Flame reactors

Inert combustion gases are injected directly into the reacting stream in flame reactors. Figures 23-22 and 22>-22d show two such devices used for maldng acetylene from light hydrocarbons and naphthas Fig. 23-22 shows a temperature profile, reaction times in ms. 

Heavy fuel oil feedstock is delivered into the suction of metering-type ram pumps which feed it via a steam preheater into the combustor of a refractory-lined flame reactor. The feedstock must be heated to 200°C in the preheater to ensure efficient atomisation in the combustor. A mixture of oxygen and steam is also fed to the combustor, the oxygen being preheated in a separate steam preheater to 210°C before being mixed with the reactant steam. 

T0377 Horsehead Resource Development Company, Inc., Flame Reactor T0378 HPT Research, Inc., Ionic State Modification (ISM) Process for the Treatment of Acid Mine Drainage... 

T0377 Horsehead Resource Development Company, Inc., Flame Reactor T0452 loule-Heated Vitrification—General... 

Flame reactor immobilizes metals into a nonhazardous, vitrified slag even at low metal... 

In general, the system requires that wastes contain less than 5% total moisture and with a particle size less than 200 mesh. Wastes must be transported to a stationary HRD facility for treatment. The HRD flame reactor system cannot treat mercury-containing wastes. 

An economic analysis of the HRD flame reactor technology was performed by the U.S. EPA using 12 separate cost categories. Based on the assumptions made in the economic analysis, the estimated cost for treating secondary lead soda slag (SLS) ranges from 208 to 932 per ton. 

The cost depends on the quantity of waste to be treated and the location of the site relative to the HRD treatment facility (D104596, pp. 2-3). Table 1 contains estimated costs associated with HRD flame reactor systems based on the following 12 EPA cost categories (D104596, p. 20) ... 

Comparative cost data in a 1994 American Academy of Environmental Engineers Report indicate HRD flame reactor treatment costs ranging from 215 per ton for SLS to 228 per ton for contaminated soil (D14632H, p. 2.14)... 

Figure 17.14. Some unusual reactor configurations, (a) Flame reactor for making ethylene and acetylene from liquid hydrocarbons [Patton et al., Pet Refin 37(li) 180, (1958)]. (b) Shallow bed reactor for oxidation of ammonia, using Pt-Rh gauze [Gillespie and Kenson, Chemtech, 625 (Oct. 1971)]. (c) Sdioenherr furnace for fixation of atmospheric nitrogen, (d) Production of acetic acid anhydride from acetic acid and gaseous ketene in a mixing pump, (e) Phillips reactor for low pressure polymerization of ethylene (closed loop tubular reactor), (f) Polymerization of ethylene at high pressure.

Effect of ion doping. Since (photo)-electronic processes are involved at the surface of titania, this oxide was modified by ion doping, both of p- and n-type, by dissolving either tri-(Ga3+, 3+) or pentavalent (Sb5+, V +) heterocations during the preparation by the flame reactor method (ref. 16), which produced homodispersed and homogeneously doped non-... 

A flame reactor is an excellent means for preparing pure or mixed oxides in the form of nonporous particles. The absence of porosity allows an average homogeneous irradiation of the particles. The morphologies (spheres, polyhedra) and the particle sizes (usually with a narrow distribution) can be mastered by adjusting the temperature, the flow rates (H2 and 02), and the concentration(s) of the compound(s) employed to generate the oxide. In the particular case of Ti02, anatase samples whose rutile content is very low can be produced. Consequently, the effect of the surface area S on the photocatalytic activity can be determined, in principle. 

Doping. Studies (52,53) have shown that if substitutional cationic doping at low levels is homogeneous, which can be achieved by the use of a flame reactor (see Sec. II.B.2, Particle Size ), it has a detrimental effect on the photocatalytic activity under UV irradiation. Furthermore, no activity is observed under irradiation in the visible spectral range in spite of an absorption by these samples. These observations regarding various reactions in different media have been attributed to electron-hole recombination at the site of the foreign cations (52,54). 

Acetylene may be produced from light hydrocarbons and naphthas by injecting inert combustion gases directly into the reacting stream in a flame reactor. Figure 19-13a and d shows two such devices Fig. 19-13 shows a temperature profile (with reaction times in milliseconds). 

FIG. 19-13 Noncatalytic gas-phase reactions, (a) Steam cracking of light hydrocarbons in a tubular fired heater, (b) Pebble heater for the fixation of nitrogen from air. (c) Flame reactor for the production of acetylene from hydrocarbon gases or naphthas. [Patton, Grubb, and Stephenson, Pet. Ref. 37(11) 180 (1958).] d Flame reactor for acetylene from light hydrocarbons (BASF), (e) Temperature profiles in a flame reactor for acetylene (Ullmann Encyclopadie der Technischen Chemie, vol. 3, Verlag Chemie, 1973, p. 335). 

SiCl4 is vaporized, mixed with dry air and hydrogen and then fed into a flame reactor. The SiCl4 hydrolyzes to Si02 and HC1 under the influence of the oxyhydro-gen reaction, which includes the formation and reaction of radicals. 

Fig. 5.13. Acetylene manufacture by autothennal combustion of hydrocarbons. Scheme of the submerg l flame reactor.

FIGURE 7.1 Reactor configuration for gas phase reactors (a) Flame reactor, (b) furnace reactor, (c) laser reactor, (d) radio frequency (RF) plasma reactor, (e) direct current (dc) plasma reactor. 

The advantages of flame reactors are tiiese h h purity gases can be used to produce a high purify solid product simplicity of reactors scale up has been demonstrated for carbon black, silica, and titania a laige range of particle diameters has been demonstrated. The disadvan-... 

In the production of ceramic TiOa powder in a flame reactor, a gas after mixing consisting of 1.0 moles/sec TiCl4, 8.0 moles/sec N2, and... 

---