energy GmbH, has developed a down-fired entrained flow reactor (EFR). Instead of burners at the side of the reactor, this gasifier only consists of a single burner in the top part, which results in a simpler and lower cost reactor. Also, the control of this single burner is easier than the former types mentioned with a resulting lower capital and operational cost related. 

Bianchi An early entrained-flow coal gasification process. 

Bi-Gas [Bituminous Gas] A coal gasification process using a two-stage, entrained-flow slagging gasifier. Developed by Bituminous Coal Research. A 120-tons-per-day pilot plant was built in 1976 at Homer City, PA, under sponsorship from the U.S. Energy Research and Development Administration and the American Gas Association. 

Hitachi. This coal gasification technology is based on an oxygen-blown entrained flow gasifier, where the majority of experience has been gained in a 150 ton coal/day unit. The gasifier is a water-cooled tube that is lined by a high-temperature-resistant castable. Pulverized coal is pneumatically... 

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