Neutral Burning

Fig. 14.19 shows a typical set of pressure versus time curves obtained from tests on a rocket motor. When the I/D ratio defined in Fig. 14.19 is increased, the head-end chamber pressure is increased drastically immediately after the ignition stage. These grains are seven-pointed-star-shaped neutral-burning grains (diameter D = 114 mm), and are made of an AP-Al-CMDB propellant with the composition nc(0-25), ng(0-31), Ita(0-08), ap(0-27), and ai(0 09). The ratio of the initial burning surface area (Ayg) to the nozzle throat area (Aj), = AygjAp and the ratio of the... 

Neumann effect = hollow charge effect 283 neutral burning 221 Neuvalin = concentrated hydrogen peroxide... 

Neutral Burning — The configuration of the propellant grain is such that the rate of gas production is nearly constant over the period of burning. 

Lower flammability limit (LFL) Minimum ignition energy Molecular explosive Muzzle velocity Neutral-burning propellant Oxygen balance Percussive explosive Point of origin Primary explosive Primers... 

Hard-burned magnesias may be used in a variety of appHcations such as ceramics (qv), animal feed supplements, acid neutralization, wastewater treatment, leather (qv) tanning, magnesium phosphate cements, magnesium compound manufacturing, fertilizer, or as a raw material for fused magnesia. A patented process has introduced this material as a cation adsorbent for metals removal in wastewater treatment (132). 

After epoxidation, propylene oxide, excess propylene, and propane are distilled overhead. Propane is purged from the process propylene is recycled to the epoxidation reactor. The bottoms Hquid is treated with a base, such as sodium hydroxide, to neutralize the acids. Acids in this stream cause dehydration of the 1-phenylethanol to styrene. The styrene readily polymerizes under these conditions (177—179). Neutralization, along with water washing, allows phase separation such that the salts and molybdenum catalyst remain in the aqueous phase (179). Dissolved organics in the aqueous phase ate further recovered by treatment with sulfuric acid and phase separation. The organic phase is then distilled to recover 1-phenylethanol overhead. The heavy bottoms are burned for fuel (180,181). 

Chemical recovery ia sodium-based sulfite pulpiag is more complicated, and a large number of processes have been proposed. The most common process iavolves liquor iaciaeration under reduciag conditions to give a smelt, which is dissolved to produce a kraft-type green liquor. Sulfide is stripped from the liquor as H2S after the pH is lowered by CO2. The H2S is oxidized to sulfur ia a separate stream by reaction with SO2, and the sulfur is subsequendy burned to reform SO2. Alternatively, ia a pyrolysis process such as SCA-Bidemd, the H2S gas is burned direcdy to SO2. A rather novel approach is the Sonoco process, ia which alumina is added to the spent liquors which are then burned ia a kiln to form sodium aluminate. In anther method, used particulady ia neutral sulfite semichemical processes, fluidized-bed combustion is employed to give a mixture of sodium carbonate and sodium sulfate, which can be sold to kraft mills as makeup chemical. 

Stannic Oxide. Stannic oxide tin(IV) oxide, white crystals, mol wt 150.69, mp > 1600° C, sp gr 6.9, is insoluble in water, methanol, or acids but slowly dissolves in hot, concentrated alkaH solutions. In nature, it occurs as the mineral cassiterite. It is prepared industrially by blowing hot air over molten tin, by atomizing tin with high pressure steam and burning the finely divided metal, or by calcination of the hydrated oxide. Other methods of preparation include treating stannic chloride at high temperature with steam, treatment of granular tin at room temperature with nitric acid, or neutralization of stannic chloride with a base. 

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