Process vacuum distillation unit

Atmospheric and vacuum distillation units (Figures 4.3 and 4.4) are closed processes, and exposures are expected to be minimal. Both atmospheric distillation units and vacuum distillation units produce refinery fuel gas streams containing a mixture of light hydrocarbons, hydrogen sulfide, and ammonia. These streams are processed through gas treatment and sulfur recovery units to recover fuel gas and sulfur. Sulfur recovery creates emissions of ammonia, hydrogen sulfide, sulfur oxides, and nitrogen oxides. 

Product distribution focuses on middle distillates (Table 9-15 Figure 9-24) with the process focused as a resid processing unit and inserted into a refinery just downstream from the vacuum distillation unit. 

Well over 50 large-scale EO model-based RTO applications have been deployed for petroleum refining processes. These model applications have been deployed in petroleum refineries Liporace et al., 2009 Camolesi et al., 2008 Mudt et al., 1995, both on separation units (crude atmospheric and vacuum distillation units) and on reactor units (including fluidized catalytic crackers (FCC), gasoline reformers, and hydrocrackers). 

While originally designed for cracking the overhead stream from vacuum distillation units, known as vacuum gas oil (4), most FCC units currently operate with some higher boiling vacuum distillation bottoms (Resid) in the feed. Table 5.1 illustrates the difficult challenges faced by refiners, process licensors and FCC catalysts producers the resid feeds are heavier (lower API gravity), contain many more metals like Ni and V as well as more polyaromatic hydrocarbons prone to form coke on the catalysts (Conradson Carbon Residue, or CCR). 

The process specifications on raw material speed through furnaces coils imposed the use of two or four parallel passes, e.g. the fumaees from the atmospherie distillation unit, vacuum distillation unit, catalytic reforming unit, coker unit, catalytic cracking unit. The conventional control structure of radiant section for a typical tubular furnace from the atmospheric distillation unit (output capacity 3.5 Mt/year) is presented in figure 1 [1]. Because the conventional temperature control system only controls one outlet temperature or in the best case the temperature of the mixing point, in current operations there are several situations [1, 2, 3] ... 

The current oil sands bitumen upgrading processes for the production of synthetic crude oil (Table 4) begin with diluted bitumen being processed through the diluent recovery units. The diluent recovery units are atmospheric distillation units that serve three purposes 1) distill off diluent naphtha and return it to the froth treatment process 2) distill off light gas oil and send it directly to a light gas oil hydrotreater and 3) produce hot atmospheric topped bitumen as feedstock for vacuum distillation unit and downstream bitumen conversion processes. 

Middle distillates are withdrawn and brought up to specification with separate processes, e.g., hydrodesulfurization. The heavy oil from the bottom of the crude unit can be used for oil blending or can be processed further in vacuum distillation units to recover a light distillate, used in blending diesel oils. 

Cmde is distilled and the bottoms, atmospheric resid, is sent to a vacuum distillation unit (VDU) sometimes called a vacuum pipestill (VPS) for further fractionation. Vacuum fractionation is used to separate the atmospheric resid into several feed streams or distillates. Conventional solvent processing uses selected solvents in physical processes to remove undesirable molecules... 

Crude oil was first distilled in batch distillation, like a lab technique, beginning in the 1850s. Advancements were made by increasing the size of the batch vessel. A continuous process was developed by using a series of batch stills - called a battery. The first continuous pipestill appeared in the 1920s and the modem pipestill came on the scene in the 1930s. A typical lube vacuum distillation unit is shown below (Fig 6). 

As shown in Figure 1, hydrocracking often is an in-between process. The required hydrogen comes from catalytic reformers, steam/methane reformers or both. Liquid feeds can come from atmospheric and/or vacuum distillation units delayed cokers fluid cokers visbreakers or FCC units. Middle distillates from a hydrocracker usually meet or exceed finished product specifications, but the heavy naphtha from a hydrocracker usually is sent to a catalytic reformer for octane improvement. The fractionator bottoms can be recycled or sent to an FCC unit, an olefins plant, or a lube plant. 

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