Full capacity

Availability refers to fraction of time which the facilities are able to produce at full capacity. Figure 14.10 shows the main sources of non-availability of an equipment item. 

Electric-arc furnaces offer the advantages of low constmction costs, flexibiHty in the use of raw materials, and the abiHty to produce steels over a wide range of compositions (carbon, alloy, and stainless) and to operate below full capacity. 

In Example 23.2 the system was not capable of transmitting its full capacity. Let us consider that with the use of series compensation it can be fully loaded up to... 

Pony motors are additional, small motors connected to the same fan shaft. They are typically about 1/4 the size of the full size motor. Pony motors do not lend themselves to gear box applications and are, therefore, primarily applied to belt drive applications. The big motor operates when full capacity is required and the small motor simply free wheels. At reduced capacity, the small motor operates and the big motor spins freely. 

Periodic equalizing charge is not required for float ser ice if floated at 2.25 volts per cell. However, equalizing is required for recharging to full capacity. When floated below 2.25 volts per cell, equalizing is required. 

The liner (grey area) is m full-capacity position with the seal point at the top anC the pumping chamber at (he bottom All lipuid coming Into the pump at the left is moving out of it at the right. 

As inlet pressure rises above set pressure, dome pressure reduction will be such as to provide modulating action of the main valve piston proportional to the process upset. The spool/feedback piston combination will move, responding to system pressure, to alternately allow pressure in the main valve dome to increase or decrease, thus moving the main valve piston to the exact lift that will keep system pressure constant at the required flow. Full main valve lift, and therefore full capacity, is achieved with 5% overpressure. As system pressure decreases below set pressure, the feedback piston moves downward and opens the inlet seat to admit system pressure to the dome, closing the main valve. 

Figure 12-46D, Part 1. View toward inlet of 4 Vj-in. diameter brazed aluminum impeller. Note Regardless of the metal of manufacture, enclosed impellers with back-leaning blades are extremely useful in applications requiring a steep head-volume characteristic and the highest attainable efficiency. Applications include parallel operation with other compressors or boosting of another compressor s output. The power-volume curve will show a self-limiting feature at higher volumes. This feature is very beneficial when the driver has limited power available but operation throughout the full capacity range is required. (Used by permission A C Compressor Corporation.)...

Two of the machines will operate full-time the third will serve as a standby. For such a situation, the suction header would be sized for the suction capacity of two machines. In practice, it may be better to run all three machines at reduced speed. Then when one comes down for some reason, the other two can speed up to carry the full load. Of course, this type of operation cannot be accomplished with a fixed speed drive. For the situation described, the design load is still the full capacity of two machines or four cylinders. 

Observations should be made that the plant is not being manually coaxed, that it is not humidifying and that the compressors have not tripped but are cycling under part-load conditions. Instruments should be indicating correctly. In cases where it is impractical to fully load the plant, ascertain that an appropriate amount of refrigeration is being employed. This situation is best avoided, as much of the plant is not being demonstrated to full capacity. 

Air compressed to 100 psig, to be used at 90 psig, provides no possibility of storage. Storage is practical at the other pressures selected. Compressor units B and C will operate at full load at their rated or lower pressures. Since the receiver pressure will fall during the 10 minutes when air is used faster than the compressor can replenish it, the unit will be operating at full capacity and will supply some of the demand. The full demand need not be stored. 

Before installing a new chain, carefully check all sprocket teeth. If the teeth are worn to a hooked shape, the sprockets should be replaced to assure full-capacity performance and satisfactory life from the new chain. Because chain drives are not as flexible as belt drives, caution must be exercised during installation. The following steps should be observed during installation ... 

The production of tubular positive plates is in principle similar to that of pasted plates. A number of manufacturers use the same gray oxide as the basic filling substance. Sometimes the share or red lead or minium (Pb304) is increased above 25 or even to 100wt.%. The latter is more economic when the manufacturer runs his own minium plant then the expense of the chemical oxidation of lead oxide (PbO) to minium (Pb304) may be compensated by reduced formation cost. Furthermore, curing is not required, because of the high oxidation state, and the battery starts with full capacity when formed. 

In all tests, the temperature in the first- and second-stage reactors was kept within the necessary temperature limits of 288°-482°C. Because the carbon monoxide concentration was low in many of the tests, the second stage was not used to full capacity as is indicated by the temperature rise in runs 23, 24, and 27. The temperature profile shows the characteristic rise to a steady value. With the space velocities used (<5000 ft3/ft3 hr), the temperature profile is fully developed in the first stage within 30.0 in. of the top of the catalyst bed. A characteristic dip in temperature was observed over the first 8-10 in. of the catalyst bed in all runs. This temperature profile may indicate the presence of deactivated catalyst in this region, but, until the catalyst can be removed for examination, the cause of the temperature drop cannot be determined. There is no evidence that this low temperature zone is becoming progressively deeper. It is possible that an unrecorded brief upset in the purification system may have poisoned some of the top catalyst layers. 

The overall reaction releases 3 X 108 kj for each gram of deuterium consumed. That energy corresponds to the energy generated when the Hoover Dam operates at full capacity for about an hour. Additional tritium is supplied to facilitate the process. Because tritium has a very low natural abundance and is radioactive, it is generated by bombarding lithium-6 with neutrons in the immediate surroundings of the reaction zone ... 

In other words, these equations show that if the production of both products does not absorb the full capacities of both steps, then the slack capacities of these two processes can be represented by the variables 5j and S2. Since slack capacity means that a certain amount of process capacity remains unused, it follows that the economic value of slack capacity is zero. Realizing that negative production rates and negative slack variables are infeasible, the problem can be formulated as ... 

The other two curves in Figure 23.47 assume a 25 MW gas turbine (GT) running at full capacity with HRSG in addition to steam turbines17. Both curves assume excess power generation at low values of Rsite is exported. 

In 1969, the chemical industry was operating at an average 81% of capacity. For ammonia the rate was even less than this. This meant that the large new plants were probably just breaking even, but the smaller, less efficient ones, which had to run at full capacity to show a profit, were losing money. The result was that about 20 of the smaller and less efficient ammonia plants were shut down. 

The deionization system will be designed to handle the proposed expansion. It should be large enough that the ion exchange unit can replenish storage tanks while the plant is running at full capacity. 

The problem with the economic analysis as presented in Example 10-1 is that it considers the plant to be operating at full capacity (a mature plant). Often it takes a couple of years, after the plant begins producing, for the sales volume to equal the plant capacity. During this time the return on the investment is less than that calculated for the mature plant. This is shown in Example 10-2. 

For the chemical plant the fixed charges, those that do not vary with the throughput, are depreciation, taxes, and insurance. The labor, utilities, supplies, and sales also cost more per pound of product if the plant is not running at full capacity, but their total cost is less than if the plant were running at full capacity. 

The R.O.I. analysis fails to take into account any startup expenses or to consider how long it will take the plant to reach full capacity. It ignores the fact that research and development costs, marketing expenses, and engineering expenses, are all made at different points of time. It considers only the mature plant. 

The total amount of money needed for research and development, engineering, marketing, and construction prior to the startup of a plant is 25,000,000. After the plant is completed it will take 3 years before the plant runs at full capacity. Diming these years the net proceeds before depreciation are estimated to be ... 

It will be assumed that the plant runs at full capacity after January 1975. The profit made in the first 3 months of operation will be assumed to cover all startup expenses. 

If the plant operates at full capacity for 11 years, the net present value in 1975 is ... 

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