As an example, the GPSA Handbook provides a function that allows the user to calculate relative pressure drops based on changes in conditions such as flowrate (1). This is possible using the HYSYS spreadsheet operation, which can calculate pressure drop as a function of imported conditions, then export the pressure drop to the corresponding equipment. HYSYS users may wish to have pressure drops vary with process conditions (e.g., flow). Updating Pressure Profile as Conditions Change There are many sources of information (the GPSA Handbook is one useful reference) that can help in providing guidelines as mentioned before, engineering and operating companies often have their own guidelines for estimating pressure losses. However, compressor and/or pump curves (in the case of centrifugal compressors or pumps) can be used to provide the pressure-flow relationship. In many cases, the discharge pressure will simply be specified. If piping pressure drop is included in the simulation, it either needs to be lumped into equipment pressure drop (e.g., at a separator), or alternatively modeled as a pipe or simply a valve with fixed pressure drop. Generally, piping pressure loss is less than 2 psi/100 ft. Piping pressure drop can vary widely the HYSYS pipe sizing utility can be used to predict the pressure drop. The HYSYS Tray Sizing Utility can be used as a guide to estimate tray and packing pressure drops. Packed bed pressure drops are usually significantly smaller, and a preliminary estimate of 0.01 psi/ft (0.2 kPa/m) can be used. TowersĪ pressure drop of 0.1 psi/tray is typical but can vary significantly, depending on tray type, liquid and vapour loads.
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Filters can introduce significant pressure drop at higher pressures, 10 psi is typical for dirty filters. For compressor scrubbers and associated piping, use a pressure drop of approximately 4 psi (30 kPa) for every 300 psia (2,075 kPa) working pressure up to 1,200 psia (8,300 kPa). SeparatorsĪ pressure drop of 5 psi (35 kPa) is usually reasonable above moderate pressures (e.g., 150 psi). For a better estimate (especially on the shell side of an exchanger), use a rigorous rating program such as HTFS-TASC. Typically this should range from 3 to 10 psi (20-70 kPa). Here we provide a few guidelines: Exchangersįor gas pressure drop in exchangers (shell/tube, air-cooled, double pipe), assume 1-2% of operating pressure. Many engineering and operating companies have their own guidelines in terms of setting appropriate pressure drops.
#TEE VS MIXER ASPEN HYSYS UPDATE#
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Often one needs to more accurately model pressure profile, such as when plant pressure drop is estimated in order to determine compression requirements. For most unit operations in HYSYS (Steady-State), pressure profiles and/or pressure changes in equipment are specified parameters.