Bypass designs

The fix for the erratic reflux drum pressure problem was to provide for separate pressure control of the fractionator column and the reflux drum. A new pressure control valve was installed upstream of the condenser and the old condenser outlet control valve was removed. A hot gas bypass, designed for 20% vapor flow, was installed around the pressure control valve and condenser. A control valve was installed in the hot gas bypass line. The column pressure was then maintained by throttling the new control valve upstream of the condenser. The reflux drum pressure w as controlled by the hot gas bypass control valve and the psv saver working in split range. The new system is shown in the figure below. 

In general, flooded condenser pressure control is the preferred method to control a tower s pressure. This is so because it is simpler and cheaper than hot-vapor bypass pressure control. Also, the potential problem of a leaking hot-vapor bypass control valve cannot occur. Many thousands of hot-vapor bypass designs have eventually been converted—at no cost—to flooded condenser pressure control. 

Figure 1. 3-Valve bypass design used on medium vacuum/Schlenk lines.

A battleshort is a design feature that provides the capability to short or bypass certain safety features in a system to ensure completion of a mission without interruption that would normally result from the triggering of a safety interlock. Battleshorts are typically manual switches that bypass designed-in safety interlocks during emergency situations a battleshort is a un-safety design feature. 

A further novelty of the HU cell system is the design and arrangement of the electrical bypass switch installed underneath, not next to, the circuit of... 

Quench Converter. The quench converter (Fig. 7a) was the basis for the initial ICl low pressure methanol flow sheet. A portion of the mixed synthesis and recycle gas bypasses the loop interchanger, which provides the quench fractions for the iatermediate catalyst beds. The remaining feed gas is heated to the inlet temperature of the first bed. Because the beds are adiabatic, the feed gas temperature increases as the exothermic synthesis reactions proceed. The injection of quench gas between the beds serves to cool the reacting mixture and add more reactants prior to entering the next catalyst bed. Quench converters typically contain three to six catalyst beds with a gas distributor in between each bed for injecting the quench gas. A variety of gas mixing and distribution devices are employed which characterize the proprietary converter designs. 

In contrast, the total artificial heart (TAH) is designed to overtake the function of the diseased natural heart. While the patient is on heart—lung bypass, the natural ventricles are surgically removed. Polyurethane cuffs are then sutured to the remaining atha and to two other blood vessels that connect with the heart. 

For a properly designed and operated cyclone, the sharpness iadex is constant, typically 0.6. The cut size and apparent bypass are a function of the cyclone geometry, the volumetric feed rate, the material relative density, the feed soflds concentration, and the slurry rheology. The relationship for a standard cyclone geometry, where if is the cylinder diameter ia cm and inlet area = 0.05 vortex finder diameter = 0.35 ... 

It is quite common ia the designs for fine classification to recontact the coarse stream transversely or ia counterflow with air before dischargiag it (see Fig. 9). This removes dry fine particles not removed ia the primary classification. That is, these particles are swept back iato the feed and given another chance to exit with the fine particles. Such an arrangement iacreases the overall sharpness iadex and reduces the overall apparent bypass. Another variation is to reenter the air from the sohd/gas separation of the coarse stream. 

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