Free operation

From the standpoint of commercialization of fuel ceU technologies, there are two challenges initial cost and reHable life. The initial selling price of the 200-kW PAFC power plant from IFC was about 3500/kW. A competitive price is projected to be about 1500/kW orless for the utiHty and commercial on-site markets. For transportation appHcations, cost is also a critical issue. The fuel ceU must compete with conventional mass-produced propulsion systems. Furthermore, it is not clear if the manufacturing cost per kilowatt of small fuel ceU systems can be lower than the cost of much larger units. The life of a fuel ceU stack must be five years minimum for utiHty appHcations, and reHable, maintenance-free operation must be achieved over this time period. The projection for the PAFC stack is a five year life, but reHable operation has yet to be demonstrated for this period. 

In order to ensure virtually failure-free operation, a pohcy of changing this spring at 50,000 cycles of operation might be adopted. 

Pumps are designed to give trouble-free operation for a long period of time. The ANSI B73.1M pumps are designed for a bearing life of no less than two years (29), and API 610 pumps for a minimum of five years (30). However, in real appHcations, a typical mean time between faUures (MTBF) is often found to be significantly less, and sometimes it is as short as a few weeks. Whereas in some instaUations the seals last from three to four years, in others these are replaced monthly. The reason for such wide variations in pump component life is often not poor pump design but equipment misappHcation. 

Pan and cascade burners are generally more limited ia flexibiHty and are useful only where low sulfur dioxide concentrations are desired. Gases from sulfur burners also contain small amounts of sulfur trioxide, hence the moisture content of the air used can be important ia achieving a corrosion-free operation. Continuous operation at temperatures above the condensation poiat of the product gases is advisable where exposure to steel (qv) surfaces is iavolved. Pressure atomiziag-spray burners, which are particularly suitable when high capacities are needed, are offered by the designers of sulfuric acid plants. 

The quahty of feed water required depends on boiler operating pressure, design, heat transfer rates, and steam use. Most boiler systems have sodium zeohte softened or demineralized makeup water. Feed-water hardness usually ranges from 0.01 to 2.0 ppm, but even water of this purity does not provide deposit-free operation. Therefore, good internal boiler water treatment programs are necessary. 

Controlled catalyst circulation is one of the most important prerequisites for trouble-free operation of the FCC unit. Uniform circulation is ensured by controlling the differential pressure between the reactor and regenerator. The differential pressure in the existing plant is controlled by a differential pressure governor adjusting the position of the double slide valve upstream of the orifice chamber. 

There are many types of failures assoeiated with a gas turbine, sinee these units are very eomplex in their overall makeup. The failures in the hot seetion far outnumber the problems in the eompressor due to the high temperatures assoeiated with the hot seetion. Hot-seetion failures are usually eonneeted to problems assoeiated with fuels. Turbine failures ean be very eostly, the average eost runs about 500,000 for units between 10 and 50 MW and about 700,000 for units above 50 MW. These average failures result in downtime of between 12 and 16 weeks. The type of operation the unit experienees is a major faetor in the problem. The unit has a more trouble-free operation if it is a baseload unit. 

Cooling tower fan motors must be properly selected for long life and trouble free operation. In addition, it is important to match the motor s enclosure to the application. Motors in draw through applications that are mounted directly in the air stream, for example, experience tough duty and must be of the totally enclosed type. Motors are categorized as follows ... 

The Vendor shall be fully responsible for the trouble-free operation of the flare system constructed by him throughout the entire guaranteed period. 

We all have needs, requirements, wants, and expectations. Needs are essential for life, to maintain certain standards, or essential for products and services, to fulfill the purpose for which they have been acquired. Requirements are what we request of others and may encompass our needs but often we don t fully realize what we need until after we have made our request. For example, now that we own a mobile phone we discover we really need hands-free operation when using the phone while driving a vehicle. Hence our requirements at the moment of sale may or may not express all our needs. Our requirements may include wants - what we would like to have but do not need nice to have but not essential. Expectations are implied needs or requirements. They have not been requested because we take them for granted - we regard them to be understood within our particular society as the accepted norm. They may be things to which we are accustomed, based on fashion, style, trends, or previous experience. Hence one expects sales staff to be polite and courteous, electronic products to be safe and reliable, policemen to be honest, etc. 

Error free operation and maintenance can only occur within an effective management system. At the level of the task itself, this is provided by operating instructions. However, at a more global level, separate tasks have to be organized in a systematic manner, particularly if hazardous operations are involved, and where several individuals need to coordinate to achieve an overall objective. This section illustrates some accidents due to poor organization of work or failure to carry out checks. 

During the design of a new process plant, in order to ensure that when the plant is operational its systems (hardware, procedures, training, etc.) will provide the maximum support for error-free operation... 

Figure 13-1E. A computer facility performs dynamic simulation and analysis of reciprocating compressor installations such as this two-cylinder compressor. Interactive pulsation and mechanical analysis ensures trouble-free operation. (Used by permission Southern Gas Association s Gas Machinery Research Council.)...

Check safety latches and guides in telescoping mast for free operation before lowering operation. Keep latches and guides clean and properly lubricated. 

Check folding ladders for free operation before lowering operation. 

Many of these chronic problems are the direct result of improper installation. The guidelines provided in this chapter are not all encompassing, but they provide the basic elements that will assure long-term, trouble-free operation of pumping systems. 

Proper installation of V-belts is necessary to ensure trouble-free operation and maximum service life of the belts. The procedures and practices that should be followed in a proper installation can be broken down into three major categories pre-installation inspections of the belt and pulley, installation practices, and post-installation practices (belt tension inspection and adjustment). 

Friction Friction clutches tend to be more complex in design than positive clutches. Their complexity, coupled with reliance on friction for power transmission, demands constant care and maintenance. As a result, they require regular adjustment and good preventive maintenance to ensure trouble-free operation. 

New chemical synthesis routes leading to a better productivity and increased selectivity could be defined with regard to the new opportunities offered by HEX reactors. For example, they can lead to solvent-free operation or operations with at least dramatically reduced amount of solvent, to increase the reaction temperature or to engage in more efficient catalysis. 

Epinephrine is widely used in clinical medicine for its multiple pharmacologic effects particularly for its potent vasoconstrictor effects. For example, in a dilute solution of 1 100,000, it provides a surgical tourniquet and facilitates a blood-free operating field. It is administered by nebulizer and face mask for post-intubation croup and for viral croup. 

Inui (180) and Rostrup-Nielsen et al. (175) reported that the amount of carbon deposited on metal catalysts decreases in the order Ni Rh > Ir = Ru > Pt = Pd at 773 K and Ni > Pd = Rh > Ir > Pt Ru at 923 K. Thus, the noble metals exhibit higher selectivities for a carbon-free operation than nickel. Nevertheless, carbon deposition does also occur on noble metals. 

For oxidative detection removal of dissolved air from the mobile phase is necessary to prevent air bubble formation at the column outlet, which disturbs the electrolysis process. Vacuum filtration usually is sufficient to remove enough air for bubble-free operation. However, air readily redissolves in the mobile phase. Continuous helium sparging is therefore the only effective degassing method for longer periods. 

When a process requires an evaporation step, the problem of evaporator design needs serious examination. Although the subject of evaporation and the equipment to carry out evaporation have been studied and analyzed for many years, each application has to receive individual attention. No evaporation configuration and its equipment can be picked from a stock list and be expected to produce trouble-free operation. 

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