Travelling grates

Indurating grates differ from sintering grates in the following ways  

Some characteristics of a modern travelling grate iron ore pelletizing machine [7]. 

Hearth layer (screened product) bottom (thickness) sides (thickness) 

Initial green ball depth Fuel consumption 

Process design factors for iron ore pelletizing machines [8]. Factors are based on effective areas. 

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Fig. 4. Multiphase fluid and fluid—solids reactors (a) bubble column, (b) spray column, (c) slurry reactor and auxiUaries, (d) fluidization unit, (e) gas—bquid—sobd fluidized reactor, (f) rotary kiln, and (g) traveling grate or belt drier.

The traveling-grate furnace requires less labor, increases the output per unit of grate area, and produces more uniform product than the WetheriU. furnaces. The traveling grate is an endless chain of cast-iron bars, driven by sprockets, which traverses a firebrick chamber. Anthracite briquettes are fed to a depth of ca 15 cm. After ignition by the previous charge, the coal briquettes are covered by 15—16.5 cm of ore/coal briquettes. The latter are dried with waste heat from the furnace. Zinc vapor evolves and bums in a combustion chamber and the spent clinker faUs into containers for removal (24,25). 

The machine most commonly used for sintering iron ores is a traveling grate, which is a modification of the Dwight-Lloyd continuous sintering machine formerly used only in the lead and zinc industries. Modern sintering machines may be 4 m (13 ft) wide by 60 m (200 ft) long and have capacities of 7200 Mg/day (8000 tons/day). 

Heat hardening of green iron-ore pellets is accomplished in a vertical shaft furnace, a traveling-grate machine, or a grate-plus-ldln combination (see Ball et al., op. cit.). 

Excess air is usually 30 to 40 percent for stationary and dumping grates, while traveling grates are operated with from 22 to 30 percent excess air. Preheated air can be supplied for all types of grates but the temperature is usually limited to 395 to 422 K (250 to 300°F) to prevent excessive slagging of the fuel bed. 

Continuous-discharge spreader Dump-grade spreader Overfeed traveling grate... 

Wander-rost, m. traveling grate, -sand, m. shifting sand, -schaft, /. traveling, travels, tour, -st ke, /. translocatory starch. -tier n. migratory animal. 

The chamber is externally insulated and clad. Combustion equipment for solid fuel may be spreader or traveling-grate stokers or by pulverized fuel or fluid bed. Oil and gas burners may be fitted either as main or auxiliary firing equipment. The boilers will incorporate superheaters, economizers and, where necessary, air preheaters, grit arresters, and gas-cleaning equipment to meet clean air legislation. 

This is a very versatile stoker common in shell boilers and is used with modification in watertube boilers as the traveling-grate stoker. In shell boilers, the air supply is via forced- and induced-draft fans in combination with a balanced or slightly negative condition in the furnace. 

Chain grate stoker (traveling grate stoker) ... 

The roasting process mostly applied to sulfidic sources is carried out in appliances of different types with different design features. Without describing their features and constructional details, it may simply be mentioned here that some of the widely acclaimed roasting units are traveling grate furnaces, multiple hearth furnace, rotary kilns, and fluid-ized-bed roasters. 

The pot furnace was constructed so that the radiant heat flux, which would prevail at the top of the fuel bed in a traveling grate stoker or incinerator, could be simulated under batch conditions. The burning rates could be determined by measuring the weight loss of the fuel bed as a function of time. The pot was constructed in two sections (Figure 1)- the overbed section (combustion system) and the fuel bed section (conversion system). Secondary air (overfire air) was supplied at a number of... 

Figure 57 An idealised stationary bed process structure of a crosscurrent configuration on a travelling grate. [12]...

In water-wall incineration, unprocessed municipal solid residues is loaded into the incinerator and burned on traveling grates. Low pressure and temperature (4 MPa, 260°C) steam is produced. 

Magnetite ore Feed to travelling grate — indurating section... 

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