Freeze plug

Any infrequently used drawoff lines should be isolated (and if possible, blinded) at the column to avoid a formation of a dead leg. Water or chemicals trapped in dead legs can freeze, plug, react or enter the column at an undesirable time. In one case (275), a maintenance worker was sprayed with liquid trapped in a plugged dead leg at shutdown. 

Refrigeration system. Refrigeration is required in the HRE-2 for operation of freeze plugs and cold traps. The refrigeration system consists of a primary loop, which is not irradiated, and a secondary liquid circulating system which enters the shield. 

In liquid service in cold weather, vapor may condense in a flame arrester and the liquid formed may freeze and plug the arrester. A... 

Problem A deethanizer overhead chiller experienced tubeside plugging due to freezing. 

In certain unusual cases, about 1 borehole of 10,000, the freezing will cause problems. In these cases the freezing causes a high pressure that deforms (flattens) the pipes in the borehole. In such cases some water is confined between two frozen parts (plugs) and when that water finally freezes the occurring expansion pressure becomes high enough to deform the pipes. 

If a firewater line needs to be temporarily isolated and an isolation means is not available on the immediate portion of the system needing work, a unique solution is to use a liquid nitrogen low temperature coil line freezing apparatus. This mechanism causes an ice plug to form in the line, effectively sealing the line from leakage, during the period the temporary isolation is needed. 

In addition to the vertical mixing of solids, a degree of horizontal mixing occurs and this is especially important in long, shallow plug flow beds of the type used in fluidized bed drying or freezing (see Chapter 3). 

Benzoic acid can be used as a corrosion-inhibitor in emulsions and paints, as well as an anti-freeze formulation, plugging agent, and modifier in oil well applications. It has also found use as a textile dye carrier [6]. 

Phenyldiazomethane solidifies at dry ice-temperature. Care must be taken not to plug the vacuum take-off adapter this occurs if the temperature of the receiver flask is too low. The receiver bath was maintained manually at about -50°C by addition of small pieces of dry 1ce to an acetone bath. We prefer to use this procedure rather than a chloroform-dry ice bath which freezes at -63°C, because of the toxic nature of chloroform and the disposal problems associated with this solvent. 

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