Gas combustion

Quartz Tube Method the sample is burned in a quartz tube and a stream of purified air carries the combustion gases into a hydrogen peroxide solution. 

The sample is pyrolyzed in an 80/20 mixture of oxygen and nitrogen at from 1050 to 1100°C the combustion gases are analyzed by iodine titration or by UV fluorescence. Up to 20% of the sulfur can escape analysis, however. 

An aerosol is a suspension of either a solid or a liquid in a gas. Fog, for example, is a suspension of small liquid water droplets in air, and smoke is a suspension of small solid particulates in combustion gases. In both cases the liquid or solid particulates must be small enough to remain suspended in the gas for an extended time. Solid aerosol particulates, which are the focus of this problem, usually have micrometer or submicrometer diameters. Over time, solid particulates settle out from the gas, falling to the Earth s surface as dry deposition. 

A 101.3-mg sample of an organic compound known to contain Cl is burned in pure O2 and the combustion gases collected in absorbent tubes. The tube used to trap CO2 increases in mass by 167.6 mg, and the tube for trapping H2O shows a 13.7-mg increase. A second sample of 121.8 mg is treated with concentrated HNO3 producing CI2, which subsequently reacts with Ag+, forming 262.7 mg of AgCl. Determine the compound s composition, as well as its empirical formula. 

Volatilization gravimetric methods are time- and labor-intensive. Equipment needs are few except when combustion gases must be trapped or for a thermogravi-metric analysis, which requires specialized equipment. 

At Lake Texcoco, Mexico, bicarbonate is available in the alkaline waters from soda ash [497-19-8] (sodium carbonate) deposits (see Alkali and CHLORINE products). This supply of carbon is adequate for growing Spirulina maxima which tolerates alkaline pH values in the range 9—11 (37,38). Combustion gases have been used to grow this organism, but this carbon source is not available in many regions (49). 

A furnace may be dkect-fired or indkect-fired. The indkect-fired is known as a muffle furnace, and in such furnaces the combustion gases are separated from the stock being heated to prevent contamination. 

Flame or Partial Combustion Processes. In the combustion or flame processes, the necessary energy is imparted to the feedstock by the partial combustion of the hydrocarbon feed (one-stage process), or by the combustion of residual gas, or any other suitable fuel, and subsequent injection of the cracking stock into the hot combustion gases (two-stage process). A detailed discussion of the kinetics for the pyrolysis of methane for the production of acetylene by partial oxidation, and some conclusions as to reaction mechanism have been given (12). 

The first of these reactions takes place at temperatures of about 150°C, the second reaction proceeds at about 550—660°C. Typical furnaces used to carry out the reaction include cast-iron retorts the Mannheim mechanical furnace, which consists of an enclosed stationary circular muffle having a concave bottom pan and a domed cover and the Laury furnace, which employs a horizontal two-chambered rotating cylinder for the reaction vessel. The most recent design is the Cannon fluid-bed reactor in which the sulfuric acid vapor is injected with the combustion gases into a fluidized bed of salts. The Mannaheim furnace has also been used with potassium chloride as the feed. 

In a radiation dominated kiln environment, with hot combustion gases and reradiating walls, the characteristic time is... 

Undesirable combustible gases and vapors can be destroyed by heating to the autoignition temperature in the presence of sufficient oxygen to ensure complete oxidation to CO2 and H2O. Gas incinerators are appHed to streams that are high energy, eg, pentane, or are too dilute to support combustion by themselves. The gas composition is limited typicaUy to 25% or less of the lower explosive limit. Gases that are sufficiendy concentrated to support... 

The Megalopohs station (Fig. 4d) uses hot flue gas to dry the lignite. A cyclone separator and electrostatic precipitator permit rejection of some of the water vapor to the atmosphere rather than to the boiler. Another drying method uses a vertical shaft, heated by combustion gases, for partial drying prior to grinding. 

Referring back to equation 47, the other quantity necessary in calculating the gas conductivity is the coUision cross section, Gases contain at least four types of particles electrons, ionized seed atoms, neutral seed atoms, and neutral atoms of the carrier gas. Combustion gases, of course, have many more species. Each species has a different momentum transfer cross section for coUisions with electrons. To account for this, the product nQ in equation 47 is replaced by the summation where k denotes the different species present. This generalization also aUows the conductivity calculation to... 

The plant is designed to satisfy NSPS requirements. NO emission control is obtained by fuel-rich combustion in the MHD burner and final oxidation of the gas by secondary combustion in the bottoming heat recovery plant. Sulfur removal from MHD combustion gases is combined with seed recovery and necessary processing of recovered seed before recycling. 

The steam generator is a balanced draft, controlled circulation, multichamber unit which incorporates NO control and final burnout of the fuel-rich MHD combustion gases. The MHD generator exhaust is cooled in a primary radiant chamber from about 2310 to 1860 K in two seconds, and secondary air for afterburning and final oxidation of the gas is introduced in the secondary chamber where seed also condenses. Subsequent to afterburning and after the gas has been cooled down sufftciendy to soHdify condensed seed in the gas, the gas passes through the remaining convective sections of the heat recovery system. 

Low Level Waste Treatment. Methods of treatment for radioactive wastes produced in a nuclear power plant include (/) evaporation (qv) of cooling water to yield radioactive sludges, (2) filtration (qv) using ion-exchange (qv) resins, (J) incineration with the release of combustion gases through filters while retaining the radioactively contaminated ashes (see Incinerators), (4) compaction by presses, and (5) solidification in cement (qv) or asphalt (qv) within metal containers. 

Hot combustion gases are quenched and saturated with water in a spray chamber called a hydrator. An absorber bed of carbon or graphite rings may be mounted above the hydrator in the same stmcture to obtain more complete absorption of P40 q and to assure that the gas stream is cooled to about 100°C. Weak acid from mist collection is sprayed on the absorber bed, and product acid at 75—85% H PO leaves the hydrator through a heat exchanger. 

M. G. Zabetakis, Flammability Characteristics of Combustible Gases and Vapors, Bulletin 627, U.S. Bureau of Mines, Washington, D.C., 1965. 

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