Direct flame incineration

Catalytic Incinerators. Catalytic incinerators, often used to remove hydrocarbons from exhaust gas streams, are more compact than direct-flame incinerators, operate at lower temperatures, often require Htfle fuel, and produce Httle or no NO from atmospheric fixation. However, the catalytic bed must be preheated and carefliUy temperature controlled. Thus these are generally unsuited to intermittent and highly variable gas flows. 

Direct-Flame Incinerators. In direct-flame incineration, the waste gases are heated in a fuel-fired refractory-lined chamber to the autoignition temperature where oxidation occurs with or without a visible flame. A fuel flame aids mixing and ignition. Excess oxygen is required, because incomplete oxidation produces aldehydes, organic acids, carbon monoxide, carbon soot, and other undesirable materials. 

I he direct-flame incinerator is the simplest type of thermal oxidation system. It comprises a combustion chamber and supplementarv fuel-injection system with no energy-recovery equipment. Direct-flame incineration is suitable only for gases that support combustion without requirements for auxiliary fuel (concentrated streams) or for intermittent use. 

Direct flame incineration A fume control device in which organic pollutants in the waste gas stream are oxidized to form nonpolluting by-products. 

A catalytic afterburner, in which the surface action of catalysts allows incineration to take place at a temperature lower than a direct flame, reducing the auxiliary heat required, or... 

Ash.—10 grams of the starch are charred over a direct flame and then incinerated in a muffle at a dull red heat... 

For those processes producing contaminated gas streams that have no recovery value, incineration may be the most acceptable route when the gas streams are combustible. There are presently two methods in common use direct flame and catalytic oxidation. The former usually has lower capital-cost requirements, but higher operating costs, particularly if an auxiliary fuel is required. Either method provides a clean, odorless effluent if the exit-gas temperature is sufficiently high. 

The reviews by Spivey [3] and by Jennings et al. [156] are excellent sources for further details on catalytic incineration of volatile organics emissions. Spivey [3] describes two types of techniques for removal of VOC from off-gases, namely one without preheater and one with a direct flame preheater. From an economically point of view it is more beneficial to carry out the catalytic oxidation at lower temperatures. In a catalytic incinerator, sometimes called an afterburner, VOCs are oxidized into carbon dioxide and water. The efficiency is about 70-90%. The incinerator has a preheat burner, a mixing chamber, a catalyst bed, and a heat recovery equipment. Temperatures of about 590 K are sirfficient for the destruction of VOCs. Various catalyst geometries have been used metal ribbons, spherical pellets, ceramic rods, ceramic honeycombs, and metal honeycombs. Precious metals such as platinum and palladium are often used in catalytic incinerators. 

Three rapid oxidation methods are typically used to destroy combustible contaminants (1) flares (direct-flame-combustion), (2) thermal combustors, and (3) catalytic combustors. The thermal and flare methods are characterized by the presence of a flame during combustion. The combustion process is also commonly referred to as afterburning or incineration. ... 

Two basic methods of odor control are applied to emissions from dryers after condensing the water vapor boiler incineration by direct-flame oxidation and wet scrubbing by chemical oxidation or the use of other scrubbing agents. Incineration provides the most positive control of nuisance-causing odorous compounds. Chlorinator scrubbers have been found to be 95%-99% effective in controlling odors from fish cookers and dryers [99]. Table 53.26 shows the odor reduction obtained by boiler incineration. 

Combustion Incineration Combustion incinerators use oxidation to convert gases and vapors into less harmful material. However, not all gases and vapors end up in a harmless form. Combustion may involve direct flame or catalytic combustion. For some gases and vapors, efficiencies may reach 98%. 

Salts (Ash).—In a platinum dish, 10-20 grams of the juice are evaporated, the residue being moistened with a few drops of concentrated sulphuric acid, heated gently over a small flame until the mass chars and then in direct contact with the flame or in a muffle to complete incineration, care being taken not to heat sufficiently to fuse the ash. The weight of the sulphated salts thus obtained is diminished by one-tenth and calculated as a percentage. 

WEEE has had a direct affect on flame-retardant use, because flame retardants are used in almost all electrical and electronic equipment to prevent fires from short circuits. This directive lays down rules for disposal and recycling of all electrical and electronic equipment that goes back to the previous incinerator discussion. For flame retardants, this directive affects how the plastic parts, cable jackets, and enclosures are flame retarded. If the plastic cannot be reground and recycled, it must go to the incinerator, in which case it cannot form toxic by-products during incineration. This has led to the rapid deselection of brominated FR additives in European plastics that are used in electronics, or the complete removal of FR additives from plastics used in electronics in Europe. This led, in turn, to increases in electrical fires in Europe, and now customers and fire-safety experts demand low environmental impact and fire safety. However, the existing nonhalogen flame-retardant solutions brought in to replace bromine have their own balance-of-property issues, and so research continues to develop materials that can meet WEEE objectives. 

Many cremation facilities of the 1870s were as yet very unreliable and costly to operate - some had cremation times of up to 5-6 hours per corpse -, so that some were tom down again after just a few cremations. But much better capacities and fuel efficiencies were quickly reached The Gorini oven at Riolo, for instance, which started operation on September 6, 1877, needed only 100-150 kg (220-330 lbs) and 1.5-2h per corpse. The oven by Toisoul and Fradet needed ca. 100 kg and just one hour per corpse.25 In these ovens, the body was directly exposed to the flames, which were produced either by the incineration of the fuel or by combustion of the fuel gases from the gas generator. 

DISPOSAL AND STORAGE METHODS dilute solutions and discharge directly into sewage treatment facilities spray into incinerator or bum in paper packaging storage should be away from heat, sparks, and open flames. 

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