Turbine motor operations

The prime mover is the unit that first converts an energy source into a mechanical force. Typical prime movers are internal combustion motors, gas turbines, water turbines, steam engines and electrical motors. The discussion will be limited to the prime movers that are most used in modern well drilling and production operations. These are internal combustion motors, gas turbine motors and electric motors. 

Air (or Gas) Downhole Motors. Some positive displacement mud motors can be operated on unstable foam. In general, these mud motors must be low-torque, high-rotalional-speed motors. Such motors have found limited use in air and gas drilling operations where directional boreholes are required. Recently a downhole turbine motor has been developed specifically for air and gas drilling operations. This downhole pneumatic turbine motor is a high-torque, low-rotational-speed motor. 

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. 

In this section the design and the operational characteristics and procedures of the most frequently used downhole motors will be discussed. These are the downhole turbine motor and the downhole positive displacement motor. 

Unless a measure while drilling instrument is used, there is no way to ascertain whether the turbine motor is operating efficiently since rotation speed and/or torque cannot be measured using normal surface data (i.e., standpipe pressure, weight on bit, etc.). 

Downhole turbine motors can only be operated with drilling mud. 

The major reason most turbine motors are designed with various add-on motor sections is to allow flexibility when applying turbine motors to operational situations. 

Using the basic performance data given in Table 4-110 for the 6-f--in. outside diameter turbine motor with 212 stages, determine the stall torque, maximum horsepower and pressure drop for this motor if only one motor section with 106 stages were to be used for a deviation control operation. Assume the same circulation flow rate of 400 gal/min, but a mud weight of 14 Ib/gal is to be used. 

The last column in Tables 4-110 and 4-111 show the thrust load associated with each circulation floWrate (i.e.,-pressure drop). This thrust load is the result of the pressure drop across the turbine motor rotor and stator blades. -The magnitude. of this pressure drop, depends. on the individual internal design details of the turbine motor (i.e., blade angle, number of stages, axial height of blades and The radial width of the blades) and the operating conditions. The additional pressure. drop results in thrust, T (lb), whicit is... 

A 6-J--in. outside diameter turbine motor (whose performance data are given in Tables -4-110 and 4-111) is to be used for a deviation control direction drilling operation. The motor will use a new 8- -in. diameter diamond bit for the drilling operation. The directional run is to take place at a depth of 17,552 ft (measured... 

Total Pressure Loss. Using Table 4-110 and Equations 4-150 and 4-151, the pressure loss across the turbine motor can be determined for the various circulation flowrates and the mud weight of 16.2 Ib/gal. These data together with the above bit pressure loss data are presented in Table 4-113. Also presented in Table 4-113 are the component pressure losses of the system for the various circulation flowrates considered. The total pressure loss tabulated in the lower row represents the surface standpipe pressure when operating at the various circulation flowrates. 

Planning for a positive displacement motor run and actually drilling with such a motor is easier than with a turbine motor. This is mainly due to the fact that when a positive displacement motor is being operated, the operator can know the operating torque and rotation speed via surface data. The standpipe pressure will yield the pressure drop through the motor, thus the torque. The circulation flowrate will yield the rotational speed. 

The downhole turbine motor designed to be activated by the flow of incompressible drilling mud cannot operate on air, gas, unstable foam or stable foam drilling fluids. These downhole turbine motors can only be operated on drilling mud or aerated mud. 

The operators were not running the turbine. The turbine was spinning, because it was coupled to the pump, but there was no motive steam to the turbine. The operators reported that the turbine was not needed, as the motor was pulling only 90 percent of its maximum amperage load. The question is, dear reader, whether the pump will run faster if the motive-steam flow is opened to the turbine. And the answer is, no. While the turbine will produce shaft work, and will help... 

Instead of applying the fundamental conservation equations, as described above, another modeling approach is to characterize gas turbine performance by utilizing real steady state engine performance data, as in (Hung, 1991). It is assumed that transient thermodynamic and flow processes are characterized by a continuous progression along the steady state performance curves. This is known as the quasi-static assumption. The dynamics of the gas turbine, e.g. combustion delay, motor inertia, fuel pump lag etc. are then represented as lumped quantities separate from the steady-state performance curves. Very simple models result if it is further assumed that the gas turbine is operated at all times close to rated speed (Rowen, 1983). 

The steam generated in the core r on is separated from the reactor coolant in the steam separators on top of the moderator tank cover, and its content of water droplets and moisture is lowered on the passage through the steam driers. The "dried" steam collects in the top portion of the RPV, from where it is conveyed to the turbine plant through four steam lines. The steam lines connect to nozzles with built in "flow limiters", evenly distributed along the vessel circumference own medium operated isolation valves are provided on the inside and outside of the containment wall, the outer valve is equipped also with a motor operated actuator to ensure leaktightness after closure. 

A steam turbine is a rotary equipment driver tiiat uses steam as its source of energy. Safety considerations relate to the intended use as well as to the selection, installation, and operation of the turbine. Steam turbines are used either as emergency backup to critical motor-operated equipment or as economical alternatives to electrical motors. When the safety of the process plant depends on the reliable operation of a steam turbine, the turbine system should be designed to start up and reach operating speed in a way that minimizes hazards. 

Except for some portable mixers, high-shear mixers, and a few special mixers, most mixers operate below standard motor speeds. Typical motor speeds of 1800 or 1200 rpm (30 or 20 rps) are reduced to between 350 and 30 rpm (5.8 and 0.5 rps) for most mixer applications. Portable and side-entering mixers usually operate near the upper portion of this speed range from 420 to 170 rpm (7 to 2.8 rps). Turbine mixers operate in the middle range, from 125 to 37 rpm (2.1 to 0.6 rps), and high viscosity mixers operate from 45 to 20 rpm (0.75 to 0.33 rps) and slower. 

Because both electricity and heat are desirable and useful products of SOFC operation, the best applications are those which use both, for example residential combined heat and power, auxiliary power supplies on vehicles, and stationary power generation from coal which needs heat for gasification. A residential SOFC system can use this heat to produce hot water, as currently achieved with simple heat exchangers. In a vehicle the heat can be used to keep the driver warm. A stationary power system can use the hot gas output from the SOFC to gasify coal, or to drive a heat engine such as a Stirling engine or a gas turbine motor. 

In today s operations a mud motor or a mud turbine are mostly used for directional drilling. Rotary drilling may be carried out between mud motor / turbine drilling i.e. the use of these is often restricted to a certain interval only. 

The laboratory tubular centrifuge is similar to the industrial model. It operates with a motor or turbine drive at speeds to 50,000 rpm, generating 65,000 G at the latter speed in the 4.5 cm diameter bowl. The nominal capacity range is 30—2400 cm /min. This centrifuge is uniquely capable of separating far finer particles than any other production centrifugation equipment except the botde centrifuge. It is widely used in the production of flu vims. 

The primaiy advantages of a centrifugal pump are simplicity, low first cost, uniform (nonpulsating) flow, smaU floor space, low maintenance expense, quiet operation, and adaptability for use with a motor or a turbine drive. 

---