Preheat local

Naphtha desulfurization is conducted in the vapor phase as described for natural gas. Raw naphtha is preheated and vaporized in a separate furnace. If the sulfur content of the naphtha is very high, after Co—Mo hydrotreating, the naphtha is condensed, H2S is stripped out, and the residual H2S is adsorbed on ZnO. The primary reformer operates at conditions similar to those used with natural gas feed. The nickel catalyst, however, requires a promoter such as potassium in order to avoid carbon deposition at the practical levels of steam-to-carbon ratios of 3.5—5.0. Deposition of carbon from hydrocarbons cracking on the particles of the catalyst reduces the activity of the catalyst for the reforming and results in local uneven heating of the reformer tubes because the firing heat is not removed by the reforming reaction. 

Drying rotary oil- or gas-fired Particulates, SO2, NO, VOC, CO, and smoke Proper combustion controls, fuel-oil preheating where required local exhaust system, cyclone and a scrubber or baghouse... 

Economizer corrosion rates are enhanced by higher heat-transfer rates excessive heat flux may create localized nucleate boiling zones where gouging, as a result of chemical concentration effects, can occur. Air heaters are also located in the exit gas system. They do a job similar to that of economizers except that they preheat combustion air. 

Normally, after being heated, these streams are used in the boiler area (deaerator feedwater, cold return condensate, boiler feedwater, RO feedwater) or in the combustion chamber (air preheat). However, economizers can be used to recover and supply heat elsewhere, such as hot process water or hot utihty water, especially as used in the food processing and pulp/paper industries. Additionally, recovered flue gas waste heat can be used indirectly i.e., remote process streams can be heated locally with hot steam condensate, and then the cooled return steam condensate can be reheated in the flue gas economizer. An... 

Note that the temperature profile differs from the total heat profile because the heat per unit volume depends not only on the local temperature but also on the local density of the flame gas. In the preheat zone the profile of conducted heat coincides with the profile of total heat, whereas in the reaction zone the conducted heat gradually drops to zero. The difference between total heat and conducted heat represents the heat gained by chemical reaction. The volume integral of the total heat is approximately H, and the volume integral of the conducted heat is approximately H"... 

It is probably best to consume steam generated in small waste-heat boilers, locally, in steam reboilers and preheaters. Turbine drivers are... 

Gases are preheated, mixed, and fed downwards to the bed by a conical diffuser and baffle to assist uniform flow across the whole bed. Despite these precautions, localized hot spots form on the gauzes. Such hot spots vary in intensity and position and this phenomenon is termed flickering . 

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