Operational flexibility

Carbon brick and block ate used to line the cupola well (73) or cmcible. When properly installed and cooled carbon linings last for many months or even years of intermittent operation. Their resistance to molten iron and both acid and basic slags provides not only insurance against breakouts but also operational flexibility to produce different iron grades without the necessity of changing refractories. Carbon is also widely used for the tap hole blocks, breast blocks, slagging troughs, and dams. 

Fuel cells, which rely on electrochemical generation of electric power, could be used for nonpolluting sources of power for motor vehicles. Since fuel cells are not heat engines, they offer the potential for extremely low emissions with a higher thermal effidency than internal combustion engines. Their lack of adoption by mobile systems has been due to their cost, large size, weight, lack of operational flexibility, and poor transient response. It has been stated that these problems could keep fuel cells from the mass-produced automobile market until after the year 2010 (5). 

Reduced air preheat and reduced firing rates lower peak temperatures in the combustion zone, thus reducing thermal NO,. This strategy, however, carries a substantial energy penalty. Emissions of smoke and carbon monoxide need to be controlled, which reduces operational flexibility. 

The rotational operation of a CFB leads to a vortex motion in the freeboard which tends to inhibit particle loss by elutriation. Because of the relatively compact nature of the CFB and the operating flexibility provided by the rotational motion, the CFB has been proposed for a variety of applications including coal combustion, flue gas desulfurization, gas combustion, coal liquefaction and food drying. 

There is no umbrella answer. The choice is dictated by project pe (new tower or retrofit), current economics, operating pressures, anticipated operating flexibility, and physical properties. 

A cylinder liner such as that shown in Figure 11-6 may be used to help prolong the life of the cylinder and improve operating flexibility. Any dtunage caused by the action of the piston or heat generated by compression will affect the cylinder liner, which may be removed and replaced. As the surface of the liner wears, it is much easier and quicker to repair it than to repair the cylinder itself. In addition, liners enable the diameter of the piston to be varied without changing the cylinder and thus provide flexibility to respond to different conditions of pressure and flow rate. 

This concept can be especially significant for a low-pressure vessel wl minimum wall thickness is desired. For example, assume the caiv .,.i i.ons for a 50-psig MAWP vessel indicate a wall thickness of 0.20 in., and it is decided to use K-in. plate. This same plate might be used if a MAWP of 83.3 psig were specified. Thus, by specifying the hi MAWP (83.3 psig), additional operating flexibility is available at e dally no increase in cost. Many operators specify the MAWP based on... 

Type Tray Manufacturer Efficiency Capacity Turn-down Pressure Drop Operating Flexibility... 

In general, the number of boosters determines the operational flexibility of the unit with respect to the refrigeration load. A single booster unit operates continuously, regardless of load. A two booster unit can operate at 50% load by shutting off one unit at lower load levels it uses a pressure controller on the steam actuated by the condenser pressure. Because jets are not usually very flexible with respect to steam consumption and vacuum, load control may be in increments as compared to continuous variation. If a 100-ton unit is expected to operate an appreciable portion of the time at 25% of load, it may prove economical to install a four-booster unit and to operate only one for this period. Auxiliary ejectors remove uncondensed water vapor and air from the main condenser. 

The liquid distributor is the most important internal structure of a packed column. The distributor strongly influences packing efficiency. It must spread the liquid uniformly, resist plugging/fouling, provide free space for gas flow, and allow operating flexibility. 

The detergent industry requires process equipment having high operation flexibility, low energy demand, low operation cost, consistent production yield, and, of course, ecological optimization with respect to effluents and air pollution control. To comply with these requirements, the continuous S03/gas sulfonation and double-step neutralization are the basic principles applied in multitube falling film reactor and Neutrex neutralization (Fig. 5). 

When the first of our new pilot plants was designed we had the option of full computer control. We decided to Install stand-alone solid state controllers and safety systems to allow the fullest operating flexibility and the best possible data retrieval. The computers chosen for the latter have the capability when we wish to control temperature, pressure or feeds using our own algorithms. 

Technology Throughput Cost per assay Accuracy Robustness Operational flexibility... 

Greater operating flexibility More constant steam demand... 

With the feed divided as in equation (17.2-1), the two tanks act together the same as one tank of volume V= Vj + V2. There is thus no inherent performance advantage of multiple CSTRs in parallel, but there may be increased operating flexibility. 

In building B-46, three separate operations are performed consolidation, demachlnlng, and cone swagglng. A rotary press Is used to consolidate A-5 explosive Into a grenade. To pick up the dust from this pressing operation, flexible rubber hoses (2.0 in.) are used. These lines are then connected to a stainless steel line that runs Into a wet collector. 

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