| abstract |
The application describes a variety of special pigging methods and materials, using mixtures of crushed frozen material with its melt liquid, typically also containing a freezing point depressant. One proposal is to form the pig as two adjacent bodies (2a,b) at different temperatures, so that further freezing of the less cold body (2b) by the colder body (2a) raises its solids fraction adjacent the interface (2c) and enables higher-shear cleaning on the conduit wall (9). Other proposals include the use of air voids between ice pigs to enhance their cleaning effect, and the targeting of pigs containing chemically active agents at predetermined locations in a conduit system. |