Crude units

FIG. 13-87 Crude unit with atmospheric and vacuum towers. [Kleinsch7 odt and Hammer, Exchange Networks for Cixide Units . Chem. Eng. Prog., 79(7),. 3.3 (1983).]... 

FIG. 13-92 Methods of providing reflux to crude units, a) Top reflux, (h) Pump-back reflux, (c) Pump-around reflux. 

Tray requirements depend on internal-reflux ratios and ASTM 5-95 gaps or overlaps, and may be estimated by the correlation of Paclde (op. cit.) for crude units and the correlation of Houghland, Lemieux, and Schreiner (op. cit.) for main fractionators. 

FIG. 13-94 Configuration and conditions for the simulation of the atmospheric tower of crude unit. 

The crude unit is the first unit in the refining process. Here, the raw crude is distilled into several intermediate products naphtha, kerosene, diesel, and gas oil. The heaviest portion of the crude oil,... 

Huang F and Elshout RV (1976) Optimizing the Heat Recover of Crude Units, Chem Eng Prog, 72 68. 

Economic analysis performed for refineries in certain markets have calculated that the benefit of being able to increase kerosene and jet fuel production yield was an improvement of 3-6 cents per barrel over previous operational conditions. On an 180000 barrel per day crude unit this equates to a benefit of 2000000-4000000 per year. Several other refiners are utilizing NMR analyzers on the feed and products of crude units for control and optimization, AGIP has an NMR analyzer for monitoring the feed. 

R. Seshadri, A. Offerman, J. Cijntje, R. McFarlane, and V. Longh, Optimization of a refinery crude unit. Pet. Tech. Q., 1-7, Winter 2002. 

Fires involving hydrocarbons, e.g., hot oil pumps in crude units... 

The Tosco incident illustrates the importance of safe work practices and, in particular, the need to provide strong principled leadership in the field. Over the past few years, the quality of raw feedstock had varied and problems had heen reflected in the operation of the chemical desalter. Consequently, a marked deterioration in quality was noted in the crude unit operation. Before 1999, a number of serious incidents had occurred at the rehnery, some of which involved fatalities. The refinery had also undergone several recent personnel changes. 

Wastewater reuse is a good way to reduce overall pollutant loadings. However, water quality is critical in water reuse. The contaminants present must be compatible with the reuse. For example, reuse waters with high solids content are not satisfactory for crude unit desalting. Stripped foul water containing low H2S and ammonia and high concentrations of phenols has essentially no solids. It is suitable for crude unit desalter wash water if the phenols extracted by the crude are subsequently converted by hydroprocessing units into nonphenolic compounds [36]. Some other examples include ... 

The atmospheric crude unit separates crude oil into several fractions including LPG, naphtha, kerosene, gas oil and residues. The heavy residues are then sent to the vacuum unit where they are further separated into vacuum gas oil and vacuum... 

Install Storage Tank Agitators on Crude Oil Tanks. Agitation of the vessel contents prevents the deposit of settleable solids and hence reduces the need for cleaning. It must be noted that agitation does not be itself reduce the amount of waste generated it simply transfers the solids downstream to the crude unit - they eventually end-up either in asphalt or coke. 

Our crude unit heater is very old we have to operate it manually. We have three air blowers to produce the combustion air we always run two with one on standby. Once a week we switch the blowers by shutting one down and turning on the one that was idle. 

Fractionation of petroleum in the refinery, to obtain streams with specific boiling ranges for various downstream processes, is performed by distillation in a crude unit. To determine how Ni and V compounds are distributed as a function of boiling point is, therefore, useful for evaluating their impact in the refinery. Petroleum may also be fractionated by solvent separation and chromatography to obtain more detailed information on the distribution of Ni and V compounds. This section will review the available literature on how metals are distributed in petroleum by boiling point and solubility class. It will also include some discussion of the structure of heavy oil in general and asphaltenes in particular. Vercier etal. (1981) have provided an excellent review of methods and procedures involved in petroleum fractionations. 

If a 100,000 heat exchanger is to be added to an existing crude unit, the cost of installing it will normally be far less than the 230,000 calculated from Table 8.2. This is because the sewers, control room, and instrument loops are already in place. The foundation, piping, and insulation of the exchanger might cost 80,000 to 160,000. It is simply not possible to estimate an installed cost of one or two items of process equipment without considering each case on an individual basis. 

Crude unit with both atmospheric and vacuum distillation, 200,000 BSD 96... 

To preserve their properties for downstream processing or product blending, the distillation cuts from each crude unit activity enter separate and distinct stream balance rows. 

Corrosion rates of steel in a crude unit secondary tower overhead. 19... 

For convenience, the discussion of materials for these various processes is divided into five chapters. Crude units and utilities are discussed in this chapter. FCCs, fluid cokers, delayed cokers, sour water strippers, and sulfur plants are covered in Chapter Two. Desulfurizers, reformers, hydrocrackers, and flue gas are discussed in Chapter Three. Hydrogen plants, methanol plants, ammonia plants, and gas treating are discussed in Chapter Four. Underground piping, pipelines, production equipment, and tankage associated with the refinery industry are covered in Chapter Five. Discussed throughout these chapters are many common environments and equipment (e.g., sour or foul water, distillation, etc.) that appear in the various types of refinery process plants. 

The initial corrosion control system used in a crude unit is a desalter. Modern desalters separate oil and water electrostatically. The internals used to accomplish electrostatic separation are normally of a proprietary design. The vessel itself is usually carbon steel. The bottom is often cement lined to protect it from salt water corrosion. The payout on a desalter is difficult to establish. Desalters are normally used when the salt content of the crude exceeds 20 lb per 1,000 barrels (ptb). When high reliability of the unit is desired, crudes with salt contents of 8 to 10 ptb are desalted. When desalting is used, the target is 1 ptb or less. Fluctuations in salt content are particularly troublesome to the downstream equipment therefore, the desalter should be designed for the maximum anticipated salt content. 

Reprinted with permission from Crude Unit Overhead Corrosion," Hydrocarbon Processing, May 1972, Gulf Publishing Co., Houston, TX.)... 

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