Crude unit process equipment

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. 

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. 

Process lines (a) which interconnect nozzles on process equipment more than 20 feet apart (closer process equipment can be directly connected by pipe lines) (b) product lines which run from vessels, exchangers or more often from pumps to the unit limits, to storage or header arrangement outside the plant (c) crude or other charge lines which enter the unit and usually run in the yard before connecting to exchangers, furnaces or to other process equipment, e.g., holding drums or booster pumps. 

The light crude will define the design basis for the atmospheric section of the crude unit since its volume of distillates will exceed that which can be produced from the heavy crude. All equipment sizing will be based on heat and material balance data calculated for the various tight crude cases. As would be expected, the heavy crude will define the facilities for processing the atmospheric tower bottoms, either a vacuum unit or, if this is not planned, the reduced crude heat exchange equipment. To further complicate the... 

Another factor that increases fouhng is the presence in the process streams of trace quantities of certain active metals such as iron, nickel, vanadium, and particularly copper. These metals are present because of their original occurrence in the crude streams, or from corrosion of process equipment constructed from the metals or their alloys. Surfaces of these metals are also active catalysts for fouling reactions. Here again, the interdependence of corrosion and fouling is illustrated, since metal contaminants resulting from corrosion in up-stream units may be reduced by the use of corrosion inhibitors. 

This input to design refers to the long-term stability of the raw material sources for the plant. It is only of importance where the raw materials can or do contain impurities which can have profound effects on the corrosivity of the process. Just as the design should cater not only for the norm of operation but for the extremes, so it is pertinent to question the assumptions made about raw material purity. Crude oil (where HjS, mercaptan sulphur and napthenic acid contents determine the corrosivity of the distillation process) and phosphate rock (chloride, silica and fluoride determine the corrosivity of phosphoric acid) are very pertinent examples. Thus, crude-oil units intended to process low-sulphur crudes , and therefore designed on a basis of carbon-steel equipment, experience serious corrosion problems when only higher sulphur crudes are economically available and must be processed. 

Clarifying filters or clarifying presses are installed between diazotization kettle and dissolution tank and the reaction vessel. The crude pigment slurry from the coupling vessel is filtered in a filter press and a pressure vessel equipped with an agitator (for thermal aftertreatment) connected to a filter press completes the processing unit for the synthesis. 

Complex process units such as catalytic crackers, hydrocrackers, ethylene units, hydrotreaters, or large crude distilling units typically containing high fire potential equipment. 

In the fourth step, the preprocessor generates plant performance data for the FCC, gas oil hydrocracker, motor reformer and BTX reformer. For each of these process units, the preprocessor calls the appropriate process simulator which computes the usage of equipment and utilities, product yields, and product properties for all base and alternate operations specified by the user. For all of the FCC operations, the feed properties are those of the atmospheric plus vacuum gas oil from the base crude mix blended with a specified fraction of deasphalter overhead. 

Review team members or consultants retained to support a review should be chosen that are intimately familiar with the hydrocarbon or chemical processes under examination. For example a crude separation operator should not be chosen to support a review of a refinery gas plant, however he could serve as a reviewer for another crude separation unit. The typical review team should also have a balanced number of individuals from different organizations such as company employees, consultants, equipment fabricators, etc. Hopefully one group s self interest should not be able to outweigh and unduly sway the entire groups outlook. 

Step 1. Synthesis or selecting the structure of the flowsheet identification of the equipment, interconnecting and specifying the initial design values. In this step, a crude approximate flowsheet is created to consider recycles, purges, and possible separation schemes make a simple, linear model to assess the effects of major parameters and structural variations do necessary laboratory work get more details for physical properties, thermodynamics, utilities, and process units write unit models, if necessary and fix the flowsheet layout. 

---