Operational unit

During storage, sediments decant with the water phase and deposit along with paraffins and asphalts in the bottoms of storage tanks as thick sludges or slurries (BS W). The interface between the water-sediment and the crude must be well monitored in order to avoid pumping the slurry into the refinery s operating units where it can cause serious upsets. 

In many applieations, eg. within the nuclear, offshore and subsea fields it has been required to have a small unit, that could be placed unattended, close to the scanning object and operated from a remote operation unit. 

A new countercurrent continuous centrifugal extractor developed in the former USSR (214) has the feature that mechanical seals are replaced by Hquid seals with the result that operation and maintenance are simplified the mechanical seals are an operating weak point in most centrifugal extractors. The operating units range between 400 and 1200 mm in diameter, and a capacity of 70 m /h has been reported in service. The extractors have been appHed in coke-oven refining (see Coal conversion processes), erythromycin production, lube oil refining, etc. 

Bed Expansion and Bed Density. Bed density can readily be deterrnined for an operating unit by measuring the pressure differential between two elevations within the bed. This is a highly useful measurement for control and monitoring purposes. 

Nation Operative units Power, net MWe Total number of units Power, net MWe ... 

Flare noise (roar of combustion) is the most serious because it is elevated and the sound carries. The flare can be located at a remote distance from the operating unit or surrounding community. Noise of steam injection into the burner can be reduced by using multiple no22les. Furnace noise from air intake, fuel systems, and combustion blower forced draft/induced draft (FD/ID) fans can be reduced by acoustics. The plot plan should be evaluated for noise generation and to find the means of alleviating or moving noise to a less sensitive area. 

Open areas around the operating units of a plant act as buffers to the surrounding community. Sufficient clearance should be allowed so that, if tall stmctures coUapse, other on-site buildings or equipment, or off-site properties are not affected. Adequate roadways providing entry to the plant are extremely important, and multiple entries and exits are advisable. An overcrowded plant can lead to damage or shutdown of adjacent units and may impede the movement of vehicles and materials in case of emergency (85). Another consideration is community fire-fighting assistance, first aid, and medical facihties. 

The dmm dryer is a continuously operated unit that uses rotating heated dmms for the evaporation contact area. This method of drying can be used with materials high in volatiles. In several designs, the volatiles can be withdrawn and coUected for reuse, as appropriate. 

Effects of Impurities nd Solvent. The presence of impurities usually decreases the growth rates of crystalline materials, and problems associated with the production of crystals smaller than desired are commonly attributed to contamination of feed solutions. Strict protocols should be followed in operating units upstream from a crystallizer to minimize the possibiUty of such occurrences. Equally important is monitoring the composition of recycle streams so as to detect possible accumulation of impurities. Furthermore, crystalliza tion kinetics used in scaleup should be obtained from experiments on solutions as similar as possible to those expected in the full-scale process. 

Since the dryer is a batch-operating unit, it is commonly used in the pharmaceutical industiy to maintain batch identification. In addition to pharmaceutical materials, the conical mixer diyer is used to dry polymers, additives, inorganic salts, and many other specialty chemicals. 

The batch-operating units consist of only one jacketed, cyhndiical vessel with the necessary nozzles and ports for product inlet and out-... 

Often, analysts will want to run special short-term tests with the operating unit in order to identify the cause of the trouble being experienced By the unit. Operators are naturally leery of running tests outside their normal operating experience because their primaiy focus is the stable control of the unit, and tests outside their experience may result in loss of control. Multiple tests with few results may decrease their cooperation. 

Today s eddy eurrent brake system is far superior to the meehanieal switeh-operated units of the past. Modern eontrols take advantage of all of the sophistieated logie found in mieroproeessor teehnology. This eontrol system is funetionally deseribed in Figure 4-147. Eaeh blaek box represents a separate eontrol funetion with a master eontrol ealled the eddy eurrent brake eontroller. ... 

Instrument and Plant Air Systems. A typical setup for a large plant could include three to four 50% instrument air compressors and two 100% plant air compressors, with steam drives for normally operated units and electrical drives for spares. Common practice would provide an interconnection to allow makeup from plant air into instrument air, but not vice versa, and two sets (two 100% driers per set—one on-stream and one regenerating) of 1007c instrument air driers. Two main receivers on instrument air near the compressors with several minutes holdup time and satellite receivers at process trains would be likely and proper for feasibility cost estimating. 

Keep in mind rail tariff breaks for numbers of cars in a string so that the ability to handle the required numbers can be provided. If the operation is large enough, as for large coal mining operations, unit trains (100 cars) are used. 

These models are usually overall plant or corporation oriented and are geared toward running the business. If utilities are included, they are probably keyed to production levels of operating units or, in the case of the polyolefin plant, a characteristic set of utilities is charged against each unit of each specialty product. Often, recycle streams within segments of the operation are not pertinent and not included. 

Here the safe operating units are basieally the upper limits of pressure and temperature for whieh the plant was designed to be operated safely. 

SYSTEM SETUP is a utility for changing file destination, source directories, operating units, and screen colors. 

FIGURE 5.49 Schematic of liver operational units the classic iobule and the acinus.(See also Fig. 5.3S.)(Used with permission.)... 

Short Guide to Reducing Human Error in Process Operation (United Kingdom Atomic Energy Authority, 1987)... 

The Operating Unit Status Report contains production and outage log information on power reactor operation from ECC countries, Spain, and Switzerland. 

Tliis is tlie probability if n or fewer failures in the time period specified by t. For example, consider tlie case of a standby redundancy system with one operating unit and one on standby (i.e., a system tliat can survive one failure). If the failure rate is 2 units per year, then tlie 6-nionth reliability of the system is... 

The standard bearing monitor solves the most basic problem common to all sealless pumps—detecting normal bearing wear so that routine maintenance can be accomplished before serious motor damage occurs. It responds to bearing wear in both the axial and radial directions and is over 98% effective on 70,000 operational units. 

A single pump is the cheapest first-cost installation. However, if downtime has any value such as in lost production, in hazards created in rest of process, etc., then a stand-by duplicate unit should be considered. A spare or stand-by can be installed adjacent to the operating unit, and switched into service on very short notice, provided it is properly maintained. Spare pumps which do not oper-... 

It is impossible to design a practical fluid power system without some means of controlling the volume and pressure of the fluid, and directing that flow to the proper operating units. This is accomplished by the inclusion of control valves in the hydraulic circuit. 

The teed to the cat cracker in a typical refinery is a blend of gas oils from such operating units as the crude, vacuum, solvent deasphalting, and coker. Some refiners purchase outside FCC feedstocks to keep the FCC feed rate maximized. Other refiners process atmospheric or vacuum residue in their cat crackers. In recent years, the trend has been toward heavier gas oils and residue. Residue is most commonly defined as the fraction of feed that boils above 1,050°F (565 C). Each FCC feed stream has different distillation characteristics. 

---