Line Blowing

A common prestartup practice is to pressurize the column with air or nitrogen. The column then serves as a vapor reservoir for blowing lines connected to the column, to remove construction debris. The following guidelines eire recommended (Fig. 11.1)  

This problem is best avoided by roughly calculating the expected flow in each line before blowing it. If likely to be excessive, either the flow rate (or rate of column depressuring) should be monitored and properly constrained, or blowing the line from the column should be avoided. 

Disconnect instrument Blow tie-in just prior to line-blowing termination 

If tray damage may occur, blow by connecting hose to PI isolation valve. In this case, close isolation valve at the column. 

With valve trays, this section will tend to depressure faster than top section. 

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Figure 11.1 Good line-blowing practices, illustrated with reference to a column feed line.

All instruments, except for those that are directly required for monitoring the line-blowing operation, should be disconnected or at least blocked off dming line blowing to avoid debris entering the impulse lines. With the impulse-lines disconnected, the tie-ins of the instruments to the lines should be blown free of debris just before blowing a line is terminated. 

Any control or trip valves should be removed and replaced by pipe spools prior to line blowing. 

Alternatively, it has been recommended (182a) that the F-factor (UgP where u = superficial velocity and p = fluid density) of the gas or liquid used for line blowing is at least as great as, and preferably 25 percent greater than, the maximum F-factor anticipated in the line (under normal or upset conditions, whichever is greater). The basis of the latter rule and a sample calculation are detailed elsewhere (182a). 

Age, centrifuge, charge, clean, cool, concentrate, crystallize, decant, distill, dry, evacuate, extract filter, filter-in-place, heat, heat-to-reflux-and-age, line-blow, line-flush, open/close-vent, pH-adjust, pressurize, purge, QC-test, quench, quench-in-place, react, react-distill, start-sweep, sto sweep, transfer, transfer-through-heat-exchanger, utilize, vent, wash-cake, yield-react Elute-column, equilibrate-column, load-column, regenerate-column, wash-column Crystallize-continuously, Distill-continuously, Dry-continuously, Extract-continuously, filter-continuously, react-continuously... 

POM/TPU blends can be used in chain wheels, surfboard mast feet, switch buttons, clips for toys, car body part and fuel lines, blow moldings, and sports equipment. 

SBD Nominal <630°C Ambient Reagent steam line blow down (taken to be 300% normal flow through flibe to steam heat exchanger)... 

Atmospheric air entering a vessel or tank when liquid levels are lowered Compressed air leakage into a process from a compressor or blower Compressed air used in line blowing Compressed air used for agitation Air in solution in feedstocks or products Failure to purge a system properly following a turnaround Air used in oxidation processes... 

Figure 3.2 schematically depicts a typical spinning preparation line (blow room) for cotton. It starts on the left with a bale breaker, followed by several cleaning units and a mixer, and is completed with a dust and foreign matter extractor. The next step is carding (not shown). 

Fig. 17. General diagram of the peat-bog study site. Arrows show groundwater flow lines. Blow up of peat core stratigraphy is attached...

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