Heat tracing systems fluid

Fluid Tracing Systems Steam tracing is the most common type of industrial pipe tracing. In 1960, over 95 percent of industrial tracing systems were steam traced. By 1995, improvements in electric heating technology increased the electric share to 30 to 40 percent. Fluid systems other than steam are rather uncommon and account for less than 5 percent of tracing systems. 

A selection of components surface-mounted to carrier plates is shown in Figure 4.34. The carrier plates support the internal fluidic pipes and can also be equipped with electrical heaters to permit trace heating of the fluid. The surface-mounted components of this system are compatible with the backbone concept introduced in the following. 

The entire 8-inch (20 cm) piping system was insulated and steam traced except for the heater tubes within the heater. Operations assumed the heat transfer fluid froze in the four heater tube passes. Each pass was a bare 4-inch (10 cm) diameter heater tube with 5 bends and the equivalent of 72 ft. (22 m) of straight pipe. The foreman and the operations team discussed the situation and decided to light and maintain a small fire on the burner to slowly thaw the material in the heater tubes. This method had been successful for a startup several weeks earlier. 

A second type of polythermal path traces temperature as reactants mix into the equilibrium system. This case differs from a sliding temperature path only in the manner in which temperature is determined. The modeler assigns a temperature To to the initial system, as before, and a distinct temperature Tr to the reactants. By assuming that the heat capacities CP, CPk, and CPr of the fluid, minerals, and reactants are constant over the temperature range of interest, we can calculate temperature (< ) from energy balance and the temperature T(c ) at the onset of the step according to... 

The unit operation of erystallization is governed by some very complex interacting variables. It is a simultaneous heat and mass transfer process with a strong dependence on fluid and particle mechanics. It takes place in a multiphase, multicomponent system. It is concerned with particulate solids whose size and size distribution, both incapable of unique definition, vary with time. The solids are suspended in a solution which can fluctuate between a so-called metastable equilibrium and a labile state, and the solution composition can also vary with time. The nucleation and growth kinetics, the governing processes in this operation, can often be profoundly influenced by mere traces of impurity in the system a few parts per million may alter the crystalline product beyond all recognition. 

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