Catalyst dust

Typical applications in the chemical field (Beaver, op. cit.) include detarring of manufactured gas, removal of acid mist and impurities in contact sulfuric acid plants, recovery of phosphoric acid mists, removal of dusts in gases from roasters, sintering machines, calciners, cement and lime Idlns, blast furnaces, carbon-black furnaces, regenerators on fluid-catalyst units, chemical-recoveiy furnaces in soda and sulfate pulp mills, and gypsum kettles. Figure 17-74 shows a vertical-flow steel-plate-type precipitator similar to a type used for catalyst-dust collection in certain fluid-catalyst plants. 

After the reactor, a filter protects the flow controller from any catalyst dust. Caution must be applied because, if significant catalyst dust collects, results can be ruined even if the filter is at a lower temperature than the reactor. The flow controller also indicates the volumetric flow of the experiment. To operate properly, the flow controller needs a minimum 5 psig pressure at the gauge before the controller. This is important at low pressure experiments. 

In addition, a significant amount of fine catalyst dust is produced in FCCUs as a result of the constant movement of the catalyst grains against each other. Much of this dust, consisting primarily of alumina and relatively small amounts of nickel, is carried with the carbon monoxide strewn to the carbon monoxide burner. 

The catalyst dust is then separated from the resulting carbon dioxide stream via cyclones and/or electrostatic precipitators and is sent off-site for disposal or treatment. Generated wastewater is typically sour water from the fractionator containing some oil and phenols. Wastewater containing metal impurities from the feed oil can also be generated from the steam used to purge and regenerate catalysts. 

Catalytic Hydrocracking Heater stack gas (CO, SO, NO, hydrocarbons and PM), fugitive emissions (hydrocarbons) and catalyst regeneration (CO, NO, SO, and catalyst dust). 

Dust explosions (ASTM E789) that can occur during catalytic reactor shutdown and cleaning are due to the production of finely divided solids through attrition. Many catalyst dusts can bum explosively in air. Thus, control of dust generated by catalyst attrition is essential (Mody and Jakhete, 1988). 

Wind (aeolian) transport (relocation by wind) can also occur and is particularly relevant when catalyst dust and coke dust are considered. Dust becomes airborne when winds traversing arid land with httle vegetation cover pick up small particles such as catalyst dust, coke dust, and other refinery debris and send them skyward. Wind transport may occur through suspension, saltation, or creep of the particles. 

The catalyst dust is highly reactive and may cause a violent explosion when pipes or heat exchangers are opened for maintenance. 

Ignition of hydrogen leaking from a hydrogenation autoclave stirrer gland was attributed to traces of hydrogenation catalyst dust outside the reactor. 

In early July 1991, local newspapers provided detailed accounts of the vessel rupture mechanism. The large vertical pressure vessel that catastrophically ruptured was called an F-7 Slurry Drum, and its function was to separate heavy oil and catalyst dust. Newspapers... 

After a new catalyst charge is installed in an upstream unit, catalyst dust may be carried over into the column and induce foaming. Measures for preventing this should be considered. 

Oxides, smoke, oil, metal fumes, dust Smoke, metal fumes, oil, grease Catalyst dust, ash from sludge... 

The Catoxid catalyst is robust and is compatible with the oxychlorination reaction. Catalyst makeup is required only for attrition losses. The catoxid catalyst dust moves through the oxychlorination fluid bed reactor and leaves the system with the oxy catalyst fines. 

Any catalyst dust formed by attrition and lost in the cyclones has to be replaced at regular intervals. It is also necessary to replace a small proportion of the circulating equilibrium catalyst to compensate for gradual permanent deactivation and maintain conversion. About 3% of fresh catalyst is added to a imit on a daily basis to maintain the necessary catalyst inventory. The whole operation is continuous and a unit may be operated for several years without shut down. An important feature of the process is that heat transferred from the regenerator to the reactor by the hot catalyst as a heat transfer agent is an integral part of the energy balance. 

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