Mechanical problems

This term describes a situation whereby the drill string cannot be moved up or down or rotated anymore. The pipe can become stuck as a result of mechanical problems during... 

A more sophisticated and increasingly popular method of on-condItion maintenance is to monitor the performance of equipment on-line. For example, a piece of rotating equipment such as a turbine may be monitored for vibration and mechanical performance (speed, inlet and outlet pressure, throughput). If a base-line performance is established, then deviations from this may indicate that the turbine has a mechanical problem which will reduce its performance or lead to failure. This would be used to alert the operators that some form of repair is required. 

The specific advanced properties of the ceramic insulator eliminate the need for oil or resin insulation. The metal vacuum envelope of the tube provides higher beam stability, more robust design, and even X-ray shielding up to certain levels. Furthermore, even difScult mechanical problems (e.g. mounting, coohng, or beam emission) can be solved by an appropriate customised tube design. 

Our discussion shows that the Ising model, lattice gas and binary alloy are related and present one and the same statistical mechanical problem. The solution to one provides, by means of the transcription tables, the solution to the others. Flistorically, however, they were developed independently before the analogy between the models was recognized. 

The classical-mechanical problem for the vibrational motion may now be solved using Newton s second law. The force on the x component of the i atom is... 

One of the first successful techniques for selectively removing solvent from a solution without losing the dissolved solute was to add the solution dropwise to a moving continuous belt. The drops of solution on the belt were heated sufficiently to evaporate the solvent, and the residual solute on the belt was carried into a normal El (electron ionization) or Cl (chemical ionization) ion source, where it was heated more strongly so that it in turn volatilized and could be ionized. However, the moving-belt system had some mechanical problems and could be temperamental. The more recent, less-mechanical inlets such as electrospray have displaced it. The electrospray inlet should be compared with the atmospheric-pressure chemical ionization (APCI) inlet, which is described in Chapter 9. 

Air control louvers or dampers, popular in the past for air flow control, are used primarily for only very low scale air flow control. Louvers are used in many winterized heat exchangers in extremely low ambient temperature locations to retain and recirculate warm air in completely enclosed heat exchangers, sometimes in very compHcated control schemes. The use of louvers on the discharge side of a fan to control air flow is inefficient and creates mechanical problems in the louvers because of the turbulence. A fan is a constant volume device, thus use of louvers to control flow is equivalent to... 

In addition to these mechanical problems there are two aspects of the compression process which relate specifically to ethylene. Eirst, there is a tendency for small amounts of low molecular weight polymer to be formed and, second, the gas may decompose into carbon, hydrogen, and methane if it becomes overheated during compression. Cavities in which the gas can collect and form polymer, which hardens with time or in which the gas can become hot, need to be avoided. 

There are advantages and disadvantages in both processes the solvent process requires no special equipment but uses an excess of benzene whose recovery adds to the cost of the product. The bad mill method uses no excess benzene but requires special equipment which has frequent mechanical problems. 

Selection. The widely used cathode materials iaclude Hg, Pb, Al, Zn, Ni, Fe, Cu, Sn, Cd, and C. Because of mechanical iaconvenience, mercury is not an attractive electrode material for large cells. The preferred material is lead or an amalgam. Because Pb is soft and has a tendency to deform, however, it presents some mechanical problems. The problems can be overcome by hot dip or electroplating on steel, copper, or other rigid base material. 

For purposes of data correlation, model studies, and scale-up, it is useful to arrange variables into dimensionless groups. Table 6-7 lists many of the dimensionless groups commonly founa in fluid mechanics problems, along with their physical interpretations and areas of application. More extensive tabulations may oe found in Catchpole and Fulford (Ind. Eng. Chem., 58[3], 46-60 [1966]) and Fulford and Catchpole (Ind. Eng. Chem., 60[3], 71-78 [1968]). 

Evaporative condensers are used quite extensively. In most cases commercial evaporative condensers are not totally suitable for chemical plants due to the hostile atmosphere which usually abounds in vapor and dusts which can cause either chemical (corrosion) or mechanical problems (phigging of spray nozzles). 

The pusher-type furnace is relatively free from mechanical problems because all mechanical parts are located outside the hot zone. It employs a roller-conveyor usually and will handle charges weighing considerably more per square meter than a belt-conveyor furnace. Pushers are driven by electric motors, compressed air, or hydraulic systems and can be automatically timed and synchronized with door-... 

Running unbal- Preventive maintenance and operator checklist anced, vibration inspections due to worn bear-, effective vibration monitor/shutdown device ings or other mechanical problem such as product accumulation behind filter screen. ... 

Mechanical problems. Pipe strain distorting the pump casing. 

Mechanical problems. Air aspiration thru the packing/seal. 

A chart for vibration diagnosis is presented in Table 19-9. While this is a general criterion or rough guideline for diagnosis of mechanical problems, it can be developed into a very powerful diagnostic system when specific problems and their associated frequency domain vibration spectra are... 

The previous problems are some of the more common types encountered on a gas turbine train. Regular and preventive maintenance is the key to a successful operation. Problems will arise, but by proper monitoring of the aerothermal and mechanical problems, preventive maintenance can often avert major or catastrophic failures. 

John J. France of Sulzer Chemtech USA Inc. provided expert information on troubleshooting distillation columns to the Rio Grand Chapter of AIChE. Checklists were provided for troubleshooting mechanical problems based on considerable successful field experience. This portion of the presentation is presented here with permission. 

Fluidized-bed adsorbers have several disadvantages. The continuous handling and transport of solids is expensive from an equipment standpoint fluidized-bed systems must be large to be economical. Solids handling also presents a potential for mechanical problems. Careful control is required to keep the adsorbent fluidized, while minimizing adsorbent loss with the gas-phase attrition of the adsorbent can be high, requiring substantial makeup. 

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