Direct drive

An alternative type of downhole mud motor is the mud turbine, (multistage axial flow turbine) which directly drives the bit. The tool consists of an upper section containing the turbine blades and lower section with bearings. As mud is pumped through the upper section the blades are turned. Turbines are designed to rotate at higher speed than the displacement motor. The higher rotation speed requires diamond or composite bits. 

Portable or fixed mixers up to 5hp normally use propellers and run at either direct drive speeds of 1,150 or l,750rpm or at single reduction gear drive speeds between 300 and 420 rpm. They may either be clamped on the rim of open tanks or mounted with a fixed assembly for open or closed tank operation. These mixers are the most economical and are usually used in tanks without baffles. They are rugged and long-lasting. 

Making an active clamp from a controller IC that does not support its direct drive depends upon which signals are brought out from the IC. Figure 4—8 gives a couple of ideas. 

The device consists of a low thermal mass test cell of 110 ml volume. This is made of stainless steel with a 0.015-mm wall thickness, but test cells made from other materials can be used. The contents of the cell are mixed using either a magnetically driven stirring bar or a direct drive agitation test cell. The test cell is... 

This type consists of a propeller or disk-type wheel within a mounting-ring panel or cage. The wheel or housing is constructed from either sheet metal, cast aluminium, plastic, or plastic-coated material. It may be a direct drive with the wheel on the motor shaft or belt driven. 

Direct-drive fans should not be used in area in which explosive or flammable gases or vapors are handled by the fan... 

Vane axial fans develop a greater static pressure than tube axial fans. They are constructed from a variety of materials, depending on the application. They may use either a direct drive or a belt drive. More expensive models... 

Bifurcated A fan in which the direct drive motor is separated from the airstream, reducing corrosion rare, allowing higher operating temperatures, and reducing wear and tear on bearings. 

Both reciprocating engines and turbines are used as prime movers in production facilities to directly drive pumps, compressors, generators, cranes, etc. Reciprocating engines for oil field applications range in horsepower from 100 to 3,500, while gas turbines range from 1,500 to in excess of 75,000. 

ARR. 4 SWSI For direct drive Impeller overhung on prime mover shaft. No bearings on fan Prime mover base mounted or integrally directly connected. 

The downhole turbine motors that are hydraulically operated have some fundamental limitations. One of these is high rotary speed of the motor and drill bit. The high rotary speeds limit the use of downhole turbine motors when drilling with roller rock bits. The high speed of these direct drive motors shortens the life of the roller rock bit. 

The basic gas turbine generates in the open-cycle mode and Figure 15.4 illustrates this. Air is drawn into a compressor and after compression passes into a combustion chamber. At this stage, energy is supplied to the combustion chamber by injecting fuel, and the resultant hot gases expand through the turbine. The turbine directly drives the... 

The rotary compressor is adaptable to direct drive by the use of induction motors or multi-cylinder gasoline or diesel engines. These compressors are compact, relatively inexpensive, and require a minimum of operating attention and maintenance. They occupy a fraction of the space and weight of a reciprocating machine having equivalent capacity. 

In positive lubrication systems, a gear-type pump is normally used to provide positive circulation of clean oil within the compressor. In some cases, the main compressor shaft directly drives this pump. In others, a separate motor-driven pump is used. 

Direct drive three-phase electric motor... 

It is possible to readjust the blade angles on site but, if so, great care must be taken to get them all at the same angle. The procedure is not to be recommended. Most such fans are direct drive, so the speed cannot be changed except electronically. 

We are applying the principles of statistical experimental design to the development of low-density polymer foams for use as direct-drive high-gain targets for Laser Inertial Confinement Fusion (ICF). Both polystyrene (PS) and resorcinol-formaldehyde (RF) foams are being developed. 

The proportionality coefficient L, termed the intercept ratio, depends on a number of factors such as the turbine size, the turbine design, the application (electrical or direct drive), and so on. It must be determined from performance data and usually lies in the range of 0.05 and 29. 

Drivers are required for many different types of process machine on a site. Power can be generated and distributed to drive electric motors, or direct drives can be used. Direct drives are inflexible as far as the utility system operation is concerned. A combination of direct drives and electric motors is usually the best solution for the site as a whole. 

The way ahead lies in brushless direct drives or imbalance compensation systems that can only be realized with the application of electronics. 

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